•V8 Multifunction Receiver •RXU-3 Receiver User Guide •RXU ...System 2000.net User Guide •V8 Multifunction Receiver •RXU-3 Receiver •RXU-TM Transmitter Monitor Version

System 2000.netUser Guide• V8 Multifunction Receiver• RXU-3 Receiver• RXU-TM Transmitter Monitor

Version 3.0 February 2006

System 2000.netUser Guide• V8 Multifunction Receiver• RXU-3 Receiver• RXU-TM Transmitter Monitor

Version 3.0 February 2006

PHOENIX GEOPHYSICS

Printed in Canada on water resistant Xerox® Laser Never-Tear paper.

This User Guide was created in Adobe FrameMaker 7.0. Writing and Production: Stuart Rogers.

Copyright 2006 Phoenix Geophysics Limited.

All rights reserved. No part of this Guide may be reproduced or transmitted in any form or by any means electronic or mechanical, including photocopying, recording, or information storage and retrieval system, without permission in writing from the publisher. Address requests for permission to:

Phoenix Geophysics Limited, 3781 Victoria Park Avenue, Unit 3, Toronto, ON Canada M1W 3K5, or [email protected].

Information in this document is subject to change without notice.

V8 Multi-Function Receiver, V5 System 2000, System2000.net, SSMT2000 and the Phoenix logo are trademarks of Phoenix Geophysics Limited. All other trademarks referred to in this document are the properties of their respective owners.

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Contents

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 1About System 2000.net™ . . . . . . . . . . . . . . . . 2System applications . . . . . . . . . . . . . . . . . . . . . . . . . . 3System configurations . . . . . . . . . . . . . . . . . . . . . . . . 4

Radio communications . . . . . . . . . . . . . . . . . . . . . . . . 4Electric and magnetic channels . . . . . . . . . . . . . . . . . . . 4

Table 1-1: System 2000.net configurations . . . . . . . . . . 5Data storage and processing . . . . . . . . . . . . . . . . . . . . 6

Time series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Stacked waveforms and stack results . . . . . . . . . . . . . . . 6

Phoenix System 2000.net advantages . . . . 7

How to get further information and support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

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Chapter 2: Quick Start Reference . . . . . . . . . . . . . . . . . . . 9Before you begin . . . . . . . . . . . . . . . . . . . . . . . 10Installing the PC software . . . . . . . . . . . . . . . . . . . . . 10

Step 1: Calibrate equipment . . . . . . . . . . . . 11

Step 2: Plan your survey . . . . . . . . . . . . . . . 11

Step 3: Create and install startup files. . . 12

Step 4: Transport equipment to the field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Step 5: Set up the transmitter and RXU-TM (controlled source methods) . . 12

Step 6: Set up remote instruments . . . . . . 13

Step 7: Set up the V8. . . . . . . . . . . . . . . . . . . .13

Step 8: Check the acquisition parameters . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Step 9: Start recording . . . . . . . . . . . . . . . . . .14

Step 10: Adjust for quality control . . . . . . .14Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Transmitter signal . . . . . . . . . . . . . . . . . . . . . . . . . . .15Standard deviation . . . . . . . . . . . . . . . . . . . . . . . . . .15Plotted curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Cycle completion. . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Step 11: Move to the next site . . . . . . . . . . .15

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Chapter 3: Common Operations . . . . . . . . . . . . . . . . . . . 17Installing and connecting system

components. . . . . . . . . . . . . . . . . . . . . . . . . . 18Handling locking-ring connectors . . . . . . . . . . . . . . . . 18Connecting electrodes . . . . . . . . . . . . . . . . . . . . . . . 20

Shared vs. separate electrodes . . . . . . . . . . . . . . . . . . 20Separate electrodes for MT/AMT . . . . . . . . . . . . . . . . . 21

Installing porous pot electrodes . . . . . . . . . . . . . . . . . 23Connecting the GPS antenna . . . . . . . . . . . . . . . . . . . 24Installing and connecting magnetic sensors. . . . . . . . . 25Installing an air-loop sensor . . . . . . . . . . . . . . . . . . . 28Installing and removing the CompactFlash card . . . . . . 29Formatting a CF card . . . . . . . . . . . . . . . . . . . . . . . . 32Connecting the external battery. . . . . . . . . . . . . . . . . 33Connecting the V8-EX. . . . . . . . . . . . . . . . . . . . . . . . 34Changing the V8-EX internal battery . . . . . . . . . . . . . 34

Starting and shutting down an RXU . . . . . 35

Understanding RXU LED indications . . . . . 35Original indication sequence . . . . . . . . . . . . . . . . . . . 36

System startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Initial satellite lock. . . . . . . . . . . . . . . . . . . . . . . . . . 36During data acquisition . . . . . . . . . . . . . . . . . . . . . . . 37

New indication sequence. . . . . . . . . . . . . . . . . . . . . . 38System startup and shutdown. . . . . . . . . . . . . . . . . . . 38Instrument status . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Table 3-1: Error and warning LED indications . . . . . . . 39System error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Satellite lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Clock status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Table 3-2: Clock status LED indications . . . . . . . . . . . 41Instrument mode . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Table 3-3: Instrument mode LED indications. . . . . . . . 42Summary of complete sequence . . . . . . . . . . . . . . . . . .42Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Using the new indication sequence. . . . . . . . . . . . . . . 45

Starting the V8 and navigating the user interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Starting and shutting down the V8. . . . . . . . . . . . . . . 47About controls, control areas, and “focus” . . . . . . . . . 47Moving the focus . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Moving the focus in tab order . . . . . . . . . . . . . . . . . . . .49Moving the focus in random order . . . . . . . . . . . . . . . . .49Moving the focus within a control area . . . . . . . . . . . . . .49

Scrolling through lists. . . . . . . . . . . . . . . . . . . . . . . . 49Activating menu and button commands . . . . . . . . . . . 50Entering and changing values . . . . . . . . . . . . . . . . . . 51

Typing text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51Scrolling through lists. . . . . . . . . . . . . . . . . . . . . . . . .51Editing spreadsheets . . . . . . . . . . . . . . . . . . . . . . . . .51

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Saving settings when closing windows . . . . . . . . . . . . 52Saving and loading settings files . . . . . . . . . . . . . . . . 53

Entering survey information . . . . . . . . . . . . 53

Entering Box information and changing mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Understanding gain . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 3-4: Channel gain factors and signal strength . . . 56Setting up instrument type, serial number, channels,

and gains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Channel terminology . . . . . . . . . . . . . . . . . . . . . . . . 56

Understanding instrument modes. . . . . . . . . . . . . . . . 57Setup mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58CS Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58CS Pause. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58CS Standby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Coil Cal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Box Cal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59GPS Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Pot Res Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Pot-Coil Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Setting up remote control . . . . . . . . . . . . . . 60

Setting up filtering and coupling . . . . . . . . 60Setting the low pass filter . . . . . . . . . . . . . . . . . . . . . 61

Low pass filter graphs . . . . . . . . . . . . . . . . . . . . . . . .61Setting the line frequency filter . . . . . . . . . . . . . . . . . 66Setting coupling parameters . . . . . . . . . . . . . . . . . . . 66

Customizing the V8 by setting options . . 67Customizing data and plot appearance . . . . . . . . . . . . 70

Checking instrument status . . . . . . . . . . . . 70

Calibrating the equipment . . . . . . . . . . . . . . 71Calibrating the V8 . . . . . . . . . . . . . . . . . . . . . . . . . . 72Calibrating coil sensors (MTC-30/50) . . . . . . . . . . . . . 74Calibrating air-loop sensors. . . . . . . . . . . . . . . . . . . . 77Cancelling a calibration. . . . . . . . . . . . . . . . . . . . . . . 79Viewing calibration results . . . . . . . . . . . . . . . . . . . . 80Importing calibration files . . . . . . . . . . . . . . . . . . . . . 80

Saving data files . . . . . . . . . . . . . . . . . . . . . . . 81

Upgrading instrument capabilities . . . . . . 82

PC requirements . . . . . . . . . . . . . . . . . . . . . . . 83

Ensuring quality data . . . . . . . . . . . . . . . . . . 83Storage and handling . . . . . . . . . . . . . . . . . . . . . . . . 83Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Survey requirements . . . . . . . . . . . . . . . . . . . 85

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Chapter 4: Table Files and TblEdit . . . . . . . . . . . . . . . . . 87About table files . . . . . . . . . . . . . . . . . . . . . . . 88Startup table files. . . . . . . . . . . . . . . . . . . . . . . . . . . 88Site table files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

About TblEdit . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Exploring TblEdit . . . . . . . . . . . . . . . . . . . . . . . 89Starting TblEdit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89The main window . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Menus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

The File menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91The Edit menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91The Utilities menu . . . . . . . . . . . . . . . . . . . . . . . . . . 92The View menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92The Help menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Creating and modifying table files . . . . . . 94Opening and saving table files . . . . . . . . . . . . . . . . . . 94Editing acquisition parameters. . . . . . . . . . . . . . . . . . 94Editing frequency stepping parameters. . . . . . . . . . . . 96Editing coil and loop sensor calibration parameters . . . 97Editing the current sensor parameters . . . . . . . . . . . . 99

Setting gain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Table 4-1: CMU-1 gain factors and signal strength. . . 100Editing communication settings . . . . . . . . . . . . . . . . 101Using table files . . . . . . . . . . . . . . . . . . . . . . . . . . . 102Editing Raw Parameters . . . . . . . . . . . . . . . . . . . . . 103

Viewing and printing System 2000.net files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Converting table files to V5 System 2000 format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

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Chapter 5: RXUPilot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107About Palm OS™ handheld devices . . . . . 108Additional documentation and software. . . . . . . . . . . 108

Meazura . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108Symbol SPT1800 . . . . . . . . . . . . . . . . . . . . . . . . . . 109Graffiti tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Infrared port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

About RXUPilot . . . . . . . . . . . . . . . . . . . . . . . 111Launching RXUPilot . . . . . . . . . . . . . . . . . . . . . . . . 111Updating the display. . . . . . . . . . . . . . . . . . . . . . . . 113Viewing and changing RXU serial number . . . . . . . . . 114Viewing location, GPS status, and clock status. . . . . . 114

Number of satellites acquired . . . . . . . . . . . . . . . . . . 115UTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Latitude, longitude, and elevation . . . . . . . . . . . . . . . 115Clock error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Clock status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Controlling calibration. . . . . . . . . . . . . . . . . . . . . . . 116Viewing and changing parameters . . . . . . . . . . . . . . 117

Accessing parameters . . . . . . . . . . . . . . . . . . . . . . . 117Changing parameter values . . . . . . . . . . . . . . . . . . . 119

Saving parameters (startup.tbl) . . . . . . . . . . . . . . . . 119Loading saved parameters . . . . . . . . . . . . . . . . . . . 120Viewing instrument status. . . . . . . . . . . . . . . . . . . . 121

Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121S/W Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Battery 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122Battery 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122Battery 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122GPS FPGA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122Front End FPGAs . . . . . . . . . . . . . . . . . . . . . . . . . . .122DSP Status:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122Disk Free Space . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Setting up radio communication . . . . . . . . . . . . . . . 122Network Status. . . . . . . . . . . . . . . . . . . . . . . . . . . .123IP Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123Unit Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123Maximum Slaves. . . . . . . . . . . . . . . . . . . . . . . . . . .123Tx Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124Network Addr. . . . . . . . . . . . . . . . . . . . . . . . . . . . .124Encryption Key . . . . . . . . . . . . . . . . . . . . . . . . . . . .124Mstr Rng/Brng . . . . . . . . . . . . . . . . . . . . . . . . . . . .124Master or Slave status . . . . . . . . . . . . . . . . . . . . . . .124

Using master bearing to aim directional antennas . . . 124Monitoring radio network quality . . . . . . . . . . . . . . . 125Controlling data acquisition . . . . . . . . . . . . . . . . . . . 126Viewing station statistics . . . . . . . . . . . . . . . . . . . . 127

Enabling continuous update . . . . . . . . . . . . . . . . . . . .128Interpreting station statistics . . . . . . . . . . . . . . . . . . .128Scrolling through station statistics . . . . . . . . . . . . . . . .129

Installing RXUPilot upgrades . . . . . . . . . . 129

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Chapter 6: The RXU-3E Receiver . . . . . . . . . . . . . . . . . . 131About the RXU-3E . . . . . . . . . . . . . . . . . . . . . 132Starting and shutting down the RXU-3E . . . . . . . . . . 132

Calibrating the RXU-3E . . . . . . . . . . . . . . . . 132Cancelling a calibration . . . . . . . . . . . . . . . . . . . . . . 135

Setting up radio communication . . . . . . . 135Setting up the network. . . . . . . . . . . . . . . . . . . . . . 135Acquiring remote channels . . . . . . . . . . . . . . . . . . . 136

Setting up local electric channels . . . . . . 138

Operating and monitoring the RXU-3E. . 139

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Chapter 7: The RXU-TM Transmitter Monitor and CMU-1 Current Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

About the RXU-TM and CMU-1 . . . . . . . . . 142Starting and shutting down the RXU-TM . . . . . . . . . . 142

Calibrating the equipment . . . . . . . . . . . . . 143Calibrating the RXU-TM. . . . . . . . . . . . . . . . . . . . . . 143Calibrating the CMU-1 sensor . . . . . . . . . . . . . . . . . 145Cancelling a calibration . . . . . . . . . . . . . . . . . . . . . . 150

Setting up radio communication . . . . . . . 150Setting up the network . . . . . . . . . . . . . . . . . . . . . . 150

Setting up the RXU-TM, current sensor, and transmitter . . . . . . . . . . . . . . . . . . . . . 151

Operating and monitoring the RXU-TM . 154Setting up frequency stepping. . . . . . . . . . . . . . . . . 154Setting channel gain . . . . . . . . . . . . . . . . . . . . . . . 156

Table 7-1: Gain factors and signal strength. . . . . . . . 156Controlling data acquisition . . . . . . . . . . . . . . . . . . . 156

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Chapter 8: Radio Communication . . . . . . . . . . . . . . . . . 159About System 2000.net radio . . . . . . . . . . 160Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

Radio Type (Master or Slave) . . . . . . . . . . . . . . . . . . 160Network address . . . . . . . . . . . . . . . . . . . . . . . . . . 161Unit address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Encryption key . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162Antennas and masts . . . . . . . . . . . . . . . . . . . . . . . . 162

Types of antennas . . . . . . . . . . . . . . . . . . . . . . . . . 162Aiming directional antennas . . . . . . . . . . . . . . . . . . . 163Types of masts . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Communication content and schedule. . . . . . . . . . . . 164

Factors affecting radio communication . 166System gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Transmitter power . . . . . . . . . . . . . . . . . . . . . . . . . 166Transmitter gain . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Receiver gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167Receiver sensitivity . . . . . . . . . . . . . . . . . . . . . . . . .167

Path loss. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Table 8-1: Path loss examples (2.4GHz). . . . . . . . . . 168Gain margin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

Increase system gain . . . . . . . . . . . . . . . . . . . . . . . .168Decrease path loss . . . . . . . . . . . . . . . . . . . . . . . . .168

Setting up radio communication . . . . . . . 169Assembling antenna tripods . . . . . . . . . . . . . . . . . . 169Installing an omni-directional antenna on a tripod . . . 170Installing an omni-directional antenna on a mast. . . . 172Installing a whip antenna . . . . . . . . . . . . . . . . . . . . 173Operating the RXU radio . . . . . . . . . . . . . . . . . . . . . 173Operating the V8 radio . . . . . . . . . . . . . . . . . . . . . . 174Network initialization . . . . . . . . . . . . . . . . . . . . . . . 174

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Chapter 9: Frequency Stepping . . . . . . . . . . . . . . . . . . . 177About System 2000.net frequency

stepping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178Phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

Table 9-1: Recommended frequencies forfrequency domain operation. . . . . . . . . . . . . . . . . 179Automatic modes . . . . . . . . . . . . . . . . . . . . . . . . . 181

Table 9-2: Transmission codes and resulting waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Creating a frequency schedule file . . . . . 186Converting the schedule to binary format . . . . . . . . . 188Examining a binary schedule file . . . . . . . . . . . . . . . 189

Activating a schedule file . . . . . . . . . . . . . . 189

Setting up the Auto Stepping frequency table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

Specifying non-pattern and pattern frequencies. . . . . 191Selecting a frequency-stepping pattern . . . . . . . . . . 192Setting up the schedule . . . . . . . . . . . . . . . . . . . . . 194Setting up automatic current reduction (roll-off)

for T-200 and TXU-30 transmitters . . . . . . . . . . . . 195

Activating Auto Stepping . . . . . . . . . . . . . . 196

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Chapter 10: Spectral Induced Polarization (SIP) . . . . . 199Using the SIP function . . . . . . . . . . . . . . . . 200Array layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

Setting up SIP survey and site parameters . . . . . . . . . . . . . . . . . . . . . . . . . 202

Entering survey and instrument information . . . . . . . 202Entering array layout information. . . . . . . . . . . . . . . 203Entering channel information. . . . . . . . . . . . . . . . . . 207Calculating co-ordinates . . . . . . . . . . . . . . . . . . . . . 208Modifying calculated co-ordinates. . . . . . . . . . . . . . . 209Completing SIP Site setup. . . . . . . . . . . . . . . . . . . . 209

Setting up SIP acquisition parameters . 209Setting up filtering and coupling . . . . . . . . . . . . . . . 210Setting up frequency stepping. . . . . . . . . . . . . . . . . 211

Acquiring SIP data . . . . . . . . . . . . . . . . . . . . 212Viewing channel results . . . . . . . . . . . . . . . . . . . . . 212Evaluating the data and correcting gain . . . . . . . . . . 213Changing location along the survey line . . . . . . . . . . 214

xii xii

Chapter 11: Controlled Source AMT (CSAMT) . . . . . . . 217Using the CSAMT function . . . . . . . . . . . . . 218Array layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

Setting up CSAMT survey and site parameters . . . . . . . . . . . . . . . . . . . . . . . . . 219

Entering survey and instrument information . . . . . . . 219Entering array layout information. . . . . . . . . . . . . . . 220Entering channel information. . . . . . . . . . . . . . . . . . 221Calculating co-ordinates . . . . . . . . . . . . . . . . . . . . . 222Modifying calculated co-ordinates. . . . . . . . . . . . . . . 223Completing CSAMT site setup . . . . . . . . . . . . . . . . . 223

Setting up CSAMT acquisitionparameters . . . . . . . . . . . . . . . . . . . . . . . . . 223

Setting up filtering and coupling . . . . . . . . . . . . . . . 224Setting up frequency stepping. . . . . . . . . . . . . . . . . 225

Acquiring CSAMT data . . . . . . . . . . . . . . . . . 226Viewing channel results . . . . . . . . . . . . . . . . . . . . . 226Evaluating the data and adjusting gain. . . . . . . . . . . 227Changing location along the survey line . . . . . . . . . . 228

xiii xiii

Chapter 12: Time Domain Electromagnetics (TDEM, TEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

Using the TDEM function . . . . . . . . . . . . . . 232Site layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232Polarity considerations . . . . . . . . . . . . . . . . . . . . . . 233

Current source phase . . . . . . . . . . . . . . . . . . . . . . . 233Transmitting loop orientation . . . . . . . . . . . . . . . . . . 233Sensor orientation . . . . . . . . . . . . . . . . . . . . . . . . . 233

Latest detectable signal . . . . . . . . . . . . . . . . . . . . . 233TDEM apparent resistivity . . . . . . . . . . . . . . . . . . . . 234

Table 12-1: Time of latest detectable signal (ms) . . . 235Depth of investigation. . . . . . . . . . . . . . . . . . . . . . . 235

Setting up TDEM survey and site parameters . . . . . . . . . . . . . . . . . . . . . . . . . 235

Entering survey and instrument information . . . . . . . 236Entering array layout information. . . . . . . . . . . . . . . 236

Ramp length . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237Tx Loop Turns. . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

Entering channel information. . . . . . . . . . . . . . . . . . 238Updating co-ordinates . . . . . . . . . . . . . . . . . . . . . . 240Modifying calculated co-ordinates . . . . . . . . . . . . . . 240Completing TDEM site setup . . . . . . . . . . . . . . . . . . 241

Setting up TDEM acquisition parameters . . . . . . . . . . . . . . . . . . . . . . . . . 241

Setting up filtering . . . . . . . . . . . . . . . . . . . . . . . . . 242Setting up frequency stepping. . . . . . . . . . . . . . . . . 243Setting up sampling windows . . . . . . . . . . . . . . . . . 244Setting up automatic polarity correction . . . . . . . . . . 244

Acquiring TDEM data . . . . . . . . . . . . . . . . . . 245Viewing channel results . . . . . . . . . . . . . . . . . . . . . 245Evaluating the data and adjusting gain. . . . . . . . . . . 246Changing location along the survey line . . . . . . . . . . 247

xiv xiv

Chapter 13: Magnetotellurics (MT) and Audio-frequency MT (AMT) . . . . . . . . . . . . . . . . . . . . . . 249

AMT and MT techniques . . . . . . . . . . . . . . . 250Duration of soundings. . . . . . . . . . . . . . . . . . . . . . . 250Local, Remote, and Far Remote stations . . . . . . . . . . 251Telluric vs. magnetic deployments . . . . . . . . . . . . . . 251

Steps in a typical survey. . . . . . . . . . . . . . . 252Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Choose the sites . . . . . . . . . . . . . . . . . . . . . . . . . . 252Allocate and schedule the equipment. . . . . . . . . . . . . . 253Obtain permissions. . . . . . . . . . . . . . . . . . . . . . . . . 253Create a standard set of parameters. . . . . . . . . . . . . . 254

Calibrating the equipment . . . . . . . . . . . . . . . . . . . . 254Setting up the survey sites . . . . . . . . . . . . . . . . . . . 255

Form a 3-person crew. . . . . . . . . . . . . . . . . . . . . . . 255Keep records throughout . . . . . . . . . . . . . . . . . . . . . 255Conduct an inventory and inspection . . . . . . . . . . . . . 255Verify the location . . . . . . . . . . . . . . . . . . . . . . . . . 256Determine the centre and place the instrument . . . . . . . 256Set up the telluric lines . . . . . . . . . . . . . . . . . . . . . . 256Adjust for E-line difficulties . . . . . . . . . . . . . . . . . . . 257Set up the magnetic sensors . . . . . . . . . . . . . . . . . . 260Adjust for sensor difficulties . . . . . . . . . . . . . . . . . . . 262Measure and record electrode resistance and

dipole voltages. . . . . . . . . . . . . . . . . . . . . . . . . . 262

Start up and verify operation . . . . . . . . . . . . . . . . . . .264Protect the equipment. . . . . . . . . . . . . . . . . . . . . . . .264Complete the layout sheet . . . . . . . . . . . . . . . . . . . . .265Acquire data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265Retrieve the equipment. . . . . . . . . . . . . . . . . . . . . . .265

Processing the data . . . . . . . . . . . . . . . . . . . . . . . . 266Exporting and interpreting the data . . . . . . . . . . . . . 266

Setting up a survey site . . . . . . . . . . . . . . . 266Verifying your location . . . . . . . . . . . . . . . . . . . . . . 266Choosing the site centre . . . . . . . . . . . . . . . . . . . . . 267

Setting up telluric dipoles (E-lines) . . . . 267Connecting electrodes to the instrument. . . . . . . . . . 269Measuring electrical characteristics . . . . . . . . . . . . . 270

Setting up magnetic sensors. . . . . . . . . . . 273Choosing sensor locations. . . . . . . . . . . . . . . . . . . . 273Installing coil sensors . . . . . . . . . . . . . . . . . . . . . . . 273Connecting the sensors to the V8 . . . . . . . . . . . . . . 273

Setting up the instrument . . . . . . . . . . . . . 275Powering up the instruments and acquiring data . . . . 275

xv xv

Retrieving the equipment. . . . . . . . . . . . . . 277Shutting down the instrument . . . . . . . . . . . . . . . . . 278Remeasuring electrical characteristics. . . . . . . . . . . . 278Collecting the equipment . . . . . . . . . . . . . . . . . . . . 278

Setting up MT/AMT survey and site parameters . . . . . . . . . . . . . . . . . . . . . . . . . 279

Entering survey information . . . . . . . . . . . . . . . . . . 280Setting the North Reference . . . . . . . . . . . . . . . . . . . 280

Entering telluric channels information . . . . . . . . . . . . 281Entering magnetic channels information . . . . . . . . . . 282Incrementing the station position. . . . . . . . . . . . . . . 282Completing MT/AMT site setup. . . . . . . . . . . . . . . . . 282

Setting up MT/AMT acquisitionparameters . . . . . . . . . . . . . . . . . . . . . . . . . 283

Frequency ranges . . . . . . . . . . . . . . . . . . . . . . . . . 283Combining instrument types . . . . . . . . . . . . . . . . . . .285

Table 13-1: MTU ⁄MTU-A sampling rates (number of samples per one-second record). . . . . . . . . . . . . . . . . . . . 285

Setting the Data Type. . . . . . . . . . . . . . . . . . . . . . . 286Setting up filtering and coupling . . . . . . . . . . . . . . . 286Setting gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

Table 13-2: Gain factors and signal strength. . . . . . . 287Setting acquisition times. . . . . . . . . . . . . . . . . . . . . 287Setting sampling parameters. . . . . . . . . . . . . . . . . . 288

Acquiring MT/AMT data . . . . . . . . . . . . . . . 289Monitoring MT/AMT acquisition . . . . . . . . . . . . . . . . 290

Appendix A: Time Zone Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Appendix B: Magnetic Declination Resources. . . . . . . . . . . . . . . . . . . . 297

xvi xvi

Appendix C: V8 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Processors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

Frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . 300Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

Clocking and synchronization. . . . . . . . . . . . . . . . . . 300Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

Data storage and transfer . . . . . . . . . . . . . . . . . . . . 301

External connections . . . . . . . . . . . . . . . . . . 301Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Electric channel inputs . . . . . . . . . . . . . . . . . . . . . . 301Battery connector . . . . . . . . . . . . . . . . . . . . . . . . . 301GPS antenna connector. . . . . . . . . . . . . . . . . . . . . . 302Radio antenna connector. . . . . . . . . . . . . . . . . . . . . 302

Communications . . . . . . . . . . . . . . . . . . . . . . 302

Mechanical and environmental. . . . . . . . . 302Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302Operating temperature . . . . . . . . . . . . . . . . . . . . . . .302

User interface . . . . . . . . . . . . . . . . . . . . . . . . 302Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302Keypad. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302

Related products. . . . . . . . . . . . . . . . . . . . . . 303RXU-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303RXU-TM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303V8-EX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303MTU family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303MTU-A family . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303MTU-TXC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304CMU-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304MTU-2ESD, MTU-5ESD . . . . . . . . . . . . . . . . . . . . . . 304MTU-2ES, MTU-5S . . . . . . . . . . . . . . . . . . . . . . . . . 304MTU-5LR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304MTU-AI family . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304

xvii xvii

Appendix D: Sample Layout Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305Obtaining a supply of Layout Sheets . . . 306 Table D-1: Layout Sheet part numbers. . . . . . . . . . . 306

Appendix E: Sample Equipment Checklist. . . . . . . . . . . . . . . . . . . . . . . 309

Appendix F: Meazura Quick Start Guide . . . . . . . . . . . . . . . . . . . . . . . . 311

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

xviii xviii

1 Chapter 1 1

Chapter

Introduction

This chapter provides general information on Phoenix Geophysics and the System 2000.net family of instruments, including:

• Phoenix V8 Multifunction Receiver• Phoenix RXU-3E Controlled Source Receiver• Phoenix RXU-TM Transmitter Monitor• Geophysical applications• Data processing• Radio communication• System advantages• Support

2 Chapter 1 Introduction About System 2000.net™ 2

About System 2000.net™System 2000.net is a family of geophysical instruments comprising the V8™ Multifunction Receiver, the RXU-3E™ Controlled Source Receiver, and the RXU-TM™ Transmitter Monitor. Additional components include the CMU-1™ Current Sensor, the MTC-50™ and AMTC-30™ magnetic sensors, and the V8-EX™ expansion unit and battery pack. System 2000.net is the eighth generation of receiver technology developed by Phoenix since 1975.

Each of the instruments is available in various configurations and can optionally be equipped for wireless communication in the unlicensed Industrial, Scientific, and Medical (ISM) frequency band.

The V8 Multifunction Receiver is the heart of the system. It can acquire up to eight channels of data itself, and can incorporate and display data from multiple RXU-3E two- or three-channel receivers and an RXU-TM transmitter monitor as well. The V8 can also remotely control the RXU instruments.

The RXU-3E receivers use the same controlled source acquisition and communication hardware and software as the V8, but do not have a display screen. They can be controlled and monitored using a handheld Palm

OS® device.

The system builds upon many of the most attractive features of the highly successful Phoenix V5, V6A, and V5 System 2000, including light weight and permanent synchronization via Global Positioning System (GPS) satellites. The full-size ASCII keyboard and full-size, full-colour, sunlight-readable display of the V8 give the operator hands-on control of the entire data acquisition process for all the most common IP and EM geophysical techniques.

When equipped with a V8-EX expansion unit, the V8 can acquire a total of eight channels simultaneously—up to seven electric channels and/or three magnetic channels. The RXU-3E receivers can acquire two or three electric channels.

System 2000.net instruments are synchronized to UTC ±0.2µs, and are optimized to operate with transmitters


similarly synchronized. The GPS synchronization and optional radio communication mean that no cable links are required between the receivers and the transmitter.

The receivers use the same circuit-board stack as the world-leading V5 System 2000 MTU and MTU-A receivers. The V8 produces the same time series format for these techniques too, so both systems can be used together in the same survey.

Phoenix Geophysics Ltd. gratefully acknowledges the support of the Government of Canada through the National Research Council's Industrial Research Assistance Program (NRC-IRAP). IRAP is Canada's premier innovation assistance program for small and medium-sized Canadian enterprises and is regarded world-wide as one of the best programs of its kind. Phoenix has received approximately CDN$100 000 from the Industrial Research Assistance Program, and a further CDN$90 000 in Government Research Tax Credits in support of the System 2000.net project.

System applications

Geophysicists use System 2000.net for many industrial and scientific applications. EM techniques are valuable in exploration for:

• Oil and gas• Diamonds (kimberlites)• Base and precious metals (as deep as 2000m)• Groundwater• Geothermal reservoirs• Industrial minerals

...and for monitoring, engineering, and pure research applications.

The following EM techniques are available or planned:

• Induced Polarization (IP)• Controlled Source Audiofrequency Magnetotellurics

(CSAMT)• Magnetotellurics (MT, AMT, V8 only)• All common Time and Frequency Domain

Electromagnetics (TDEM, FDEM)• Resistivity


The system will also be able to record or monitor time series data from any suitable sensor, including geophones.

System configurations

System 2000.net components are highly flexible and can be configured in a number of different ways to suit customer requirements. (See Table 1-1, “System 2000.net configurations,” on page 5.)

Radio communications. Any of the System 2000.net instruments can be ordered with radio communications capability. An “R” appended to the model number indicates that the instrument is equipped with the radio feature.

Radio communication between instruments allows the operator of the V8 to control remote RXU instruments and view real-time data from them. The receivers can also incorporate statistics from other instruments (a transmitter monitor or remote noise reference, for instance) in their own calculations.

Electric and magnetic channels. The number of electric (E) channels that can be measured varies from two to seven. Electric channels can use two separate electrodes (necessary for tensor measurements in MT and AMT), or they can share electrodes (useful in linear arrays for SIP and other techniques). The choice of shared or separate electrodes has no effect on magnetic channels (if equipped).

The number of electric channels appears with the letter “E” after the hyphen in the model number, unless the instrument also has magnetic channels.

The V8 can optionally be fitted with the V8-EX expansion unit. The V8-EX houses a rechargeable battery and provides eight additional binding posts and three multi-pin connectors for channel connections.

Future development will allow the use of multiconductor cable for electric channels with the V8.

When the V8-EX is not used, one of a series of jumper boards can be installed instead. These jumper boards reconfigure the internal wiring of the V8 to suit the channel arrangement required.


Table 1-1: System 2000.net configurations

Modela

a. An “R” appended to the model number indicates radio communication capability.

E channels H channels

Applications and NotesSeparate Mode Shared Mode

V8-3E, -3ER 2 3 — SIP. V8-EX not supported.

V8-3H, -3HR — — 3 MulTEM, LoTEM. Typically used with one magnetic sen-sor.

V8-6, -6R 2 3 3 MT, AMT, CSAMT, MulTEM, LoTEM. V8-EX supported, but not required.

V8-7E, -7ER 4 7 — Small-scale dipole-dipole IP. Requires V8-EX or multi-conductor cable.

V8-8, -8R 4 7 3 Same as V8-7E, plus CSAMT.

RXU-3E, -3ER 2 3 — CSAMT, SIP.

RXU-3, -3R 2 — 1 Time Domain EM.

RXU-TM, -TMRwith CMU-1

— — — All controlled-source applications. Monitors, controls, stores, and reports transmitter parameters.

RXU-TC, -TCR — — — Transmitter controller for controlled-source applications where current monitoring is not required.


Data storage and processing

System 2000.net instruments are equipped with removable CompactFlash™ cards (CF cards) as the data storage medium. These small, re-usable cards can store up to 512MB of data.

If radio communication is established, the V8 can process and include the data from RXU-3E instruments (including a remote noise reference station) and an RXU-TM Transmitter Monitor. If radio communication is absent or unreliable, the V8 displays only its own results; however, all the instruments save their own data for post-processing, regardless of the radio state.

Time series. In MT and AMT surveys, the entire time series from each channel is stored on the CF card for later transfer to a PC. Processing takes place on the PC.

Stacked waveforms and stack results. In types of surveys other than MT and AMT, processing occurs in real time and the V8 displays the results in graphical and/or numeric form.

The instruments acquire a “stacked waveform” approximately every 10s (or at least one signal period). From this, the instruments calculate an estimate of several geophysical parameters (e.g., amplitude, phase, resistivity, chargeability). The individual estimates are called “stack results”. Stack results are saved on the CF card; stacked waveforms can also be saved if desired. (At frequencies <0.1Hz, this amounts to saving the time series.)

When a new stacked waveform is processed, the V8 reprocesses all the accumulated stack results from the same station. The result is an overall estimate of the geophysical parameter and an estimate of its accuracy. If more than four stacked waveforms are available, the V8 uses a robust calculation technique so that a small number of gross errors has a small effect on the statistics.

If transmitter monitor data (from an RXU-TM) is not available, the V8 uses assumed values for current and phase. If transmitter monitor data is available (even delayed by up to five minutes), it is incorporated into the calculations.

7 Chapter 1 Introduction Phoenix System 2000.net advantages 7

Phoenix System 2000.net advantagesPhoenix Geophysics has been at the forefront of EM system development since the introduction of the MT-16 in 1980, representing the third generation of MT technology.

First-generation systems had appeared in the 1950s when Cagniard in France and Tikhonov in Russia developed the MT method and began using analog instruments, processing their data largely by hand. Second-generation equipment introduced in the mid-1960s included minicomputers, tape recorders, and truck-mounted AC generators. Since Phoenix’s entry into the market, successive generations of equipment have added more and more sophisticated computing capability, increased numbers of channels and functions, battery power, remote reference capability, and the locating and synchronizing functions of the Global Positioning System. At the same time, Phoenix has been able to continuously reduce both the capital and operating costs associated with EM surveys.

The V8 equipment and software available today leads the world in EM instrumentation. The low power, 24-bit acquisition units are small, lightweight, simple to operate, and highly flexible. Far more data is collected than ever before, providing the highest quality results. Phoenix products are the only receivers on the market that do not require cable connections among multiple instruments.

The field configuration and spacing of the instruments is completely flexible, to suit the requirements of the application. Because no cable links are required between the instruments, System 2000.net has an important advantage in areas with rugged topography, lakes, water courses, or other access difficulties. The GPS synchronization means that sites even very remote from the survey can be used to acquire reference data, vastly improving the quality and reliability of the survey results.

8 Chapter 1 Introduction How to get further information and support 8

How to get further information and supportContact us at:

Phoenix Geophysics Ltd. 3781 Victoria Park AvenueUnit 3Toronto, ON, CanadaM1W 3K5

Telephone: +1 (416) 491-7340Fax: +1 (416) 491-7378e-mail: [email protected]

Web site: www.phoenix-geophysics.com

9 Chapter 2 9

Chapter

Quick Start Reference

This chapter provides an outline of the general process involved in conducting a survey with System 2000.net equipment. It also serves as an aid to finding further information within this User Guide.

10 Chapter 2 Quick Start Before you begin 10

Before you beginTo familiarize yourself with System 2000.net, you should read several other sections of this User Guide:

Install the necessary Phoenix software on your PC before continuing. Several programs are provided on the CD-ROMs supplied with your system. You need to install the startup table editing program and the visualization and post-processing software associated with the geophysical method(s) for which you purchased a licence.

Installing the PC software

Use the following sections to determine which software programs you need. To install the software, open the corresponding folder on the Phoenix software CD-ROM and double-click the Setup.exe file. Follow the on-screen instructions.

To learn about: See page:

The user interface and operations com-mon to all methods and equipment

17

The RXU-3E 131

The RXU-TM 141

Controlling RXUs with a handheld device 107

Radio networking 159

For this requirement: Install this software:

All systems TblEdit and V8Sim

CSAMT CMT Pro

SIP SIP Pro

TDEM TEM Pro

MT and AMT SSMT2000*

*SSMT2000 is supplied on a separate CD-ROM

11 Chapter 2 Quick Start Calibrate equipment 11

Step 1: Calibrate equipmentAll instruments and sensors (current monitors and induction coils or loops) must be calibrated before use. Calibration also serves to verify that the instruments and sensors are working properly.

Instructions for calibrating can be found in this Guide at these locations:

Step 2: Plan your surveyDetermine the geophysical method and the layout parameters (e.g., electrode spacing) that you will use in your survey. Read the chapter on the geophysical method to learn about layouts, arrays, site parameters, and acquisition parameters; read Chapter 9, “Frequency Stepping” on page 177, to learn how to set up controlled source frequencies:

To calibrate this equipment: See page:

V8 72

RXU-3E 132

RXU-TM 143

CMU-1 current monitor 145

MTC-50, AMTC-30 sensor 74

AL-100 air-loop sensor 77


SIP 199

CSAMT 217

TDEM 231

MT, AMT 249

Controlled Source Frequency Stepping 177

12 Chapter 2 Quick Start Create and install startup files 12

Step 3: Create and install startup filesIf a table file named “startup.tbl” is present on the CompactFlash card when an instrument is powered on, the settings in that file will be loaded into memory automatically. This feature makes it easy to program a number of instruments with identical settings and also allows acquisition by an RXU to begin automatically. (The V8 will not begin acquiring automatically, regardless of the setting in the file.)

For instructions on creating startup.tbl files, see Chapter 4, “Table Files and TblEdit” on page 87. Create the startup files and copy them to the CompactFlash cards you will be using. Install the cards in the instruments.

Step 4: Transport equipment to the fieldUse the sample equipment checklist in Appendix E on page 309 as a model to create your own checklist. Gather your instruments, tools, and other equipment and transport them to the field.

Step 5: Set up the transmitter and RXU-TM (controlled source methods)If you are using any of the controlled source methods, set up the RXU-TM and your transmitter and its power source:

For instructions on setting up the RXU-TM, see Chapter 7, “The RXU-TM Transmitter Monitor and CMU-1 Current Sensor” on page 141.

13 Chapter 2 Quick Start Set up remote instruments 13

For instructions on using Phoenix transmitters and motor generators, refer to the User Guides provided with that equipment.

Power up the RXU-TM and wait for it to acquire GPS lock.

Start up the transmitter and adjust the output as required.

Use RXUPilot to verify that the frequency and output current displayed by the transmitter gauges match the frequency and current monitored by the RXU-TM.

Note The CMU-1 current monitor measures current at a part of the waveform different from where it is measured by the transmitter itself. The RXU-TM will normally report a value that is 10% to 20% lower than the transmitter gauge.

Step 6: Set up remote instrumentsIf you are using both RXU and V8 instruments, set up the RXU instruments and power them on. Make sure they have been calibrated and have GPS lock.

For instructions on setting up an RXU, see Chapter 6, “The RXU-3E Receiver” on page 131.

For instructions on setting up radio communication, see Chapter 8, “Radio Communication” on page 159.

Step 7: Set up the V8Set up the V8 and power it on. Make sure it is calibrated and has GPS lock.

Open the Site Setup dialog box for the geophysical method you are using and complete the setup information:

14 Chapter 2 Quick Start Check the acquisition parameters 14

If you are using radio communication, check the network status: the Update cells in the Box spreadsheet should be highlighted in red.

Step 8: Check the acquisition parametersClose the Site Setup dialog box and open the Acquisition Parameters dialog box. Check that the settings (especially the frequency table in controlled source methods) are correct.

Step 9: Start recordingSelect the Start Recording command on the instrument(s). If you are using a radio network and have selected Remote Control from the V8, all instruments on the network will start recording within a few seconds.

Step 10: Adjust for quality controlExamine the real-time results of the acquisition and make adjustments as necessary.

Gain. Check the status bar and/or the signal strength bar charts to see if saturations are occurring, and reduce the gain on affected channels. In TDEM, the blue bars should reach no more than 40% of full scale; the green bars may reach 100% of full scale, especially in early time windows. In other controlled source methods, the green bars should reach no more than 40% of full scale.


SIP site setup 202

CSAMT site setup 219

TDEM site setup 235

MT, AMT site setup 279

15 Chapter 2 Quick Start Move to the next site 15

Transmitter signal. In controlled source methods (other than CSAMT), evaluate the transmitter signal. Phase should be close to zero and the current should be uniform across the frequency spectrum (except perhaps in the highest frequencies where current strength may fall off).

In CSAMT, the transmitter is generally too far away from the receiver for effective monitoring.

Standard deviation. Evaluate the standard deviation of signal amplitude: it should be no more than about 1% (5% for CSAMT). Evaluate the standard deviation of phase: it should be no more than about 10 milliradians (5 degrees for CSAMT).

Local conditions may sometimes prevent these levels from being reached.

Plotted curves. Evaluate the plotted curves, which should be smooth. Error bars should be relatively small.

Cycle completion. In controlled source methods, wait until a full cycle of the frequency table has been completed. The total time of the table will have

elapsed, the curve on the plots will be complete, and the status bar will again display frequencies from the beginning of the table.

If the plotted curves are not satisfactory, you should record more than one complete cycle of the frequency table.

Step 11: Move to the next siteWhen results are satisfactory at the first site, stop recording by putting the instrument in Standby mode or by saving the Setup.tbl file and choosing the Shutdown command.

Move the equipment to the next site in the survey plan.

Return to the Site Setup dialog box and either enter new co-ordinates or use the Next Site command to have the V8 automatically calculate co-ordinates.

Repeat the sequence of recording data and adjusting for quality control.

16 Chapter 2 Quick Start Move to the next site 16

17 Chapter 3 17

Chapter

Common Operations

This chapter contains task-oriented procedures for field operations that are common to most geophysical techniques.

Instructions are provided for:

• Making equipment connections• Navigating the V8 user interface• Calibrating the equipment• Customizing the V8• Ensuring quality data

18 Chapter 3 Common Operations Installing and connecting system components 18

Installing and connecting system componentsThis section describes how to connect the various components of System 2000.net. Some components are required for every setup; some are optional or depend on the equipment configuration.

All instruments require these connections:

• Ground electrode• GPS antenna• Battery (unless the battery is contained in the

V8-EX expansion unit)

In addition, instruments may require these connections:

• E-channel electrodes• H-channel magnetic sensors • Short-range, long-range, or directional radio

antenna• V8-EX expansion unit (V8 only)• Jumper board (V8 only)

Connection of radio antennas is described in Chapter 8, Radio Communication.

Warning To prevent damage to the instrument, always connect the ground electrode to the GND terminal first, before making any other connections. See “Connecting electrodes” on page 20.

Handling locking-ring connectors

Many connections are made with military-grade cylindrical bayonet-lock connectors equipped with protective caps or locking rings. Most of these caps can be joined together in pairs to keep them clean while the equipment is in use.

Fig. 3-1: Military-grade cylindrical connector and cap.

!


The GPS antenna and battery connections are made with similar but smaller locking connectors; the instrument terminals have caps, but the cable ends do not.

Fig. 3-2: GPS and Battery connectors.

To remove a protective cap:

• On an instrument or a magnetic sensor, push on the cap and turn it counterclockwise.

• On a cable end, hold the cap in one hand and with the other hand, push the locking ring toward the cap and turn the ring counterclockwise.

To make cable connections:

• Fit the cable end to the receiving connector and turn the locking ring clockwise until it locks in place.

To disconnect a cable:

• Push the locking ring toward the connection and turn the ring counterclockwise.

Fig. 3-3: Cables joined with military-grade cylindrical connectors and connector caps joined for protection from dirt.


To keep connectors clean:

1. When a connection is made, always join the two loose protective caps and lock them to each other. (See Fig. 3-3 and 3-4.)

2. When disconnecting equipment, always replace the protective caps immediately and lock them in place.

Fig. 3-4: Sensor connector caps joined for protection before burial.

Connecting electrodes

For MT and AMT surveys, buried porous pot electrodes should be used. For other survey techniques, metal rods driven into the ground or porous pot electrodes in shallow holes can be used. If porous pot electrodes are used, they should be bedded in a salty mud mixture to reduce contact resistance.

It is important that the instrument be grounded before any other connections are made, and that all electrodes have the lowest contact resistance possible.

Shared vs. separate electrodes. A single electrode can be shared by two channels on the same instrument. Sharing is typical in controlled source techniques, and is the default configuration of the V8 and RXU-3E. A channel is measured across each pair of adjacent binding posts.

Note A single electrode can not be shared by two instruments. If an electrode station must be used by two instruments, install two electrodes, separated by at least 1m. Less separation will result in crosstalk and phase errors.


The receiver terminals are marked 1, 2, 3 (shared mode) or 1, 2 (separate mode), and GND.

Separate electrodes for MT/AMT. Separate mode is typical in MT/AMT surveys where two orthogonal dipoles are used. In this case, channel 1 is the North-South dipole, and channel 2 is the East-West dipole.

Fig. 3-5: V8 terminal connections for MT/AMT.

Fig. 3-6: RXU terminal connections for MT/AMT.

To connect electrodes for MT/AMT:

1. Connect the four E-lines to their appropriate terminals:

• North electrode to channel 1 red terminal

• South electrode to channel 1 black terminal

• East electrode to channel 2 red terminal

• West electrode to channel 2 black terminal

2. Double check the connections.

North East

WestSouth

North

EastWest

South


Warning To prevent damage to the instrument, always connect the ground electrode to the GND terminal first, before making any other connections.

To connect a cable to the instrument:

1. If necessary, remove 2–2.5cm of insulation from the end of the cable, and twist the strands tightly together.

2. Wrap the exposed end of the coaxial shield with two or three layers of electrician’s tape.

Fig. 3-7: An electrode cable stripped and wrapped with electrician’s tape.

3. Unscrew the binding post nut on the instrument until it stops. (The nuts cannot be removed.)

4. Thread the twisted strands of the cable through the hole in the shaft of the terminal and wrap the free end clockwise around the shaft. If your cable is very thick, you may have to cut some of the strands at the insulation in order to fit the wire through the hole in the shaft.

Fig. 3-8: Cable threaded through the instrument terminal shaft. Wrap the free end around the shaft before tightening the terminal.

5. Tighten the binding post nut securely.

6. Make sure that there are no loose strands that could touch other wires or the instrument case.

!


Installing porous pot electrodes

Figure 3-9 shows a porous pot electrode installed for long-term soundings. For short soundings, the loose dirt cover is not required. The cable from the electrode to the instrument is called an E-line.

Have a quantity of salt water (50g/L) prepared.

Fig. 3-9: Electrode installation.

To install an electrode:

1. Dig a small hole about 20–50cm deep, removing any sizeable rocks.

2. Loosen the dirt at the bottom of the hole, or replace a bit of the loose dirt just removed.

3. Pour in at least 1L of salt water and mix it with the dirt to form a uniform mud. In porous or sandy soil and in hot weather, you may need to use more salt water—enough to keep the electrode damp for the duration of the sounding.

4. Place the electrode upright in the hole, rotating it back and forth to position it solidly in the mud, leaving the electrode cable extended outside the hole.

5. For long-term soundings (e.g., MT, AMT), cover the electrode completely by filling the hole with loose dirt.

6. Connect the electrode cable to the instrument GND terminal or to the E-line cable, as described in the next section.

To connect E-lines to the electrodes:

1. Remove 2–2.5cm of insulation from the ends of the cables.

salty mud mixture

loose dirt to cover electrode (MT, AMT)~15–45 cm

~20–50cm

electrode cable spliced to E-line and wrapped with electrical tape


2. Hold the E-line and the electrode cable side by side with the ends pointing in the same direction.

3. Divide the strands of the electrode cable in half, twist one half tightly around the bare end of the E-line, and then twist the remaining half over top of the first half. This assures a good electrical connection.

4. Wrap the joined wires with two or three layers of electrician’s tape.

5. Tie an overhand knot near the splice, treating the two cables as if they were one. (The splice can remain connected for the duration of the survey. The knot prevents the splice from being pulled apart when the electrodes are moved.)

Tip Other than in monitoring applications, cable splices will be temporary—they’ll have to be separated when you retrieve the equipment after the last sounding. To save time, when you wrap a splice, always leave the free end of the electrician’s tape doubled back or twisted onto itself. When you retrieve the equipment, the loose end of tape will be easy to grasp and unwrap, even when wearing gloves.

Connecting the GPS antenna

The global positioning system (GPS) antenna must always be connected to the V8, RXU, and RXU-TXM when operating or calibrating the equipment, because the satellites provide the necessary time signals. The cable has two connectors: one with slots for quick connection to the instrument, and one with threads for connection to the antenna.

Fig. 3-10: GPS antenna cable connectors.

to GPS antenna

to instrument


To connect the GPS antenna:

1. Screw the threaded connector of the antenna cable to the underside of the antenna head. (See Fig. 3-10 on page 24.)

2. Fit the slotted connector to the GPS ANT connector on the instrument as described on page 19.

3. Open the antenna tripod and position the GPS antenna so that it is level, stable, and has unobstructed sight lines to as much of the sky as possible. If necessary, tape the antenna tripod to another object (e.g., a stake, post, or larger tripod) so that it is raised above tall grass or shrubs.

Installing and connecting magnetic sensors

Magnetic sensors can be connected individually to the three multi-pin connectors on the V8-EX. Alternatively, they can be connected using a 3-way cable that connects to the AUXILIARY connector on the V8 itself. Follow the instructions for “Handling locking-ring

connectors” on page 18 when making these connections.

If using a 3-way cable, be sure that each sensor is connected to the correct pigtail. The cable is marked with one ring for Hx, two rings for Hy, and three rings for Hz. (See Fig. 3-11.)

Connect the single-connector end of the 3-way cable to the AUXILIARY terminal on the V8.

Fig. 3-11: Three-way sensor connector cable.

For best results, sensors should be buried in a shallow trench in order to minimize vibration-induced noise.

Hz

Hy

Hx

to V8


Correct identification, careful levelling, and accurate orientation are crucial to obtain good sensor data.

Tip To identify the sensor cables, tie a loose single overhand knot about 40cm from the end of the Hx cable before connecting it to the V8. Tie two overhand knots in the Hy cable, and three in the Hz cable. With this method, even if the lines become disorganized around the V8, it will be easy to verify that the cables are connected to the correct terminals.

Be sure that no metal objects such as belt buckles, vehicles, or shovels are close enough to distort compass readings.

If you tie a short piece of rope around the coil before burying it, you’ll be able to pull the coil free of the ground more easily when retrieving the equipment. Never try to free a coil by pulling on the cable; the connector may break.

To position and orient a horizontal coil sensor:

1. Designate the sensor as Hx or Hy and record its serial number on the Layout Sheet.

2. If you are keeping track of equipment deployment, then also record the identifying number of the sensor cable to be used.

3. Gather up:

• the sensor

• one end of the sensor cable

• a shovel

• a spirit level

• a handheld compass

4. Carry the equipment to the location chosen for that sensor, pulling the sensor cable as you go.

5. Lay the sensor on the ground and use the compass to orient it reasonably accurately. Be certain that the free end is to the (nominal) north for Hx, or to the (nominal) east for Hy.


Tip To orient a coil easily, open the handheld compass fully and rotate the housing to the desired azimuth. Then hold it at waist level directly over the coil and align the compass North marking with the needle. Sight past the long edge of the compass to the side of the coil to judge its alignment.

Adjust the coil as necessary until it lines up perfectly with the long edge of the compass.

To bury a horizontal coil sensor:

1. Use a shovel to mark the outline of a trench about 10–15cm beyond each end of the oriented sensor and the same distance from each side.

2. Move the sensor aside and dig the trench about 40cm deep, keeping the bottom smooth and level and piling the soil alongside the trench.

3. Connect the cable to the sensor.

4. Lay the sensor in the trench in the correct orien-tation, using the spirit level to place it as accurately level as possible. You may have to deepen or fill in part of the trench to do this.

5. Use the compass to orient the sensor as accurately as possible.

Note If you adjust the sensor in any direction, always recheck the accuracy of both orientation and level.

6. Taking care not to disturb the sensor, replace the soil in the trench and pack it down gently. (Do not mound the soil over the coil, or you will increase wind noise.)

7. If there is excess cable, lay it out in S-shapes. In windy areas, weight down the cables with rocks or dirt every metre or so as you return to the site centre.

To install a vertical coil sensor:

1. On the Layout Sheet, record the Hz coil serial number.

Align coil with compass edge


2. If you are keeping track of equipment deployment, then also record the identifying number of the sensor cable.

3. Gather up:

• the sensor


• a shovel

• a post-hole digger or an auger

• a spirit level

4. Carry the equipment to the location chosen for the sensor, pulling the cable as you go.

5. Dig a narrow hole deep enough to completely bury the sensor. If this is too difficult, dig as deeply as possible and plan to mound additional soil over the top of the coil.

6. Connect the cable to the sensor.

7. Place the sensor in the hole and steady it by replacing about half the excavated soil.

8. Use the spirit level to position the coil vertically as accurately as possible, measuring at two places at right angles to each other on the side of the coil.

9. Taking care not to disturb the coil, replace the remaining soil. If necessary, build a gently-sloping mound of additional soil over the top until the coil is completely buried.

10. If there is excess cable, lay it out in S-shapes. In windy areas, weight down the cables with rocks or dirt every metre or so as you return to the site centre.

Installing an air-loop sensor

If the ground is too rocky to allow burial of a vertical coil, use an air-loop as the Hz sensor instead.

To install an air-loop sensor:

1. On the Layout Sheet, record the Hz air-loop serial number.

2. If you are keeping track of equipment deployment, then also record the identifying number of the sensor cable.

3. Gather up:


• the sensor


• a tape measure

4. Carry the equipment to the location chosen for the sensor, pulling the cable as you go.

5. Arrange the air-loop flat on the ground so that:

• The air-loop forms a perfect square (opposite corners should be 8.8m apart).

• The pre-amplifier is at one corner of the square.

• The cable to the V8 exits the pre-amplifier toward the right when viewed from within the air-loop.

Fig. 3-12: Air-loop cable must exit the pre-amplifier toward the right when viewed from within the air-loop.

6. Weight down the air-loop and its cable with rocks or dirt every metre or so. If there is a risk of distur-

bance by humans or animals, consider burying the air-loop completely.

Installing and removing the CompactFlash card

The instruments store their parameters and data on a CompactFlash (CF) card. The CF card fits into a slot in the front of the RXU or the side of the V8, protected by a small watertight cover. If you try to operate the instrument without a CF card installed, the V8 Status bar will display an error message. The LED of an RXU will flash an error code.

CF cards are expensive and contain your valuable data. Protect them from damage by storing them in plastic or fabric cases when they are not in use.

Warning Never insert or remove a CompactFlash card when the instrument is powered! Serious damage to the unit may result.

Hz 8.8m

!


Fig. 3-13: CompactFlash cards in protective case.

To access the CompactFlash card slot:

1. Locate the card slot on the front of the RXU or the side of the V8. If the instrument is inside its canvas case, you many have to peel back the flap that covers the card slot.

2. Unlock the card slot cover by lifting the ring on the handle and turning it 90° counterclockwise.

3. Lift the slot cover away from the instrument.

To insert the CompactFlash card:

1. Ensure that the instrument is powered off.

2. Hold the CompactFlash card by the bottom corners, with the front of the card facing the hole for the slot cover lock. See Figs. 3-14 and 3-15 on page 30.

3. Slide the card gently into the slot and press it into place.

Fig. 3-14: Inserting the CompactFlash card in the V8.


Fig. 3-15: Inserting the CompactFlash card in the RXU.

To remove the CompactFlash card:

1. Ensure that the instrument is powered off.

2. Eject the card partially by pressing the small square button beside it. (See Fig. 3-16 on page 31.)

3. Hold the card by the two corners and withdraw it from the slot.

Fig. 3-16: CompactFlash card eject button.


To replace the card slot cover:

1. Align the ring of the slot cover at right angles to the length of the cover.

2. Place the bevelled edge of the cover against the instrument case and push the cover handle fully into the case.

3. Turn the cover handle one-quarter turn clockwise to lock.

Warning Never operate the instrument without a CompactFlash card installed and the card slot cover locked in place.

Formatting a CF card

CompactFlash cards must be correctly formatted before use.

Note The formatting utility provided by SanDisk corporation is not compatible with Phoenix instruments. CompactFlash cards must use the FAT or FAT16 file system applied by the Windows formatting utility. Do not format as FAT32 or NTFS.

If you experience PC system crashes when inserting a CompactFlash card into the reader, the problem may be caused by static electricity. Touch a grounded object such as an unpainted area of the computer case before inserting the card.

To format a CompactFlash card:

1. Insert the card into a card reader connected to the PC.

2. Double click My Computer.

3. Right-click the CompactFlash card drive letter and click Format…

4. If your operating system is Windows XP, be sure that the File system is set to FAT. (In earlier Windows versions, the file system is always FAT.)

5. If desired, type a volume label (a name for the disk).

!


6. If Quick Format is selected, clear the checkbox.

7. Click Start.

When formatting is complete (it takes only a few seconds), click Close. The card is ready for use in Phoenix instruments.

Connecting the external battery

Each instrument is powered by a 12V DC battery, which should be fully charged prior to use. (Follow the instructions provided on the Battery Charging Quick Reference Guide.) RXU instruments use an external battery; the V8 can use an external battery or the V8-EX with an internal battery.

If you are providing your own batteries, ensure that they have the capacity to power an instrument for your planned acquisition durations.

Newer Phoenix BTU-type (gel) batteries are shipped with the cable ends bolted to the battery terminals; older batteries were shipped with the cable unattached.

For long-term soundings, a special cable is available that allows two batteries to be connected in parallel. This cable can also be used to replace a battery without turning the instrument off.

Note Make all other connections, and always a ground connection, before connecting a battery to the instrument.

To connect a BTU-type battery:

1. Examine the battery terminals and clean off any corrosion that might prevent a good electrical connection. (Use sandpaper, emery cloth, or a knife blade to carefully clean the terminals.)

2. If the cable ends are not bolted to the battery terminals, attach the alligator clamps to the terminals (red clamp to the positive [+] terminal, black clamp to the negative [–] terminal). Ensure that the connection is secure and of correct polarity.


Tip On batteries with spade terminals, attach the alligator clamps so that they grip the edges rather than the flat surfaces of the terminals. The greater tension from the clamp springs helps ensure a good connection.

3. Fit the slotted connector to the EXT BATT terminal on the instrument as described on page 18.

Connecting the V8-EX

The V8-EX expansion unit provides eight additional binding posts, three multi-pin connectors, and optionally an internal battery. The V8-EX attaches to the V8 on the side opposite the CF card slot.

To connect the V8-EX:

1. Ensure the V8 is powered off.

2. Remove the protective cover from the side of the V8.

3. Remove the protective cover from the connector on the V8-EX.

4. Align the three guide pins and the threaded shaft on the V8-EX with the matching holes on the side of the V8.

5. Turn the knob on the side of the V8-EX clockwise until the V8-EX is firmly screwed to the V8.

To disconnect the V8-EX:

1. Ensure the V8 is powered off.

2. Turn the knob on the side of the V8-EX fully counterclockwise until the V8 separates from V8-EX.

3. Replace the protective covers on the connectors of both the V8 and V8-EX.

Changing the V8-EX internal battery

The V8-EX can house an optional lithium-ion battery, making the V8 and battery combination more easily portable.

35 Chapter 3 Common Operations Starting and shutting down an RXU 35

To change the V8-EX battery:

1. Use a Phillips screwdriver to fully loosen the two stainless steel screws on the bottom of the V8-EX. (The screws cannot be removed.)

2. Lift up the triangular wire handle and pull the battery pack out of the V8-EX.

3. Insert the replacement fully-charged battery and tighten the two stainless steel screws.

Starting and shutting down an RXU

To start an RXU:

• Press the red POWER switch on the top of the instrument to the ON position and release it.

After a short delay, the red LED between the N and S terminals will flash, then light steadily for about 30s.

To shut down an RXU:

• Press the POWER switch down (toward the POWER label) and release it.

The LED will light steadily, then go out when shutdown is complete.

Warning Disconnecting the battery before shutting down the RXU may result in damage to equipment or loss of data. Always wait for the LED indicator to go out before disconnecting the battery.

Understanding RXU LED indicationsThe LED between the two centre electrode terminals (see Fig. 3-17 on page 36) provides an indication of the RXU status. There are two possible coded sequences for the flashing patterns of the LED. Early models of RXU use a sequence similar to that of Phoenix System 2000 MTU receivers. Later models use

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36 Chapter 3 Common Operations Understanding RXU LED indications 36

a new sequence that provides more information to the operator.

Fig. 3-17: Instrument LED indicator.

Original indication sequence

In models with early firmware, for most indications the LED flashes in a sequence that repeats every 12s. This sequence combines information about the number of satellites acquired and the status of the instrument (standing by, recording, idling after recording).

System startup.

• During system startup, the LED flashes once, then again, then lights steadily for about 30s. This pattern is the same as in the early firmware and in System 2000 MTUs.

Initial satellite lock. To synchronize with UTC and begin data acquisition, transmitter control, or calibration, the RXU must receive signals from at least four GPS satellites. (The instrument may actually acquire up to eight satellites, but only indicates the first four.) Under normal conditions, satellite lock takes less than 10min. A longer delay may indicate poor antenna positioning or a faulty antenna or cable.

• Before acquisition, the LED pattern is 1s on, 1s off, for each satellite acquired, for up to four satellites.

Fig. 3-18: Before data acquisition, one satellite acquired.

Fig. 3-19: Before data acquisition, two satellites acquired.

| | | | |…seconds

| | | | | | | | | | | | |seconds


Fig. 3-20: Before data acquisition, three satellites acquired.

Fig. 3-21: Before data acquisition, satellite lock achieved (four or more satellites acquired).

During data acquisition. The RXU can acquire site or calibration data any time after the initial four-satellite lock has been achieved. It is not necessary for satellite lock to continue uninterrupted, because the RXU internal clock stays synchronized with UTC for several hours even if satellite lock is temporarily lost.

• During Controlled Source acquisition, the LED pattern is the same as before acquisition (as just described).

• During MT or AMT data acquisition, the LED flashes in a pattern of one second on, two seconds off, for

each satellite acquired, to a maximum of four satellites.

Fig. 3-22: During MT/AMT acquisition, one satellite acquired.

Fig. 3-23: During MT/AMT acquisition, two satellites acquired.

Fig. 3-24: During MT/AMT acquisition, three satellites acquired.

Fig. 3-25: During MT/AMT acquisition, four or more satellites acquired.

| | | | | | | | | | | | |seconds

| | | | | | | | | | | | |2seconds

| | | | | | | | | | | |seconds

| | | | | | | | | | | ||seconds

| | | | | | | | | | | |seconds

| | | | | | | | | | | | |seconds


Tip You can learn the exact number of acquired satellites by checking the GPS window of the RXUPilot program. Or, if the instruments are on a radio network with a V8, you can check the Options dialog box on the V8. The number of satellites may vary from 0 to 8.

After data acquisition. The RXU can be programmed to continue operating at idle or to shut down at the end of site data acquisition. It will idle after calibration data acquisition.

• If the RXU shuts down, the LED will go out.• If the RXU is idling, the LED will flash in a pattern of

one second on, 5 seconds off.

Fig. 3-26: Idling after site or calibration data acquisition.

New indication sequence

In models with later firmware, for most indications the LED flashes in a sequence that repeats every 15s.

Seven seconds are used to indicate the status of the instrument, including warning and error messages. Two seconds are used to indicate the status of satellite lock. The satellite indication is always aligned with UTC seconds :00, :15, :30, and :45. Two seconds are used to indicate the status of the on-board clock, and four seconds are used to indicate the instrument mode.

System startup and shutdown.

• During system startup, the LED flashes once, then again, then lights steadily for about 30s. This pattern is the same as in the early firmware and in System 2000 MTUs.

• During system , the LED lights steadily until shutdown is complete. Do not disconnect battery power until the LED goes out.

Instrument status. Seven seconds of the sequence are used to indicate either that the instrument is performing normally or that there is an error or a potential error, such as overheating or low battery voltage.

| | | | | | | | | | | | |seconds


• If the instrument is performing normally, the LED is off for one second, then lights steadily for 5 seconds, then goes off for one second.

Fig. 3-27: Indication of normal operation.

• If an abnormal condition exists, the LED will flicker rapidly for 350ms as an alert, and will then flash from one to seven times, 50ms on, 350ms off (see Fig. 3-28). Table 3-1 explains the meaning of the number of flashes.

Fig. 3-28: Pattern of flashes indicating errors and warnings.

| | | | | | | | | | | |seconds

satellites and clocknormal operation

| | | | | | | | | | | | |seconds

warnings/ errors

alert satellites and clock

Table 3-1: Error and warning LED indications

Flashes Messagetype

Meaning

1 Warning Battery voltage is less than 11V.

2 Error CompactFlash card is not installed.

3 Warning Instrument internal temperature exceeds 60°C.

4 Warning Instrument is in record mode but disk space is <50MB (AMT), <10MB (MT), or <2MB.The 50MB and 10MB warnings appear for 5 minutes only. The 2MB warning is continuous.

5 Warning The number of saturated records has increased.

6 — Reserved for future use.

7 Error Calibration failed.

8–14 — Reserved for future use.


System error. In some circumstances, the instrument may not be able to start up normally. This problem can be caused by damaged circuit boards or corrupt firmware files, for example.

• In the case of a fatal system error, the LED flashes constantly, 100ms on, 100ms off (see Fig. 3-29).

Fig. 3-29: Pattern of flashes indicating system error.

If the instrument displays this indication, contact Phoenix technical support.

Satellite lock. To synchronize with UTC and begin data acquisition, transmitter control, or calibration, the RXU must receive signals from at least four GPS satellites. (The instrument may actually acquire up to eight satellites, but only indicates the first four.) Under normal conditions, satellite lock takes less than 10min. A longer delay may indicate poor antenna positioning or a faulty antenna or cable.

• After the 7-second instrument status indication, the LED pattern is 250ms on, 250ms off, for each satellite acquired, for up to four satellites (see Fig. 3-30). If no satellites have been acquired, the pattern is 1.9s on, 0.1s off (see Fig. 3-31).

Fig. 3-30: Pattern of flashes indicating four (or more) satellites acquired.

Fig. 3-31: A single long flash indicates zero satellites acquired.

| | | | | | | | | | | | |seconds

…

| | | | | | | | | | | | |seconds

satellitesnormal operation

UTC HH:MM:00, :15, :30, or :45

| | | | | | | | | | | | |seconds

satellitesnormal operation


Clock status. Once the instrument acquires the minimum number of satellites, the on-board clock synchronizes to GPS time. Within the following 12.5min, the satellites send a correction message and the on-board clock synchronizes to UTC. (The difference between GPS time and UTC is the number of UTC leap seconds, which are not incorporated in GPS time.) If satellite lock is subsequently lost, accurate time is maintained by an oven-controlled crystal oscillator (OCXO). Recording of site data or calibration data cannot begin unless the clock is synchronized to either satellites or OCXO.

• After the satellite indication, the LED pattern is 250ms on, 250ms off, from zero to four times (see Fig. 3-32). Table 3-2 explains the meaning of the number of flashes.

Fig. 3-32: Pattern of flashes indicating clock status.

A complete pattern of eight equally spaced flashes indicates both satellite lock and clock synchronization to GPS or UTC. The RXU is ready to record site data or calibration data.

Instrument mode. The next four seconds of the sequence indicate whether or not the instrument is recording (either site data or calibration data). The possible instrument modes are: setup, standby, recording (site data or calibration data), or idling after recording.

• In these four seconds of the sequence, the LED pattern is 900ms on, 100ms off, from one to four

| | | | | | | | | | | | |seconds

satellitesnormal operation clock

Table 3-2: Clock status LED indications

Flashes Meaning

0 Clock is not yet initialized.

1 Clock is synchronized to CPU real-time clock.

2 GPS synchronization is in progress.

3 Clock is synchronized to OCXO.

4 Clock is synchronized to GPS or UTC.


times (see Fig. 3-33). Table 3-3 explains the meaning of the number of flashes.

Fig. 3-33: Pattern of flashes indicating instrument mode.

Summary of complete sequence. Figure 3-34 shows the complete 15s indication sequence. In summary:• Constant rapid, equally spaced flashes indicate a

fatal system error.• A fast flicker followed by very short flashes

indicates an error or warning.

• A steady 5-second light indicates normal operation; be prepared to read the satellite count and clock status one second after this light goes off.

• A steady 1.9s light indicates no satellites acquired• Short, equally spaced flashes indicate satellite and

clock status; eight flashes in a row means the instrument is fully synchronized and ready to record.

• Longer flashes with a short space between them indicate setup or recording mode.

Table 3-3: Instrument mode LED indications

Flashes Meaning

1 Instrument is in Setup mode.

2 Instrument is standing by before recording or calibrating, or is paused during recording.

3 Instrument is recording site data or calibration data.

4 Instrument is idling after recording site data or calibration data.

| | | | | | | | | | | | |seconds

modesatellites clock


Fig. 3-34: Complete new indication sequence.

Examples. The following figures show examples of LED indications under various conditions.

| | | | | | | | | | | | | | | | | | | | |seconds

number of satellites mode

warnings/ errors

alert zerosatellites

normal operationclockstatus

alternate patterns

normal patterns

fatal system error

UTC HH:MM:00, :15, :30, or :45

warnings/ errors

alert

normal operation

(sequence repeats…)


Fig. 3-35: Example of normal operation in record mode (site data or calibration data).

Fig. 3-36: Example of idling after acquisition with internal temperature exceeding 60°C.

| | | | | | | | | | | | | | | | |seconds

satellites modenormal operationclockstatus

| | | | | | | | | | | | | | | | |seconds

number of satellites modealert

clockstatus

warning:high temperature


Fig. 3-37: Example of operation in standby mode when synchronized to OCXO, with a low battery warning.

Using the new indication sequence

Normally you will use the RXUPilot program to learn the details of GPS synchronization, instrument mode, and so on. However, the LED indications do give you a quick way to learn if everything is operating as expected, without having to examine a number of windows in RXUPilot.

The most important indication is the steady 5-second light. This light tells you that the instrument is operating normally. If you see an alert and warning or error indication instead, take immediate steps to correct the cause.

If the 5-second light indicates normal operation, then watch the following flashes to learn the satellite and clock status. For several minutes after powering on, you should expect to see the 1.9s zero-satellite indication and a clock indication of zero, one, or two flashes. After a few minutes the satellite indication will change to show the number of satellites acquired.

Once the satellite indication reaches four flashes, you should see the clock indicator also change to four flashes. Taken together, these eight identical flashes indicate full GPS and clock synchronization.

| | | | | | | | | | | | | | | | |seconds

number of satellites modealert

clockstatus

warning:low battery

46 Chapter 3 Common Operations Starting the V8 and navigating the user interface 46

After the clock is synchronized, you may see the number of satellites drop to less than four; at that point, the clock status will change to three flashes to indicate synchronization to the crystal oscillator. This is also a normal condition.

Finally, check the longer flashes of the mode indication. If you are recording or calibrating, you should see three flashes. When calibration is complete or data recording has ended according to a schedule, you will see four flashes. If you have set up for MT/AMT to record automatically at a later time, you should see two flashes.

If the LED indications are not what you expect to see, use the RXUPilot program to find out where the problem lies.

Starting the V8 and navigating the user interfaceWhen powered on, the V8 presents a Windows®-like user interface, with standard controls such as menus, buttons, and text fields, as well as spreadsheet-style lists and plotted curves. Unlike PC applications, however, the V8 does not have a mouse or other pointing device, so all commands must be given with the keyboard.

Note Illustrations of the V8 windows and dialog boxes in this Guide are taken from a PC emulation program, not a V8 receiver. The appearance of the windows and dialog boxes may vary slightly from what you see on a V8, and the data values do not necessarily reflect typical field conditions.


Starting and shutting down the V8

To start the V8:


After a short delay, the main window appears (see Fig. 3-38).

You can customize the V8 to start up in a Site Setup dialog box instead of the main window. See “To set startup and shutdown options:” on page 69.

To shut down the V8:

• Choose the Shutdown command on the main window or press the POWER switch down (toward the POWER label) and release it.

Warning When shutting down the V8, always wait until shutdown is complete (the display goes blank) before disconnecting the battery.

Fig. 3-38: The V8 main window.

About controls, control areas, and “focus”

At any given time in most windows of the interface, one area or control will have “focus.” When a control has focus, that control will be activated when the Enter key

!


is pressed, or its value can be changed by scrolling or by typing a new value. A few windows, containing menus only, do not initially place focus on any control.

In many windows, there are several control areas. The keyboard commands make it easy to move the focus from one control area to another, or from one control to another within an area.

For example, the SIP Setup dialog box contains nine control areas (see Fig. 3-39):

• the Survey Information area• the Line text box• the Site text box• the Done button• the Calculate Coord. button• the Next Site button• the Channel spreadsheet• the Box spreadsheet• the Array Layout area

When a button or spreadsheet has focus, a coloured border appears around it. In Figure 3-39, the Channel spreadsheet has focus, indicated by the red border.

In a spreadsheet or a control area containing text boxes, the cell or text box that has focus appears with foreground and background colours reversed. In Figure 3-39, the first cell in the Channel spreadsheet has focus.

Fig. 3-39: SIP Site Setup dialog box.


Moving the focus

There are several ways to move the focus, depending on the type of control or control area.

Moving the focus in tab order. You can press the Tab key (or Shift +Tab) to move the focus from one control or control area to another. However, you cannot change the order in which the controls receive focus.

Moving the focus in random order. Notice that in Figure 3-39, all the controls or control areas except the spreadsheets have a highlighted letter in their names. The highlighted letter allows you to move the focus directly to that control.

To move the focus directly to a control or control area:

• Press and release the Ctrl key and then type the highlighted letter. (Unlike on a PC, do not hold the Ctrl key while typing the letter.)

Tip In windows or dialog boxes that contain spreadsheets, you can move the focus to the first spreadsheet just by pressing Ctrl.

Moving the focus within a control area. To move the focus among spreadsheet cells, text boxes, and groups of controls within an area, press the ARROW keys.

To move the focus within a control area:

• from one control to another within a control area or from one row to another in a spreadsheet, press the UP ARROW or DOWN ARROW key.

• from column to column in a spreadsheet or among the letters of a text box, press the LEFT ARROW or RIGHT ARROW key.

Scrolling through lists

Scrolling lists are controls with a preset series of values you can choose from. You cannot type a new value in a scrolling list.


When a scrolling list has focus, it appears with white foreground on a magenta background:

Fig. 3-40: A scrolling list that has focus.

To scroll through a list:

• Press the space bar to scroll in one direction; press Enter to scroll in the opposite direction.

The value that is displayed takes effect when you move the focus away from the list or when you close the dialog box containing the list.

Activating menu and button commands

Commands are available on buttons and in menus, and most have a highlighted letter for random access.

To activate a command button do one of the following:

• Press the Tab key to move the focus to the command button and press either the Enter key or the space bar.

• Press and release Ctrl, then type the highlighted letter on the button. (Unlike on a PC, do not hold the Ctrl key while typing the letter.)

To activate menus:

1. Press the F1 Menu key to place the focus on the menus.

2. Use the ARROW keys to move the focus to the desired menu.

3. Press Enter to activate the menu.

To activate menu commands, do one of the following:

• Press the UP ARROW or DOWN ARROW key to choose a menu command and then press Enter.

• Press and release the Ctrl key and then type the highlighted letter in the menu command name.


(Unlike on a PC, do not hold the Ctrl key while typing the letter.)

Tip If you have memorized the highlighted letters for the menu commands, you can type Ctrl and the letter for a command without pressing the F1 Menu key or opening the individual menus.

Entering and changing values

The V8 uses three kinds of fields: text boxes, scrolling lists, and spreadsheet cells.

Typing text. Many areas of the interface allow you to type text values, such as survey names or dipole lengths. Typing on the V8 is similar to typing on a PC. If characters are selected, typing replaces them. If no characters are selected, typed characters appear at the cursor location.

When the focus moves to a text box, the entire contents are selected. As on a PC, you can use the LEFT ARROW and RIGHT ARROW keys to move the cursor, and

you can select characters by holding the Shift key while moving the cursor.

To enter or change values in a text box:

• Use any method described earlier to move the focus to the text box, move the cursor or select text as desired, and then type the new value using the keyboard.

Scrolling through lists. When the focus moves to a scrolling list, the current list item will be highlighted in magenta.

To scroll through a list:

• When the scrolling list has focus, press the space bar to scroll in one direction; press Enter to scroll in the opposite direction.

Editing spreadsheets. Spreadsheets are used to group parameters and calculate or display values. V8 spreadsheets behave slightly differently from PC spreadsheets. On a PC, you can type directly in any cell that has focus. In most spreadsheet cells on the V8, you must make each entry in a dialog box before the


entry will appear in the spreadsheet cell. In the Channel spreadsheet of the Site Setup windows, some cells are actually scrolling lists, although they do not appear highlighted in magenta.

To enter or change values in a spreadsheet cell:

1. Use the ARROW keys to move to the cell you want to change.

2. Press Enter or the space bar.

If the cell is a scrolling list in the Channel spreadsheet, the next value in the list appears. Otherwise, a dialog box appears. The dialog box may contain a text box or a scrolling list highlighted in magenta.

3. In a dialog box, either scroll to the list item you want and press the Tab key, or type the value you want and press Enter.

4. Press Enter to activate the OK button and close the dialog box.

To delete rows from a spreadsheet:

1. Use the ARROW keys to move to any cell in the row you want to delete.

2. Press Delete.

To add rows to a spreadsheet:

• With the focus on any cell in a spreadsheet, press Insert.

A new blank row is inserted and other rows are moved down to make room.

Saving settings when closing windows

The values you set in dialog box controls are saved automatically, so there is no Save command. When you are satisfied with your settings, you can simply close the dialog box. You can, however, save some settings to a file for future use (a setup.tbl file) or for automatic loading next time the V8 is powered on (a startup.tbl file). See the next section for instructions.

To close a window or dialog box, do any of the following:

• Press Ctrl and type D.

53 Chapter 3 Common Operations Entering survey information 53

• Press Esc.• Press the Tab key repeatedly until the Close or

Done button has focus and then press Enter.

Saving and loading settings files

You can save settings to a file for future use. Two types of parameter table (*.tbl) files are available:

• a setup.tbl file that you can reload manually on the V8

• a startup.tbl file that the V8 or RXU loads automatically when it is powered on

The files are saved on the CompactFlash card in the \DATA directory. If you save a startup.tbl file, you can use a PC to copy the file to the \DATA directory of other CF cards for use in RXU instruments.

You can also create table files on a PC using the TblEdit program. See Chapter 4, “Table Files and TblEdit” on page 87 for more information.

To save a setup.tbl or startup.tbl file:

• From the Setup menu in an Acquisition window, choose either Save Startup(*.tbl) File or Save Setup(*.tbl) File.

To load a setup.tbl file:

• From the Setup menu in an Acquisition window on the V8, choose Load Setup(*.tbl) File.

To use a startup.tbl file:

• Insert the CF card containing the startup.tbl file (in the \DATA directory) in the RXU or V8 you want to use. The file will be loaded automatically when you power the instrument on.

Entering survey informationThe Survey Information area of the Site Setup window for each geophysical method allows you to keep some basic records concerning the project. (See Fig. 3-41 on page 54.)

54 Chapter 3 Common Operations Entering survey information 54

Fig. 3-41: Survey Information area of a Site Setup window.

The information you enter here is saved on the CompactFlash card in a file with the extension TBL.

The survey information you can enter comprises:

• A Project name• Your Company name• Your Client’s name, if you are contracting• A description of the Survey Area• The instrument Operator’s name• A Comment• A Line name or number• A Site name or number

Text in each box can be up to 64 characters long, except the Comment text, which can be 128

characters long, and the Line and Site names, which can be 15 characters long. Survey information can be changed at any time, regardless of whether the instrument is recording data or not.

If the instruments are on a radio network, each time you choose Start Recording from the Acquisition menu, the V8 will transmit the Site name and Line number to the other instruments.

To enter the Survey Information:

1. In the Site Setup window, press Ctrl and type S to move the focus to the Survey Information area.

2. Press the UP ARROW or DOWN ARROW key to move the focus to each text box and type the desired infor-mation.

3. Press Ctrl, L to move to the Line textbox and type the identifier you have chosen for the current survey line.

4. Press Ctrl, T to move to the Site textbox and type the identifier you have chosen for the current site on the survey line.

55 Chapter 3 Common Operations Entering Box information and changing mode 55

Entering Box information and changing modeOne requirement common to all geophysical methods except MT/AMT is to define the instrument(s) used in the survey. The word “box” appears in the interface as a short term for “instrument.” The term refers to any networked devices used in the survey, including transmitters, the V8, and remotes such as the RXU-TM.

You enter instrument information in the Site Setup window for the particular method you are using.

Five types of information can be entered for each instrument:

• Instrument type or function• Serial number• Number of channels• Gains• Operating mode• Remote control

Because the number of entries in the Box spreadsheet influences memory allocation, you can only add or delete instruments and channels when the instrument is in Setup mode. This mode is selected by default when you first open a Site Setup window. If you need to change the number of instruments or channels at a later time, first change the mode to Setup as described under “Understanding gain” on page 55.

Understanding gain

The “correct” setting for channel gain is dependent on local conditions of signal strength and noise. The objective is to set the gain as high as possible, without causing saturated records. As you build experience with your equipment in your locale, you will be able to judge the best settings to start with, and when to modify them.

Table 3-4 shows the peak signal strength that can be recorded at each gain setting.


If gains are set too high, records will be saturated and data quality will be poor. To evaluate your gain settings, monitor the instrument during acquisition as described in the chapters for the individual techniques. The number of saturated records appears in the status bar (“Sat’d Recs:”). If more than a few records are saturated, reduce the gain.

You can set a warning threshold in the Options and Status screen, so that the status bar will change colour when too many saturations have occurred. See “Customizing the V8 by setting options” on page 67.

Setting up instrument type, serial number, channels, and gains

The first five columns in the Box spreadsheet contain information on the instruments and their channels, including the gain factors to be used (see Fig. 3-42).

Fig. 3-42: Box types, serial numbers, channels, and gains in the Box spreadsheet.

Channel terminology. In TDEM, the receiver records the rate of change of the magnetic field, or dB/dt, so the channels are referred to as “B” channels. In other methods, magnetic channels are referred to as “H” channels. In all methods, electric channels are referred to as “E” channels.

Table 3-4: Channel gain factors and signal strength

Gain Setting Peak Signal Strength

0.25 10.0V

1 2.5V

4 0.6V

16 0.15V


Note Gain can only be changed on the V8 that is being set up and on remote instruments that are connected over the radio network. If you want to change remote channel settings, set up the radio network first, then return to the Box spreadsheet to change remote channel settings.

The second line of the Box spreadsheet refers to the V8 itself, so the Box Type and Box SN (serial number) cells are read-only on this line. (The first line of the spreadsheet refers to the transmitter monitor. )

To enter serial numbers, channels, and gains:

1. Press Ctrl, B to move the focus to the Box spreadsheet.

2. Press the ARROW keys to move the focus to the row you want to work with. If you are setting up the V8 Receiver itself, skip to step 5.

3. In the Box Type column, scroll through the list and choose the instrument type—either Transmitter or Auxiliary Box.

4. Press the RIGHT ARROW key to move to the Box SN column and enter the serial number of the instrument.

5. Press the RIGHT ARROW key to move to the Channels column and if necessary, enter the number of channels that will be used on the instrument. (If the instrument is on the radio network, the number of channels may already be displayed.)

6. Press the RIGHT ARROW key to move to the E Gain column and choose a setting from the scrolling list. (See Table 3-4 on page 56 for the effect of each setting on dynamic range.)

7. Press the RIGHT ARROW key to move to the H Gain column (B Gain in TDEM) and choose a setting from the scrolling list.

Understanding instrument modes

System 2000.net instruments have a number of operating modes, for recording data, calibrating, setting up, etc. The mode changes automatically when you choose commands from the Acquisition menus,


but you can also set the mode directly or read the current mode in the Box spreadsheet Mode column.

Possible instrument modes are:

• Setup • CS Record (Controlled-Source Record)• CS Pause (Controlled-Source Pause)• CS Standby (Controlled-Source Standby)• Shutdown • Coil Cal • Box Cal • GPS Reset • Pot Res Check • Pot-Coil Check • Record

Setup mode. This is the default mode of the V8 or RXU when you power it on, unless you have programmed it to start up in Record mode for MT/AMT. An instrument must be in Setup mode before you can change channel or instrument information in a Site Setup window.

CS Record. The instrument enters this recording mode when you select Start Recording (or Resume

Recording after pausing) from the Acquisition menu of a controlled-source (CS) method Acquisition window. The instrument acquires data from all channels when in this mode. Remote-controlled instruments on a radio network will change to this mode in tandem with the V8.

CS Pause. the instrument enters this mode when you choose Pause Recording from the Acquisition menu of a controlled-source (CS) method Acquisition window. This mode interrupts controlled-source recording without closing the station data file. It is useful when you want to adjust gain (or filter) settings without starting a new file. Remote-controlled instruments on a radio network will change to this mode in tandem with the V8.

CS Standby. the instrument enters this mode when you choose Standby from the Acquisition menu of a controlled-source (CS) method Acquisition window. This mode interrupts controlled-source recording and closes the station file. When you select Start Recording again, the new station file name is automatically incremented. Use this mode when you


want to make separate measurements at a single site or when you want to move the array along the survey line without shutting down the instrument. Remote-controlled instruments on a radio network will change to this mode in tandem with the V8.

Shutdown. The instrument enters this mode when you select the Shutdown command from the Setup menu or the main window.

Coil Cal. The instrument enters this mode when you perform a sensor (coil) calibration. The V8 must already be calibrated itself in order to calibrate a sensor.

Box Cal. The instrument enters this mode when you perform an instrument calibration.

GPS Reset. If an instrument has been moved a great distance since it last achieved satellite lock, it can take up to 30min to acquire satellite signals. Resetting the GPS receiver can significantly reduce this delay. This mode is more easily accessed by a command button in the Options and Status dialog box.

Pot Res Check. This mode has not yet been implemented. In future releases, the instrument will measure contact resistance on E channels when this mode is selected.

Pot-Coil Check. This mode has not yet been implemented. In future releases, the instrument will verify that there are no open circuits on E, H, or B channels when this mode is selected.

Record. The instrument enters this mode when you select Start Recording Immediately from the MT/AMT Acquisition menu, or when the instrument begins recording on the schedule defined in the MT/AMT Acquisition Setup window.

To change mode:

• In most cases, you should use the menu commands in the Acquisition or Calibration windows and allow the instrument to change mode itself. However, if you need to change mode directly, move the focus to the Mode cell for the instrument you want to change and scroll through the list to the mode you want.

60 Chapter 3 Common Operations Setting up remote control 60

The mode changes as soon as you select OK.

Setting up remote controlIn a radio network, the V8 can control the recording mode of other instruments. If you enable remote control, other instruments on the network will change their recording mode when you change the V8 recording mode. (Changing to modes unrelated to recording, such as GPS Reset or Calibration, has no effect on remotes.)

To set up remote control:

• In the Box spreadsheet, move the focus to the Remote Control column and choose Yes to enable remote control or No to disable it.

If you choose not to enable remote control, you must change the remote instrument mode manually. If the radio network is working, you can make the change from the V8. (If the network is not operating, you can

make the change using RXUPilot at the remote instrument. See Chapters 5, 6, and 7 for instructions.)

To change a remote instrument mode manually:

• Move the focus to the Mode cell for the remote instrument you want to change and scroll through the list to the mode you want.

The instrument mode changes when you select OK.

Setting up filtering and couplingSystem 2000.net instruments have a number of filter and coupling settings that help to reduce the effects of noise and static shift. These reductions improve the signal-to-noise ratio and help to prevent saturated records caused by input exceeding the dynamic range of the instrument.

Filtering and coupling are set from the Acquisition Parameters dialog box in each of the geophysical

61 Chapter 3 Common Operations Setting up filtering and coupling 61

methods. (Other settings in the dialog box will vary with the method, and so placement of the filter and coupling controls may also vary slightly.)

Setting the low pass filter

The input low pass (LP) filter has five settings, numbered from 0 to 4. The choice of setting depends on the dipole contact resistance: the higher the resistance, the weaker the filter that should be used.

A filter setting that is too strong for the contact resistance will introduce phase shift error into the upper frequencies, and plots of apparent resistivity will show a sharp rolloff at these frequencies. (This rolloff may be hard to recognize if near surface resistivity changes rapidly with depth.)

When strong VLF radio signals are present (within approximately 150km of a transmitter), a special VLF filter that provides a sharper cutoff between 10kHz and 20kHz may improve data quality.

To determine the best value for a given electrode resistance, examine the effect of various filter settings as shown in the graphs discussed next.

The low pass filter allows optimization over a range of electrode resistance. Set the filter to the weakest value that effectively reduces noise.

Low pass filter graphs. Figures 3-44, 3-45, and 3-46 starting on page 63 show frequency response versus electrode resistance with various LP Filter settings, using the AMT method as an example. The numbers beside the data point symbols in the legends correspond to the the cutoff frequency selected in the LP Filter area of the Acquisition Parameters dialog box.

Fig. 3-43: Correspondence between graph legend and LP Filter setting.


The filter should be set to the lowest value that effectively reduces noise, because phase shift error in the higher frequencies increases with the strength of the filter.

Values greater than 4 are shown on the graphs for completeness, although data acquired with such settings are generally not useable.

Note Because the calibration function of the data processing software attempts to correct for the filter effects, it is still possible to acquire useable data at frequencies above the curves on the graphs.

Figures 3-44 and 3-45 contrast the effect of no feedback versus a feedback corner frequency of 10kHz. Feedback provides a means to optimize the instrument, and is enabled when the instructions for setting low pass filter parameters are followed. (Feedback is automatically disabled for TDEM methods.)

Figure 3-46 shows the effect of turning off the VLF trap.


Fig. 3-44: Response curves for broadband (no feedback corner frequency) with VLF trapping On.

Input L = 1 mH - No feedback - VLF Trap

100

1000

1000

010

0000

100 1000 10000 100000

Pot resistance - ohm

Freq

uenc

y - 3

0° o

r 2 d

B e

rror -

Hz 0

1234567


Fig. 3-45: Response curves for AMT (10kHz feedback corner frequency) with VLF trapping On.

Input L = 1 mH Feedback corner 10 kHz - VLF Trap

100

1000

1000

010

0000

100 1000 10000 100000


Freq

uenc

y - 3

0° o

r 2 d

B e

rror -

Hz 0

1234567


Fig. 3-46: Response curves for AMT (10kHz feedback corner frequency) with VLF trapping Off.

Input L = 1 mH Feedback corner 10 kHz - No VLF Trap

100

1000

1000

010

0000

100 1000 10000 100000


Freq

uenc

y - 3

0° o

r 2 d

B e

rror -

Hz 0

1234567


To set the low pass filter:

1. In the Acquisition Parameters dialog box, press Ctrl, P and select the appropriate filtering, according to the electrode resistance:

2. Check or clear the VLF trap checkbox as appro-priate.

Note To accurately measure contact resistance ≥2000Ω, you must disconnect the channel input cables from the V8. Measure from the ground terminal to each cable end, and between the two cable ends of each dipole.

Setting the line frequency filter

Be sure to set the Line Frequency filter according to the local power line frequency: 50 or 60Hz. This filter setting reduces noise from the power grid.

To set the Line Frequency filter:

• In the Acquisition Parameters dialog box, press Ctrl, L and select either 50Hz or 60Hz, to match the local line frequency:

Setting coupling parameters

The Coupling setting governs the high pass filter.

When the V8 is set to AC coupling, it uses a high pass filter with a corner frequency of 2Hz that removes self-potential from the dipole. Because signal strength increases with wavelength, this design allows acquisition of lower frequencies without saturating the input channels. For most MT and AMT soundings, use AC coupling.

In the case where the DC potential measured on the electrodes is very low (less than about 20 mV) and the target wavelengths are >1000s, you may find that DC

67 Chapter 3 Common Operations Customizing the V8 by setting options 67

coupling (no filter) improves MT or AMT results. For TDEM methods, always use DC coupling.

To set Coupling:

• Press Ctrl, C and select either AC or DC coupling for the E channels (H channels are not used in SIP):

Customizing the V8 by setting optionsYou can customize the V8 in a number of ways. For example, you can change the colours of some elements and adjust the contrast of the screen or turn off the backlight. You can also set thresholds, or Warning levels, for certain conditions. If the Warning level is exceeded, the condition will be highlighted on the Status bar at the bottom of the screen in your chosen

warning colour. (In some cases, a Warning dialog box will appear instead.)

You can choose whether times are shown as local times or as UTC. You can choose whether to have the V8 start up in one of the Setup windows rather than the main window, and whether to display a confirmation dialog box when the shutdown command is given. Lastly, you can choose whether to save your settings in a file for automatic use at the next start-up.

To customize the data displays, see “Customizing data and plot appearance” on page 70.

To access the customization options:

• From the Setup menu in any Acquisition window, choose Options and Status.

The Options dialog box appears (see Fig. 3-47).


Fig. 3-47: The Options dialog box.

To change the display contrast:

• Move the focus to the Contrast slider bar and use the ARROW keys to adjust the slider.

To toggle the backlight on and off:

• Select or clear the Turn on screen backlight checkbox.

To change colours:

1. In the Options and Status spreadsheet, move the focus to one of the colour parameter values at the bottom of the spreadsheet:

• Text colour

• Warning colour

2. Scroll through the list of available colours until you find the one you want.

The change will take effect within a second or two.


To set the Warning thresholds:

• In the Options and Status spreadsheet Warning column, set minimum values for any of the first seven rows:

• Free disk space

• Temperature (internal instrument temperature)

• Battery 1 (voltage of the first external battery)

• Battery 2 (voltage of a second, optional, external battery; special cable required)

• Battery 3 (voltage of the battery in the V8-EX)

• Saturated records

• GPS satellites (a value of 3 is recommended)

To set local or UTC time:

1. Move the focus to the Time Zone area and to the desired standard: UTC or Local.

2. Press Enter or the space bar to activate your choice.

3. If you chose Local time, move the focus to the Local and UTC time difference box, and scroll to the correct time difference.

To set startup and shutdown options:

• To have the V8 start up in the Site Setup dialog box of the currently selected geophysical method, select Enter <method> window on power up.

To have the V8 start up in the main window, clear the Enter <method> window on power up checkbox.

• To have a confirmation dialog box appear when you choose the Shutdown command, select Confirm on shutdown or quit.

To have the V8 shutdown without confirmation, clear the Confirm upon shutdown or quit checkbox.

• To have the current parameters saved in a file (startup.tbl) to be used at the next start-up, select Save Startup.tbl file on exit or shutdown.

70 Chapter 3 Common Operations Checking instrument status 70

Customizing data and plot appearance

During data acquisition, you can change the appearance of listed data and plotted data in several ways. You can choose to see only a spreadsheet-style list of numerical data, or only a graphical plot of the data, or both.

To display plots, lists, or both:

1. From any Acquisition window, activate the View menu.

2. To see both a graphical plot and a spreadsheet listing of data, choose Plot + List.

3. To see only a graphical plot, choose Plot Only.

4. To see only a spreadsheet listing of data, choose List Only.

You can also customize the appearance of the graphical plot. For example, you can choose symbol sizes and colours, change the scale or the grid, and so on.

Note Plot parameters vary depending on the geophysical method in use. Detailed information is provided in the chapter on each method.

To customize data plots:

1. From the Acquisition window, activate the View menu and choose Plot Parameters, or type the shortcut: Ctrl, M.

2. Change the settings in the Plot Parameters dialog box that appears.

Checking instrument statusAlthough a few key operating parameters are shown in the status bar at the bottom of the Acquisition windows, you may want more detailed information on the status of the V8 or of other instruments on the radio network. For example, you may want to know the operating temperature, remaining disk space, or battery condition of an instrument. The Options and

71 Chapter 3 Common Operations Calibrating the equipment 71

Status dialog box provides quick access to this information.

To check instrument status:

1. From the Setup menu in any Acquisition window, choose Options and Status, or type the shortcut: Ctrl, O.

The Options dialog box appears and displays the Status spreadsheet (See Fig. 3-47 on page 68.).

2. Scroll through the Select box serial number list at the bottom of the dialog box to the instrument you want to examine. (Only the V8 and instruments currently on the radio network are listed.)

3. Press the UP ARROW or DOWN ARROW key to scroll through the spreadsheet.

Calibrating the equipmentThis section applies to all equipment generally and to the V8 in particular. For detailed information on calibrating RXU instruments, see Chapters 6 and 7.

Before each survey begins, all instruments and sensors must be calibrated. Once the equipment is set up, the process takes about 10 minutes for a V8 or RXU and one hour or more (in half-hour increments) for magnetic sensors. Calibration of a current sensor takes about half an hour for use with lower output transmitters and up to four hours for use with a high-output transmitter (e.g., a T-200), in 12-minute increments. Each calibration must be completed in a single session; it cannot be interrupted and resumed.

Warning Starting a calibration erases any corresponding existing files.

Calibration is independent from operation: once an instrument is calibrated it can be used for any of the geophysical methods and any acquisition parameters. The instrument uses the calibration results and your gain and filter settings to calculate instrument response for any filter settings that may be used.

If magnetic sensors are used, the usual practice is to calibrate the V8 and then the sensors immediately

!


after, at the survey remote reference site or the first acquisition station. However, an instrument can be calibrated on its own, even indoors if GPS signals can be received.

No additional equipment is needed to perform a calibration.

Note For best results, the instrument should be at operating temperature when you start the calibration. In normal ambient conditions, an instrument will reach a stable operating temperature 10–15 minutes after it is powered on. In cold weather, allow more time before you start the calibration. You can monitor the internal temperature in the Options and Status dialog box.

Calibrating the V8

A V8 must be calibrated before acquiring data or calibrating sensors. Because calibration requires GPS satellite lock, it is usually done outdoors. However, if the GPS antenna can be positioned outdoors and connected to the V8 with an extended cable, then the calibration can be done indoors.

The V8 stores the resulting calibration file in the \CAL directory on its internal disk. The file is named SSSS.CLB, where SSSS is the serial number of the V8. Do not rename, move, or delete the directory or the calibration file.

To determine the calibration status:

1. From the main window, choose Calibrate.

2. Look at the status bar at the bottom of the Calibration window.

Fig. 3-48: Calibration status bar.

If calibration files exist, the status bar will read Box Cal OK and/or Coil Cal OK. If the files don’t exist, the status bar will read Box No Cal and/or Coil No Cal.


Tip If you intend to calibrate a V8 and magnetic sensors in the same session, plan for enough time and choose an outdoor location suitable for both. To work efficiently, begin the layout of the sensors while the V8 calibration is in progress.

Tools and equipment required:

• V8 to be calibrated• Battery and cable• GPS antenna and cable

To calibrate a V8:

1. Connect the GPS antenna to the V8 as described on page 24.

2. Connect the battery to the V8 as described on page 33.

3. Power up the V8 by pushing the red POWER switch up to the ON position and releasing it.

4. If the instrument starts up in an Acquisition window, exit to the main window.

5. In the main window, type Ctrl, B to open the Calibration window.

6. From the status bar that appears at the bottom of the screen (see Fig. 3-49), note the number of GPS satellites that have been acquired. Wait if necessary until at least four satellites have been acquired; calibration cannot proceed without a minimum of four satellites.

Fig. 3-49: The status bar, showing the number of GPS satellites acquired.

7. From the Setup menu, select either 50Hz or 60Hz, according to the local power grid frequency.

8. If the V8 temperature is stable, then from the Calibration menu, choose Box Calibration.

Calibration begins immediately. The status bar displays Box No Cal, then Box In Progress.

9. Wait approximately 10 minutes while the instrument calibrates itself, until the status bar reads Box Cal OK.

10. If you want to calibrate sensors, continue with the next procedure.


11. If you are not continuing with sensor calibration, exit to the main window.

Calibrating coil sensors (MTC-30/50)

MT, AMT, and CSAMT techniques usually require one or more magnetic sensors, either coils or loop. Magnetic sensors must be calibrated (using a calibrated V8) before acquiring data. Sensors can only be calibrated outdoors, although the layout requirements for calibration are not as rigorous as for data acquisition. Sensor calibration takes at least one hour, and can be extended in increments of half an hour to a maximum of four hours. The noisier the area, the more time is needed to ensure a quality calibration.

Electrical noise, physical vibration, and temperature variation all contribute to poor calibration data. Although the sensors do not have to be buried to be calibrated, do choose a location protected from wind and sunlight, and away from sources of electrical noise and vehicle or pedestrian traffic. If these conditions cannot be met, plan to bury the coils in shallow

trenches. (If sunlight is the only potential problem, plan to cover each sensor with a tarpaulin.)

Tip The remote reference site to be used in a survey is often the best place to perform calibrations, because it is chosen for its low-noise characteristics.

The V8 stores the resulting calibration files in the \CAL directory on its internal disk. The file names are determined by the serial numbers and sensor types entered by the operator in the Coil Calibration dialog box. The V8 will add the extension CLC to each file name. Do not rename, move, or delete the \CAL directory.

Note The instrument that is used to calibrate sensors must already be calibrated itself. (The instrument calibration file (*.CLB) must be listed in the Options and Status dialog box, and the status bar must read Box Cal OK.)


• Sensors to be calibrated and a cable for each• Calibrated V8 with magnetic channels


• Battery and cable• GPS antenna and cable• A ground electrode and cable • Optionally, tarpaulins for covering the sensors or a

shovel for burying them

To lay out a site for coil calibration:

1. Choose a location for the coils and position the V8 about 10m away.

2. Install a ground electrode and connect it to the GND connector on the V8.

3. Ten metres away, lay the coils parallel, flat on the ground about 3m apart, with all the connectors oriented toward the V8.

4. If you are going to bury the coils, dig a trench alongside each, about 30cm deep and slightly longer than the coil.

5. On a Layout Sheet, note the serial number of each coil and designate it as either Hx, Hy, or Hz.

6. Connect the sensors to the V8 (see “Handling locking-ring connectors” on page 18).

7. To minimize wind-induced noise, ensure that the sensor cables lie flat on the ground. (Place weights on them every metre or so if necessary.)

8. If you are burying the coils, cover them with the earth removed from the trenches.

9. Complete the Layout Sheet for the site.

Fig. 3-50: Coil calibration layout.

12V

GPS~3m

~3m

~10m

V8


To calibrate sensors:

1. If you are not continuing in the same session after calibrating a V8, then start up a calibrated instrument and select Calibration from the main window.

2. From the Setup menu, select either 50Hz or 60Hz, according to the local power grid frequency.

3. From the Calibration menu, choose Coil Calibration.

The Coil Calibration dialog box appears.

Fig. 3-51: The Coil Calibration dialog box.

4. Choose a calibration duration from the Coil Calibration time list. If you know that the area is electrically noisy, set this parameter to a higher number.

5. In each serial number text box, type the 4-digit serial number of the sensor. If no sensor is connected to any of the Hx, Hy, or Hz channels, leave the text box blank for that channel.

6. For each sensor, choose the coil type from the corresponding list.

Note Be certain that the serial numbers and coil types are correct and are correctly identified as being Hx, Hy, or Hz as you noted when you laid out the coils. An error here means that all data acquired with the affected sensor(s) will be invalid—a potentially costly mistake.

7. To start the calibration, choose OK; to cancel the calibration, choose Cancel.

Calibration begins as soon as you select OK. The status bar displays Coil No Cal, then Coil In Progress.

8. Wait until the status bar displays Coil Cal OK before closing the Calibration window. (Sensor calibration may take a few minutes longer than the time set in the Coil Calibration dialog box.)


Calibrating air-loop sensors

In MT or AMT surveys where the ground is too hard or rocky to bury a vertical coil sensor, an air-loop sensor can be substituted.

Calibration of an air-loop uses an excitation loop as the signal source. (See Fig. 3-52.)

Air-loops and coil sensors can be calibrated at the same time on any of the three H channels, as long as the serial numbers and sensor types are entered correctly in the dialog box.


• Sensor(s) to be calibrated and a cable for each• adapter cable• Air-loop “CAL Box” and cable• Calibrated V8• Battery and cable• GPS antenna and cable• A ground electrode and cable

• 250m of #12–#18 gauge copper wire for the excitation loop

• Measuring tape (≥50m)• A shovel• Marking stakes• A compass and tripod

To lay out the excitation loop:

1. Review the diagram on page 78.

2. Prepare the wire for the excitation loop by marking it with coloured tape at 25m, 75m, 125m, 175m, and 200m. The tape will mark the corners and the end of the loop. Wind the wire onto a portable spool.

3. Set up a compass on a tripod where you plan the centre of the loop.

4. Sight from the compass toward one of the planned corners and have an assistant place a stake to mark 1.6m, 10.4m, and 35.35m. These stakes mark two corners of the AL-100 loop, and one corner of the excitation loop.


Fig. 3-52: Air-loop sensor calibration.

5. If more than one AL-100 loop is to be calibrated, repeat step 4, sighting at a 90° angle to the first corner.

6. Stake the remaining corners of the excitation loop by sighting at 90° increments and measuring 35.35m.

7. Starting at the midpoint between two corners, walk the perimeter of the loop, unwinding the copper wire from the portable spool as you go. Align the tape markings at the corners to verify your compass sightings and measurements.

8. Connect the excitation loop ends to the Air-loop CAL Box.

To lay out the AL-100 air-loop:

1. Using the stakes at the 1.6m and 10.4m measurements, position two opposite air-loop corners as shown in the diagram. (The four corners of the AL-100 loop are marked with tape and a preamplifier.)

2. Gently pull the remaining two corners into position.

10.4m1.6m

35.35m

50m x 50m excitation loop

(#12–#18 Cu)

Air-loopCAL Box

RedBlack

V8

Hz

Hy Hx

Looppre-amplifiers

GPS

25m 25m

12V

8.8m


Fig. 3-53: Air-loop CAL Box.

3. Verify that:

• The air-loop sides are parallel to the excitation loop sides.

• The air-loop forms a perfect square. (Opposite corners are 8.8m apart.)

• The pre-amplifier is at one corner of the air-loop.

• The cable to the V8 exits the pre-amplifier toward the right when viewed from within the air-loop.

To connect the V8:

1. Position the calibrated V8 near the Air-loop CAL Box.

2. Install the ground electrode and connect it to the GND connector on the V8.

3. On a Layout Sheet, note the serial number(s) of the air-loop(s) and connect the cable(s) to the V8 as either Hx or Hy.

4. Connect the Air-loop CAL Box to the V8 as Hz.

5. Complete the Layout Sheet.

To calibrate air-loop sensors:

• Follow the instructions for calibrating coils on page 76, being sure to choose LOOP as the coil type.

Cancelling a calibration

You can cancel a calibration that is in progress. However, if you do so, there will be no calibration file for the instrument or sensors that were being


calibrated. Starting a calibration erases any corresponding existing files; cancelling a calibration writes no new files. The instrument or sensor(s) will have to be recalibrated before use.

To cancel a calibration:

• From the Calibration menu, choose Stop Calibration.

Viewing calibration results

You can view the results of a calibration in graphical form.

To view calibration results:

1. From the View menu, select the type of calibration file you want to see, Coil or Box.

2. Either type the file name in the File name text box or select a file from the spreadsheet.

3. Choose OK to display the calibration results.

4. If you want, change the appearance of the plot by choosing Plot Parameters from the View menu.

Importing calibration files

If you want to use a saved calibration file but the file is not stored on the V8, you can import the file. This capability lets you calibrate sensors once and use them on different instruments without having to recalibrate. You can also import an instrument (box) calibration file, if for some reason it has been removed from the V8. (Normally, however, it would be better to simply recalibrate the V8, as the process takes only 10 minutes.)

Note Files for sensors that were calibrated under field conditions (temperature, power grid frequency, etc.) different from those at the survey site are not suitable for import. You must recalibrate the sensors under current conditions.

To import a calibration file:

1. Install a CF card in a PC card reader and create a folder at the card’s root level named NEWCAL.

2. Copy the calibration file into the NEWCAL folder.

81 Chapter 3 Common Operations Saving data files 81

3. With the V8 powered off, install the CF card in the V8 card slot.

4. Start up the V8.

The calibration file will be automatically copied to the V8 CAL directory.

Saving data filesSystem 2000.net instruments normally save both the raw time series and the stacked waveforms on the CompactFlash card. If the instruments are on a radio network, they will also save the stacked waveforms from remote instrument channels.

In the future, the geophysical statistics may also be saved. This feature (Statistics file log) is not yet implemented.

For testing purposes or to save disk space, you can turn off the logging of these file types. To reduce network traffic, you can turn off logging of remote instruments. To save multiple, smaller files instead of

one large file (useful in monitoring applications), you can specify file duration in integral factors of 24 hours.

To control data logging:

1. On the V8, from the Setup menu in any Acquisition window, choose Options and Status.

2. If the instruments are on a radio network, press Ctrl, S and select the serial number of the instrument you want to configure.

3. In the Options and Status spreadsheet, move the focus to either Waveform file log or Stack result file log and scroll to the value you want to use.

Note To help prevent the loss of data, file logging reverts to the defaults (save time series and save stack results from all instruments) when you restart the instrument or when you choose a geophysical method from the main window.

To specify file duration:

1. On the V8, from the Setup menu in any Acquisition window, choose Options and Status.

82 Chapter 3 Common Operations Upgrading instrument capabilities 82

2. If the instruments are on a radio network, press Ctrl, S and select the serial number of the instrument you want to configure.

3. In the Options and Status spreadsheet, move the focus to File close time and scroll to the value you want to use.

If you choose By schedule, the files will be closed when you select Standby from the Acquisition menu, or when you exit a geophysical method, or (in MT/AMT) when the Data record end time is reached.

Upgrading instrument capabilitiesSystem 2000.net instruments are capable of a variety of geophysical methods, each of which is licenced separately. You can purchase the hardware with a licence for only one method or for several methods, and you can upgrade to additional methods later.

To add capability to your instrument, contact Phoenix to purchase the licence for the method(s) you want to add. (You will need to provide the serial number of the instrument you want to upgade.) Phoenix will provide a new licence file that you then import to the instrument.

To import a new licence file:

1. Install a CF card in a PC card reader and create a folder at the card’s root level named LICNEW. (If the CF card has already been used in a V8 or RXU, the folder may already exist.)

2. Copy the new licence file into the LICNEW folder.

3. With the V8 or RXU powered off, install the CF card in the instrument card slot.

4. Start up the instrument.

The instrument will import the licence file and the new method(s) will be fully functional.

83 Chapter 3 Common Operations PC requirements 83

PC requirementsTo process data or to create and edit parameter table files or frequency-stepping schedules for the V8 and/or

the RXU-TM, you will need a PC running Microsoft®

Windows® 98 or later, equipped with:

• a CompactFlash card reader• Phoenix data processing software• the TblEdit program, or • Notepad or a spreadsheet program such as

Microsoft Excel, and• Phoenix Generate Frequency Stepping Table utility

(FreqTabl.exe)

To install the Phoenix PC software:

1. Insert either the CD-ROM or floppy disk into the PC drive.

2. Run the Setup.exe program contained on the disk and follow the on-screen instructions.

Ensuring quality dataPhoenix instruments are designed to acquire the highest quality data possible, but many factors outside the instrument can affect quality. This section highlights ways that you can maximize the results you get from your Phoenix equipment.

Storage and handling• To keep cables tangle-free, gather them carefully

into figure-8 shapes after use. Inspect cables frequently for breaks in the insulation.

• Never try to move a coil sensor by pulling on its cable.

• Always store porous pot electrodes in salt water (50g/L) to prolong their life and reduce contact resistance.

84 Chapter 3 Common Operations Ensuring quality data 84

Warning Electrodes contain small amounts of toxic lead-chloride that gradually seeps through the porous ceramic base. Avoid touching the bottom surface of the electrodes, and wash hands thoroughly if there is any possibility of contamination. Dispose of depleted electrodes according to local hazardous waste guidelines.

• Make sure batteries are fully charged before use and before storage.

• Disconnect all cables before storage and transport, to prevent damage to connectors.

• Keep protective caps in place on connectors, or joined to each other when cables are connected.

Maintenance• Monitor the DC potential measured on the

electrodes. The lead-chloride gradually leaches out of the electrodes, and they must be refurbished or replaced from time to time. Consistently high potentials indicate a problem. To test the electrodes, put them in a container with a few centimeters of salt water and measure the

resistance between any pair. Resistance should be <100Ω. Also measure the DC potential between the pair. Self-potential should be <10mV (<2mV when new).

• Test your batteries after each use. If a reading falls to 10V, the battery should probably be replaced.

• Test your batteries after each charge, allowing at least two minutes after disconnecting from the charger before taking the measurement. If a reading falls below 12.75V, the battery should probably be replaced.

Operations• After calibration, allow time to acquire simultaneous

baseline data from all the instruments at the calibration site. Compare results to ensure all the equipment is performing properly. (This process also helps to develop a model of the data characteristics you can expect during the rest of the survey.)

• Test all hand-held GPS receivers to ensure uniformity of readings within acceptable variance.

!

85 Chapter 3 Common Operations Survey requirements 85

Be aware that map grids may contain errors or distortions, but the graphics themselves are created accurately from photographs. Therefore, test your receivers with reference to natural landmarks when possible.

• When using a compass, keep the area clear of local sources of magnetic distortion such as vehicles, belt buckles, shovels, sensor coils, etc.

• During sensor calibration, avoid movement of local sources of magnetic distortion.

• Take compass readings twice, from opposite directions (two crew members can do this simultaneously).

• Have at least two people record and check the information on the Layout Sheet, and initial it as correct.

Survey requirementsEnsure that you have all the required tools and equipment before beginning your work:

• Equipment Checklist and Layout Sheets (see Appendices D and E for examples)

• V8 and other instruments if used, sensors, cables, etc. per checklist

• Tools per checklist• PC with CompactFlash card reader, if required.• Setup software, if required (WinTabEd Off-line

Editor)• Processing software (SSMT2000, SyncTSV, MTEdit,

MTPlot), etc• A supply of CD-R or DVD disks for archiving data.

86 Chapter 3 Common Operations Survey requirements 86

87 Chapter 4 87

Chapter

Table Files and TblEdit

Table files are disk files containing the operating parameters of System 2000.net instruments. They have several purposes:

• to copy the same settings into multiple instruments • to save the current state of an instrument so that it

can be configured identically at a later time• to provide input for data processing

This chapter explains how to use the TblEdit program on a PC to view, create, and modify table files. It also explains some useful utility functions of the program.

88 Chapter 4 TblEdit About table files 88

About table filesAll the system and user-changeable parameters of System 2000.net instruments are stored in a table in system memory. The parameters can also be saved in a disk file, called a table file, with the extension tbl.

A table file does not have to contain all possible parameters, and may contain unnecessary parameters. Missing parameters are supplied by the instrument when it is powered up. Unnecessary parameters are ignored. RXUs have fewer parameters than V8s, so these instruments will simply ignore parameters that do not apply.

Table files are stored in binary format. They can only be read by Phoenix software, although they can be converted to text files if desired.

The format of table files used by System 2000.net instruments differs from that used by System 2000 MTU and MTU-A instruments. In order to process MT data acquired by a V8, the site table file must be converted to the earlier (Version 1) format.

Startup table files

If a table file named “startup.tbl” is present on the CompactFlash card when the instrument is powered on, the settings in that file will be loaded into memory automatically. This feature makes it easy to program a number of instruments with identical settings and also allows acquisition to begin automatically without having to program the instrument in the field. Startup table files contain only a subset of the parameters.

Site table files

Table files are necessary for post-acquisition data processing. The files contain information that the processing programs need in order to associate the raw data with the correct sites, calibration files, and conditions of acquisition.

Site table files contain all the parameters, and are saved automatically by the instruments. In controlled source methods, a site file is saved when the instrument has been recording or is paused and you

89 Chapter 4 TblEdit About TblEdit 89

choose Standby from the Acquisition menu, or Site Setup from the Setup menu. In MT or AMT acquisition, a site file is saved when recording stops, either because the programmed end time has been reached or because you chose Setup from the Acquisition menu.

Site files are named in the format ssssHhaa, where:

• ssss is the serial number of the instrument• H is the month in hexadecimal (1–9, A, B, C)• h is the day of the month in alphanumeric format

(1–9, a–v)• aa is an alphabetic code denoting the order of

repeated soundings on the same day (aa, ab, … zz)

About TblEditThe TblEdit (“Table Editor”) program is a simple Windows-based program. It allows you to:

• View, create, and modify startup table files• View and modify site table files

• Convert table, calibration, stack result, and frequency stepping schedule files to text format

• Convert site table files to a format compatible with SSMT2000 (the MT and AMT data processing program)

Exploring TblEditThis section explains the basics of TblEdit:

• Starting the program• Understanding the main window, toolbar, and

menus

Starting TblEdit

Start TblEdit as you would any other Windows-based program: either double click a desktop shortcut or launch the program from the Start menu.

90 Chapter 4 TblEdit Exploring TblEdit 90

The main window

When you launch the TblEdit program, the main application window appears (see Fig. 4-1).

All actions in TblEdit take place in dialog boxes, so you can reduce the size of the main window if you want by dragging the window borders.

Fig. 4-1: TblEdit main window.

Across the top of the main window are the menus:

Fig. 4-2: Menus.

Below them is the toolbar:

Fig. 4-3: Toolbar.

The menus and the toolbar both allow you to perform the most common tasks. The menus include some additional tasks that are not available from the toolbar.

At the bottom of the main window is the status bar:

Fig. 4-4: Status bar.

The status bar indicates the state of the program on the left, and the state of the Caps Lock, Num Lock, and Scroll Lock keys on the right.


Menus

This section explains the commands available on the menus. Most have toolbar equivalents, explained in the next section.

The File menu. Four commands and (possibly) several shortcuts appear on the File menu (see Fig. 4-5). The commands allow you to open, save, or rename table files and exit the program. The shortcuts appear as a numbered list of recently used files.

Fig. 4-5: The File menu.

The Edit menu. Six commands appear on the Edit menu (see Fig. 4-6). Each of the first five commands

opens a dialog box in which you can view and change a subset of parameters controlling:

• Data acquisition • Frequency stepping schedules• Coil and airloop sensor calibration• Current sensor calibration• Radio network communications

The last command, Raw Parameters, opens a dialog box in which you can view all instrument parameters by their code names and change those that are not read-only. This command is primarily for troubleshooting; you should not normally have to use it.

Fig. 4-6: The Edit menu.


The Utilities menu. Five commands appear on the Utilities menu (see Fig. 4-7). The first four commands allow you to print table files, calibration files, stack result files, and frequency stepping schedule files. (The “print” commands actually convert the binary files to text files that you can then open and print from Notepad or another text editor.)

The fifth command converts a table file from System 2000.net format to V5 System 2000 format. This conversion is necessary for compatibility with SSMT2000, the MT and AMT data processing program.

Fig. 4-7: The Utilities menu.

The commands on the Utilities menu do not have toolbar equivalents.

The View menu. Two commands appear on the View menu (see Fig. 4-8), allowing you to toggle the display of the toolbar and the status bar. A checkmark beside the command indicates that the item is currently displayed.

Fig. 4-8: The View menu.

The Help menu. The AboutTblEdit command on the Help menu opens a dialog box that provides program version information and contact information for Phoenix Geophysics Ltd.

Tools

The toolbar below the menus contains nine tools corresponding to the most commonly used menu commands. This section explains the icon and purpose of each tool.


Fig. 4-9: Hover the mouse pointer over a tool icon to learn its purpose.

To learn the purpose of a tool when using the program, hover the mouse pointer over the tool icon and read the tooltip or the Status bar message. (See Fig. 4-9.)

Tool Icon

Command

Open file.

Save file.

Edit Acquisition parameters.

Edit Frequency Stepping parameters.

Edit Coil Calibration parameters.

Edit Current Sensor parameters.

Edit Radio network parameters.

Edit the raw parameters.

Open the About TblEdit dialog box.

Tool tip

Status bar message

94 Chapter 4 TblEdit Creating and modifying table files 94

Creating and modifying table filesMost of the parameters that you can modify are described elsewhere in this User Guide. Please read Chapter 3, “Common Operations,” Chapter 8, “Radio Communication,” Chapter 9, “Frequency Stepping” and the chapters describing individual geophysical methods to gain an understanding of what values you should use in your table files.

Opening and saving table files

When TblEdit is launched, it starts with a complete set of parameters in memory, so there is no need for a “New file” command.

You can modify these default parameters and save them as a new file, or you can open an existing file on disk and modify it.

To create a new table file:

• From the File menu, choose Save or Save As… and give the file a name. (The default is startup.tbl.)

To open an existing file:

1. From the File menu, choose Open, or click on the toolbar.

2. Navigate to the file you want to use and double click it.

Editing acquisition parameters

Since the possible values for instrument parameters will vary according to the geophysical method being used, it’s important to start by defining the method and setting up the acquisition parameters.


Note In the Acquisition Parameters dialog box, CS_Record, CS_Pause, and CS_Standby correspond to the Record, Pause, and Standby commands on any of the V8 Controlled Source Acquisition menus.

To edit acquisition parameters:

1. From the Edit menu, choose Acquisition

Parameters… or click on the toolbar.

The Acquisition Parameters dialog box appears (see Fig. 4-10).

Fig. 4-10: Acquisition Parameters dialog box.

2. Select the Technique (geophysical method) you want to use.


3. Set the remaining parameters as appropriate for your survey.

Warning Remember that table settings saved in a startup.tbl file will be loaded and used immediately upon powering the instrument. Use caution when choosing the Mode Request. Box Calibration or Sensor Calibration will erase any corresponding files that may be on the CompactFlash card. CS_Record will start acquiring data immediately.

Editing frequency stepping parameters

The Frequency Stepping Parameters dialog box in the TblEdit program is almost identical to the Acquisition Parameters dialog box of the V8. In addition to letting you choose a saved schedule file or set up Auto Stepping, the TblEdit dialog box has the ability to save a schedule file and to display the contents of a schedule file.

To edit frequency stepping parameters:

1. From the Edit menu, choose Frequency Stepping

Parameters… or click on the toolbar.

The Frequency Stepping Parameters dialog box appears (see Fig. 4-11 on page 97).

2. To set up Auto Stepping, follow the instructions under “Setting up the Auto Stepping frequency table” on page 190 and click Calculate Stepping Table.

3. To designate a saved schedule file for use, select it from the Freq. stepping control list.

4. To view a saved schedule file, click Open Schedule File…, navigate to the TFS file you want to use, and click Open.

The Frequency Stepping Schedule spreadsheet displays the file contents.

5. If desired, edit the values displayed in the Frequency Stepping Schedule spreadsheet. You can also click Insert Row or Delete Row to change the schedule.

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Note Frequencies that cannot be accurately produced by the instruments will be highlighted in red in the spreadsheet. See Chapter 9 for recommended frequencies.

To save a schedule file:

1. When the Frequency Stepping Schedule spreadsheet contains the settings you want to save, click Export Schedule File…

2. Navigate to the folder where you want to save the file, name it using a numeral greater than or equal to 2 as the file name and the extension .TFS, and click Save.

Note If you want to create a large number of schedule files, you can save the files with more meaningful names. However, you will have to rename such files to numerical names before an RXU or V8 can use them.

Fig. 4-11: Frequency Stepping Parameters dialog box.

Editing coil and loop sensor calibration parameters

It is important to calibrate sensors before they are used to acquire data. Although you may not choose to have an instrument start up in sensor calibration mode,


you can still assign values to the calibration parameters in the startup table file.

Three parameters need to be set: the sensor type, the calibration time, and the sensor serial numbers, which the instrument uses to create calibration file names.

The serial numbers can be omitted at this point if the instrument is not going to start up in sensor calibration mode, but they must be supplied before sensor calibration begins.

To edit coil and loop sensor calibration parameters:

1. From the Edit menu, choose Coil Calibration… or

click on the toolbar.

The Coil Calibration dialog box appears (see Fig. 4-12).

tFig. 4-12: Coil Calibration dialog box.

2. Select the Coil Type to be calibrated.

The parameters for corner frequencies and test signal amplitude and gain are displayed in the first five text boxes and the calibration file name prefix appears in the three serial number text boxes. The default calibration multiplier appears in the Calibration time text box.


3. Edit the Calibration time (x30min) multiplier if necessary, using a value of at least 2. (Use a larger value in noisy areas.)

4. If the sensor serial numbers are known, add them to the end of the prefix in each H sensor serial number text box.

5. If no sensor will be calibrated on an H channel, delete the contents of the corresponding H sensor serial number text box.

Note Be certain that the sensor serial numbers and coil types are correct and are correctly identified as being Hx, Hy, or Hz as they will be connected in the field. An error here means that all data acquired with the affected sensor(s) will be invalid—a potentially costly mistake.

Editing the current sensor parameters

It is important to calibrate the current sensor before it is used to acquire data. Although you may not choose to have an instrument start up in sensor calibration

mode, you can still assign values to the calibration parameters in the startup table file.

If you are not calibrating, you need to set the gain factor to be used during acquisition.

Four parameters can be set: the sensor type; the calibration time; the sensor serial number, which the instrument uses to create the calibration file name; and the instrument gain.

The serial number can be omitted at this point if the instrument is not going to start up in sensor calibration mode, but it must be supplied before sensor calibration or data acquisition begins.

To edit current sensor calibration parameters:

1. From the Edit menu, choose Current Sensor

Settings… or click on the toolbar.

The Current Sensor dialog box appears (see Fig. 4-13).


Fig. 4-13: Current Sensor dialog box.

2. Select the Sensor Type: Mod CMU-1 for high-power transmitters like the T-200, CMU-1 for other transmitters.

The nominal gain and test signal amplitude are displayed in the first two text boxes.

3. In the Current sensor S/N text box, type the prefix CSEN followed by the current sensor serial number.

4. Edit the Calibration time (x12min) multiplier if necessary, using a value of at least 2 for CMU-1 sensors and at least 20 for Mod CMU-1 sensors. (Use a larger value in noisy areas.)

Setting gain. It is essential to set the gain correctly before and during data acquisition. An incorrect setting can make the data unusable because every record will be saturated. Table 4-1 shows the peak signal strength that can be recorded on the current sensor channel at each gain setting.

Table 4-1: CMU-1 gain factors and signal strength

Gain SettingPeak Current

CMU-1 Mod CMU-1

0.25 50A —

1 20A 200A

4 5A 100A

16 1.25A 25A


To set the current sensor channel gain:

• Determine the peak current expected from the transmitter and select the appropriate gain.

Editing communication settings

If your instruments are equipped with the radio option, then you can set up the parameters for network communication using TblEdit. See Chapter 8, “Radio Communication” on page 159 to gain an understanding of what values you should use in the table file.

To edit communication parameters:

1. From the Edit menu, choose Communication

Settings… or click on the toolbar.

The Communication Settings dialog box appears (see Fig. 4-14).

Fig. 4-14: Communication Settings dialog box.

2. Choose the Radio Type according to whether this instrument will be the Master or a Slave.

Note If you are saving a startup table file to be used in multiple instruments, choose Slave as the Radio Type. There can be only one Master on the network.

3. Choose the Radio Frequency band that is used by the instruments.

4. Select the Radio power from the drop-down list.


5. Set the Network address to a number from 1 to 65 535.

6. Set the Encryption key to a number from 1 to 65 535.

7. In the Tx Box S/N text box, type the serial number of the RXU-TMR to be used.

8. In the Ref. Box S/N text box, type the serial number of the remote noise reference instrument.

9. In the Auxn Box S/N text boxes, type the serial numbers of the RXU-3ER instruments from which you want to receive data channels.

Note If you are saving a startup table file to be used in multiple RXUs, do not complete the Auxn Box S/N text boxes. An RXU can only acquire 6 channels (3 of its own, 2 from the noise reference, and 1 from the transmitter monitor.

Using table files

When you are satisfied with the parameter settings you have made, save the table file to the hard drive of your

PC. You can give the file any meaningful name. However, to have an instrument use the file automatically, it must be named “startup.tbl” and it must be copied to the \DATA directory of the CompactFlash card that will be used in the instrument.

To use table files in the instruments:

1. Copy the .tbl file(s) to the \DATA directory of the CompactFlash card you will be using in the instrument.

2. If you want a .tbl file to be used automatically when the instrument is powered on, name the file “startup.tbl”.

3. When using the V8, if you want to load a table file, choose Load Setup from the Setup menu of any acquisition window and type the file name in the dialog box.

4. When using an RXU, if you want to load a table file, choose Load Table from the Utilities window in RXUPilot and tap the file name in the list of files.


Editing Raw Parameters

The Raw Parameters command opens a dialog box in which you can view all instrument parameters by their code names and change those that are not read-only. This command is primarily for troubleshooting; you should not normally have to use it.

Warning Modifying parameters incorrectly may produce invalid results, cause data loss, or may prevent data acquisition or processing altogether. Phoenix Geophysics Ltd. accepts no responsibility for data loss or invalid results or interpretations based on parameters incorrectly modified.

DO NOT MODIFY PARAMETERS unless you fully understand the consequences or are advised by Phoenix Geophysics Technical Support.

To access raw parameters:

• From the Edit menu, choose Raw Parameters…

or click on the toolbar.

The Raw Parameters dialog box appears (see Fig. 4-15).

Fig. 4-15: Raw Parameters dialog box.

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104 Chapter 4 TblEdit Viewing and printing System 2000.net files 104

The default sort order is numeric (by the first column); to sort alphabetically by parameter code, select Sort by code.

To jump directly to a parameter, type its code in the Lookup by code box and click Lookup.

You can change the width of a column by dragging the vertical bar to the right of the column heading.

To edit raw parameters:

• Scroll to the row containing the code that you want to edit, click in the Value column of that row, and type the new value.

Viewing and printing System 2000.net filesNone of the files used by System 2000.net instruments are human-readable—they are in binary, or machine-readable format.

TblEdit allows you to convert the files to plain ASCII text files, which can then be viewed or printed from a text editor such as Notepad or OpenOffice. The text files are saved with the same file name but with the extension .txt, in the same folder as the original file.

To convert a System 2000.net binary file to ASCII:

1. From the Utilities menu, choose the Print… command for the type of file you want to convert (see Fig. 4-16).

Fig. 4-16: The Print commands on the Utilities menu.

2. Browse to the folder containing the file(s) you want to convert. You can choose more than one file by holding down Shift or Ctrl while clicking the file names.

105 Chapter 4 TblEdit Converting table files to V5 System 2000 format 105

3. Click Open.

4. In Windows Explorer, browse to the folder containing the original file and open the .txt file(s) you just created. If desired, print the file using your text editor’s Print command.

Converting table files to V5 System 2000 formatSystem 2000.net table files use 8-character parameter codes and contain many more parameters than V5 System 2000 table files, which use 4-character codes. In order to use SSMT2000 to process MT and AMT data acquired with System 2000.net instruments, you must convert the table files to the correct format. (The

program uses the same file name for the converted table files and saves the original table file with the new extension, .tb2.

To convert a table file from System 2000.net format to V5 System 2000 format:

1. From the Utilities menu, choose Convert Tbl File(s) To Version 1…

2. Browse to the folder containing the file(s) you want to convert and select them. You can choose more than one file by holding down Shift or Ctrl while clicking the file names.

3. Click Open.

4. When processing data with SSMT2000, choose the .tbl files as usual.

106 Chapter 4 TblEdit Converting table files to V5 System 2000 format 106

107 Chapter 5 107

Chapter

RXUPilot

System 2000.net RXUs are equipped with infrared transceivers, allowing them to be controlled and monitored by the RXUPilot™ program running on a Palm OS™ handheld device.

This chapter explains in general terms the use of the handheld device and the RXUPilot program. More specific information is given in the chapters on the RXU-TM and the RXU-3E.

108 Chapter 5 RXUPilot About Palm OS™ handheld devices 108

About Palm OS™ handheld devicesThe Palm operating system (OS) is a product of Palm, Inc., and is widely used in handheld personal digital assistants (PDAs) such as PalmPilots, Hand Eras, and Symbol Technologies terminals. Although any Palm OS device can be used with the RXUPilot software, most are not suitable for field conditions. For this reason, Phoenix offers ruggedized terminals from Symbol Technologies and ACEECA (Meazura) for use in the field. The Meazura terminal is the standard offering; it is waterproof (submersible) and operates in temperatures from 0°C to 50°C. Optionally, the Symbol Technologies SPT1800 terminal can be purchased. The SPT1800 operates from –20°C to 50°C and has a more conveniently located infrared port.

Each handheld terminal is equipped with a touch screen and special stylus for user input, and an infrared (IR) transceiver for communication with the RXU.

The stylus acts in a manner similar to a mouse on a PC. The touch screen allows user input through the use of a special alphabet, called Graffiti™, instead of a keyboard. It is advisable to learn the Graffiti alphabet before attempting to use the RXUPilot software.

Additional documentation and software

The manufacturers of the handheld terminals provide their own documentation. Copies are provided as PDF files on the System 2000.net software CD. PC software for the Meazura terminal is supplied on a CD shipped with the terminal. PC software for the SPT1800 (SPTDSKEN) is supplied on the System 2000.net software CD.

The PC software is used to upgrade or reinstall the RXUPilot program. It is not needed for normal operation of RXUs.

Meazura. The Quick Start Guide for the Meazura terminal is reproduced in Appendix F on page 311. Meazura users may also find it helpful to read Chapters


3 and 16 of the Symbol SPT1800 Product Reference Guide. These chapters explain the Graffiti writing system and the installation and removal of applications.

Symbol SPT1800. Customers who purchase Symbol terminals should read the Quick Reference Guide and Product Reference Guide provided in Adobe Acrobat PDF on the System 2000.net software CD.

Refer to the Quick Reference Guide (QRG) for information on the following:

• parts of the SPT terminal• installing the battery• starting the SPT terminal• writing with the stylus• resetting the SPT terminal• maintaining the SPT terminal• troubleshooting the SPT terminal

Refer to the Product Reference Guide for complete information on the terminal, including most importantly:

• Chapter 1, Getting Started, which explains the physical controls, use of the stylus, connection of the charging cradle, and installation of the PC software.

• Chapter 3, Working with your SPT Terminal, especially pages 3–6 to 3–15, which explain the Graffiti writing system.

• Chapter 16, Installing and Removing Applications.

Graffiti tutorial. A tutorial on the Graffiti writing system is included as one of the Palm OS system applications. Because it is most efficient to use the Graffiti alphabet with the RXUPilot software, customers are advised to learn the writing system by using the tutorial.

To use the Graffiti tutorial:

1. Tap the Applications Launcher icon on the

handheld terminal.

2. If necessary, change the category to All or System.

3. Tap the Graffiti icon (see Fig. 5-1).

4. Follow the instructions on the handheld screen.


Fig. 5-1: Launch the Graffiti tutorial from the Applications Launcher, System category.

If you do not wish to use the Graffiti writing system, you can use the on-screen keyboards by tapping either the abc or 123 dots in the bottom corners of the writing area.

Infrared port

The infrared (IR) port on the RXU is located between the E-channel terminals marked E and S (channel 1). The IR port on the Meazura terminal (and on most

other Palm OS devices) is located on the narrow top edge. The IR port on the Symbol terminal is located on the back. (See Fig. 5-2.)

Hold the handheld terminal so that its IR port points directly at the RXU port, within a metre distance. If RXUPilot reports the RXU out of range, check that there is a direct line of sight between the ports, and/or move the handheld terminal closer to the RXU.

Fig. 5-2: Location of IR port on the back of the Symbol terminal.

If several instruments are operating close together (in a laboratory, for example), it may be necessary to temporarily shield the IR ports of instruments other

Infrared Port

111 Chapter 5 RXUPilot About RXUPilot 111

than the one you are establishing a connection with. Once communication is established, shielding is not necessary.

Tip Many of the windows in the RXUPilot program take several seconds to refresh after you make a change, close a dialog box, or update the window. Keep the IR ports properly aligned until the terminal beeps to indicate completion.

About RXUPilotRXUPilot is a software program for Palm OS™ handheld devices that allows you to control and monitor System 2000.net RXUs.

Warning In order to allow complete flexibility, RXUPilot provides access to all the system parameters in the RXU. Care should be taken not to change any parameters except as described in this User Guide. Random changes to parameters may cause operational or data problems that will be difficult to diagnose or correct.

RXUPilot functions are divided into seven groups:

• Instrument address (serial number)• GPS status• Calibration control• Communication status• Acquisition control• Station statistics display• Utilities

The following sections explain the use of the program and each functional group in general terms. Instructions specific to the RXU-3E and the RXU-TM are provided in chapters 6 and 7.

Launching RXUPilot

The RXUPilot program is already loaded on the handheld terminal. Refer to the Symbol SPT1800 Product Reference Guide on the System 2000.net software CD for instructions on uninstalling or reinstalling the program.

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Note You must be familiar with the handheld terminal and the Palm operating system to use RXUPilot. Follow the recommendations under “Additional documentation and software” on page 108 before attempting to use RXUPilot.

To launch RXUPilot:

1. Tap the Applications Launcher icon on the

handheld terminal.

2. If necessary, change the category to All or Phoenix.

3. Tap the RXUPilot icon (see Fig. 5-3).

Fig. 5-3: Launch RXUPilot from the Applications Launcher.

The program starts and requests an instrument serial number (see Fig. 5-4).


Fig. 5-4: RXUPilot at start-up.

4. Enter the serial number of the instrument you want to communicate with, and tap OK.

The main program window appears (see Fig. 5-5).

Fig. 5-5: RXUPilot main window.

Updating the display

Most windows in the RXUPilot program are populated with current information when they are opened. From that time, they do not update automatically; the information is correct only at the moment that it is beamed from the RXU. To know the current state of the instrument, you must update the information manually.


To update an RXUPilot window:

1. Aim the IR port at the RXU IR port and tap Update.

2. Keep the IR ports aligned until the handheld terminal beeps to indicate all information has been received.

Viewing and changing RXU serial number

The RXUPilot program uses the serial number of the RXU as an address when beaming over the infrared port. An RXU will not respond to the RXUPilot program if the RXU serial number is not entered correctly.

When you want to change the RXU that you are communicating with, change the serial number in the Address function.

If you encounter Out of IR Range errors even when holding the handheld terminal close to the RXU port, check that the serial number in the Address function matches the instrument you are working with.

To check or change the serial number:

1. Either tap Address on the RXUPilot main window or choose Change Box Address from the Options menu in any window.

The Box Address dialog box appears:

Fig. 5-6: Box Address dialog box.

2. If necessary, change the RXU serial number. and tap OK.

Viewing location, GPS status, and clock status

An RXU cannot be calibrated, acquire data or control a transmitter until it is synchronized to GPS signals. GPS also provides accurate time, latitude, longitude, and


elevation information. RXUPilot allows you to view this information.

To check GPS, clock, and location status:

1. Aim the IR port at the RXU IR port and tap GPS on the RXUPilot main window.

The GPS Status window appears (see Fig. 5-7).

Fig. 5-7: GPS Status window.


The window displays the following read-only information:

Number of satellites acquired. Four satellites must be acquired at least briefly to initiate synchronization and determine position. After initial synchronization, the number of satellites can vary without affecting the RXU synchronization; it will use its own internal clock.

UTC. “Universal Time Co-ordinated”. This is the UTC date and time at the moment the parameter was beamed by the RXU.

Latitude, longitude, and elevation. Latitude is in the format DDmm.mmm,P and longitude is in the format DDDmm.mmm,P, where D is degrees, m is minutes, and P is the compass point (N, E, S, or W). Elevation is in metres above sea level.

Clock error. If satellite synchronization is lost and then regained, there may be a an error of a few microseconds in the internal clock. The RXU will correct this error gradually over several minutes as long as the number of satellites remains at four or more.


Clock status. The RXU clock will be in one of four states:

• Uninitialized • Set to RTC, the Real Time Clock of the CPU• Aligned to GPS because four or more satellites are

currently acquired• Aligned to OCXO (oven-controlled crystal

oscillator) because contact has not been maintained with at least four satellites. The onboard OCXO allows the instrument to stay synchronized with other instruments for several hours without receiving GPS signals.

Controlling calibration

RXUs must be calibrated before use. Current monitors used with an RXU-TM must be calibrated using a calibrated RXU-TM. See Chapters 6 and 7 for further information.

The illustrations that follow are from an RXU-TM. RXU-3E instruments do not offer sensor calibration, since they do not use magnetic or current sensors.

To control calibration:

1. Aim the IR port at the RXU IR port and tap Cal on the RXUPilot main window.

The Calibration window appears (see Fig. 5-8).

Fig. 5-8: Calibration window.


3. Follow the instructions in Chapters 6 and 7 to set up and carry out the calibrations.


Viewing and changing parameters

The View Table function lets you view all operational parameters within the RXU and also lets you change a subset of them.

Normally you will not need to use the View Table function; however, specific instructions on changing some parameters are provided elsewhere in this Guide as necessary.

Accessing parameters. There are several hundred parameters in total. The first step is to transfer all of them to the handheld terminal.

To transfer all parameters:

1. Tap Utilites on the RXUPilot main window.

The Utilities window appears (see Fig. 5-9).

Fig. 5-9: Utilities window.

2. Tap View Table.

3. Read the warning and tap OK.

The Parameters window appears (see Fig. 5-10).


Fig. 5-10: Parameters window.

4. Aim the IR port at the RXU IR port and tap Update.

The handheld terminal beeps once per second for about 15 seconds while parameters are transferred. When the transfer is complete, the display is refreshed (see Fig. 5-11 on page 118).

Fig. 5-11: The Parameters window, updated.

The parameters appear in alphabetical order. You can scroll through them in order or randomly.

To access parameters in alphabetical order:

• Press the Scroll Buttons on the handheld terminal or tap the up and down arrows at the right of the window.

To access parameters randomly:

1. In the Graffiti text input area, write the first character of the parameter name.


The list scrolls to show the first parameter in the alphabetical list starting with that letter.

2. Tap the down arrow or press a Scroll Button if necessary until the parameter you want to access appears in the window.

Changing parameter values. Parameters that are read-only are marked with the ® symbol beside the value. Only parameter values not marked with the ® symbol can be changed.

Warning In order to allow complete flexibility, RXUPilot provides access to all the system parameters in the RXU. Care should be taken not to change any parameters except as described in this User Guide. Incorrect parameter settings may cause operational or data problems that will be difficult to diagnose or correct.

To change a parameter value:

1. Access the parameter name as just described.

2. Aim the IR port at the RXU IR port and tap the parameter name.

The Edit Parameters dialog box appears, showing the current value of the parameter (see Fig. 5-12).

Fig. 5-12: Editing the SNTX parameter.

3. Change the current value to the new value.

4. Aim the IR port at the RXU IR port and and tap Send.

The RXU parameter is updated with the new value.

Saving parameters (startup.tbl)

An RXU can be programmed to start up in a predetermined mode when it is powered on. If a special file, called startup.tbl, is on the CompactFlash card when the instrument is powered on, the contents of the file will be read and the instrument parameters and mode will be set accordingly. The intent of the startup file is to allow acquisition times and parameters to be set up so that operation in the field will be automatic.

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The startup.tbl file can be created on a PC and saved on the CF card, or the RXU can be programmed and the settings can be saved using RXUPilot.

The startup.tbl file contains only the user-changeable parameters, not the entire list that is visible in the View Table function. Also, in the acquisition start time parameter (STIM), only the time, not the date, is saved.

Note It is not advisable to save a startup.tbl file when the instrument is in a calibration mode, because any existing calibration file on the disk will be erased as soon as the instrument is next powered on.

To save parameters in a startup.tbl file:

1. Set all the parameters and the mode (Record, Setup, Standby, etc.) as you want them to be when the RXU is next powered on.

2. From the main window of RXUPilot, tap Utilities.

The Utilities window appears (see Fig. 5-13).

Fig. 5-13: Utilities window.

3. Tap Save Table, read the warning, and tap Yes.

The RXU saves the current settings in a startup.tbl file on the CF card.

Loading saved parameters

If a startup.tbl file exists on the CF card, it will be loaded when the instrument is powered on. However, changes to the parameters made after that point do not affect the file (unless you use the Save Table command described earlier). If you make changes to


the RXU settings and then decide you want to revert to the state saved in the startup.tbl file, you can do so by loading the file from disk into memory.

To load saved parameters:


2. Tap Load Table, read the warning, and tap Yes.

The RXU replaces the current settings with those in the startup.tbl file.

Viewing instrument status

RXUPilot provides quick access to several critical parameters, such as battery voltage, internal temperature, and space available on the CF card.

To view instrument status:


2. Tap Status.

The Unit Status window appears (see Fig. 5-14).

Fig. 5-14: Unit Status window.


Hardware. This text string is a code for the instrument type and version. If you experience problems with the instrument, you may be asked to provide this information to Phoenix Technical Support.

S/W Version. This text string is a code for the firmware installed in the instrument. If you experience problems with the instrument, you may be asked to provide this information to Phoenix Technical Support.


Battery 1. The voltage of the first external battery, as measured by the instrument.

Battery 2. If two external batteries are connected using a special cable, then this value is the voltage of the second external battery. If only one external battery is connected using the standard cable, then this value is the same as the Battery 1 reading.

Battery 3. This parameter is reserved for future use. Disregard any value shown.

Temperature. The internal temperature of the instrument. If the instrument temperature nears 60°C, it must be cooled or damage may result.

To cool an instrument:

1. Take the instrument out of its canvas case, position it with the terminals uppermost to maximize the surface exposed to the air, and shade the instrument from the sun.

2. Make sure air can flow freely around the instrument case.

3. If the temperature remains high, turn the instrument off for 15 minutes to let it cool down.

GPS FPGA. The status of the GPS subsystem. Any value other than “Loaded” indicates a problem; contact Phoenix Technical Support.

Front End FPGAs. The status of the input subsystems. Any value other than “All loaded” indicates a problem; contact Phoenix Technical Support.

DSP Status: The status of the Digital Signal Processors. Any value other than “All loaded” indicates a problem; contact Phoenix Technical Support.

Disk Free Space. The amount of storage space in megabytes available on the CF card.

Setting up radio communication

If the RXU is part of a radio network, you can set up the parameters governing wireless communication and monitor network status. See “Radio Communication” on page 159 for further information.


To access radio communication parameters:

1. Aim the IR port at the RXU IR port and tap Comm on the RXUPilot main window.

The Radio Comm Status window appears (see Fig. 5-15). The radio type is shown in the window title.

Fig. 5-15: Radio Comm Status window.



Network Status. If the RXU is communicating over the radio network, the Status will be Up. If not, it will be Down. It is normal for the status to alternate between Up and Down several times when the network is initializing.

IP Address. The Internet Protocol address assigned to the instrument, based on the instrument serial number.

Unit Address. The radio’s unit address, assigned by the master radio. If the unit address is zero, the instrument is not yet on the network.

Maximum Slaves. If this radio is the master, then it will report the number of slaves that have been configured. This value provides a quick check of the total number of instruments in the field that are communicating with the master. If this radio is a slave, then Maximum Slaves is not applicable (N/A).

The Radio Comm Status window also displays the following editable information. See Chapter 8, “Radio Communication” for a full explanation.


Tx Power. Radio’s Transmit Power setting.

Network Addr. Radio Network Address. All units must have the same Radio Network Address.

Encryption Key. Radio Encryption Key. All units must have the same Encryption Key.

Mstr Rng/Brng. Master range (Rng) in metres and bearing (Brng) in degrees from true north, or from magnetic north if the DECL (declination) parameter is not zero.

Master or Slave status. Only one radio can be the master; all others must be slaves.

To set up radio communication:

1. If this instrument is to be the Master radio, tap Master. Otherwise, tap Slave.

2. Set the Tx Power according to local conditions: lower power for low path loss, higher power for greater path loss.

3. If required, change the Network Addr. All instru-ments must use the same address.

4. If required, change the Encryption Key. All instru-ments must use the same key.

If other instruments are set up on the Network, the Network Status will change from Down to Up.

Using master bearing to aim directional antennas

If you are using directional antennas on slave radios, they must be accurately aimed toward the master, or radio communication will be poor or non-existent. If communication is established, you can read the Master bearing from the Radio Comm Status window as described on page 124. However, if no communication is established but the master radio’s position is known, you can input the master’s latitude and longitude and the RXU will calculate the range and bearing.

See “Viewing and changing parameters” on page 117 for instructions on how to use the View Table function in this procedure.


To enter the master radio position:

1. From the RXUPilot main window, tap Utilities.

2. Tap View Table.

3. Read the warning and tap OK.

4. Align the IR ports and tap Update.

5. When the window is refreshed, change the MSTRLAT and MSTRLNG parameters to the latitude and longitude of the master radio.

Within five seconds, the RXU will calculate the master radio range and bearing.

6. Return to the Radio Comm Status window and read the calculated range and bearing (Mstr Rng/Brng).

7. Use a compass to aim the directional antenna accurately at the calculated bearing.

Monitoring radio network quality

If you have set up an RXU-3ER to receive statistics from other RXUs (normally the transmitter monitor and the remote noise reference), you may want to monitor

the quality of communication with those instruments. The RXU sends a “ping” (a data packet requesting acknowledgement) every minute to test the network. If network quality is poor, then several minutes may pass between successful pings. You can monitor the network quality from the Radio Comm Status window.

To monitor network quality:

1. Aim the IR port at the RXU IR port and tap Remotes on the Radio Comm Status main window.

The Remote Units window appears (see Fig. 5-16 on page 126).


Fig. 5-16: Remote Units window.


If network communication is good, then each remote instrument that is to send statistics will be listed, and the time of the last ping will be within one or two minutes. If network communication is poor or there are other problems, the time of the last ping will be several minutes or the instrument may not be listed at all.

Controlling data acquisition

When the RXUs have been set up for the correct geophysical method and radio contact has (optionally) been established, you can control acquisition of data by the RXU.

The controls allow you to choose a geophysical method and start, stop, or pause recording. You can also enter a Standby mode that closes the data files for the current station without changing other parameters. You can then start a new record set at the current location, or move to the next station and start recording there.

Note You must stop acquisition (which puts the RXU into Setup mode) before you can change settings or parameters in the other windows of RXUPilot.

To control data acquisition:

1. Aim the IR port at the RXU IR port and tap Acquire on the RXUPilot main window.

The Controlled Source Acquisition window appears:


Fig. 5-17: Controlled Source Acquisition window.


3. Tap the commands in the window to control data acquisition.

Note The geophysical methods available are controlled by the licences you have purchased. Methods you have not purchased will not appear in the list of available methods.

Viewing station statistics

When data acquisition is in progress, you can monitor the statistics from any of the channels (local or remote) that are being acquired by an instrument.

1. Aim the IR port at the RXU IR port and tap Stats on the RXUPilot main window.

The Station Statistics window appears:

Fig. 5-18: Station Statistics window.



Enabling continuous update. Because data is acquired continuously, it is useful to have the statistics window updated automatically. Otherwise, you must tap Update each time you want to refresh the display.

To enable continous updating:

1. Aim the IR port at the RXU IR port and tap the Continuous checkbox on the Station Statistics window.

2. Keep the IR ports aligned.

The window will be updated approximately every four seconds and a beep will sound.

3. If the Mode changes to Out of Range, statistics cannot be transferred because the IR ports are not aligned or are too far apart. Realign the ports and keep them close together.

Interpreting station statistics. The top line of the Station Statistics window displays the current Mode

of the instrument: CSRecord (Controlled Source Record), Standby, or Setup. The second line (Present Freq) displays the value from the frequency-stepping table that is currently in use. The two arrows are used for scrolling (see the next section). Beneath the arrows are the station statistics themselves, in tabular format:

• Freq is the frequency for which statistics are displayed and applies to all columns in the table.

• Time is the UTC time of the last stack included in the calculation and applies to all columns in the table.

• SnCh is the Serial Number of the instrument, a slash, and the number of the Channel. Each Sn/Ch pair serves as a heading for the two columns below it.

• Ampl is the Amplitude of the signal in volts followed by the percent standard deviation. Micro-, milli-, and kilo- are indicated by u, m, and k, respectively.

• Phse is the Phase of the signal in degrees followed by its standard deviation in degrees.

• Rho is the Apparent Resistivity in ohm metres followed by the percent standard deviation. Micro-,

129 Chapter 5 RXUPilot Installing RXUPilot upgrades 129

milli-, and kilo- are indicated by u, m, and k, respectively.

Scrolling through station statistics. You can view the statistics in real time as they are calculated, or you can review statistics that were calculated for frequencies recorded earlier in the frequency-stepping schedule.

The window displays only two channels at a time. You can scroll through all the channels that are being acquired by the instrument.

To review statistics for other frequencies:

• Press the up or down Scroll Buttons on the handheld terminal to cycle through the frequencies that have been recorded.

To review statistics for other channels:

• Tap either the left or right arrow on the Station Statistics window to scroll through the channels.

Note If Continuous updating is enabled, pressing the Scroll Buttons will disable it. Tapping the left or right arrow on the screen, however, does not affect the state of Continuous updating.

Installing RXUPilot upgradesFrom time to time, Phoenix may release upgrades to the RXUPilot program. There are two ways to install the upgrade:

• Use the Palm Desktop software provided with your handheld terminal to install the new version at the next HotSync

• Beam the program from one handheld terminal to another.

In either case, the program will automatically be placed in the Phoenix category of the terminal’s Applications Launcher.

Refer to the instructions provided with your handheld terminal to learn how to use the Desktop software and

130 Chapter 5 RXUPilot Installing RXUPilot upgrades 130

how to beam a program from one handheld terminal to another.

131 Chapter 6 131

Chapter

The RXU-3E Receiver

This chapter explains the use of the RXU-3E receiver, including:

• Calibration• Radio setup• Channel setup (local and remote)• Operation

132 Chapter 6 The RXU-3E About the RXU-3E 132

About the RXU-3EThe RXU-3E is a two- or three-channel receiver designed to augment the channels acquired by a V8. It can be configured as a station receiver or a remote noise reference.

The RXU is controlled and monitored using the RXUPilot program on a handheld terminal. Read Chapter 5, “RXUPilot”, before operating the RXU-3E.

If a radio network is operating, the RXU can also be controlled and monitored from a V8.

Starting and shutting down the RXU-3E

To start the RXU-3E:



To shut down the RXU-3E:


Warning When shutting down the RXU-3E, always wait until shutdown is complete (the LED goes out) before disconnecting the battery.

Calibrating the RXU-3EBefore each survey begins, instruments must be calibrated. Once the equipment is set up, the process takes about 10 minutes. Each calibration must be completed in a single session; it cannot be interrupted and resumed. Because calibration requires GPS satellite lock, it is usually done outdoors. However, if the GPS antenna can be positioned outdoors and connected to the RXU with an extended cable, then the calibration can be done indoors.

Calibration is independent from operation: once an instrument is calibrated it can be used for any of the

!

133 Chapter 6 The RXU-3E Calibrating the RXU-3E 133

geophysical methods and any acquisition parameters. The instrument uses the calibration results and the operator’s gain and filter settings to calculate instrument response for any filter settings that may be used.

The RXU stores the resulting calibration file in the \CAL directory on its CompactFlash disk. The file is named ssss.CLB, where ssss is the serial number of the RXU. Do not rename, move, or delete the directory or the calibration file.

No additional equipment except the handheld terminal is needed to perform a calibration.

Tip For best results, the instrument should be at operating temperature when you start the calibration. In normal ambient conditions, an instrument will reach a stable operating temperature 10–15 minutes after it is powered on. In cold weather, allow more time before you start the calibration. To learn the internal temperature, select View Table from the Utilities window and examine the TEMP parameter.


• RXU to be calibrated• Battery and cable• GPS antenna and cable• Handheld terminal and RXUPilot software

To calibrate an RXU-3E:

1. Connect the GPS antenna to the RXU as described on page 24.

2. Connect the battery to the RXU as described on page 20.

3. Power up the RXU by pushing the red POWER switch up to the ON position and releasing it.

After a brief delay, the LED indicator between the North and South E-line terminals will light steadily for about 30s, then start flashing.

4. Launch the RXUPilot program.

5. Check GPS status. Wait until the RXU is synchro-nized to GPS.

6. From the RXUPilot main window, tap Cal.

The Calibration window appears:

134 Chapter 6 The RXU-3E Calibrating the RXU-3E 134

Fig. 6-1: Calibration window before instrument calibration.

7. Tap Box Cal.

If the RXU is synchronized to GPS, calibration begins immediately (see Fig. 6-2 on page 134).

Fig. 6-2: Instrument (Box) calibration in progress.

Tip If Current Mode is Box Cal but the Box Cal status line displays a message other than In progress, it is likely because GPS synchronization has not been achieved. Double check the GPS status window.

8. After about 10 minutes, tap Update periodically to see if calibration is complete. If calibration completed successfully, the Box Cal status line will display Cal file present (see Fig. 6-3).

135 Chapter 6 The RXU-3E Setting up radio communication 135

Fig. 6-3: Instrument (Box) calibration completed.

9. Tap Stop to end calibration and return to Setup mode.


You can cancel a calibration that is in progress. However, if you do so, there will be no calibration file for the instrument. Starting a calibration erases any corresponding existing files; cancelling a calibration writes no new files. The instrument will have to be recalibrated before use.


• In the Calibration window, tap Stop.

The calibration is aborted and the RXU returns to Setup mode.

Setting up radio communicationThis section explains how to set up the RXU to communicate with other instruments on a network. See Chapter 8 for complete information on System 2000.net radio, and follow those instructions to connect the instrument and antenna before beginning.

Setting up the network

Use the RXUPilot program on the handheld terminal to set up the radio network.


To set up the network:

1. Aim the IR port at the RXU IR port and tap Comm on the RXUPilot main window.

The Communication Status window appears (see Fig. 6-4).

Fig. 6-4: Communication Status window.



4. If required, change the Network Addr, keeping the IR ports aligned. All instruments must use the same address.

5. If required, change the Encryption Key, keeping the IR ports aligned. All instruments must use the same key.


Acquiring remote channels

An RXU can acquire statistics from remote channels and incorporate them into its own calculations. Typically, three remote channels will be acquired: one from the transmitter monitor (RXU-TM) and two from the remote noise reference (an RXU-3E). However, the channels could come from other RXU-3E or V8 instruments, to a maximum of 6 channels (including local channels).

Before the RXU can acquire these channel statistics, you must assign the serial numbers of the instruments performing each function.


To acquire remote channels:

1. Align the IR ports and on the RXUPilot main window, tap Acquire.

The Controlled Source Acquisition window appears (see Fig. 6-5 on page 137).

Fig. 6-5: Controlled Source Acquisition window.

2. Tap Remotes.

The Configure Remotes window appears (see Fig. 6-6), displaying the serial numbers of the Transmitter Monitor (Tx Controller), the remote Noise Reference, and up to five remote RXU-3ER and/or V8-R instruments (Remote 1 through Remote 5).

Fig. 6-6: Configure Remotes window.

3. To the right of the instrument you want to configure, tap Set.

4. In the dialog box that appears, enter the serial number of the remote instrument and tap OK. (See Figs. 6-7, 6-8, and 6-9 on page 138.)

138 Chapter 6 The RXU-3E Setting up local electric channels 138

Fig. 6-7: Transmitter Monitor serial number dialog box.

Fig. 6-8: Remote Noise Reference serial number dialog box.

Fig. 6-9: First Remote RXU or V8 serial number dialog box.

5. Repeat steps 3 and 4 for the remaining remotes, remembering that the RXU is limited to six channels total, including its own local channels.

Setting up local electric channelsThis section explains how to connect electrodes to the RXU. For general techniques and instructions on installing electrodes and setting up the instrument in the field, see Chapter 3.

139 Chapter 6 The RXU-3E Operating and monitoring the RXU-3E 139

It is important to connect the channel electrodes to the correct terminals on the instrument. When electrodes are shared, each pair of terminals forms a channel. The channels are marked 1, 2, and 3 on the side of the instrument below the terminals. When the E channel dipoles are not parallel to the transmitter dipole, the dipole closest to the transmitter should be connected as channel 1. If the E channels are parallel to the transmitter dipole, adopt a consistent method for designating channel order for all instruments.

To set up local E channels:

1. Determine the location of the station electrodes and place the RXU-3E near one of the inner electrodes.

2. Install a ground electrode and connect it to the RXU-3E.

3. Install the channel electrodes and connect them to the RXU-3E, being careful to use the correct terminals.

Note Two separate instruments cannot share an electrode. If two instruments need to share the same electrode location, install two electrodes separated by at least a metre, to prevent cross-talk.

Operating and monitoring the RXU-3EThis section explains the remaining tasks in setting up a station and operating the instrument.

To finish site installation and operate the RXU-3E:

1. Connect the GPS antenna.

2. Connect the radio antenna, if used.

3. Connect the battery.

4. Power up the RXU-3E by pushing the red POWER switch up to the ON position and releasing it.

140 Chapter 6 The RXU-3E Operating and monitoring the RXU-3E 140


5. Use the RXUPilot program to control data acqui-sition and monitor station statistics. See Chapter 5

for further information. Alternatively, control and monitor the RXU from a V8 over a radio network. See Chapter 3, “Common Operations” and the chapters on individual geophysical methods for instructions.

141 Chapter 7 141

Chapter

The RXU-TM Transmitter Monitorand CMU-1 Current Sensor

This chapter explains the use of the RXU-TM transmitter monitor, including:

• Calibration• Radio setup• Field setup• Frequency stepping setup• Operation

142 Chapter 7 The RXU-TM About the RXU-TM and CMU-1 142

About the RXU-TM and CMU-1The RXU-TM is a single channel instrument designed to monitor and/or control the output of a Phoenix current source (transmitter), in conjunction with the CMU-1 Current Sensor.

The RXU-TM is controlled and monitored using the RXUPilot program on a handheld terminal. Read Chapter 5, “RXUPilot”, before using the RXU-TM.

If the instrument is radio-equipped, it can also be controlled from a V8 on the network.

The CMU-1 current sensor is made in two versions, with different sensitivities. Sensors with serial numbers from 1000 to 1999 are for use with low- to moderate-power transmitters such as the T-3, T-4, and T-30. These sensors can be used with a maximum current of 50A. Sensors with serial numbers from 9000 to 9999 are for use with high-power transmitters such as the T-200. These sensors can be used with a maximum current of 200A.

Starting and shutting down the RXU-TM

To start the RXU-TM:



To shut down the RXU-TM:


Warning When shutting down the RXU-TM, always wait until shutdown is complete (the LED goes out) before disconnecting the battery. !

143 Chapter 7 The RXU-TM Calibrating the equipment 143

Calibrating the equipmentBefore each survey begins, instruments must be calibrated. Once the equipment is set up, the process takes about 10 minutes for the instrument and half an hour or more for the current sensor. Each calibration must be completed in a single session; it cannot be interrupted and resumed. Because calibration requires GPS satellite lock, it is usually done outdoors. However, if the GPS antenna can be positioned outdoors and connected to the RXU with an extended cable, then the calibration can be done indoors.

Calibration is independent from operation: once an instrument is calibrated it can be used for any of the geophysical methods and any acquisition parameters. The instrument uses the calibration results and the operator’s gain and filter settings to calculate instrument response for any filter settings that may be used.

The RXU stores the resulting calibration files in the \CAL directory on its CompactFlash disk. The instrument calibration file is named ssss.CLB, where ssss is the

serial number of the RXU. Current sensor calibration files are named CSENssss.CLC, where ssss is the serial number of the current sensor. Do not rename, move, or delete the directory or the calibration files.

No additional equipment except the handheld terminal is needed to perform a calibration.

Calibrating the RXU-TM

Tip For best results, the instrument should be at operating temperature when you start the calibration. In normal ambient conditions, an instrument will reach a stable operating temperature 10–15 minutes after it is powered on. In cold weather, allow more time before you start the calibration. To learn the internal temperature, select View Table from the Utilities window and examine the TEMP parameter.


• RXU to be calibrated• Battery and cable• GPS antenna and cable


• Handheld terminal and RXUPilot software

To calibrate an RXU-TM:

1. Connect the GPS antenna to the RXU as described on page 24.

2. Connect the battery to the RXU as described on page 20.

3. Ensure that a CompactFlash disk has been installed.

4. Power up the RXU by pushing the red POWER switch up to the ON position and releasing it.


6. Check GPS status. Wait until the RXU is synchro-nized to GPS.

7. From the RXUPilot main window, tap the Cal button.

The Calibration window appears (see Fig. 7-1 on page 144)

Fig. 7-1: Calibration window before instrument calibration.

8. If the Current Mode is not Setup, exit the Calibration window, open the Acquire window, and tap Stop. Then return to the Calibration window.

9. Tap the Box Cal button.

If the RXU is synchronized to GPS, calibration begins immediately (see Fig. 7-2).


Fig. 7-2: Instrument (Box) calibration in progress.

Tip If Current Mode is Box Cal but the Box Cal status line displays a message other than In progress, it is likely because GPS synchronization has not been achieved. Double check the GPS status window.

10.After about 10 minutes, tap the Update button periodically to see if calibration is complete. If calibration completed successfully, the Box Cal status line will display Cal file present (see Fig. 7-3).

Fig. 7-3: Instrument (Box) calibration completed.


Calibrating the CMU-1 sensor

The process is very similar to instrument calibration, but takes at least 25 minutes. In electrically noisy conditions, a longer calibration is beneficial. Current sensors designed for use with high-output transmitters such as the T-200 (“CMU-1 (mod)”) require up to four hours for proper calibration.


The RXU-TM must already be calibrated before using it to calibrate a current sensor.

Note Newer models of the Phoenix T-4 current source have a CMU-1 sensor built in.

To prepare for calibrating the current sensor:

1. Choose a location for calibration where the current sensor can be located several metres away from any current-carrying wires or sources of electromagnetic noise.

2. Connect the GPS antenna to the RXU-TM as described on page 24.

3. Connect the battery to the RXU-TM as described on page 20.


5. Make a note of the current sensor serial number, or the T-4 serial number.

6. Connect the current sensor (CMU-1) to the RXU-TM using a two-way (6273B0) cable, or connect the T-4 to the RXU-TM using a 62951 cable.

Note Do not connect the two-way cable to a transmitter. Such a connection disables the calibration current generator, preventing valid calibration.

Do not put any wires through the current sensor aperture. Power the T-4, with output turned off.

7. Power up the RXU-TM by pushing the red POWER switch up to the ON position and releasing it.


9. Check GPS status. Make sure the RXU-TM is synchronized to GPS.

To calibrate the current sensor:

1. From the RXUPilot main window, tap the Cal button.

The Calibration window appears (see Fig. 7-4).


Fig. 7-4: Calibration window before sensor calibration.

2. If the Current Mode is not Setup, tap Stop to return to Setup mode.

3. Tap Sensor Cal.

The Sensor Calibration window appears (see Fig. 7-5).

Fig. 7-5: Sensor Calibration window.

4. If the Serial # shown is not that of the sensor you are calibrating, tap the Change button to the right of it.

The Sensor Serial Number dialog box appears:


Fig. 7-6: Sensor Serial Number dialog box.

5. If you are calibrating an external CMU-1, edit the serial number to match the sensor you are calibrating and tap OK.

If you are calibrating a CMU-1 built in to a T-4, enter “T4-” plus the serial number of the T-4 trans-mitter.

6. In a similar way, set the Sensor Gain to 100 for the CMU-1 or T-4, or to 5 for the CMU-1 (mod) (see Fig. 7-7).

Fig. 7-7: Sensor Gain dialog box.

7. Set the Signal Amp (calibration test signal amplitude) to –0.05 for the CMU-1 or T-4, or to –0.10 for the CMU-1 (mod) (see Fig. 7-8).

Fig. 7-8: Test Signal Amplitude dialog box.


8. Set the calibration Time (x 0.2 hr) to at least 2 for the CMU-1 or T-4, or to at least 20 for the CMU-1 (mod) (see Fig. 7-9).

Fig. 7-9: Sensor Calibration Multiplier dialog box.

9. Tap Sensor Cal.

Calibration of the current sensor begins immediately (see Fig. 7-10).

Fig. 7-10: Sensor calibration in progress.

10.After the scheduled calibration time has passed, update the Calibration window and verify that the Sensor Cal status reads Cal file present (see Fig. 7-11).


150 Chapter 7 The RXU-TM Setting up radio communication 150

Fig. 7-11: Sensor calibration completed.


You can cancel a calibration that is in progress. However, if you do so, there will be no calibration file for the instrument or sensor that was being calibrated. Starting a calibration erases any corresponding existing file; cancelling a calibration writes no new file. The instrument or sensor will have to be recalibrated before use.


• In the Calibration window, tap Stop.

The calibration is aborted and the RXU-TM returns to Setup mode.

Setting up radio communicationThis section explains how to set up the RXU-TM to communicate with other instruments on a network. See Chapter 8 for complete information on System 2000.net radio, and follow those instructions to connect the instrument and antenna before beginning.

Setting up the network

Use the RXUPilot program on the handheld terminal to set up the radio network.

151 Chapter 7 The RXU-TM Setting up the RXU-TM, current sensor, and transmitter 151

To set up the network:

1. Aim the IR port at the RXU-TM IR port and tap the Comm button on the RXUPilot main window.

The Communication Status window appears (see Fig. 7-12).

Fig. 7-12: Communication Status window.

2. Keep the IR ports aligned as you complete the next steps.



5. If required, change the Network Addr. All instru-ments must use the same address.

6. If required, change the Encryption Key. All instru-ments must use the same key.


Setting up the RXU-TM, current sensor, and transmitterThis section explains how to make various connections to the RXU and transmitter. For general techniques and instructions on installing electrodes and setting up the instrument in the field, see Chapter 3.


It is important to connect the current monitor correctly. Ensure that the transmitter electrode wires are correctly identified as positive or negative, and that the transmitter wire passing through the current monitor aperture passes in the correct direction, as marked on the sensor. Use a length of tinned copper braid grounded at one end only to serve as a Faraday shield against electrical pick-up from the transmitter wire.

Follow the instructions in the User Guide for the transmitter you are using to set it up with low-resistance current electrodes and proper grounding.

Newer T-4 transmitters have an internal CMU-1 current monitor. Refer to the T-4 User Guide for instructions.

Note Do not turn on the transmitter or connect the positive electrode cable to the transmitter until you have set up the current sensor.

Fig. 7-13: RXU-TM, CMU-1, and transmitter setup.

12V

Transmitter

CMU-1

RXU-TMGPS

+–Tinned copper braid

Two-way cable (6273B0)

to Tx negative electrode to Tx positive electrode


Fig. 7-14: RXU-TM and T-4 transmitter setup.

To set up the RXU-TM and current sensor:

1. See Figure 7-13 for an illustration of the completed setup using an external CMU-1. See Figure 7-14 for an illustration of the completed setup using a T-4 with internal CMU-1.

2. Connect the GPS antenna to the RXU-TM as described on page 24.

3. Connect the battery to the RXU-TM as described on page 20.


5. If you are using a newer T-4 transmitter with built-in CMU-1, then connect the RXU-TM to the T-4 using cable number 62951 and skip to step 13.

6. If you are using an external CMU-1, connect the current sensor (CMU-1) to the RXU-TM using one pigtail of a two-way (6273B0) cable.

7. Thread the positive transmitter electrode cable through a 30cm length of tinned copper braid.

8. Thread the cable and braid through the aperture of the current sensor, in the direction indicated by the TX+ marking on the sensor.

9. Connect the positive electrode cable to the trans-mitter.

10. Ensure that the tinned braid extends approximately equally on either side of the sensor aperture.

11.Connect the braid to the transmitter ground electrode.

12V

T-4

RXU-TMGPS

+

–

Cable (62951)

+

–

Output terminals (to loop)

BP24/72

154 Chapter 7 The RXU-TM Operating and monitoring the RXU-TM 154

12.Connect the RXU-TM to the transmitter’s external control terminal using the second pigtail of the two-way cable.

13. Power up the RXU-TM by pushing the red POWER switch up to the ON position and releasing it.


Operating and monitoring the RXU-TMYou can use the RXUPilot program to control data acquisition and monitor station statistics locally. See Chapter 5 for further information. Alternatively, control and monitor the RXU from a V8 over a radio network. See the chapters on individual geophysical methods for instructions.

Setting up frequency stepping

This section explains how to use the RXUPilot program to set up automatic frequency stepping.

Frequency stepping can be controlled by a schedule file saved on the RXU-TM CompactFlash card, or by setting the value of a number of parameters within the RXU-TM. See Chapter 9, “Frequency Stepping”, for further information.

To set up file-based frequency stepping:

1. Launch RXUPilot and tap Utilities.

2. Tap View Table and update the parameters.

3. If the value of the RQST parameter is not 1, change it to 1, which puts the RXU-TM into Setup Mode.

4. Change the value of the AUTO parameter to match the name of the schedule file you want to use.

For example, if you want to use schedule file 3.TFS, change the value of AUTO to 3.


When you begin recording data, the RXU-TM will control the transmitter using the frequency stepping table contained in the selected schedule file.

To set up parameter-based frequency stepping:

1. Launch RXUPilot and tap Utilities.

2. Tap View Table and update the parameters.

3. If the value of the RQST parameter is not 1, change it to 1, which puts the RXU-TM into Setup Mode.

4. Change each of the following parameters to suitable values, as explained in Chapter 9, “Frequency Stepping”:

• WFRM, the waveform code

• FRQ0 to FRQ19, non-pattern and pattern frequencies

• FEND, the approximate lowest frequency

• FPOC, frequencies per octave

• TPFR, minimum time per frequency

• CPFR, minimum cycles per frequency

• TTOT, total duration of schedule in seconds

• CRMX, maximum current at low frequencies

• FCMX, current roll-off corner frequency

5. Change the value of the AUTO parameter to 1.

When you begin recording data, the RXU-TM will control the transmitter using the frequency stepping schedule determined by the parameters.


Setting channel gain

It is essential to set the gain correctly. An incorrect setting can make the data unusable because every record will be saturated. Set the gain before data acquisition, and change it if necessary during acquisition as the transmitter output changes. Table 7-1 shows the peak signal strength that can be recorded on the current sensor channel at each gain setting, as it appears in the V8 Site Setup window and the RXUPilot View Table function.

To set current sensor channel gain:

1. Determine the peak current expected from the transmitter and the appropriate gain from Table 7-1.

2. If the RXU-TM is in Record mode, change it to Standby or Setup mode.

3. Do one of the following:

• Use the V8 Site Setup window and the radio network to set the H Gain of the RXU-TM to the correct gain.

• Use the View Table function in the Utilities window of the RXUPilot program to change the value of the HGNC parameter.

Controlling data acquisition

Use the RXUPilot program to control data acquisition and monitor station statistics. See Chapter 5 for further information. Alternatively, control and monitor the RXU-TM from a V8 over a radio network. See the chapters on individual geophysical methods for instructions.

Table 7-1: Gain factors and signal strength

Gain Setting Peak Current

V8 SiteSetup

RXUPilotHGNC

CMU-1 Mod CMU-1

0.25 –1 50A —

1 0 20A 200A

4 1 5A 100A

16 2 1.25A 25A



159 Chapter 8 159

Chapter

Radio Communication

Any of the instruments in the System 2000.net family can be equipped with radio modems for wireless communication.

This chapter provides instructions on setting up and operating the radio network. It also provides background information and suggestions to help ensure reliable communication among instruments.


160 Chapter 8 Radio About System 2000.net radio 160

About System 2000.net radioSystem 2000.net instruments equipped with the optional radio feature communicate over a spread-spectrum, frequency-hopping radio network operating in the Industrial, Scientific, and Medical (ISM) bands. The model number of an instrument equipped with the radio feature has the suffix “R”.

Depending on local regulations and frequency band allocation, the ISM band may be 902–928MHz or 2.4000–2.4835GHz. The 2.4GHz band is more common, and is the standard configuration of Phoenix instruments.

The data protocol is TCP/IP (Transport Control Protocol/Internet Protocol) and the radio protocol is TDMA (Time Division Multiple Access). TCP/IP ensures the integrity of the data. TDMA manages multiple communications by allocating a short, dedicated time slot to each instrument. Therefore, communication occurs between only two instruments at a time without interference from others on the network.

When conditions are suitable, the various instruments in a survey transmit and receive status information and data in real time. A V8 can also control RXU instruments on the network. For example, a V8 could set up an RXU as a reference or acquisition station or cause it to start and stop acquisition; or, a V8 could send the same frequency-stepping schedule to all the instruments on the network.

If radio communication is interrupted, the instruments will continue to acquire, process, and store data. When communication is re-established, the data acquired within the last 5 minutes will be transmitted.

Lengthy interruptions or complete failure of the network do not prevent completion of the survey, because all the instruments store their data on CompactFlash cards. The data can later be transferred to a PC for post-processing.

Configurations

Radio Type (Master or Slave). In any System 2000.net radio network, one instrument must be designated as


the master, and all the others as slaves. The slave radios can communicate only with the master radio, not with each other. The master acts as a TCP/IP router, relaying communications among the other instruments. For this reason, the master should have the tallest antenna mast. If there are several remotes sending data to the V8, it’s best to designate the V8 as the master and the remotes as slaves. However, any station can be designated as the master radio if necessary.

Note The master-slave relationship is strictly a radio concern. It should not be confused with the relationship between a V8 and remote RXUs where the V8 controls the remote instruments. The V8 does not have to be the radio master to be able to control remotes. Any type of instrument can be a radio master or slave.

On a V8, set the Radio Type to Master or Slave in the Options and Status dialog box. On an RXU, select either Master or Slave in the Communications Status window of the RXUPilot program.

Network address. The Radio Network Address is an arbitrary number between 0 and 65 535 that you set on each instrument. All instruments that are to communicate with each other must use the same radio network address. If two surveys are being carried out close to each other, you can prevent them from interfering with each other by using a different radio network address for each survey.

On a V8, set the Radio Network Address in the Options and Status dialog box. On an RXU, set the Network Addr in the Communications Status window of the RXUPilot program.

Unit address. A unique Radio Unit Address is assigned by the master radio to each instrument on the network. The unit address can be any number from 0 to 199, so theoretically, up to 200 instruments can be connected on a single network. However, because of the amount of data to be transmitted and the variability of radio conditions, the practical limit will probably be less than ten instruments on a network.

The radio system determines the unit address automatically as each slave establishes contact with


the master radio. If the unit address is zero, the instrument is not communicating on the network.

On a V8, view the Radio Unit Address in the Options and Status dialog box. On an RXU, view the Unit Address in the Communications Status window of the RXUPilot program.

Encryption key. The Radio Encryption Key provides enhanced security for your data. Like the Radio Network Address, it can be any number between 0 and 65 535, and must be the same for all instruments that are to communicate with each other.

If security of communication is a concern, use large random numbers for both the Radio Network Address and the Radio Encryption Key.

On a V8, set the Radio Encryption Key in the Options and Status dialog box. On an RXU, set the Encryption Key in the Communications Status window of the RXUPilot program.

Power

The Radio’s Transmit Power is adjustable. In the 900Mz band, it can range from 1mW to 1W. In the 2.4GHz band, it can range from 10mW to 1W.

The default setting in both frequency bands is 1W.

In some countries, maximum transmission power in the ISM band is limited by law.

On a V8, set the Radio’s Transmit Power in the Options and Status dialog box. On an RXU, set the Tx Power in the Communications Status window of the RXUPilot program.

Antennas and masts

A variety of antennas and masts are available to suit different conditions.

Types of antennas. Three types of antenna are available:


• small whip antennas that mount directly on the instruments

• omni-directional antennas with a higher gain than the whip antennas, and that are normally mounted on a mast or tripod

• directional antennas, also with a higher gain than the whip antennas, and mounted on a mast or tripod

For survey conditions where there is good line of sight and relatively short distances between slaves and the master, the whip antennas are suitable on the slaves, with either a whip antenna or (preferably) an omni-directional antenna on the master.

Where topography or vegetation block the line of sight, or where longer distances separate the instruments, omni-directional or directional antennas are necessary on all instruments.

Aiming directional antennas. Directional antennas must be aimed accurately or poor communication will result. Instruments can calculate the compass bearing to the master radio to help you aim the antennas.

If the master radio’s position is received by a slave instrument, or if you enter the master radio’s position manually, the slave instrument will calculate the compass bearing (and distance) to the master radio.

Note When radio communication is established, latitude and longitude values entered manually will be overwritten by actual values received from the master radio, and bearing will be recalculated.

Latitude is in the format DDmm.mmm,P and longitude is in the format DDDmm.mmm,P, where D is degrees, m is minutes, and P is the compass point (N, E, S, or W).

The bearing is given in degrees relative to true north unless a value for Declination has been entered in the Site Setup dialog box of a V8 or the DECL parameter of an RXU (from the Parameters window of the RXUPilot program). If declination has been set, then bearing is relative to magnetic north.

On a V8, set the Radio master latitude and Radio master longitude in the Options and Status dialog box. On an RXU, set the Radio master latitude from the


Parameters window of the RXUPilot program by assigning a value to the MSTRLAT parameter. Set the Radio master longitude by assigning a value to the MSTRLNG parameter.

On a V8, read the Radio master bearing and Radio master distance in the Options and Status dialog box. On an RXU, read the Mstr Rng/Brng from the Communications Status window of the RXUPilot program.

Types of masts. For good radio communication, the most critical factor is the height of the antennas above the ground. A tripod mount and two types of masts are available:

• land-surveyor’s tripod modified to accept an antenna, approximately 2m high

• medium-height (8m) military-grade mast with guy wires

• tall (15m) military-grade mast with guy wires

For use with slave radios, the tripod is a good choice, as it is light and portable. Generally, you should use either the 8m or 15m mast for the master radio

antenna, since it must be able to communicate with all the slave radios.

Communication content and schedule

When the instruments on a network are powered on, the slaves attempt to contact the master at random short intervals. For quickest network configuration, power the master radio first, then power each of the slave instruments at different times so they are not competing to contact the master.

When the master connects with a slave, it assigns a unique unit address to that instrument and automatically updates it with several parameters, such as the master’s latitude and longitude. (See “Aiming directional antennas” on page 163 for a discussion of how to use this information.)


Note If there are more than 6 radios on the network, it is normal for the Net indicator to alternate between Off and On until all the slave radios have been configured by the master.

Once the radio network is established, the master sends a ping to each slave once per minute as a test of continued communication. (A ping is simply a short data packet that requests an acknowledgement.) Instruments on the network that are set up to request stack results from each other will also ping each other and track the time from the last successful ping.

If the V8 is successfully communicating with a remote instrument, the Update cell for that instrument in the Box spreadsheet of the Site Setup window will be highlighted in red.

When you choose Start Recording from the V8 Acquisition menu, the V8 sends the following information to the station RXUs (i.e., not the transmitter monitor or noise reference RXUs) on the network:

• Site name

• Line number• Geophysical factor (IP only)

If you set Remote Control to Yes in the V8 Site Setup dialog box, the V8 will also control the recording status of the RXUs. Each time you choose a command from the Acquisition menu (Start Recording, Pause Recording, Standby), the V8 will send the same command to each of the RXUs currently on the network.

When the instruments are acquiring data, they calculate geophysical parameters such as resistivity, phase, and chargeability from stacked waveforms. The slaves send these statistics to the master, which then forwards them to the other instruments along with its own statistics.

All instruments on the network can incorporate other instruments’ statistics in their own calculations. However, only the V8 has the processing power and memory to handle statistics from the entire network. RXUs are limited to 6 channels—typically three local

166 Chapter 8 Radio Factors affecting radio communication 166

channels, two noise-reference channels, and the transmitter monitor (RXU-TM) channel.

If radio communication is interrupted or of poor quality, instruments will try to resend their results. When viewing stack results in the V8 Acquisition window, you will see a time lag reported for channels that are not up to date. Instruments will not try to resend data that is older than 5 minutes.

Factors affecting radio communicationThree factors determine the success of radio communication among instruments:

• system gain• path loss• interference

For reliable communications, system gain must be well above path loss. Interference is generally an uncontrollable variable.

System gain

System gain is the combined effect of:

• transmitter power• transmitter gain• receiver gain• receiver sensitivity

The receiver sensitivity is not adjustable; however, system gain can be increased by increasing the transmitter power or changing antennas to increase transmitter and/or receiver gain.

Transmitter power. On the V8, the Radio’s Transmit Power is user selectable from the Options and Status dialog box. On RXUs, Tx Power is user selectable from the Communications Status window.

In the 900 MHz band, four power levels are available: 1mW, 10mW, 100mW, and 1W, corresponding to 0, 10, 20, and 30dBm.

In the 2.4GHz band, seven power levels are available: 10mW, 50mW, 100mW, 250mW, 500mW, 750mW, and 1 W.


Note The default value for transmitter power on all instruments is 1W—the maximum available. You can reduce the output power to conserve battery power in areas of good radio reception, or when testing instruments in a laboratory setting.

Transmitter gain. The transmitting antenna may be a normal-gain or high-gain antenna. The transmitter gain is the antenna gain minus cabling loss between the antenna and the instrument.

Receiver gain. Similar to transmitter gain. The receiving antenna may be a normal-gain or high-gain antenna. The receiver gain is the antenna gain minus cabling loss between the antenna and the instrument.

Receiver sensitivity. Radio receiver sensitivity in the System 2000.net family is –105dBm.

The maximum system gain is the maximum transmitter power plus the receiver sensitivity (30 + 105 = 135dBm), plus the antenna gains, minus the cable loss.

Path loss

Path loss is the reduction in signal strength due to distance or obstacles between antennas.

A flat terrain with unimpeded line of sight between instruments is the best environment for radio communication. Path loss will increase unpredictably in hilly or wooded terrain or where there are other obstacles between the instrument antennas.

The only ways to overcome or reduce path loss are to increase the height of the antennas above the ground or, if directional antennas are in use, to aim the antennas more accurately.

Table 8-1 presents examples of path loss for different antenna heights and distances. The figures are real averages taken from rural environments, using the 2.4GHz band.


Gain margin

The difference between system gain and path loss is the gain margin, and must be at least 10dB for reliable communication. The following methods can be used to increase gain margin:

Increase system gain.

• Increase the radio transmitter power.• Change to a high-gain antenna on one or more

instruments.

• Change to a shorter antenna cable.

Decrease path loss.

• Change to a directional antenna on one or more slave instruments and aim the antenna(s) at the master antenna.

If radio communication has been established, the master will transmit its latitude and longitude to the slaves. If not, you can enter that information manually. The instrument will then calculate the bearing so you can aim the antenna accurately.

• Increase the height of the antennas above the ground. In particular, the antenna on the master radio should always be positioned as high as possible.

• Reposition the antennas, attempting to get line-of-sight between instruments.

Table 8-1: Path loss examples (2.4GHz)

Distance (km)

Base Height (m)

Remote Height (m)

Path Loss (dB)

5 15 2.5 121.5

5 30 2.5 115.9

8 15 2.5 129.1

8 15 5 122.7

8 15 10 110

169 Chapter 8 Radio Setting up radio communication 169

Setting up radio communicationThis section explains the physical setup of radio antennas and masts, and how to control the radio network from the instruments.

Assembling antenna tripods

When Phoenix ships an antenna tripod, the mast section is attached upside down to reduce overall length. Before using a tripod for the first time, you must reinstall the mast section right side up.

To assemble an antenna tripod:

1. Remove the six Phillips screws holding the mast to the tripod, as shown in Figure 8-1.

Fig. 8-1: Remove 6 screws.

2. Pull the mast out of the tripod, reverse it so the mast points upward, and replace the six screws. (See Fig. 8-2.)


Fig. 8-2: Tripod with mast reinstalled.

Installing an omni-directional antenna on a tripod

Eight pieces of equipment are required to install the antenna on a tripod:

• antenna• 1m antenna cable• 5m antenna cable

• cable connector• mounting tube• mounting tube collar• two large mounting screws

The shorter cable is intended to remain connected to the antenna, and the antenna is intended to remain connected to the mounting tube, for the duration of the survey. The cable connector joins the shorter cable to the longer cable, which connects to the instrument. This arrangement makes it easy to detach the antenna from the instrument when moving from site to site.

Warning Antenna cable is heavy and not very flexible. In cold temperatures, it also becomes brittle. To prevent cable breaks, do not bend antenna cable sharply or allow it to kink.

To install the antenna on a tripod:

1. Slide the mounting tube collar onto the mounting tube and position it 2–3cm below the screw hole in the tube (but at least 15cm from the bottom of the tube). (See Fig. 8-3 on page 171.)

!


Fig. 8-3: Antenna in mounting tube with collar in place.

2. Use the hexagonal wrench supplied to tighten the three set screws around the circumference of the collar.

3. Connect the 1m cable to the antenna.

4. Remove the locking screw from the antenna base.

5. Insert the 1m cable into the end of the mounting tube nearest the collar.

6. Slide the mounting tube over the cable and fit the tube to the antenna base, aligning the screw holes.

7. Replace the antenna locking screw and tighten it.

8. Feed the 1m cable into the top of the tripod mast and slide the mounting tube into the mast. (See Fig. 8-4 on page 172.)

9. Insert the two large screws into the holes on either side of the mast and tighten until the mounting tube is secure.

10.Use the cable connector to join the 5m cable to the 1m cable.

11.Remove the protective cap from the instrument antenna terminal and connect the 5m cable to the instrument.

Antenna

Antenna locking screw

Mounting tube collar

Set screw

Mounting tube

≥15cm


Fig. 8-4: Antenna assembly secured in tripod mast.

Installing an omni-directional antenna on a mast

The only major difference between tripod and mast installation is that two U-bolts are used instead of a collar and set screws.

To install the antenna on a mast:

1. Connect the 1m cable to the antenna.

2. Remove the locking screw from the antenna base.

3. Insert the 1m cable into the end of the mounting tube nearest the screw hole.

4. Slide the mounting tube over the cable and fit the tube to the antenna base, aligning the screw holes.

5. Replace the antenna locking screw and tighten it.

6. Use the two U-bolts supplied to fasten the mounting tube securely to the top of the antenna mast.

7. Use the cable connector to join a 15m or 20m cable to the 1m cable.

8. Follow the manufacturer’s instructions to raise and stabilize the mast.

Antenna

Mounting tube collar

Mounting tube inside mast

1m cable inside mast

cable connector

5m cable to instrument

Securing screws


9. Remove the protective cap from the instrument antenna terminal and connect the cable to the instrument.

Warning Antenna cable is heavy and not very flexible. In cold temperatures, it also becomes brittle. To prevent cable breaks, do not bend antenna cable sharply or allow it to kink.

Installing a whip antenna

The small whip antennas connect directly to the instrument without a cable. They are effective only when path loss is relatively small.

To install a whip antenna:

1. Remove the protective cover from the antenna connector on the side of the instrument.

2. Screw the antenna onto the connector.

3. Position the antenna so that it points straight up.

Operating the RXU radio

RXU radios can be operated locally with the RXUPilot program on a handheld terminal, or remotely from the V8 once radio communication is established. See Chapter 5, “RXUPilot”, for instructions on using the handheld terminal, and the chapters on the individual RXU instruments for instructions on operating RXU radios locally.

To monitor and control the RXU radio from the V8:

1. From any acquisition window, type Ctrl, O to open the Options and Status dialog box.

2. Select the serial number of the RXU from the Select box serial number scrolling list.

3. In the spreadsheet, scroll down until the radio options are visible. (See Fig. 8-5 on page 174.)

4. Change the radio options as required.

Changes take effect when you move the focus to another control.

!


Fig. 8-5: V8 radio options.

Operating the V8 radio

The setup and monitoring of radio communication on the V8 is done from the Options and Status dialog box.

To set up and monitor the V8 radio:

1. From any acquisition window, type Ctrl, O to open the Options and Status dialog box.

2. In the spreadsheet, scroll down until the radio options are visible. (See Fig. 8-5.)

3. If the V8 is the master radio, set the Radio type to Master. Otherwise, set the Radio type to Slave.

4. Set the Radio encryption key to a value between 0 and 65 535. The encryption key must be the same for all instruments in the network.

5. Set the Radio network address to a value between 0 and 65 535. The network address must be the same for all instruments in the network.

6. Watch the Radio unit address in this dialog box and the Net indication in the status bar to monitor radio communication.

Network initialization

After you configure the radios, the network initializes automatically. The master radio adds each slave radio to the network one at a time. However, each time a slave is added to the network, the master radio must go offline in order to increment a parameter in the modem. It is normal, therefore, to see the network


status alternate between “up” and “down” several times during the first few minutes of communication, until all the slaves are online.


177 Chapter 9 177

Chapter

Frequency Stepping

This chapter explains how to create and manage frequency stepping tables for controlled-source methods.

178 Chapter 9 Freq. Stepping About System 2000.net frequency stepping 178

About System 2000.net frequency steppingPhoenix current source controllers and System 2000.net receivers are capable of transmitting and receiving specific signal frequencies according to a GPS-synchronized schedule.

Schedules can be created on a PC and the files transferred to the instruments, or a schedule can be created by the instruments in real-time, calculated from a small set of parameters. If the instruments are on a radio network, either of these schedule types can be set up on a V8 and then transmitted wirelessly to all the other instruments.

Depending on the capabilities of the the current source, the schedules can specify a variety of bipolar or unipolar waveforms, in either time domain or frequency domain modes.

The output current of some Phoenix current sources, such as the T-200 and the TXU-30, can also be controlled by the frequency schedule tables.

Frequency. System 2000.net instruments derive frequencies from a 921.6kHz base frequency, and therefore may not be able to produce exactly the requested frequency. Use at least 6 (preferably 8) significant digits when specifying a frequency. The instruments will calculate the closest approximation possible. For best results in frequency domain methods, use frequencies from Table 9-1 on page 179.

Phase. For synchronization with other Phoenix GPS-equipped instruments, the phase is such that if the waveform were extended backward in time, the centre of the positive on time (or the negative on time in unipolar negative) would align with 2000/01/01 00:00:00 UTC.

Note Leap seconds may occur at the beginning of January or July every few years, as determined by the International Earth Rotation and Reference Systems Service (IERS). If a leap second happens to occur while the transmitter is generating a waveform, there may be a discrepancy of 1s in its phase. To prevent problems, consult the IERS Web site (www.iers.org) for notifications, and avoid transmitting during the occurrence of a leap second.

http://www.iers.org


Table 9-1: Recommended frequencies for frequency domain operation

1024.0000 512.0000 256.0000 128.0000 64.00000 32.0000061.44000 30.72000

7680.000 3840.000 1920.000 960.0000 480.0000 240.0000 120.0000 60.00000 30.00000948.1481 474.0741 237.0370 118.5185 59.25926 29.62963

56.88889 28.444441706.667 853.3333 426.6667 213.3333 106.6667 53.33333 26.66667

51.20000 25.600006400.000 3200.000 1600.000 800.0000 400.0000 200.0000 100.0000 50.00000 25.00000

3072.000 1536.000 768.0000 384.0000 192.0000 96.0000 48.00000 24.0000047.40741 23.70370

2844.444 1422.222 711.1111 355.5556 177.7778 88.8889 44.44444 22.22222341.3333 170.6667 85.3333 42.66667 21.33333

5120.000 2560.000 1280.000 640.0000 320.0000 160.0000 80.0000 40.00000 20.00000614.4000 307.2000 153.6000 76.8000 38.40000 19.20000

9600.000 4800.000 2400.000 1200.000 600.0000 300.0000 150.0000 75.0000 37.50000 18.75000568.8889 284.4444 142.2222 71.1111 35.55556 17.77778

34.13333 17.066678533.333 4266.667 2133.333 1066.667 533.3333 266.6667 133.3333 66.6667 33.33333 16.66667

Frequency (Hz)


Table 9-1: Recommended frequencies for frequency domain operation (cont’d)

Period (s) Frequency Period (s) Frequency Period (s)16.00000 8.000000 4.000000 2.000000 1.000000 1.000000 0.500000 2.000000 0.250000 4.00000015.36000 7.680000 3.840000 1.920000 0.960000 1.041667 0.480000 2.08333315.00000 7.500000 3.750000 1.875000 0.937500 1.066667 0.468750 2.133333 0.234375 4.26666714.81481 7.407407 3.703704 1.851852 0.925926 1.080000 0.462963 2.16000014.22222 7.111111 3.555556 1.777778 0.888889 1.125000 0.444444 2.25000013.33333 6.666667 3.333333 1.666667 0.833333 1.200000 0.416667 2.400000 0.208333 4.80000112.80000 6.400000 3.200000 1.600000 0.800000 1.250000 0.400000 2.500000 0.200000 5.00000012.50000 6.250000 3.125000 1.562500 0.781250 1.280000 0.390625 2.56000012.00000 6.000000 3.000000 1.500000 0.750000 1.333333 0.375000 2.666667 0.187500 5.33333311.85185 5.925926 2.962963 1.481481 0.740741 1.350000 0.370370 2.700000 0.185185 5.40000011.11111 5.555556 2.777778 1.388889 0.694444 1.440000 0.347222 2.88000010.66667 5.333333 2.666667 1.333333 0.666667 1.500000 0.333333 3.000000 0.166667 5.99999910.00000 5.000000 2.500000 1.250000 0.625000 1.600000 0.312500 3.200000 0.156250 6.4000009.60000 4.800000 2.400000 1.200000 0.600000 1.666667 0.300000 3.333333 0.150000 6.6666679.37500 4.687500 2.343750 1.171875 0.585938 1.7066678.88889 4.444444 2.222222 1.111111 0.555556 1.800000 0.277778 3.600000 0.138889 7.1999998.53333 4.266667 2.133333 1.066667 0.533333 1.875000 0.266667 3.7500008.33333 4.166667 2.083333 1.041667 0.520833 1.920000 0.260417 3.840000

Frequency (Hz)


Automatic modes. Two different automatic frequency-stepping modes are available: the file-based mode and the Auto Stepping mode. In the Auto Stepping mode, the instrument builds a frequency-stepping table that can contain up to 100 entries, including up to 20 that

you specify. The advantage of the Auto Stepping mode is that you can set only a few parameters and have the instrument calculate all the table entries automatically. (If you want to specify more entries, it is better to use the file-based mode.)

Table 9-1: Recommended frequencies for frequency domain operation (cont’d)

Frequency Period (s) Frequency Period (s) Frequency Period (s) Frequency Period (s) Frequency Period (s)0.1250000 8.00000 0.0625000 16.00000 0.0312500 32.00000 0.01562500 64.0000 0.00781250 128.0000.1200000 8.33333 0.0600000 16.66667 0.0300000 33.33333 0.01500000 66.6667 0.00750000 133.3330.1171875 8.53333

0.1111111 9.00000 0.0555556 18.00000 0.0277778 36.00000 0.01388889 72.0000 0.00694444 144.0000.1041667 9.60000 0.0520833 19.20000 0.0260417 38.40000 0.01302083 76.80000.1000000 10.00000 0.0500000 20.00000 0.0250000 40.00000 0.01250000 80.0000 0.00625000 160.000

0.0937500 10.66667 0.0468750 21.33333 0.0234375 42.666670.0925926 10.80000 0.0462963 21.60000 0.0231482 43.20000 0.01157407 86.4000 0.00578704 172.800

0.0833333 12.00000 0.0416667 24.00000 0.0208333 48.00001 0.01041667 96.0000 0.00520833 192.0000.0781250 12.80000 0.0390625 25.600000.0750000 13.33333 0.0375000 26.66667 0.0187500 53.33333 0.00937500 106.6667 0.00468750 213.333

0.0694444 14.40000 0.0347222 28.80000 0.0173611 57.60000 0.00868056 115.2000 0.00434028 230.4000.0666667 15.00000 0.0333333 30.00000 0.0166667 59.99999 0.00833333 120.0000 0.00416667 240.000

0.00390625 256.000


The file-based mode allows you to create schedules on a PC. Each file can contain up to 100 entries specifying the waveform, the frequency, the current, and the schedule.

The easiest way to create a frequency schedule file is by using the TblEdit program on a PC. This program creates and reads schedule files in the binary format required by the instruments. See Chapter 4, “Table Files and TblEdit” on page 87 for more information on TblEdit, before continuing with this chapter.

Alternatively, you can create schedule files in any spreadsheet or text-processing program that can save in Comma Separated Values (.csv) format. After saving the files, you can use a small utility program called FreqTabl or Generate Frequency Stepping Table to convert the files to binary (.tfs) format. This method of creating schedule files is described in the following pages.

When the binary files are saved on an instrument’s CompactFlash card, you can choose which one to activate, either from a scrolling list in the Acquisition Parameters dialog box of a V8, or by setting an RXU parameter using the RXUPilot program. You can also activate a schedule on the V8 and then transmit that schedule to all the other instruments on a radio network.

The system calculates each schedule in the automatic modes to begin at 00:00:00 UTC each day and repeat continuously. For this reason, it is best to plan your schedules so that an integral number of repetitions can occur in a 24-hour period. If the total duration of your schedule does not divide evenly into 24h and you happen to be working at 00:00:00 UTC, you will experience an abrupt return to the first frequency in the schedule.

Table 9-2 on page 183 illustrates the waveform that will be generated for each Time and Frequency domain code setting in the schedule files.


Table 9-2: Transmission codes and resulting waveforms

Domain RatioON:OFF

Duty Cycle

Waveform Code

Time 1:1 50%bipolar

TD50

Time 1:2 33.33%bipolar

TD33

Time 1:3 25%bipolar

TD25

= Aligned with 2000/01/01 00:00:00 UTC.

1 : 1 : 1 : 1

1 : 2 :1 : 2

1 : 3 : 1 : 3


Frequency — 100%bipolar

FD

Frequency 10:8 55.55%bipolar

FD9

Time 1:1 50%unipolarpositive

TD50P

Time 1:2 33.33%unipolarpositive

TP33P

Table 9-2: Transmission codes and resulting waveforms (cont’d)

DomainRatio

ON:OFFDuty Cycle

Waveform Code

= Aligned with 2000/01/01 00:00:00 UTC.

1 : 1

f 9f+( )

:1 1

1:1

1 : 1 : 1 : 1

1 : 2 :1 : 2


Time 1:3 25%unipolarpositive

TD25P

Time 1:1 50%unipolarnegative

TD50N

Time 1:2 33.33%unipolarnegative

TD33N

Time 1:3 25%unipolarnegative

TD25N

Table 9-2: Transmission codes and resulting waveforms (cont’d)

DomainRatio

ON:OFFDuty Cycle

Waveform Code

= Aligned with 2000/01/01 00:00:00 UTC.

1 : 3 : 1 : 3

1 : 1 : 1 : 1

1 : 2 :1 : 2

1 : 3 : 1 : 3

186 Chapter 9 Freq. Stepping Creating a frequency schedule file 186

Creating a frequency schedule file A frequency schedule file can contain from 5 to 100 lines. Each line must contain:

• The waveform type• The frequency• The requested current, if controlling a T-200 or

TXU-30 current source (zero for other current sources)

• The end-time of transmission for that frequency, relative to the start of the schedule

The “requested current” is the maximum desired current at a given frequency. Whether the current source can actually producethat much current depends on electrode placement, local resistivity, etc.

All items on the line must be separated by a comma. This is most easily achieved in a spreadsheet program

such as Microsoft® Excel or OpenOffice, using the Save as CSV function. However, you can also use a simple

text editor such as Notepad if you remember to insert the commas yourself.

To create a frequency schedule file:

1. Launch Excel (or your preferred software).

2. In Table 9-2, “Transmission codes and resulting waveforms,” on page 183, find the waveform you want to transmit, and note the corresponding Code in the last column.

3. In the first cell of the spreadsheet, type the waveform Code (see Fig. 9-1).

4. Move to the next cell on the right and type the frequency in Hz. Refer to the User Guide or Specifi-cations for your current source; do not request a frequency outside its limits.

5. Move to the next cell on the right and

• for a T-200 or TXU-30 current source, type the requested current at that frequency, in amperes.

• for other current sources, type a zero.


6. Move to the next cell on the right and type the end time for that frequency (relative to the start of the schedule) in the format 00:00:00.

Fig. 9-1: Creating a schedule file in Excel. For current sources other than the T-200 or TXU-30, Column C should have values of zero.

7. Copy the waveform Code and paste it into the first column cells for all the remaining rows you intend to use. (The waveform cannot change part way through a schedule.)

Tip When typing end-times (in any program), always use the complete format 00:00:00, even if the duration is only for minutes or seconds. Otherwise, if the file is re-opened in Excel, the durations may be corrupted by Excel’s automatic formatting.

8. Complete the remaining cells, typing a frequency, requested current, and end time in each row.

9. For the last frequency in your table, it is best to type an end time that divides evenly into 24h (see “Automatic modes” on page 181).

10.Save the file, using a numeral greater than or equal to 2 as the file name and specifying CSV as the file type. (From the File menu in Excel, choose Save As. In the Save as type box, select CSV (Comma-delimited) (*.csv)).


Fig. 9-2: Choosing CSV as the file type in Excel.

(If you are using Notepad, save the file, specifying All Files as the file type and adding .csv as the extension.)

11.Make a note to yourself of the details of the schedule contained in the file. When you activate a schedule later, you will need to know which file to choose for the schedule you want.

Note If you want to create a large number of schedule files, you can save the files with more meaningful names. However, you will have to rename such files to numerical names before an RXU or V8 can use them.

Converting the schedule to binary format

The file you create in Excel or Notepad must be converted to binary format before the System 2000.net instruments can read it. The output of the Generate Frequency Stepping Table program is a binary format file with the same name as the the CSV file, but with the extension TFS.

To convert the schedule to binary format:

1. Open the folder where you installed the Generate Frequency Stepping Table.exe program, or the folder containing the shortcuts created by the installation, and the folder where you stored the CSV file.

2. Drag the CSV file onto Generate Frequency Stepping Table.

The Generate Frequency Stepping Table window appears, displaying the contents of the schedule. The window closes automatically after about 10s.

189 Chapter 9 Freq. Stepping Activating a schedule file 189

3. Copy the binary schedule files to a CompactFlash card and install it in the instrument.

Fig. 9-3: Generate Frequency Stepping Table window.

Examining a binary schedule file

If you want to review the contents of a schedule that has been converted to binary format, simply drag the TFS file onto Generate Frequency Stepping Table in the same way as you did the CSV file.

The Generate Frequency Stepping Table window appears and displays the contents of the schedule. The window closes automatically after about 10s.

Activating a schedule fileWhen schedule files exist on the CompactFlash card installed in a V8, they will appear in the Freq. stepping control scrolling list of the Acquisition Parameters dialog box. When schedule files exist on the CompactFlash card installed in an RXU, they can be selected by setting parameters using the RXUPilot program on a handheld device.

To activate a schedule file on a V8:

1. From the Setup menu, choose Acquisition Parameters.

2. In the Freq. stepping control list, scroll to the schedule file you want to use.

The Frequency Stepping Table spreadsheet updates to show the file contents.

190 Chapter 9 Freq. Stepping Setting up the Auto Stepping frequency table 190

To activate a schedule file on an RXU:

1. Beam the parameters from the RXU to the handheld device.

2. Change the value of the AUTO parameter to the file name of the schedule you want to use.

For example, if you want to use the schedule file 3.tfs, set AUTO to 3.

Setting up the Auto Stepping frequency tableIn the Auto Stepping mode, the instrument builds a frequency-stepping table in real time in a pattern determined by parameters that you specify. The table can contain up to 100 entries, including up to 20 non-pattern frequencies that you specify. The advantage of the Auto Stepping mode is that you can set only a few parameters and have the instrument calculate all the table entries automatically. (If you want to specify more entries, it is better to use the file-based mode.)

The instrument creates the frequency stepping table using three types of parameters:

• FREQn (V8) or FRQn or FRnn (RXU), specified values for the first frequencies in the table. (0≤n≤19 on an RXU; 1≤n≤20 on a V8.)

• Lowest frequency (V8) or FEND (RXU), an approximate value for the last frequency in the table.

• Frequencies per octave (V8) or FPOC (RXU), an integer that determines the frequencies per octave to complete the table automatically. (An octave is the span between two frequencies, one of which is twice the other.)

Although you can specify all 20 values for the FREQn or FRQn/FRnn parameters, you will typically specify only a few of them, establishing a starting frequency and/or a pattern of frequency stepping, and allowing the Lowest frequency and Frequencies per octave to determine the remaining table entries based on that starting frequency or pattern.


Note When specifying the first frequencies in the table, always start with the lowest numbered parameter (FREQ1 or FRQ0) and work consecutively. Unspecified parameters should be set to a value of 0.

Specifying non-pattern and pattern frequencies

You can specify one or more frequencies at the beginning of the table—for example, a 1Hz test signal—that will not affect the automatic calculation of the remaining frequencies. As detailed below, the automatic calculation is based on the frequencies in the last octave that you specify.

To specify frequencies on a V8:

1. In the Acquisition Parameters window, press Ctrl, F to move the focus to the Frequency List spreadsheet.

2. Edit the FREQ1 frequency cell, assigning it a value less than or equal to the highest frequency your current source can transmit.

3. Edit one or more cells from FREQ2–FREQ20, assigning them the desired frequencies. End with the sequence of frequencies you want to use as the frequency-stepping pattern, with all remaining FREQn cells set to a value of 0.

To specify frequencies on an RXU:


2. Edit the FRQ0 parameter, assigning it a value less than or equal to the highest frequency your current source can transmit.

3. Edit one or more parameters from FRQ1–FR19, assigning them the desired frequencies. End with the sequence of frequencies you want to use as the frequency-stepping pattern, with all remaining FRQ1–FR19 parameters set to a value of 0.

4. Beam the new parameters to the RXU.


Selecting a frequency-stepping pattern

There are two patterns that the instruments can follow to complete the frequency table:

• Equally spaced divisions of descending octaves, starting with the last non-zero value of the specified frequencies.

• A sequence of frequencies (equally or unequally spaced) per descending octave, based on the last sequence of specified frequencies that are in descending order and span less than an octave.

To select equally spaced divisions of the octave on a V8:

1. In the Acquisition Parameters window, choose Auto Step as the Freq. stepping control.

2. Edit the Lowest frequency parameter, assigning it the approximate value of the lowest frequency you want. (As explained under “Frequency” on page 178, not all frequencies can be generated by the V8.)

3. Edit the Frequencies per octave parameter, assigning it the number of frequencies per octave you want.

4. Press Ctrl, U to update the Frequency Stepping Table.

When the V8 completes the table, it will start with the last non-zero value of FREQn and repeatedly multiply by

until the table is full or the Lowest frequency has been reached.

To select equally spaced divisions of the octave on an RXU:


2. Edit the FEND parameter, assigning it the approx-imate value of the lowest frequency you want. (As explained under “Frequency” on page 178, not all frequencies can be generated by the RXU.)

3. Edit the FPOC parameter, assigning it the number of frequencies per octave you want.

When the RXU completes the table, it will start with the last non-zero value of FRQn and repeatedly multiply by

2 1 Frequencies per octave( )⁄–


until the table is full or the FEND frequency has been reached.

To select a repeating sequence of frequencies per octave on the V8:

1. In the Acquisition Parameters window, choose Auto Step as the Freq. stepping control.

2. Start with the lowest-numbered unassigned parameter among FREQ1–FREQ20. Edit that parameter, assigning it the highest frequency of the pattern.

3. Edit the next parameters in sequence, assigning them consecutively lower frequencies in the pattern. The difference between the first and last frequencies of the sequence must be less than an octave. Ensure the remaining FREQn parameters are set to a value of 0.

4. Press Ctrl, U to update the Frequency Stepping Table.

When the V8 completes the table, it will repeatedly divide each frequency in the sequence by 2 until the table is full or the Lowest frequency has been reached.

Note The Frequency Stepping Table is not the same as the list of FREQ1–FREQ20 parameters. These parameters will not change value when the V8 creates the Frequency Stepping Table.

To select a repeating sequence of frequencies per octave on an RXU:


2. Start with the lowest-numbered unassigned parameter among FRQ0–FR19. Edit that parameter, assigning it the highest frequency of the pattern.

3. Edit the next parameters in sequence, assigning them consecutively lower frequencies in the pattern. The difference between the first and last frequencies of the sequence must be less than an octave. Ensure the remaining FRQn/FRnn param-eters are set to a value of 0.

When the RXU completes the table, it will repeatedly divide each frequency in the sequence by 2 until the table is full or the FEND frequency has been reached.

2 1 Frequencies per octave( )⁄–


Note The schedule table is not the same as the list of FRQ0–FR19 parameters. These parameters will not change value when the RXU creates the schedule.

Setting up the schedule

Three parameters control the time schedule:

• CPFR, Cycles per frequency, the minimum number of cycles generated for each frequency. (The Time per frequency parameter may cause a longer duration for a given frequency.) Use Cycles per frequency to ensure that sufficent cycles of very low frequencies are recorded.

• TPFR, Time per frequency, the duration in seconds for which each frequency is generated, unless the Cycles per frequency parameter causes a longer duration for a given frequency. Use Time per frequency to set the duration for recording of the relatively high frequencies.

• TTOT, Total time, controls the duration in seconds of the entire table. If Total time = 0, then the length of the schedule is controlled by Time per

frequency and Cycles per frequency. If Total time is not 0, then the table is truncated or the duration of the last frequency is extended accordingly. It is best to use Total time to ensure that your schedule can be repeated an integral number of times in 24h (see “Automatic modes” on page 181).

To set up the schedule on a V8:

• Edit the Time per frequency, Cycles per frequency, and Total time parameters, assigning them the appropriate values for your application.

To set up the schedule on an RXU:


2. Edit the TPFR, CPFR, and TTOT parameters, assigning them the appropriate values for your application.


Setting up automatic current reduction (roll-off) for T-200 and TXU-30 transmitters

If the transmitter load is inductive, then the achievable current will drop as frequency increases. If the output current falls too far below the requested current, a fault will be triggered. To avoid this condition, set up Auto Stepping to reduce the requested current as frequency increases. The effect of automatic current reduction is shown in Fig. 9-4 on page 195.

Fig. 9-4: Automatic current reduction.

Note Automatic roll-off of current is applicable only to T-200 and TXU-30 transmitters.

Two parameters control the automatic reduction of requested current:

LF current

Rol

loff

Increasing frequency

Req

uest

ed c

urre

nt

corn

er

196 Chapter 9 Freq. Stepping Activating Auto Stepping 196

• CRMX, Transmitted LF current (Transmitted Low Frequency current), in amperes.

• FCMX, Rolloff corner frequency, the frequency at which the requested output current will be reduced to about 70% of Transmitted LF current.

The transmitted current for each frequency f in the table is equal to:

To set up automatic current reduction on a V8:

• Edit the Transmitted LF current and Rolloff corner frequency parameters, assigning them the appropriate values for your application.

To set up automatic current reduction on an RXU:


2. Edit the CRMX and FCMX parameters, assigning them the appropriate values for your application.

Activating Auto SteppingNote If any of the frequencies in the Frequency Stepping

Table are invalid (they cannot be generated accurately from the base clock frequency of 921.6kHz), they must be changed to valid frequencies. On the V8, invalid frequencies are highlighted in red in the Frequency Stepping Table.

To activate Auto Stepping on a V8:

1. As described earlier, complete the entries for:

• the Frequency List spreadsheet

• Frequencies per octave

• Lowest frequency

• Cycles per frequency

• Time per frequency

• Total time

• Transmitted LF current

• Rolloff corner frequency

2. Press Ctrl, U to update the Frequency Stepping Table spreadsheet.

LF transmitted current

1 f( ) Rolloff corner frequency( )⁄( )2+( )-------------------------------------------------------------------------------------------------------------------


3. Review the Frequency Stepping Table spreadsheet to ensure that the values reflect your intentions, and that no values are highlighted in red, indicating invalid frequncies.

4. Change the Freq. stepping control to Auto Step.

To activate Auto Stepping on an RXU:


2. Edit the following parameters, assigning them the appropriate values for your application.

• FRQ0—FR19

• FPOC

• FEND

• CPFR

• TPFR

• TTOT

• CRMX

• FCMX

3. Set the AUTO parameter to 1.


199 Chapter 10 199

Chapter

Spectral Induced Polarization (SIP)

This chapter explains how to use the V8 in Spectral Induced Polarization (also called Complex Resistivity) surveys.


• setting up site parameters.• setting up acquisition parameters.• acquiring data.

200 Chapter 10 SIP Using the SIP function 200

Using the SIP functionThe V8 is well suited to any of the popular approaches used to measure Spectral Induced Polarization (SIP, also called Complex Resistivity or CR). Because the V8 can acquire multiple channels simultaneously and also communicate over a network with a transmitter and remotes such as the RXU-2, surveys can be carried out quickly over a large area.

Array layouts

The V8 is capable of acquiring SIP data from these electrode array types:

• dipole-dipole• pole-dipole• pole-pole• gradient• Schlumberger• inverted Schlumberger• Wenner

• inverted Wenner• random placement

The following figures illustrate the array types, using the conventional designations of A and B for the transmitter electrodes and M and N for the receiver electrodes. Lower case a is the distance between M and N, and n is an integer multiplier. Most figures show only one M-N pair, but in all methods except the Schlumberger, Wenner, and inverted Wenner arrays, multiple M-N channels can be used.

201 Chapter 10 SIP Using the SIP function 201

Fig. 10-1: Dipole-dipole array.

Fig. 10-2: Pole-dipole array.

Fig. 10-3: Pole-pole array

Fig. 10-4: Gradient array.

Fig. 10-5: Schlumberger (n > 2) and Wenner (n = 1) arrays.

Fig. 10-6: Inverted Schlumberger (n > 2) and inverted Wenner(n = 1) arrays.

M N A B

V I

a na a

M N A

BV I

a na >10a

M

N A

BV I

>10a na >10a

M NA B

V

I

a

M N

V

M N

V

a a

M NA B

V

I

ana na

M B

V

ana na

I

A N

202 Chapter 10 SIP Setting up SIP survey and site parameters 202

Setting up SIP survey and site parametersNote Illustrations of the V8 windows and dialog boxes in this

Guide are taken from a PC emulation program, not a V8 receiver. The appearance of the windows and dialog boxes may vary slightly from what you see on a V8, and the data values do not necessarily reflect typical field conditions.

A number of survey parameters are common to all geophysical methods, and so are described in Chapter 3, Common Operations. Please read that chapter before continuing.

To launch the SIP function:

• From the main window, choose SIP (press Ctrl, then type S).

The SIP Site Setup window appears (see Fig. 10-7).

Entering survey and instrument information

Complete the Survey Information area of the SIP Site Setup window as described under “Entering survey information” on page 53.

Complete the Box spreadsheet of the SIP Site Setup window as described under “Entering Box information and changing mode” on page 55.


Fig. 10-7: The SIP Site Setup window.

Entering array layout information

The information required in the Array Layout area varies depending on the type of array you use—Schlumberger, dipole-dipole, gradient, etc. However, once the information about the array type and the starting point(s) is entered, the V8 can calculate the

positions of additional channels, and increment the positions automatically as the survey progresses.

Note Use positive numbers to denote positions that are east or north of the map origin. Use negative numbers to denote positions that are south or west of the map origin.

To select the Array type:

1. Press Ctrl and type A to move the focus to the Array Layout area.

2. Scroll through the Array type list by pressing Enter or the space bar repeatedly until the array type you want to use appears.

Dipole-dipole, pole-dipole, and pole-pole arrays. In these types of arrays, it is necessary to define the positions of the transmitter and the first channel electrode, as well as the length of the dipoles (or the channel spacing, in the case of pole-pole arrays).


To set up for dipole-dipole, pole-dipole, or pole-pole arrays:

1. Press the DOWN ARROW key to move from Array type to North reference.

2. Scroll through the North reference list by pressing Enter or the space bar until the reference you want to use appears.

3. Press the DOWN ARROW key to move to Declination.

4. Type the magnetic declination for the survey location, in degrees from true north.

5. Press the DOWN ARROW key to move to Tx dipole length (AB).

6. Type the transmitter dipole length in metres.

7. Press the DOWN ARROW key to move to Rx dipole length (MN) (or Channel spacing, in the case of pole-pole arrays) and type the dipole length or channel electrode spacing in metres.

8. Press the DOWN ARROW key to move to the next text box, Tx station close to Rx (North).

9. Type the distance in metres from the survey map origin to the transmitter electrode that is closest to

the first receiver electrode, measuring in the North reference direction only (distance TxN in Fig. 10-8).

10. Press the DOWN ARROW key to move to the next text box (East) and type the distance in metres from the survey map origin to the same transmitter electrode, measuring in the East reference direction only (distance TxE in Fig. 10-8).

Fig. 10-8: Defining initial transmitter and receiver positions (dipole-dipole shown). TxN and TxE define the transmitter (Tx) electrode closest to the receiver. RxN and RxE define the receiver (Rx) electrode closest to the transmitter.

Map origin

Survey line

Receiver electrodes

Transmitter electrodes

TxN

TxE

RxN

RxE

N


11. Press the DOWN ARROW key to move to the next text box, Rx station close to Tx (North), and type the distance in metres from the survey map origin to the receiver electrode that is closest to the trans-mitter electrode just defined, measuring in the North reference direction only (distance RxN in Fig. 10-8).

12. Press the DOWN ARROW key to move to the next text box (East) and type the distance in metres from the survey map origin to the same receiver electrode, measuring in the East reference direction only (distance RxE in Fig. 10-8).

Gradient, Wenner, Schlumberger and Inverse arrays. In these types of arrays, it is necessary to define the positions of the transmitter and the first channel electrode, as well as (in some cases) the length of both the transmitter dipole (A–B) and the receiver dipole (M–N). Where a dipole length is not applicable to the method, the text box is disabled.

Note If you will be “pushing” along the survey line (moving the array in the direction from A toward B), then define the position of A and the nearest M.

If you will be “pulling” along the survey line (moving the array in the direction from B toward A), then define the position of B and the nearest N.

To set up for gradient, Wenner, Schlumberger and Inverse arrays:

1. Press the DOWN ARROW key to move from Array type to North reference.

2. Scroll through the North reference list by pressing Enter or the space bar until the reference you want to use appears.

3. Press the DOWN ARROW key to move to Declination.

4. Type the magnetic declination for the survey location, in degrees from true north.

5. Press the DOWN ARROW key to move to the next text box.

6. If Tx dipole length (AB) is enabled, type the transmitter dipole length in metres.

7. If Rx dipole length (MN) is enabled, type the dipole length in metres.


8. Press the DOWN ARROW key to move to the next text box, Tx start position (North).

9. Type the distance in metres from the survey map origin to a transmitter electrode (A if pushing, B if pulling), measuring in the North reference direction only (distance TxN in Fig. 10-9).

Fig. 10-9: Defining initial transmitter and receiver positions (gradient array shown, with the survey “pulling” from B toward A).

10. Press the DOWN ARROW key to move to the next text box (East) and type the distance in metres from the survey map origin to the same transmitter electrode, measuring in the East reference direction only (distance TxE in Fig. 10-9).

11. Press the DOWN ARROW key to move to the next text box, Rx start position (North), and type the distance in metres from the survey map origin to the receiver electrode that is closest to the trans-mitter electrode just defined, measuring in the North reference direction only (distance RxN in Fig. 10-9).

12. Press the DOWN ARROW key to move to the next text box (East) and type the distance in metres from the survey map origin to the same receiver electrode, measuring in the East reference direction only (distance RxE in Fig. 10-9).

Random placement arrays. The V8 cannot calculate values for random arrays. See “Entering channel information” on page 207 for instructions on how to set up for random arrays.

Map origin

Survey line

Receiver

Transmitter

TxN

TxE

RxN

RxE

NTransmitter

electrodes

electrode B

electrode A

Directionof surveymovement(pulling)


Entering channel information

After the instrument capabilities have been defined in the Box spreadsheet, you need to assign names and location co-ordinates to each channel, and decide whether you want to see the channel’s data displayed as it is acquired. You can also enter measurements of electrical characteristics such as electrode resistance. The contains all this information (see Fig. 10-10).

Fig. 10-10: The Channel spreadsheet.

Some of the cells in the Channel spreadsheet are automatically populated with information you entered in the Box spreadsheet, so you don’t need to retype serial numbers or channel numbers.

Three types of information need to be entered for each channel:

• an identifier, such as “Ex1”

• view status• location co-ordinates

The identifier, ID, is simply a text string that helps you remember the channel location and purpose when you view the data acquisition window. Although you can enter up to 100 characters, it’s best to use a short, 3- or 4-character identifier.

The choice of View status determines whether or not the channel will be shown in the plots or lists of data in the Acquisition window.

The location co-ordinates, + (North), + (East), – (North), and – (East), can be entered manually if necessary, but the V8 will calculate them automatically for the standard array types. (see “Calculating co-ordinates” on page 208). You only need to override the calculated values if an electrode position varies from the standard Array Layout. If your array type is Random, you will have to enter all the location co-ordinates manually.


The electrical characteristics consist of electrode contact resistance and AC and DC voltages.

To enter channel information:

1. Press Ctrl to move the focus to the Channel spreadsheet.

2. Press the ARROW keys to move the focus to the ID column in the row you want to configure.

3. Enter an identifier name.

4. In the View column, press Enter or the space bar to choose whether the channel data should be displayed during acquisition.

5. If the location co-ordinates cannot be calculated automatically, enter the distances from the survey map origin, measured in the positive and negative polarity north and east directions.

6. If desired, enter the measured contact resistance in the Res(ohm) column, and AC and DC voltages in millivolts in the AC(mV) and DC(mV) columns.

7. Repeat this procedure for each channel of each instrument.

Calculating co-ordinates

There are two command buttons that cause the V8 to calculate co-ordinates. One calculates the starting position according to the Array Layout information. The other calculates the incremental position when you move to the next site along the survey line.

Note Automatic updating is only possible for gradient, dipole-dipole, pole-dipole, and pole-pole arrays. In other array types, the distance between array positions along the survey line is not related to the array layout itself, so automatic updating is not possible.

To calculate intial co-ordinates:

• Move the focus to the Calculate Coord. button, and press Enter.

The V8 populates the Channel spreadsheet with values calculated from the Array layout parameters.

209 Chapter 10 SIP Setting up SIP acquisition parameters 209

To update co-ordinates automatically:

• Move the focus to the Next Site button and press Enter to increment co-ordinates.

Modifying calculated co-ordinates

Whenever local conditions require a modification to the pattern of electrode placement, you can simply override the automatic calculation made by the V8 and enter the actual values measured in the field.

To modify calculated co-ordinates:

1. Press the Ctrl key to move the focus to the Channel spreadsheet.

2. Press the ARROW keys to move among the spread-sheet cells in columns + (North), + (East), – (North), and – (East), and replace the calcu-lated value(s) with the actual value(s) as required.

Completing SIP Site setup

When you are satisfied with the site setup parameters, exit the setup window and set up the acquisition parameters.

To end SIP Site Setup:

• Either move the focus to the Done button and press Enter, or press Esc, or press Ctrl and type D.

The SIP Site Setup window closes and you are returned to the SIP Acquisition window.

Setting up SIP acquisition parametersThe acquisition parameters control the frequency-stepping schedule and various filters intended to reduce the effects of cultural noise.

The frequency stepping can be automatic or manual. If it is automatic, the schedule can be created from


parameters you specify, or a schedule can be loaded from a saved file.

The V8 must be in Standby mode in order to change acquisition parameters.

To put the V8 into Standby mode:

1. From the Acquisition menu, choose Standby. (The current mode is disabled.)

Fig. 10-11: The Acquisition menu, showing the V8 in Standby mode.

To set up acquisition parameters:

1. From the Setup menu, choose Acquisition Parameters, or simply press Ctrl, A.

The SIP Acquisition Parameters dialog box opens (Fig. 10-12).

Fig. 10-12: SIP Acquisition Parameters dialog box.

Setting up filtering and coupling

The low pass filter (LP Filter), Line Frequency filter, and Coupling functions are explained in Chapter 3 on page 60. Choose values for these settings that are suitable for the survey conditions.



See Chapter 9, “Frequency Stepping” on page 177 for complete information on automatic file-based or parameter-based frequency stepping.

Schedule files must be prepared on a PC and transferred to the CompactFlash card before they can be used.

Parameter-based frequency stepping can be programmed on the V8 as described in Chapter 9.

To activate a schedule file:




To activate Auto Stepping:

1. As described under “Setting up the Auto Stepping frequency table” on page 190, complete the entries for:

• The Frequency List spreadsheet





• Total time



2. Press Ctrl, U to update the Frequency Stepping Table spreadsheet, and review it to ensure that the values reflect your intentions.

3. Move the focus to the Freq. stepping control scrolling list and scroll to Auto Step.

212 Chapter 10 SIP Acquiring SIP data 212

Acquiring SIP dataOnce you have set up the parameters for your survey, you can begin acquiring data.

To acquire SIP data:

1. Follow the instructions in the User Guide for your current source to begin transmitting current.

2. From the V8 SIP Data Acquisition window, choose the Acquisition menu and select Start Recording.

The V8 begins recording data, and displays a spreadsheet of the channels that you set to View = Yes. Below the spreadsheet, the V8 displays a plot of the data acquired for the first channel in the spreadsheet. Fig. 10-13: The SIP Acquisition window while recording.

Viewing channel results

The area below the menus shows acquired data results. See “Customizing data and plot appearance” on page 70 for instructions on showing or hiding the spreadsheet list and the graphical plot, as well as the bar and curve plots.


Evaluating the data and correcting gain

As the instruments work through the frequency stepping table, the spreadsheet values and plots of apparent resistivity and phase will be updated. From this information you can decide when data quality and quantity are sufficient for the current site. Curves will be smooth, error bars small, and the listing of standard deviations will show small values.

However, as soon as the instrument(s) start recording data, you should examine the plots of signal strength versus noise. These horizontal bars can guide you in choosing better values for channel gain. If the radio network is operating, examine the remote channels as well as the local ones.

In the plot area, a thin green bar indicates peak-to-peak input, or noise. A thicker blue bar indicates signal strength. (The colours can be changed. See “Customizing the V8 by setting options” on page 67.)

Fig. 10-14: Bar chart showing noise (green) and signal (blue).

To evaluate the bar charts:

1. Check the length of the peak-to-peak bar. It should span at least 20% but no more than about 90% of the dynamic range.

If the peak-to-peak bar extends near the 100% limits, gain is set too high and records will be saturated. If the bar extends less than about 20% of the range, gain is too low and it will take a long time to record quality data.

2. Check the position of the peak-to-peak bar. It should be no more than about 10% off centre.

If the peak-to-peak bar is badly off centre, dynamic range will be much reduced. The most likely causes are a strong self-potential between electrodes or a faulty electrode.


To correct the gain:

1. From the Acquisition menu, choose Pause Recording or press Ctrl, U.

2. From the Setup menu, choose Site Setup, and change the Gain setting(s) in the Box spreadsheet.

3. Close the Site Setup window, and from the Acqui-sition menu, choose Resume Recording, or press Ctrl, R.

4. Evaluate the peak-to-peak bar and repeat the gain adjustment if necessary.

To correct an off-centre peak-to-peak bar:


2. Check the electrode placement for conditions that might cause a voltage offset (self-potential), and consider moving the electrode. (If you do move it, update the co-ordinates manually in the Site Setup window of the V8.)

3. Try replacing the electrode with an electrode known to be good.

4. From the Acquisition menu, choose Resume Recording, or press Ctrl, R.

5. Re-evaluate the peak-to-peak bar.

Changing location along the survey line

When you are satisfied with the quality and quantity of data at a survey station, you can put the V8 into Standby mode and move the array to the next position in the survey. There is no need to shut the V8 down, and by leaving it on, you retain GPS satellite synchronization, which saves time at the next site.

To put the V8 into Standby mode and move the array:

1. From the Acquisition menu, choose Standby.

2. Move your array to the next location on the survey line.

3. Return to the SIP Site Setup window and update location co-ordinates with the Next Site button, if it is enabled. If it is disabled because your Array


Type doesn’t afford automatic calculation, you must update the positions manually. (See “Modifying calculated co-ordinates” on page 209.)

The data file names will be updated automatically.

4. Close the SIP Site Setup window, and start recording data again.


217 Chapter 11 217

Chapter

Controlled Source AMT (CSAMT)

This chapter explains how to use the V8 in Controlled Source Audiofrequency Magnetotelluric (CSAMT) surveys.


• Setting up site parameters• Setting up acquisition parameters• Acquiring data

218 Chapter 11 CSAMT Using the CSAMT function 218

Using the CSAMT functionThe V8 is well suited to either scalar or vector CSAMT methods. Because the V8 can acquire multiple channels simultaneously and also communicate over a network with a transmitter and remotes such as the RXU-3, surveys can be carried out quickly over a large area.

Array layouts

The V8 is capable of acquiring CSAMT data from these array types:

• scalar (Ex, Hy or Ex, Hx, Hy)

• vector (Ex, Ey, Hx, Hy)

The number of channels depends on the hardware configuration purchased.

The following figures illustrate typical array setups with V8 and RXU-3 instruments.

Fig. 11-1: Scalar CSAMT array.

Fig. 11-2: Vector CSAMT array.

V8 RXUHy

Transmitter and RXU-TM

V8 RXUHy


Hx

219 Chapter 11 CSAMT Setting up CSAMT survey and site parameters 219

Setting up CSAMT survey and site parametersNote Illustrations of the V8 windows and dialog boxes in this


A number of survey parameters are common to all geophysical methods, and so are described in Chapter 3, Common Operations. Please read that chapter before continuing.

To launch the CSAMT function:

• From the main window, choose CSAMT (press Ctrl, then type C).

The CSAMT Site Setup window appears (see Fig. 11-3).

Fig. 11-3: The CSAMT Site Setup window.


Complete the Survey Information area of the CSAMT Site Setup window as described under “Entering survey information” on page 53.


Complete the Box spreadsheet of the CSAMT Site Setup window as described under “Entering Box information and changing mode” on page 55.


The information required in the Array Layout area describes the type of array, dipole length, azimuths, and starting position. Once this information is entered, the V8 can calculate the positions of additional channels, and increment the positions automatically as the survey progresses.

Note Use positive numbers to denote positions that are east or north of the map origin. Use negative numbers to denote positions that are south or west of the map origin.

Use Ex and Hx to denote orientation parallel to the survey profile. Use Ey and Hy to denote orientation perpendicular to the profile.

To enter the Array Layout information:


2. Scroll through the Array type list by pressing Enter or the space bar.

3. Press the DOWN ARROW key to move the focus to the North reference list and press Enter or the space bar until the reference you want to use appears.

4. Move the focus to Declination and type the magnetic declination for the survey location, in degrees from true north.

5. Move the focus to Hy azimuth and type the orien-tation of the Hy sensor, in degrees from the North reference.

6. Move the focus to Ex length and type the length of receiver dipole, in metres.

7. Move the focus to Ex azimuth and type the orien-tation of the Ex dipole, in degrees from the North reference.

8. Move the focus to Start pot coord. and in the (North) and (East) fields, type the distances in


metres from the survey map origin to the receiver electrode at the beginning of the survey line.


After the instrument capabilities have been defined in the Box spreadsheet, you need to assign names and location co-ordinates to each channel, and decide whether you want to see the channel’s data displayed as it is acquired. You can also enter measurements of electrical characteristics such as electrode resistance. The Channel spreadsheet contains all this information (see Fig. 11-4).


Some of the cells in the Channel spreadsheet are automatically populated with information you entered

in the Box spreadsheet, so you don’t need to retype serial numbers or channel numbers.


• An identifier, such as “Ex1”

• View status• Location co-ordinates

The identifier, ID, is simply a text string that helps you remember the channel location and purpose when you view the data acquisition window. Although you can enter up to 16 characters, it’s best to use a short, 3- or 4-character identifier.

Note Standard terminology uses Ex and Hx to denote orientation parallel to the survey profile, and Ey and Hy to denote orientation perpendicular to the profile.



The location co-ordinates, + (North), + (East), – (North), and – (East), can be entered manually if necessary, but the V8 will calculate them automatically for the standard array types. (See “Calculating co-ordinates” on page 222.) You only need to override the calculated values if an electrode position varies from the standard Array Layout.

The electrical characteristics consist of electrode contact resistance and AC and DC voltages.




3. Type an identifier.


5. If the location co-ordinates cannot be calculated automatically, enter the distances from the survey

map origin, measured in the positive and negative polarity north and east directions.

6. If desired, enter the contact resistance measured in ohms in the Res(ohm) column, and AC and DC voltages in measured in millivolts in the AC(mV) and DC(mV) columns.

7. Repeat this procedure for each channel of each instrument.

Calculating co-ordinates

There are two command buttons that cause the V8 to calculate co-ordinates. One calculates the starting position according to the Array Layout information. The other calculates the incremental position when you move to the next site along the survey line.

To calculate intial co-ordinates:

• Move the focus to the Calculate Coord. button, and press Enter.

The V8 populates the Channel spreadsheet with values calculated from the Array Layout parameters.

223 Chapter 11 CSAMT Setting up CSAMT acquisition parameters 223

To update co-ordinates:

• Move the focus to the Next Site button and press Enter to increment co-ordinates.


Whenever local conditions require a modification to the pattern of electrode placement, you can simply override the automatic calculation made by the V8 and enter the actual values measured in the field.



2. Press the ARROW keys to move among the spread-sheet cells in columns + (North), + (East), – (North), and – (East), and replace the calcu-lated value(s) with the actual value(s) as required.

Completing CSAMT site setup

When you are satisfied with the site setup parameters, exit the setup window.

To end CSAMT Site Setup:


The CSAMT Site Setup window closes and you are returned to the CSAMT Acquisition window.

Setting up CSAMT acquisition parametersThe acquisition parameters control the frequency-stepping schedule and various filters intended to reduce the effects of cultural noise.

The frequency stepping can be automatic or manual. If it is automatic, the schedule can be created from


parameters you specify, or a schedule can be loaded from a saved file.



1. From the Acquisition menu, choose Standby. (The current mode is disabled, so if the Standby command is unavailable, the V8 is already in Standby mode.)




The CSAMT Acquisition Parameters dialog box opens (Fig. 11-6).

Fig. 11-6: CSAMT Acquisition Parameters dialog box.













1. Press Ctrl, S and press the DOWN ARROW key to move the focus to the Freq. stepping control scrolling list, and scroll to Auto Step.

2. As described in Chapter 9, complete the entries for:






• Total time



3. Press Ctrl, U to update the Frequency Stepping Table spreadsheet, and review it to ensure that the values reflect your intentions.

226 Chapter 11 CSAMT Acquiring CSAMT data 226

Acquiring CSAMT dataOnce you have set up the parameters for your survey, you can begin acquiring data.

To acquire CSAMT data:


2. From the V8 CSAMT Data Acquisition window, choose the Acquisition menu and select Start Recording.

The V8 begins recording data, and displays a spreadsheet of the channels you set to View = Yes. Below the spreadsheet, the V8 displays a plot of the data acquired for the first channel in the spreadsheet. Fig. 11-7: The CSAMT Acquisition window while recording.


The area below the menus shows acquired data results. See “Customizing data and plot appearance” on page 70 for instructions on showing or hiding the spreadsheet list and the graphical plot, as well as the bar and curve plots.


Evaluating the data and adjusting gain


However, as soon as the instrument(s) start recording data, you should examine the plots of signal strength versus noise. These horizontal bars can guide you in choosing better values for channel gain. If the radio network is operating, check the remote channels as well as the local ones.







If the peak-to-peak bar is badly off centre, dynamic range will be much reduced. The most likely causes are a strong self-potential between electrodes or a faulty electrode.




2. From the Setup menu, choose Site Setup, and change the Gain setting(s) in the Box spreadsheet.














3. Return to the CSAMT Site Setup window and update location co-ordinates with the Next Site button, if it is enabled. If it is disabled because your


Array Layout doesn’t afford automatic calculation, you must update the positions manually. (See “Entering channel information” on page 221.)

The data file names will also be updated automati-cally.

4. Close the CSAMT Site Setup window, and start recording data again.


231 Chapter 12 231

Chapter

Time Domain Electromagnetics(TDEM, TEM)

This chapter explains how to use the V8 in Time Domain Electromagnetics (also called Transient Electromagnetics or TEM) surveys.


• Setting up site parameters• Setting up acquisition parameters• Acquiring data

232 Chapter 12 TDEM Using the TDEM function 232

Using the TDEM functionThe V8 is well suited to time domain methods. Because the V8 can acquire multiple channels simultaneously and also communicate over a network with a transmitter monitor, surveys can be carried out more efficiently and with a smaller crew.

The V8 can be configured for either MulTEM or LoTEM geophysical methods.

Site layout

The following figure illustrates a typical site setup for the MulTEM method with V8 and RXU-TM instruments. The transmitting loop size is dependent on the required depth of investigation and can vary from a few metres to several hundred metres square. The sensor shown is a single multi-turn circular coil sensor for surface installation, but could also be of a type suitable for down-hole data acquisition. If the transmitting loop is large, multiple coil sensors could be used to acquire several channels simultaneously.

Since the V8 and RXU-TM are relatively close together in this method, small whip antennas are usually sufficient for good radio communication. However, difficult terrain or heavy vegetation may require that tripod or mast antennas be used instead.

Fig. 12-1: Typical TDEM (MulTEM) layout.


V8

Transmitting loop

Sensor


Polarity considerations

Three factors can affect the polarity of the received signal:

• current source phase• transmitting loop orientation• sensor orientation

Although polarity reversal can be corrected during acquisition, the need for correction (and the possibility of introducing error) can be eliminated by setting up the transmitting loop and sensor properly to begin with. (For instructions on activating automatic polarity reversal, see “Setting up automatic polarity correction” on page 244.)

Current source phase. The RXU-TM controls the current source frequency and phase relative to the arbitrary reference time of 2000-01-01 00:00:00 UTC (disregarding leap seconds). The middle of the positive on-time (or negative on-time in unipolar negative modes) is aligned with this reference.

Transmitting loop orientation. In the conventional right-handed co-ordinate system, magnetic sensors are

aligned so that the positive directions for x, y, and z are north, east, and down, respectively. In order to create a positive down magnetic field in the middle of the transmitting loop, the positive current direction should be clockwise around the loop when viewed from above. Therefore, connect the transmitting loop wire so that it runs from the current source positive terminal, clockwise around the site perimeter, and back to the current source negative terminal.

Sensor orientation. The sensor polarity is dependent on the direction of the windings, which is determined by which side of the sensor faces upward. It is important that the sensor always be placed with the correct side facing upward. For loops equipped with stands and levelling devices, this is obvious. If your sensor has no obvious markings, consult the documentation from the manufacturer.

Latest detectable signal

The latest detectable signal in the TDEM method depends on several factors, including transmitting loop


size, current, local resistivity and signal-to-noise ratio. This section explains the calculation of the practical limits of signal detection.

TDEM apparent resistivity. The formula for late time apparent resistivity, , in TDEM is:

Equation 12-1.

where:

µ = magnetic permeability ( H/m in air)

Mt = transmitter moment = L = length of transmitter loop side (metres)I = current (amperes)V = receiver EMF (volts)Sr = receiver coil effective area (square metres)

Replacing V/Sr with the measurement noise level, Nm allows us to develop Equation 12-2 to calculate the time of latest detectable signal:

Equation 12-2.

The measurement noise level Nm is normally around 10-8 to 10-10V/m2. Assuming Nm is 10-9 V/m2 and that the transmitting loop is 100m x 100m (i.e., 104m2), we can calculate the latest detectable signal time in milliseconds for various transmitter moments and apparent resistivities. The results are shown in Table 12-1 and graphically in Fig. 12-2 following the table. The table and graph show that high current values are required to extend the time of the latest detectable signal.

ρaL

ρaL µ

4π-------

2µMt

5V Sr⁄------------------⎝ ⎠

⎛ ⎞2 3/

t 5– 3⁄=

4π10 7–

IL2

t µMt Nm⁄( )2

400 πρaL( )3

--------------------------------1 5⁄

=

235 Chapter 12 TDEM Setting up TDEM survey and site parameters 235

Fig. 12-2: Current vs. latest signal time for three different apparent resistivities.

Depth of investigation

The depth of investigation in TDEM is dependent upon the time of TDEM response and earth resistivity. As a rule of thumb, the depth of investigation can be estimated as shown in Equation 12-3.

Equation 12-3: D is depth in metres, ρ is apparent resistivity in ohm metres, and t is time in milliseconds.

Setting up TDEM survey and site parametersNote Illustrations of the V8 windows and dialog boxes in this


Table 12-1: Time of latest detectable signal (ms)

Tx Moment (A•m2)

(Ω•m)

1000 100 10

5 x 104 0.912 3.64 14.5

10 x 104 1.2 4.79 19.1

50 x 104 2.29 9.12 36.2

ρaL

0

10

20

30

40

50

60

0 10 20 30 40

Time (ms)

Am

per

es into

100 x

100 m

loo

p

1000 Ω·m

100 Ω·m

10 Ω·m

D 500ρt=


A number of survey parameters are common to all geophysical methods, and so are described in Chapter 3, “Common Operations”. Please read that chapter before continuing.

To enter the TDEM function:

• From the main window, choose TDEM.

The TDEM Site Setup window appears (see Fig. 12-3 on page 236).


Complete the Survey Information area of the TDEM Site Setup window as described under “Entering survey information” on page 53.

Complete the Box spreadsheet of the TDEM Site Setup window as described under “Entering Box information and changing mode” on page 55.

Fig. 12-3: The TDEM Site Setup window.


The information required in the Array Layout area describes the type of array, station spacing, azimuth, starting position, and transmitting loop. Once this information is entered, the V8 can calculate the


positions of additional channels, and increment the positions automatically as the survey progresses.

Ramp length. The Array Layout area also includes information on the transmitting loop, including the Ramp length. Ramp length is the time delay from the point that the current source turns off to the point that output actually falls to zero (see Fig. 12-4). The value of Ramp length depends on the electrical characteristics of the current source and the transmitting loop, and is generally two to three times the time constant (L/R) of the loop. The value you type does not have to be accurate—an estimate of 0.05ms for a T-4 or 0.12ms for a T-3 current source is reasonable.

Tx Loop Turns. It is possible to increase the strength of the primary magnetic field by running the transmitting loop wire two or more times around the site perimeter before connecting it to the current source. The Tx Loop Turns text box allows you to specify the number of turns of wire used.

Fig. 12-4: Ramp length.

To enter the Array Layout information:


2. Scroll through the Array type list and choose either LoTEM or MulTEM according to the method you are using.

3. Press the DOWN ARROW key to move the focus to the North reference list and press Enter or the space bar until the reference you want to use appears.

4. Move the focus to Declination and type the magnetic declination for the survey location, in degrees from true north.

Theoretical waveform Actual waveform with ramp


5. Move the focus to Profile azimuth and type the orientation of the profile, in degrees from the North reference.

6. Move the focus to Station space and type the distance to be used between soundings, in metres.

7. Move the focus to Ramp length and type the estimated value of the current source and trans-mitting loop ramp time in milliseconds.

8. If you are using the LoTEM method, skip to “Entering channel information” on page 238.

9. Move the focus to Tx Loop Length and type the length in metres of the longer side of the trans-mitting loop.

The value you type is automatically copied to Tx Loop Width.

10. If your transmitting loop is not square, move the focus to Tx Loop Width and type the length in metres of the shorter side of the loop.

11.Move the focus to Tx Loop Turns and type the number of turns of wire in the transmitting loop.


After the instrument capabilities have been defined in the Box spreadsheet and the Array Layout has been defined, you need to assign names and location co-ordinates to each channel, and decide whether you want to see the channel’s data displayed as it is acquired. You can also enter measurements of electrical characteristics such as electrode resistance. The Channel spreadsheet contains all this information (see Fig. 12-5).


Some of the cells in the Channel spreadsheet are automatically populated with information you entered in the Box spreadsheet, so you don’t need to retype serial numbers or channel numbers.



• An identifier, such as “B1”• View status• Location co-ordinates

The identifier, ID, is simply a text string that helps you remember the channel location and purpose when you view the data acquisition window. Although you can enter up to 16 characters, it’s best to use a short, 2- to 4-character identifier.


The location co-ordinates, North (N) and East (E), can be entered manually if necessary, but the V8 will calculate them automatically for the standard array types. (See “Updating co-ordinates” on page 240.) You only need to override the calculated values if a sensor position varies from the standard Array Layout.

The location co-ordinate Vert. (Z) is intended for use with down-hole sensors to record the depth at which the sensor is positioned. For coil sensors at the surface, leave the value as zero.

The Len/Area column serves two purposes. If the channel is recording from a dipole, such as the transmitter dipole in LoTEM, type the length of the dipole in metres. If the channel is recording from a loop sensor, type the effective area of the loop in square metres (physical area of the sensor × number of turns of wire within the sensor). The area of the transmitting loop is automatically calculated when you enter the Tx Loop Length and Tx Loop Width in the Array Layout area.

The electrical characteristics for E channels consist of electrode contact resistance in ohms, Res (ohm) and AC and DC voltages in millivolts, DC (mv) and AC (mv).





3. Type an identifier.


5. If the location co-ordinates cannot be calculated automatically, move the focus to the North (N) and East (E) columns and enter the distances in metres from the survey map origin.

6. If you are using a down-hole sensor, move the focus to the Vert. (Z) column and type the sensor depth in metres.

7. If you are setting up E channels, enter the contact resistance measured in ohms in the Res (ohm) column, and AC and DC voltages in measured in millivolts in the AC (mV) and DC (mV) columns.

8. Repeat this procedure for each channel.

Updating co-ordinates

The V8 can automatically calculate the incremental position when you move to the next site along the survey line, based on the Profile azimuth and Station space that you typed in the Array Layout area.

To update co-ordinates:

• Move the focus to the Next Site button and press Enter to increment the co-ordinates.


Whenever local conditions require a modification to the pattern of site placement, you can simply override the automatic calculation made by the V8 and enter the actual values measured in the field.



241 Chapter 12 TDEM Setting up TDEM acquisition parameters 241

2. Press the ARROW keys to move among the spread-sheet cells in columns North (N), East (E), and Vert. (Z) and replace the calculated value(s) with the actual value(s) as required.

Completing TDEM site setup

When you are satisfied with the site setup parameters, exit the setup window.

To end TDEM Site Setup:


The TDEM Site Setup window closes and you are returned to the TDEM Acquisition window.

Setting up TDEM acquisition parametersThe acquisition parameters control the frequency-stepping schedule, sampling window characteristics, and filtering intended to reduce the effects of cultural noise.

The frequency stepping can be automatic or manual. If it is automatic, the schedule can be created from parameters you specify, or a schedule can be loaded from a saved file.



1. From the Acquisition menu, choose Standby. (The current mode is disabled, so if the Standby command is unavailable, the V8 is already in Standby mode.)





The TDEM Acquisition Parameters dialog box opens (Fig. 12-7).

Fig. 12-7: TDEM Acquisition Parameters dialog box.

Setting up filtering

The Power Line Frequency filter is explained under “Setting the line frequency filter” on page 66. Choose the setting that matches the local power grid frequency.











1. Press Ctrl, S and press the DOWN ARROW key to move the focus to the Freq. stepping control scrolling list and scroll to Auto Step.

2. As described under “Setting up the Auto Stepping frequency table” on page 190, complete the entries for:






• Total time



3. Press Ctrl, U to update the Frequency Stepping Table spreadsheet, and review it to ensure that the values reflect your intentions. Remember that cells highlighted in red indicate invalid frequencies.


Setting up sampling windows

The number of sampling windows is adjustable from 5 to 21. The first window occurs during the transmission ON time, leaving from 4 to 20 windows for user data collection in the transmission OFF time. The duration and separation of the sampling windows is logarithmic and is determined automatically by the V8.

To set up sampling windows:

• Move the focus to Number of Wnd (>=5, <=21) and type the number of sampling windows you want, including the ON-time window.

Setting up automatic polarity correction

As explained under “Polarity considerations” on page 233, it is possible for polarity to be reversed, depending on the orientation of the sensor and the connections of the transmitting loop. The V8 can detect the polarity of the received signal and automatically correct reversed polarity.

However, during the first few sampling windows, it is possible for a correct polarity signal to undershoot zero, or for a reversed polarity signal to overshoot zero. This overshoot or undershoot, also called “ringing”, is caused by the electrical characteristics of the transmitting loop.

If the V8 happens to sample the signal during ringing, it is possible for it to read a negative value (undershoot) even when the signal polarity is positive. This negative value would then cause the V8 to wrongly “correct” for reversed polarity.

For this reason, it is a good policy to wait until several sampling windows have passed before reading and correcting polarity.

To enable automatic polarity correction:

• Move the focus to Auto polarity fix by Window and enter the number of the sampling window that should be used to detect signal polarity.

245 Chapter 12 TDEM Acquiring TDEM data 245

Acquiring TDEM dataOnce you have set up the parameters for your survey, you can begin acquiring data.

To acquire TDEM data:


2. From the V8 TDEM Acquisition window, choose the Acquisition menu and select Start Recording.

The V8 begins recording data, and displays a spreadsheet of the channels you set to View = Yes. Below the spreadsheet, the V8 displays a plot of the data acquired for the first channel in the spreadsheet (see Fig. 12-8).


The area below the menus shows acquired data results. See “Customizing data and plot appearance” on page 70 for instructions on showing or hiding the

spreadsheet list and the graphical plot, as well as the bar and curve plots.

Fig. 12-8: The TDEM Acquisition window while recording.


Evaluating the data and adjusting gain


However, as soon as the instrument(s) start recording data, you should examine the plots of signal strength versus noise. These horizontal bars can guide you in choosing better values for channel gain. If the radio network is operating, check the remote channels as well as the local ones.







If the peak-to-peak bar is badly off centre, dynamic range will be much reduced. The most likely causes with E channels are a strong self-potential between electrodes or a faulty electrode.




2. From the Setup menu, choose Site Setup, and change the Gain setting(s) in the Box spreadsheet. (See “Setting up instrument type, serial number, channels, and gains” on page 56.)















3. Return to the TDEM Site Setup window and update location co-ordinates with the Next Site button, if it is enabled. If it is disabled because your Array Layout doesn’t afford automatic calculation, you must update the positions manually. (See “Modifying calculated co-ordinates” on page 240.)

The data file names will also be updated automati-cally.

4. Close the TDEM Site Setup window, and start recording data again.

249 Chapter 13 249

Chapter

Magnetotellurics (MT) and Audio-frequency MT (AMT)

This chapter explains how to carry out magnetotelluric and audio-frequency magnetotelluric surveys using System 2000.net instruments.

250 Chapter 13 MT/AMT AMT and MT techniques 250

AMT and MT techniquesAMT and MT techniques are essentially the same, differing only in the frequency range captured. The lower the frequency, the greater the depth of investigation possible at a given site. MT techniques acquire data in frequencies ranging from about 400Hz to 0.0000129Hz (a period of about 21.5h), and are suitable for deeper investigations. AMT techniques acquire data in the frequency range of about 1000Hz to 10 000Hz (roughly the range of human hearing, hence the audio designation). AMT is suited to shallower depths of investigation.

Duration of soundings

The length of time it takes to acquire quality data depends on the frequencies to be studied. During data processing, a number of waveforms at each analyzed frequency are stacked. The more waveforms available, the better the data quality. Many cycles of high frequencies can be acquired in a very short time, so an AMT sounding can take as little as five minutes in a

low-noise area or perhaps an hour in an area affected by cultural noise. To acquire many cycles of MT frequencies, however, takes several hours (or several days, for the lowest frequencies).

The V8 and RXU can acquire either AMT or MT data from electric channels. The V8 can also acquire data from magnetic channels, if equipped with the corresponding sensors (MTC-50 coils for MT, MTC-30 coils for AMT). This capability permits an efficient sounding across the entire spectrum. You can acquire AMT data for a short period as soon as you set up each site, and then change the sensors and reconfigure the instruments to acquire MT data overnight.

The data format of System 2000.net is identical to that of Phoenix MTU and MTU-A instruments. Any combination can be used in a survey.


251 Chapter 13 MT/AMT AMT and MT techniques 251

Local, Remote, and Far Remote stations

Although an instrument can be used alone, best results are achieved when a remote or far remote site is available for noise-reduction techniques.

Apart from the 50Hz or 60Hz grid frequency, electrical noise from human activities tends to vary considerably over distance. The natural magnetic signal, though, tends to be the same over large distances—the lower the frequency, the less variation. The Phoenix system takes advantage of these characteristics by collecting data simultaneously at the survey (“local”) sites and at one or more reference (“remote” or “far remote”) sites. For MT data, a far remote site could be as much as 1000km from the survey area; for AMT data, 50km is a reasonable distance. Because all instruments are synchronized to UTC, data from two or even three sites can be processed in combination to greatly reduce the effects of local noise.

In some cases, it is practical to simply use two local survey sites together, with each acting as the remote

reference for the other. However, in most surveys, a single, electrically quiet site is chosen, and an instrument with five channels is installed and left in place as the reference for the duration of the survey. Part of the daily routine of retrieving and redeploying survey sites is to visit the reference site to replace the battery, verify the installation integrity, and collect the previous night’s data.

It is also possible to set up a more permanent reference site, solar- or grid-powered and equipped with automatic dial-up communication facilities. Such an installation is typical in monitoring applications or when a long-term far remote site is required.

Because it is chosen for its low noise characteristics, the reference site also makes a good location for the calibration of all equipment before the survey begins.

Telluric vs. magnetic deployments

As mentioned earlier, magnetic signals do not vary greatly with distance compared to cultural noise. It is therefore practical to acquire magnetic data at

252 Chapter 13 MT/AMT Steps in a typical survey 252

relatively few sites and telluric data at relatively many sites. This strategy keeps capital costs low because fewer 5-channel instruments have to be purchased. It also reduces operating costs, because telluric-only sites take less time to install and retrieve.

Steps in a typical surveyEvery survey is unique, but the general sequence of steps remains the same. The survey is planned so that work crews can set up one or more sites each day, allow the equipment to acquire data for a period of time, then retrieve the equipment to redeploy it at another site. In AMT surveys, or in higher-frequency MT surveys (periods shorter than 300s), the crew may stay with the equipment while the sounding is taken, because acquisition times are shorter. In full-spectrum MT surveys, the equipment is often left to acquire data overnight.

This section explains the steps in chronological order:

• Planning• Calibrating the equipment• Setting up the survey sites• Processing the data• Exporting and interpreting the data

Planning

When a survey area and objectives have been defined, the first step is to plan how the survey will be carried out. Consider the following when making your plans:

Choose the sites. Consider if the survey should be carried out along one or more lines, or on a grid. Also decide if you will orient your sites to True North, Magnetic North, or an arbitrary azimuth on a grid plan. In all cases, you will need to know the magnetic declination of your survey area. (See Appendix B on page 297 for Internet resources.)

Mark all the proposed sites with unique numbers on a topographical map.


Identify one or more remote sites that will be in quiet areas, yet close enough to be maintained daily, and add them to the map.

In the field, evaluate the proposed sites for noise sources, security of the equipment, and physical access or permission limitations. Livestock, wild animals, hikers, industrial or transport activity, power lines or electric fences, and local laws can all interfere with survey work, equipment, or data. Even vegetation, under windy conditions, can induce micro-vibrations that will add noise to the data.

Modify the plan as necessary and mark the final version on the map.

Allocate and schedule the equipment. Decide how your equipment will be allocated, that is, the type of instrument and sensors to be used at each site.

Estimate the number of sites you’ll be able to sound each day. This number will depend on the type of data to be collected (MT, AMT, or both) as well as on the factors affecting installation.

An experienced crew can install a 2-channel site in about 15 minutes; a 5-channel site in difficult conditions might take an hour. Retrieving equipment from a site usually takes about 15 to 30 minutes. Travel time must also be taken into account. Plan a progression from site to site for the most efficient use of resources.

Obtain permissions. In most cases, the land you want to survey is owned by a third party. Be sure that you allow sufficient time to contact the landowners to obtain permission to conduct your work. It is often helpful to write an explanatory note that you can give to the landowner. You might include:

• The purpose and benefits of your survey.• Personal and institutional credentials.• The anticipated schedule.• An explanation that the equipment is a passive

receiver and does not emit any radiation or noise.• An outline of the physical impact on the land—

vehicle access, shallow holes and/or trenches for the electrodes and sensors.


• A commitment to leave the area as undisturbed as possible.

Create a standard set of parameters. Although you can configure the instruments individually at each installation, it is much more efficient to put all the common information into a binary file and use it repeatedly.

A single file, called STARTUP.TBL, can be created and saved for transfer to all the instruments of the same type used in the survey. The file contains instructions to the instrument such as when to start and stop acquiring data, what frequency ranges to sample at what intervals, and so on. It also contains text that becomes part of the record, such as the names of your company and Layout Chief.

As long as the file is in the DATA folder on the instrument’s CompactFlash card, the instrument will use it automatically.

You can create the STARTUP.TBL file by programming the instrument and saving the settings, or by using the TblEdit program on a PC. However, if you want to use

both System 2000.net and V5 System 2000 instruments, it is preferable to create the STARTUP.TBL file by using the WinTabEd Offline Table Editor to ensure compatibility. Refer to the V5 System 2000 MTU/MTU-A User Guide for instructions on using the Offline Table Editor.

Calibrating the equipment

The first task in the field is to calibrate the instruments and sensors. Calibration should take place at the beginning of every survey, and may have to be repeated during a survey if equipment problems arise (damaged cables, for instance).

Usually, the reference site is the best location for calibration, because you’ve chosen it for its low noise characteristics and you have permission to use it for a longer period of time. Alternatively, you can calibrate each set of equipment when you install it for the first time in the survey. In this case, you can perform the calibration either before (preferably) or after acquiring data.


Calibration of an instrument takes about 10 minutes. Calibration of magnetic sensors requires a calibrated V8 instrument and takes at least an hour. The requirements of the physical layout are not as rigorous as for data acquisition—you don’t have to carefully orient or level the coils, for example. See “Calibrating the equipment” on page 71 for detailed instructions.

Setting up the survey sites

Once the equipment is calibrated, the actual survey work can begin. This section describes the general principles of setting up a successful survey site.

Form a 3-person crew. Experience in the field has shown that the ideal crew consists of a Layout Chief and two assistants. The Layout Chief stays at the centre of the site, using a compass to orient the assistants as they place the electrodes and/or sensors. While the assistants install the electrodes and sensors, the Layout Chief can set up the instrument itself, take electrical measurements, and write the site record on a Layout Sheet.

More or fewer people can form the crew, but productivity may not be as high.

Keep records throughout. It is important to keep careful written records of each survey site. Information from these records must be included when processing the data. The record also helps track down any technician errors or equipment problems that may arise.

Use a standard Layout Sheet and Equipment Checklist, like those shown in Appendices D and E. The sample Layout Sheet highlights in red the records that are essential—serial numbers, measurements, a sketch of the layout, etc. Optional records are printed in black.

Conduct an inventory and inspection. Before you set out each day, make sure you have all the tools and equipment you need (see the sample Equipment Checklist in Appendix E.) and check that it’s all in good condition. If the survey is just beginning, make sure there is a properly prepared CompactFlash card in every instrument. (During the survey, you will exchange cards daily as you retrieve the equipment.)


Verify the location. When you arrive at a site, ensure you are at the right site number and location as defined on the plan map. Use a handheld GPS locator or other reliable method to be sure of your location.

Determine the centre and place the instrument. The instrument is usually (but not necessarily) placed exactly at the site centre, where the dipoles cross. (Variations from the usual layout are discussed later in this chapter.) Because there is extra length in the cables connecting the electrodes, the instrument itself can be placed a metre or two off centre if necessary.

Choose a dry spot that will not pool water if there is rain. Stay away from noise sources such as power lines and roads, and avoid overhead obstructions that might block GPS signals. Try to find a spot that allows easy access in all four directions to where you’ll place the electrodes and/or sensors.

Tip In livestock farming areas, electric fences are a common source of noise. Sites must be located well away from these fences, although if the ground is very conductive, a distance of only 100m can be enough.

Set up the telluric lines. All instruments accept two dipoles to acquire telluric data. Each dipole consists of two lead-chloride porous pot electrodes buried about 25cm deep in salty mud, connected to the instrument by cables (commonly called E-lines). The dipoles form a right angle cross, with the instrument near the centre.

Fig. 13-1: Standard site layout.

Typically, each E-line is from 25 to 100m long, making two equal-length dipoles 50 to 200m long. The longer

Ex

dip

ole

Ey dipole

E-lines

electrodes true or magneticNorth

0°

90°

180°

270°

V8 or RXU


the dipole, the better the signal-to-noise ratio but the greater the AC voltage induced by the local power grid. A high AC voltage can result in unusable data (“saturated records”) when the dynamic range of the system is exceeded.

The north-south dipole is referred to as Ex and the east-west dipole is referred to as Ey.

Tip Because maps place North at the top, it is tempting to think of a north-south line as similar to a graph’s vertical y-axis, and an east-west line as similar to its horizontal x-axis. With MT techniques, though, the opposite is true: the north-south dipole is Ex, not Ey.

It’s also tempting to think of the E-line cables as forming the dipole. However, the dipoles are imaginary straight lines measured between the electrodes; they are not the same thing as the physical cables. Always measure and orient the layout from where the imaginary dipole lines cross, not where the cables connect to the instrument.

Adjust for E-line difficulties. Local conditions—boulders, trees, hills, water bodies, etc.—can often make it difficult or impossible to keep to a standard

layout. E-lines may have to be longer or shorter than normal, or a dipole may have to be oriented other than to true or magnetic north.

Obstructed dipoles. If an obstruction in the area means that one E-line has to be shortened, the other can be lengthened to compensate. For example, if a 100m dipole is planned but the north E-line can only be 30m long, you can extend the south E-line to 70m.

In some cases, the two dipoles may have to be of unequal lengths. Although not ideal, this layout is still viable.


Fig. 13-2: E-line lengths adjusted to avoid an obstruction.

Occasionally you won’t be able to orient the dipoles along the north-south and east-west azimuths you have planned. In this situation, you can “rotate the site”—orient the dipoles as much as ±44° away from the planned azimuth, while keeping their right-angle relationship. As long as the azimuth is entered accurately during data processing, the rotation of the site will not degrade data quality. (This is another

example of the importance of keeping accurate records on the Layout Sheet.)

Fig. 13-3: Site rotated to avoid an obstruction.

Note A site rotation, when corrected for magnetic declination, must not exceed ±44°. If you find that this angle is exceeded, either rotate to a smaller angle or rotate in the opposite direction.

Excess cable. In order to allow E-lines to be extended as described earlier, the cables are usually cut in

Ex

dip

ole

Ey dipole

true or magneticNorth

0°

90°

180°

270°

pond

E x di

pole

Ey dipole

true or magneticNorth

123°213°

303°33°

rocky outcrop

“N”

“E”“S”

“W”


lengths significantly greater than half the dipole length. Always lay excess cable in elongated S-shapes, no closer than 5m from the ends. If you coil the excess instead, you will create an induction loop that will distort the signal.

Fig. 13-4: Lay excess cable in S-shapes, not coils.

Slope. E-lines laid out down a steep slope can also create a problem: the measured distance between the electrodes no longer equals the actual horizontal length of the dipole. Instead, the measured distance is a vector resulting from both horizontal and vertical displacement.

Fig. 13-5: Effect of slope on dipole length.

If you encounter inclines ≥20°, you must compensate using trigonometry. One way is to calculate how much to lengthen the E-lines when laying out the site so that the horizontal component of the vector is the desired dipole length. Alternatively, you can make no compensation in the field, and instead calculate the actual horizontal dipole length before processing the data.

Wind. Try to avoid setting up close to tall trees or other vegetation that could propagate wind-induced vibrations through the roots. Always lay the cables flat on the ground, not draped over branches or rocks. You may also need to restrain the E-lines to limit wind-induced noise. Use the materials at hand, such as

≥5m

≥5m

electrode

measured

distance

actual dipole length

electrode


rocks, broken branches, or mounds of dirt or snow to hold down the cables every metre or so.

Traffic. In general, avoid areas subject to vehicle, pedestrian, or animal traffic. If you must run an E-line across a pathway, bury the cable completely to prevent disturbance. If you must run a cable across a road, look for drainage pipes crossing underneath that could be used to pass the E-lines through. Otherwise, use a commercial wire-protection cover designed for the purpose. Be aware that data quality will be greatly reduced by passing vehicles.

Set up the magnetic sensors. The V8 acquires the natural magnetic signal using coil or loop sensors. Three kinds of sensors are available:

• MTC-50 coils, for MT soundings.• MTC-30 coils, for AMT soundings.• AL-100 air-loops, used in place of vertical coils.

Usually, two sensors are placed horizontally and one vertically. However, depending on the application, the vertical sensor may be omitted.

Placement. Because all system components carry electric current, they all generate magnetic fields that can degrade the data. Therefore, component separation is important. Whenever possible, you should place each sensor in a different quadrant formed by the dipoles, as far from the V8 as the connecting cable allows. In any case, the instrument and each of the sensors must be separated from the others by at least 5m.

The horizontal coils are normally aligned with the telluric dipoles, as carefully oriented and level as possible, buried in shallow trenches. The coil placed with its free end pointing north is referred to as Hx. The coil with its free end pointing east is Hy.

The third coil, Hz, should be set as precisely vertical as possible in a hole deep enough that the entire coil can be buried (although you can bury it partially and then mound earth over the top if necessary). This vertical coil is the sensor most susceptible to electrical coupling with the E-lines, so place it as far from the other components as possible.


Substitute an air-loop if necessary. In terrain where a hole cannot be dug deep enough to even partially bury the vertical coil, you can substitute an air-loop sensor. The loop is laid out flat on the ground in a square, restrained by rocks or other weights, or shallowly buried. Unlike coil sensors, an air-loop is not shielded, and is therefore more affected by cultural noise than coils are.

Identify and orient correctly. It is critically important to identify and orient the sensors correctly. Coil sensors must be aligned so that the free end of Hx points north (connector points south), and the free end of Hy points east (connector points west). This alignment is intuitive when the coils are placed north and east of the V8 because the connectors face the instrument and the cables run directly to it. However, if the coils are placed south or west of the instrument, the connector must face away from the instrument, so the cables loop back to it. (See Figure 13-6.)

Fig. 13-6: Example layout with three coils correctly oriented (not to scale).

If an air-loop is used for the Hz channel, it must be oriented so that, when viewed from inside the loop, the cable exits from the pre-amplifier toward the right. (See Figure 13-7.)

Ex

dip

ole

Ey dipole

true or magneticnorth

0°

V8

Hy

Hx

Hz

0°

90°

90°


Fig. 13-7: Example layout with two coils and an air-loop correctly oriented (not to scale).

In all cases, you must note the serial numbers of the coils before burying them, and record on the Layout Sheet which sensor is used as Hx, Hy, and Hz. Without this information, you cannot reliably process the data, because there is no way to associate the correct sensor calibration files with the magnetic channels.

Some errors in laying out Hx and Hy coils can be corrected using advanced techniques in data

processing; however, it is better to lay out the site correctly to begin with. Errors in laying out an air-loop cannot be corrected during data processing.

Adjust for sensor difficulties. Use the same techniques as for E-line difficulties to deal with excess cable, wind, and traffic. You can usually avoid obstructions by placing the sensor in a different quadrant.

Submersion in rain water is a further consideration with sensors. Although they can withstand moisture, it is better to position them on higher ground where possible.

Measure and record electrode resistance and dipole voltages. When all the connections have been made to the instrument but before turning on the power, take measurements of the electrical characteristics of the site.

Dipole voltages. Start by recording the AC and DC potentials on the dipoles. These measurements will help you choose the best setting for gain when you program the instrument.

Ex

dip

ole

Ey dipole

true or magneticnorth

0°

V8

Hy

Hx

Hz

0°

90°

90°


When measuring dipole voltages, use a digital voltmeter. Analog meters are not sensitive enough to measure accurately in the 200mV range encountered in MT surveys.

Measure each type of voltage on the N-S and E-W dipoles. Again, lower values are better. Values ≥150mV AC may indicate the presence of power lines or other electromagnetic noise sources close to the site.

High DC potentials can also mean a faulty electrode. Test for this condition by measuring the voltage from the V8 ground terminal to each of the E-line terminals. Significantly higher potential on one electrode indicates that it should be replaced.

Unfortunately, apart from relocating the entire site, there is no way to improve high readings caused by noise.

Electrode contact resistance. When measuring contact resistance, use an analog ohmmeter. An analog meter produces more current than a digital meter (mA versus µA), and is therefore more accurate in the presence of self-potential on the E-lines.

The higher current from an analog meter is also the reason to measure dipole voltages (with a digital meter) first. The analog meter could leave a residual charge on the electrodes, causing errors if the digital readings are taken afterwards.

Measure the resistance of each E-line and each dipole, and record the values on the Layout Sheet. In other words, measure from the instrument ground terminal to each of the E-line terminals, and again between each channel’s pair of E-line terminals. A significant difference between the dipole resistance and the sum of the corresponding E-line resistances indicates a problem with the layout or a faulty measurement.

Note To accurately measure contact resistance ≥2000Ω, you must disconnect the E-lines from the instrument. Measure from the ground terminal to each E-line end, and between the two E-line ends of each dipole.

In general, the lower the contact resistance, the better. High contact resistance limits the upper range of frequencies that can be acquired. If you encounter


resistance ≥2000Ω, you may be able to reduce it using one of these methods:

• Lift the electrode, add more salt water to the mud, and rebury the electrode.

• Move the electrode to a new hole a short distance away. There may have been a large rock directly under the first hole.

• Replace the dirt in the hole with a mixture of salt water and either Bentonite (driller’s mud) or “kitty litter”—granulated clay for litter boxes.

Start up and verify operation. Once the site is properly laid out and tested, the instrument can be powered on.

If you did not load a standard STARTUP.TBL file on the CompactFlash card, you will have to set up the parameters for your data acquisition in the V8 MT/AMT Site Setup and MT/AMT Acquisition Setup windows. You will have to set up the RXU using the RXUPilot program.

It is important at this stage to verify that the instrument has acquired “GPS lock”—contact with at least four GPS satellites. Data acquisition cannot begin

unless GPS lock has been achieved (even if only briefly). You can verify GPS lock by looking at the status bar at the bottom of the V8 display or by tapping the GPS button on the RXUPilot main window.

It can take anywhere from 30s to 30min for GPS lock to be achieved, depending on factors such as limited direct view of the sky, or distance from the last site where the instrument was used.

Usually, lock is achieved within 10min. If it takes longer, try relocating the antenna or substituting another antenna or cable.

Tip If equipment has been shipped a long distance (for instance, on initial delivery from Phoenix), GPS lock can take a long time. To speed up the process, reset the GPS receiver: disconnect the GPS antenna. From the Setup menu, choose Options and Status and select GPS Reset. Reconnect the GPS antenna.

Protect the equipment. Before leaving the site, take steps to protect the equipment as required. You should always protect the instrument with a tarpaulin or sunshade. Wrap the tarpaulin tightly to protect from


snow, rain and condensation, or loosely (ventilated) to protect from the heat of the sun. In very hot climates, take the instrument out of its carrying case and erect a sunshade over it to provide maximum ventilation and protection from direct sun. In some circumstances, it may also be necessary to post a guard at the site.

Warning In hot climates, failure to protect the instrument from direct sunlight may result in equipment damage. (This warning applies whether the instrument is powered or not.)

Complete the layout sheet. Verify that all mandatory information has been entered on the Layout Sheet, and add any optional information you want to record. (The sample Layout Sheet in Appendix D shows mandatory information in red, optional records in black. Supplies of these Layout Sheets printed on waterproof, tearproof paper can be ordered from Phoenix.)

Acquire data. Once the site setup and records are complete, the crew can move on to set up the next survey site. The instrument will automatically acquire data according to the programmed schedule.

Retrieve the equipment. At the end of the data acquisition period, the crew retrieves the equipment. In AMT surveys, retrieval might happen several times in a day. In MT surveys, retrieval usually happens the next morning. The crew returns to the site to verify that it is undisturbed and to pick up the equipment. If there are problems, it’s easier to repair the installation and take a second sounding than to remove the equipment and have to return later.

The retrieval routine includes a check to make sure acquisition ended normally, and measurement of contact resistance and battery voltage. These measurements can help identify potential equipment problems.

After you shut down the instrument and remove all the equipment connections, replace the CompactFlash card with one prepared for the next site. Then gather up all the equipment and tools, restoring the site as you committed to the landowner. Finally, move to the next site to retrieve more equipment or to set up for a new sounding.

!

266 Chapter 13 MT/AMT Setting up a survey site 266

Processing the data

Each evening, you should copy the newly acquired data to a PC and to CDs or DVDs for long-term storage. Then use the suite of Phoenix software programs to process and perhaps edit the data, to judge the success of the soundings. Nightly processing allows you to identify sites that need to be repeated, and schedule them efficiently.

Exporting and interpreting the data

The final step in the survey is to carefully edit and then export the processed data (usually in EDI format) to your choice of interpretation software.

Refer to the Data Processing User Guide for instructions on using the suite of software programs.

Setting up a survey siteThe next sections explain in more detail how to install and connect the various parts of the system to acquire data at a survey site.

Tip A three-person crew can work very efficiently if the crew leader handles operations at the instrument while the two field workers install the E-lines and/or sensors. The crew leader orients the field workers as they position the E-lines. While the workers install the electrodes and sensors, the leader can install the ground electrode and make other connections and measurements at the instrument.

Verifying your location

Ensure that you are at the right site number and location as defined on the survey map. Use a handheld GPS locator or other reliable method to be sure of your location.

267 Chapter 13 MT/AMT Setting up telluric dipoles (E-lines) 267

Choosing the site centre

Scan the general area to locate the best place for the instrument, at the centre of the site.

To centre the site:

1. Take a quick sighting with a handheld compass and allow enough room to the north, south, east, and west to lay out the E-lines and/or sensors. (Remember that if there is a slope ≥20°, you may want to extend an E-line to compensate.)

2. Choose a dry spot that will stay dry if it rains.

3. Stay clear of noise sources (power lines, roads and paths, railways, etc.) and overhead obstructions.

4. Spread out a 1m by 2m tarpaulin at the chosen centre and set the instrument and battery on it near one short edge.

Note In all cases, allow enough room to keep the instrument at least 1m away from the dipole electrodes, and the sensors 5m away from the E-lines, to avoid electromagnetic interference.

Fig. 13-8: Instrument and battery positioned on tarpaulin.

Setting up telluric dipoles (E-lines)Except at magnetic-only sites, the next step is to set up the dipoles, or E-lines. Although experienced crews


often orient the dipoles using a handheld compass, for greatest accuracy, you should use a compass on a tripod.

Tip To save time in the field, use coloured adhesive tape to mark the length of half the desired dipole on precut E-line cables. As the field worker pulls the cable end away from the site centre, the crew leader can pay out the cable and call a halt when the tape marker is reached. With this method, the workers only have to use a tape measure when the standard layout can’t be followed.

To set up the dipoles:

1. Have a field worker gather up:

• an electrode

• a shovel

• a container of salt water (50g/L)

• a handheld compass

• one end of an E-line

• (a tape measure, if the layout is non-standard or the E-lines cables are not pre-marked)

2. If you are keeping track of equipment deployment, then record the electrode number and/or cable number on the Layout Sheet.

3. Sighting with the compass at the site centre, guide the field worker while the worker pulls the E-line (and tape measure if necessary) in the direction of the dipole.

Tip If you can pick out a landmark in the distance that aligns well with the dipole, you can simply direct the worker to walk straight toward it.

Be sure that no metal objects such as belt buckles, vehicles, or shovels are close enough to distort compass readings.

4. If you are working as a 3-person crew, save time by having the second field worker simultaneously pull the second E-line in the opposite direction, keeping aligned with the site centre and the first worker.

5. When the workers arrive at the measured distance, carefully fine-tune their positions.

6. Have the workers install the electrodes as described under “Installing porous pot electrodes” on page 23.


7. Lay out excess cable in S-shapes. In windy areas, have the workers weight down the cables with rocks or dirt every metre or so as they return to the centre.

8. Repeat this procedure for the second dipole.

Tip If you decide to use a handheld compass at the site centre, it’s good practice to scuff a mark in the soil under each foot as you orient the first half of each dipole. When you turn to orient the other half, don’t simply swivel around on one foot—you’ll be about a metre off centre. Instead, make sure to place your feet back in the two scuff marks after you turn.

Also, have the assistants use their compasses to verify the accuracy of the dipole orientation by sighting from each end of the dipole to the other, through the site centre.

Connecting electrodes to the instrument

This task can be done by the crew leader after burying the ground electrode, and while the workers are setting up the dipoles and/or sensors.

To connect the electrodes:

1. Connect the ground electrode to the GND terminal first.

Tip To identify the dipole electrodes, tie a loose single overhand knot about 40cm from the end of the North E-line cable before connecting it to the instrument. Tie two overhand knots in the East cable, three in the South cable, and four in the West cable. With this method, even if the lines become disorganized around the instrument, it will be easy to verify that the cables are connected to the correct terminals.


2. Connect the four E-lines to their appropriate terminals (see Fig. 13-9 and Fig. 13-10):

• North electrode to channel 1 red terminal

• South electrode to channel 1 black terminal

• East electrode to channel 2 red terminal

• West electrode to channel 2 black terminal

3. Double check that the correct electrode is connected to each terminal.

Fig. 13-9: V8 terminal connections for MT/AMT.

Fig. 13-10: RXU terminal connections for MT/AMT.

Measuring electrical characteristics

For proper data processing and as a check on the condition of the equipment and the installation, you must measure and record several electrical characteristics of the site. At sites with magnetic channels, the crew leader can make these electrical measurements while the workers are installing the sensors (see “Setting up magnetic sensors” on page 273).

North East

WestSouth

North

EastWest

South


For best results, use a digital voltmeter and an analog ohmmeter, in that order.

Tip To improve accuracy when using the ohmmeter and voltmeter, take every measurement twice, reversing the polarity the second time. Record the average of the two values.

To measure AC and DC potentials:

1. Using a digital voltmeter at the instrument, measure the AC potential in mV between the channel 1 (Ex) terminals and between the channel 2 (Ey) terminals, recording each measurement on the Layout Sheet.

2. Measure and record the DC potentials (in mV) in the same way.

If AC potential approaches 150mV or higher, there may be a strong noise source nearby. A DC potential in the same range may indicate a faulty electrode. Little can be done about a noise source, but you can test for faulty electrodes.

To test for faulty electrodes:

1. Using a digital voltmeter at the instrument, measure the AC or DC potential in mV between the GND terminal and each of the two terminals forming the dipole that has the high reading.

2. If the total potential of the dipole is significantly different from the sum of the potentials of its two electrodes, the electrode with the higher potential is probably faulty. Replace it with a different electrode and repeat all electrical measurements.

To measure contact resistance:

1. Using an analog ohmmeter at the instrument, measure the resistance in kΩ between the GND terminal and each of the E-line terminals, recording each measurement on the Layout Sheet.

2. If any of the electrodes has a resistance >2000 Ω, consider taking steps to reduce the contact resis-tance (add more salt water or driller’s mud, relocate the electrode).


Note To accurately measure contact resistance ≥2000Ω, you must disconnect the E-lines from the instrument. Measure from the ground terminal to each E-line end, and between the two E-line ends of each dipole.

3. Measure and record the resistance between the channel 1 terminals.

4. Measure and record the resistance between the channel 2 terminals.

5. If the total resistance of either dipole is significantly different from the resistance to ground of each of its electrodes, there is a problem with the instal-lation—usually the ground electrode is at fault. Double check all cables and connections, test the electrodes as just described, and repeat the resis-tance measurements.

E-line checklistUse this checklist to verify that your set-up is correct.

• Are the dipole orientations correct?• Are the dipole lengths correct?• Have cable splices been waterproofed with

electrician’s tape?• Are the cable ends correctly identified with knots

and connected to the right terminals?• Has excess cable been laid in S-shapes, no closer

than 5m from the ends?• Do the cables lie flat on the ground?• Are the cables restrained with rocks or dirt (in

windy areas)?• Are cables that cross pathways completely buried?• Have you accounted for excessive slope?• Have you made all the necessary electrical

measurements?

273 Chapter 13 MT/AMT Setting up magnetic sensors 273

Setting up magnetic sensorsNormally, all sensors are coil-type, but if the vertical component (Hz) is required and the ground is too rocky for a coil to be buried, an air-loop sensor can be substituted.

Choosing sensor locations

In most cases, you will already have laid out two dipoles. The dipoles form four quadrants with the V8 at the intersection.

Use the dipole quadrants as a guide, and place each magnetic sensor in a separate quadrant whenever possible.

If you are measuring only magnetic channels, simply keep the sensors widely separated.

To choose sensor locations:

1. Use the length of the connecting cables as a guide, and plan to place each sensor as far as possible

from the V8, from other sensors, and from the dipoles. However, stay clear of noise sources (power lines, roads and paths, railways, etc.).

2. If you must place more than one sensor in a quadrant to avoid noise or difficult terrain, keep the sensors, dipoles, and the V8 separated by at least 5m.

3. For each sensor, try to choose a dry spot, preferably one that will stay dry if it rains.

Installing coil sensors

Follow the instructions under “Installing and connecting magnetic sensors” on page 25 to install the MTC-30 or MTC-50 coil sensors, or the AL-100 air loop sensor.

Connecting the sensors to the V8

If you are using an instrument with magnetic channels only, install a ground electrode before connecting sensors. (See “Installing porous pot electrodes” on

274 Chapter 13 MT/AMT Setting up magnetic sensors 274

page 23.) Then connect the sensors. (See “Installing and connecting magnetic sensors” on page 25.)

Sensor checklistUse this checklist to verify that your set-up is correct.

• Do the free ends of the horizontal coils point north or east, no matter which quadrant they are in?

• Were the coils perfectly level and not disturbed when buried?

• Have all metal objects been removed from the vicinity of the sensors?

• Is the Hz coil exactly vertical and completely covered?

• Does the cable from the Hz air-loop exit from the pre-amplifier to the right when viewed from inside the loop?

• Do the cables lie flat on the ground?• Are the cables restrained with rocks or dirt (in

windy areas)?• Are cables that cross pathways completely buried?• Have all serial numbers been correctly recorded?

275 Chapter 13 MT/AMT Setting up the instrument 275

Setting up the instrumentTwo final connections must be made to the instrument to complete the site setup: the battery and the GPS antenna.

To complete the instrument setup:

1. Connect the GPS antenna (see “Connecting the GPS antenna” on page 24).

2. Connect the battery (see “Connecting the external battery” on page 33).

Powering up the instruments and acquiring data

Once all the components have been connected, the instruments can be powered on.

To power up the instrument :

1. Push the red POWER switch up to the ON position and release it.

2. With an RXU, if there is a STARTUP.TBL file on the CF card, the instrument will follow the instructions contained in the file; skip to step 4.

3. With a V8, or an RXU if you are not working with a pre-configured STARTUP.TBL on a CF card, set up the site and acquisition parameters as described under “Setting up MT/AMT survey and site param-eters” on page 279.

4. Verify that GPS lock has been achieved.

5. With a V8, select the desired recording command from the Acquisition menu.

Tip When preparing to leave a survey site, always ensure that the instrument has acquired the four-satellite minimum. Reposition the GPS antenna or replace the antenna and/or cable if necessary. If you leave the site without ensuring satellite lock, the instrument may not be able to acquire data, and the site will have to be resounded.

6. Cover the instrument with the tarpaulin that you first laid out under it.

• In warm weather, cover the instrument loosely for shade, weighting down the tarpaulin but

276 Chapter 13 MT/AMT Setting up the instrument 276

leaving the sides open for ventilation. (See Fig. 13-11.)

Fig. 13-11: In warm weather, wrap the tarpaulin loosely.

• In wet or damp conditions, wrap the tarpaulin tightly, folding the ends under the instrument to hold the tarpaulin in place. (See Fig. 13-12.)

Fig. 13-12: In wet or damp conditions, wrap the tarpaulin tightly.

• In very hot weather (>35°C), take the instrument out of its carrying case, position it so the connectors face upward, shade it from the sun, and ensure there is good ventilation to prevent damage from overheating. A simple lean-to sunshade can be constructed from two wooden or metal poles, stakes, and a tarpaulin. (See Fig. 13-13.)

277 Chapter 13 MT/AMT Retrieving the equipment 277

Fig. 13-13: In very hot weather, construct a sunshade and remove the instrument from its carrying case. To maximize the exposed surface area, keep the instrument upright, not lying on its side.

7. Take any other necessary precautions to protect the site, and leave the equipment to acquire data.

Final site checklistUse this checklist to verify that your set-up is correct.

• Has GPS lock been achieved?• Is the instrument in record mode?• Has the Layout Sheet been completed?• Has the instrument been protected from the

environment using a tarpaulin?• Have you collected all installation tools?

Retrieving the equipmentRetrieving the equipment from a site is a fairly straightforward reversal of the steps taken to set up. When you arrive, check the site and the equipment for signs of disturbance. You many find cables chewed through by animals, for example, indicating that the site will likely have to be re-sounded.

If everything is in order, then retrieve the equipment using the following procedures.

278 Chapter 13 MT/AMT Retrieving the equipment 278

Shutting down the instrument

Care must be taken that the instrument has shut down properly before battery power is disconnected. If the instrument has not been programmed to shut down automatically at the end of data acquisition, you must shut it down manually. See “Starting and shutting down the V8” on page 47 and “Starting and shutting down the RXU-3E” on page 132.

Remeasuring electrical characteristics

For complete and accurate records, you should repeat the electrical measurements (contact resistance and AC and DC potentials) on the dipoles before disconnecting them. It is also good practice to check the battery voltage, because a reading below 10V may indicate a worn out battery that should be replaced.

Tip The recorded contact resistance is an important factor during data processing, but the resistance changes over time. The change is probably most rapid just after electrode installation, as the salt water disperses. Therefore, during data processing, you may want to use either the post-acquisition value alone, or an average of the pre- and post-acquisition values.

Use the back of the Layout Sheet to record the measurements.

Collecting the equipment

Once you have shut down the instrument and remeasured the electrical characteristics, you can disconnect all the equipment and pack it up for use at the next survey site.

To collect the equipment:

1. Disconnect each E-line and coil it in a large figure-8 shape. Wrap a few layers of electrician’s tape through the top of the “8” to keep the lines tangle-

279 Chapter 13 MT/AMT Setting up MT/AMT survey and site parameters 279

free. (Twist the end of the tape back on itself to make it easy to take off later.)

2. Dig up the electrodes, clean off most of the dirt, and store them in a carrying case containing a few centimetres of salt water. (It is important not to let the electrodes dry out.)

3. Dig up and disconnect the sensors and/or air-loop. Coil their cables and secure them with a few wraps of electrician’s tape.

Warning Never pull a coil sensor out of the ground by pulling on the cable. Damage to the cable or connector can result. Either dig the sensor out completely, or tie a short length of rope around the coil before burying it and pull on the rope to retrieve the coil.

4. Remember to replace all the protective caps on cables and connectors, to protect them from dirt and moisture.

Tip When coiling sensor cables, avoid damage by letting the length of the cable rotate on its axis as you make each loop. Otherwise, the cable will become twisted and kinked, leading to internal breakage.

Setting up MT/AMT survey and site parametersThis section explains how to use the V8 user interface to set up site and acquisition parameters. However, it is strongly recommended that you use the TblEdit program to create a STARTUP.TBL file instead, especially for an RXU. See Chapter 4 on page 87 for instructions on using TblEdit.

To enter the MT/AMT function:

• From the main window, choose MT/AMT (press Ctrl, then type M).

The MT/AMT Site Setup window appears (see Fig. 13-14).

!


Fig. 13-14: MT/AMT Site Setup window.

There are three main sections of the MT/AMT Site Setup window:

• Survey Information • Telluric Channels • Magnetic channels

Some fields of the setup window can only be changed when the instrument is in Pause or Standby mode.

Other fields can only be changed the first time you open the MT/AMT Site Setup window after selecting the MT/AMT function from the main window. The information you enter in the setup window is saved on the CompactFlash card in a file with the extension TBL.

Entering survey information

The Survey Information area of the MT/AMT Site Setup window allows you to keep some basic records concerning the survey. Text in each box can be up to 64 characters long, except the Comment text, which can be 128 characters long. Survey information can be changed at any time, regardless of whether the instrument is recording data or not.

Setting the North Reference. It is critical that survey sites are oriented carefully and that the orientation is recorded correctly. The North Reference parameter allows the data processing software to correctly compensate for magnetic declination and site rotation.


When entering the survey information:

• If you will orient your site to true north (adjusting for magnetic declination in the field), select True North.

• If you will orient your site to magnetic north (making no adjustment in the field) select Magnetic North.

• If you will orient your site to an arbitrary azimuth on a grid plan, select User Defined.

To enter the Survey Information:

1. Press Ctrl and type S to move the focus to the Survey Information area.

2. Press the UP ARROW and DOWN ARROW keys to move the focus to each text box and type the desired information (choose the North reference from the scrolling list).

3. If you chose Magnetic North as the reference, enter the local magnetic declination from True North.

4. When the text fields are complete, press Ctrl, L to move to the Line textbox and type the identifier you have chosen for the current survey line.

5. Press the Tab key to move to the Site text box and type the identifier you have chosen for the current site on the survey line.

Entering telluric channels information

Use this section of the window to enter information about the electric channels.

To enter telluric channels information:

1. Press Ctrl, U to move the focus to the Telluric Channels area.

2. In each text box, type the corresponding E-line parameter that you recorded on the Layout Sheet. Press the ARROW keys to move from one text box to another.


Entering magnetic channels information

Use this section of the window to enter information about the magnetic channels.

To enter telluric channels information:

1. Press Ctrl, M to move the focus to the Magnetic Channels area.

2. In each text box, enter the corresponding parameter that you recorded on the Layout Sheet. Press the ARROW keys to move from one text box to another.

3. If no Hz sensor is used, leave the Hz serial number text box blank.

Note Be sure to record the serial numbers of the sensors correctly. If incorrect information is entered here, the wrong calibration files will be used.

Incrementing the station position

Notice the Next Site button on the MT/AMT Site Setup window. When you complete a station on the survey line and move to the next station, return to the MT/AMT Site Setup window and activate this button. The V8 will use the Station space, Profile azimuth, and starting co-ordinates to automatically calculate new values for the station co-ordinates.

Completing MT/AMT site setup

When you are satisfied with the site setup parameters, exit the setup window and set up the acquisition parameters.

To end MT/AMT Site Setup:

• Either move the focus to the Done button and press Enter, or press Esc, or press Ctrl, D.

The MT/AMT Site Setup window closes and you are returned to the MT/AMT Acquisition window.

283 Chapter 13 MT/AMT Setting up MT/AMT acquisition parameters 283

Setting up MT/AMT acquisition parametersThe acquisition parameters control the acquisition schedule, the size and type of data records, and various filters intended to reduce the effects of cultural noise.

The acquisition schedule can specify both the date and time, or it can be generic and specify only the time. A generic schedule will take effect on whatever day the V8 is powered on.

Frequency ranges

Phoenix instruments can acquire data in four frequency bands (numbered 2 through 5), each with different characteristics. For AMT data, the instruments acquire Bands 2, 3, and 4. For MT data, the instruments acquire Bands 3, 4, and 5.

The lowest frequencies are sampled continuously. To keep files to reasonable sizes, the two higher frequency bands are sampled only periodically.

The user defines a time slot of duration between 0 and 3600s for periodic sampling. (This corresponds to the time slot duration of 0 to 59 minutes in an MTU.) The V8 samples the two higher frequency bands alternately at the beginning of each time slot in a pattern that repeats each hour. (Regardless of the defined duration, a new time slot pattern begins at the start of each UTC hour. For this reason, choose a time slot length that will result in an integer number of time slots per hour.)

Figures 13-15 and 13-16 illustrate the way the bands are sampled:


Fig. 13-15: Sampling scheme (AMT data).

Fig. 13-16: Sampling scheme (MT data).

Band 2 refers to frequencies up to about 10 800Hz. This band is sampled at 24kHz, with each record starting on the UTC second for a duration of 0.1s (2400

scans). Up to four such records can be captured at the beginning of each even-numbered time slot. A higher number improves data quality in the frequency range 1–3kHz where signal strength is very low, but also increases file size. Band 2 is not used when the instrument acquires MT data because only the AMTC-30 sensor is designed to acquire this range.

Band 3 refers to frequencies up to about 1000Hz. This band is the intermediate range in AMT soundings and the high range in MT soundings. Band 3 is sampled at 2.4kHz, with each record starting on the UTC second for a duration of 1s (2400 scans). Up to two such records can be captured at the beginning of each odd-numbered time slot.

Band 4 refers to frequencies up to about 60Hz. This band is the low range in AMT soundings and the intermediate range in MT soundings. In AMT soundings, Band 4 is sampled continuously at 150Hz. In MT soundings, Band 4 is sampled at 150Hz, with each record starting on the UTC second for a duration of 1s (150 scans). Up to 16 such records can be captured at the beginning of each even-numbered time slot.

Band 2

Time Slot 0 1 2

Band 3

Band 4

= 1s data record0–3600s = 0.1s data record

Band 3

Time Slot 0 1 2

Band 4

Band 5

= 1s data record0–3600s


Band 5 refers to frequencies up to about 6Hz. This band is the low range in MT soundings and is not used in AMT soundings. Band 5 is sampled continuously at 15Hz.

Combining instrument types. When an MTU sampling schedule is set to V5-2000, its sampling rate is compatible with that of the V8 and MTU-A. The shaded areas in Table 13-1 show this compatibility. If you intend to combine V8 and MTU and/or MTU-A instruments in a survey, be sure to use the V5-2000 setting in the MTU instruments.

The V8 must be in Setup mode in order to change acquisition parameters.

To put the V8 into Setup mode:

• From the Acquisition menu, choose Setup. (If Setup is disabled, it is already the current mode.)

Fig. 13-17: The Acquisition menu, showing the V8 in Setup mode.


• From the Setup menu, choose Acquisition Parameters, or simply press Ctrl, A.

The MT/AMT Acquisition Parameters dialog box opens (Fig. 13-18).

Table 13-1: MTU ⁄MTU-A sampling rates (number of samples per one-second record).

Band

MTU V8 and MTU-A

V5 Compatible V5-2000

Data Type

50Hz 60Hz MT AMT

2 — — — — 24 000

3 2560 3072 2400 2400 2400

4 320 384 150 150 150

5 24 24 15 15 —


Fig. 13-18: MT/AMT Acquisition Parameters dialog box.

Setting the Data Type

A V8 can acquire AMT data (frequency Bands 2, 3, and 4) using AMTC-30 sensors, or MT data (Bands 3, 4, and 5) using MTC-50 sensors. You must set the data type parameter in order to optimize the instrument circuitry for your purpose.

To set the Data Type:

• In the Data type area, select either AMT or MT.

Fig. 13-19: Setting the data type.



Setting gain

The “correct” setting for E and H gain is dependent on local conditions of signal strength and noise. The objective is to set the gain as high as possible, without causing saturated records. As you build experience with your equipment in your locale, you will be able to judge


the best settings to start with, and when to modify them.

Table 13-2 shows the peak signal strength that can be recorded at each gain setting.

If gains are set too high, records will be saturated and data quality will be poor. To evaluate your gain settings, monitor the instrument during acquisition. The number of saturated records appears in the status bar (“Sat’d Recs:”). If more than a few records are saturated, reduce the gain.

You can set a warning threshold in the Options and Status screen, so that the status bar will change colour

when too many saturations have occurred. See “Customizing the V8 by setting options” on page 67. You can also monitor acquisition by choosing Acquisition Status from the Acquisition menu. See “Monitoring MT/AMT acquisition” on page 290 for instructions.

Setting acquisition times

For MT surveys, the instruments are usually installed during the day and left unattended overnight to acquire data. The V8 allows you to set up an appropriate schedule to start and stop acquisition automatically. To save space on the CompactFlash card, you can also program the instrument to acquire high frequency data for a shorter period of time—a subset of the overall duration.

In the following example, Band 5 is acquired for 9 hours starting at 21:00, but Bands 3 and 4 are acquired for only 5.5 hours, starting at 23:00.

Table 13-2: Gain factors and signal strength

Gain Setting Peak Signal Strength

0.25 10.0V

1 2.5V

4 0.6V

16 0.15V


For AMT data, bear in mind that the signal strength in that frequency range is about 10 times greater at night than during the day. You may want to acquire high frequency data for a subset of the total duration by specifying a High frequency record start time and High frequency record end time so that this Band is acquired after sunset.

Note All times are UTC, in the format HH:MM:SS (hours:minutes:seconds). To specify a date, use the format YYYY/MM/DD (year/month/day) followed by a space, then the time (YYYY/MM/DD HH:MM:SS).

To set acquisition times:

1. Type the Data record start time in the format described above.

If the start time has already passed when the V8 is powered but the current time is less than 12 hours after that start time, acquisition will start immediately. Otherwise, the V8 will idle in Standby mode until the start time.

2. Type the Data record end time in the same format.

3. To record high frequency data throughout the entire sounding, leave High frequency record start time and High frequency record end time set to 00:00:00.

4. If you want to reduce file size by recording the two high frequency bands for a subset of the total duration, type a time for High frequency record start time that is after Data record start time and before Data record end time; type a time for High frequency record end time that is after High frequency record start time and before Data record end time.

Setting sampling parameters

As explained under “Frequency ranges” on page 283, higher frequencies are not sampled continuously. You

21:00 23:00 04:30 06:00

Bands 3 and 4 acquisition

Band 5 acquisition

289 Chapter 13 MT/AMT Acquiring MT/AMT data 289

must define how many records are to be acquired, and how often.

To set the number of samples per record:

• In each Records of Band x per slot text box, type a value within the range shown in parentheses.

To set the time slot length:

• Type a value for the Time slot length in seconds, choosing a value that results in an integer number of time slots each hour.

Note When setting parameters for a reference site and survey sites, make sure that the time slot length and sampling parameters are identical in all instruments. Data from a reference site cannot be used if its parameters differ from those of the survey sites.

If you are combining V8, MTU, and MTU-A instruments in a survey, be aware that the time slot units are different: an MTU time slot is defined in minutes, whereas an MTU-A and V8 time slot is defined in seconds. On an MTU, be sure to choose the V5-compatible sampling rate.

To check the storage space required:

1. Activate the Calc disk required button and examine the status bar to see how many megabytes of storage your settings will require:

2. Verify that your CompactFlash card has enough storage space.

Acquiring MT/AMT data When you have completed programming the acquisition parameters, press Ctrl, D to close the MT/AMT Acquisition Parameters window.

You can override the schedule and start acquisition immediately, or you can activate the schedule you set up as described earlier.


To start acquisition immediately regardless of schedule:

• From the Acquisition menu, choose Start Recording Immediately.

If satellite lock has been achieved, the V8 will enter Record mode.

To start acquisition according to the schedule:

• From the Acquisition menu, choose Start Recording by Schedule.

The V8 idles until the scheduled start time. If satellite lock has been achieved by the scheduled start time, the V8 will begin recording.

Monitoring MT/AMT acquisition

Unlike controlled-source methods where records are stacked and results are displayed in real time, MT and AMT methods require post-processing of the time series. Therefore, it can be important to monitor the acquisition to ensure that gains are properly set, channels are all connected, and that acquisition is

proceeding normally. Use the Acquisition Status dialog box to monitor progress (see Fig. 13-20).

Fig. 13-20: MT/AMT Acquisition Status dialog box.

The first cell of the Status spreadsheet displays the instrument mode. From this you can tell if the


instrument is recording, waiting to start recording, or idling after recording.

The next three cells display the total number of records acquired and also the number of bad records and saturated records.

Records marked Bad usually indicate a problem with the instrument; contact Phoenix Technical Support.

Saturated records indicate gain is set too high. The values for AC and DC signal on each channel in the remaining cells of the spreadsheet will help you identify

the problem and adjust the gain appropriately. See “Setting gain” on page 286 for instructions.

To monitor MT or AMT acquisition:

1. From the Acquisition menu, choose Acquisition Status.

The MT/AMT Acquisition Status dialog box appears.

2. Evaluate the values for each of the cells in the Acquisition Status spreadsheet.


293 Appendix A 293

Appendix

Time Zone Map

294

Appendix A Time Zone Map

294

11 10 9 8 7 6 5 4 3

295


295

2 1 0 1 2 3 54

296


296

5 6 7 8 9 10 1211

297 Appendix B 297

Appendix

Magnetic Declination Resources

298 Appendix B Magnetic Declination Resources 298

The following Internet sites (valid July 2005) provide background information on magnetic declination. These sites also include on-line or downloadable calculators that provide an approximate magnetic declination, given a latitude, longitude, and date.

http://gsc.nrcan.gc.ca/geomag/field/mdcalc_e.php

http://www.thecompassstore.com/decvar.html#

http://geomag.usgs.gov/index.html

For further resources, type the terms “magnetic declination”, with or without “chart map” or other relevant terms into an Internet search engine such as:

http://www.google.com

http://www.thecompassstore.com/decvar.html#

http://gsc.nrcan.gc.ca/geomag/field/mdcalc_e.php

http://geomag.usgs.gov/index.html

http://www.google.com

299 Appendix C 299

Appendix

V8 Specifications

This Appendix provides specifications for the V8.

The values and specifications given here are typical, and are subject to change without notice. They are not claimed to be worst-case specifications.

300 Appendix C Specifications 300

General

Processors• 586 main processor• auxiliary processors

Channels

Instruments acquire and store up to seven electric field channels (E), and three magnetic field channels (H; standard or TDEM), with an overall maximum of 8 channels simultaneously.

Sampling

Frequency range. 10 000Hz to 0.00005Hz (20 000s).

Resolution. One analog-to-digital converter per channel, 24 bits, 96 000 samples/second (main channels); 16–24 bits, up to 5MHz (TDEM channels).

Clocking and synchronization

Sample times are synchronized with UTC using a combination of global positioning system (GPS) signals and stable oven-controlled crystal oscillator (OCXO) clock.

Long-term absolute accuracy when locked to GPS is 1µs or better.

Typical short-term stability governed by OCXO during

GPS dropouts is ±5 x 10-9.

Any Phoenix GPS-equipped devices (MTUs, current sources, related controllers, etc.) can be synchronized at any location worldwide without communication among the units.

Calibration

Units perform multi-frequency self-calibration and magnetic sensor calibration on command. The resulting files contain a complete calibration of the instrument or sensor over its useful frequency range, independent of


the mode of operation (e.g., line frequency, AC/DC coupling). For more information on file format and content, see “Calibrating the V8” on page 72.

Power

Input. 12VDC

Consumption. Varies to a maximum of approximately 15W, depending on the geophysical application and the radio power setting, if used.

Protection. Units shut down automatically when battery voltage is low. All inputs are protected against power surges.

Data storage and transfer

Calibration and acquisition data are stored on a removable CompactFlash card of up to 512MB capacity.

Data can be transferred to a PC by physically transferring the CompactFlash card.

External connectionsMulti-pin connectors are military grade, environmentally sealed.

Ground

An external binding post provides the case ground, which should be connected to a porous pot electrode.

Electric channel inputs

Units are equipped with four binding posts, marked WNSE for ease of cable connection in MT and AMT applications. Additional numeric markings identify the binding posts for use in separate- or shared-electrode modes for other applications.

Battery connector• Circular, 4-pin, shell size 8.


• Surge protection and overload protection on all pins.

• Pin A: Battery 1, +12VDC.• Pin B: Battery 2, +12VDC.• Pin C: Battery common.• Pin D: Battery common.

GPS antenna connector• Circular, BNC-type.

Radio antenna connector• Reverse TNC bulkhead connector.

CommunicationsThe V8 and RXU auxiliary receivers incorporate frequency-hopping spread-spectrum radios operating in the unlicensed ISM bands. In some markets this is

the 2.4000–2.4835GHz band; in others, the 902–928 MHz band.

Mechanical and environmentalCase. Environmentally-sealed diecast aluminum.

Weight. 7kg.

Dimensions. 355mm x 250mm x 110mm.

Operating temperature. –20°C to +50°C.

User interfaceDisplay. 640 x 480 full-colour sunlight-readable LCD.

Keypad. 67-key full ASCII sealed keypad.

Software. Proprietary graphical user interface.


Related productsSeveral other products for similar or specialized applications are available or under development.

RXU-3

A radio-capable 2- or 3-channel (E) receiver used in a network of V8 and RXU instruments. Provides an infrared interface to allow setup and monitoring from Palm OS® handheld devices.

RXU-TM

A radio-capable single channel transmitter controller and monitor used in a network of V8 and RXU instruments. Provides an infrared interface to allow setup and monitoring from Palm OS® handheld devices.

UTC signal output:

• 921 600Hz

• 1Hz• 1/60Hz

Geophysical current source control output:

• 0.001Hz to 10kHz

Control waveforms are referenced to zero phase at UTC 2000 Jan 01 00:00:00.

V8-EX

An expansion cabinet that attaches to the V8, providing a lithium-ion battery pack and additional binding posts for multi-channel acquisition.

MTU family

System2000 receivers, 2–5 channels for MT data.

MTU-A family

System2000 receivers, 2–5 channels for AMT data.


MTU-TXC

A radio-enabled control unit used to synchronize other equipment, such as current sources, to System 2000 and System 2000.net equipment. Specifications similar to the RXU-TM.

CMU-1

A current monitor that provides feedback to the MTU-TXC on the actual transmitted waveform.

MTU-2ESD, MTU-5ESD

Used in remote reference and monitoring applications, these instruments use a 33.6kb/s dialup telephone connection for control and data transfer.

MTU-2ES, MTU-5S

Also used in monitoring applications, these instruments use a serial interface for control and data transfer, typically connecting to a fibre optic or copper wire modem.

MTU-5LR

Used in surveys with extended depths of investigation, these instruments employ a ring-core fluxgate magnetic sensor and low sample rates.

MTU-AI family

These instruments, under development in 2003–04, provide an infrared interface to allow setup and monitoring from Palm OS® handheld devices.

305 Appendix D 305

Appendix

Sample Layout Sheet

This appendix contains a sample Layout Sheet as used by Phoenix survey personnel. You can design and print your own Layout Sheets, or order a supply from Phoenix, printed on the same waterproof, tear-proof paper as this User Guide.

306 Appendix D Sample Layout Sheet 306

Obtaining a supply of Layout SheetsTo purchase Layout Sheets from Phoenix, send us your order using these part numbers:

Table D-1: Layout Sheet part numbers

Content Part Number

Binder only 7355

30 Layout Sheets for left-handed writers 7356

30 Layout Sheets for right-handed writers 7357

Binder plus 30 left-handed sheets 8081

Binder plus 30 right-handed sheets 8082

309 Appendix E 309

Appendix

Sample Equipment Checklist

Instrument & Components ID Number ID Number ID Number ID NumberMTU BoxFlash MemoryBatteryBattery CableGPS AntennaGPS cablePot 1Pot 2Pot 3Pot 4Pot 5Sensor 1Sensor 2Sensor 3AirloopSensor cable 1Sensor cable 2Sensor cable 33-way Sensor connectorE-line cable 1E-line cable 2E-line cable 3E-line cable 4Ground pot cableParallel cable, PCPC

Tools Qty Req'd Qty LoadedShovelLevelElectrician's TapeColoured TapeRanger CompassBrunton Compass Brunton Mount Brunton TripodCable Reel & CableMeasuring TapeWire stripper/cutterWater SaltBentonite or granular clayLayout Binder & SheetsPencilsMapAnalog OhmmeterDigital VoltmeterGPS Receiver

Use one column for each scheduled site

Phoenix Geophysics LimitedMT 5-Component Survey Equipment Checklist

311 Appendix F 311

Appendix

Meazura Quick Start Guide

Quick Start Guide

1. Setup

3. Charging

Front View

Rear ViewTop View

Bottom View

Power

DirectionalArrows

Backlight

Center

Menu

Home Calculator

Find

MZIO™ Module

Infrared Port

Battery Pack

Battery Clip

Stylus

Communications andCharging Connector

Module Fasteners

Meazura™ SetupWhen powering up your Meazura™ for the first time, press the Power button and follow the on-screeninstructions to setup the device. This includes calibration of the touch sensitive screen and setting yourlocation, date and time. During this procedure, you can at your option take a Graffiti writing tutorialfor entering text and special characters on your Meazura™.

Touchsensitivescreen

GraffitiPad

• Plug the Communications cable into a USB or Serial port on your computer (as picturedin figure 2a/b below).

• Connect the communications cable to the communication connector located at the bottomof the Meazura™ (as pictured in figure 1 left).

• Ensure the Meazura™ Desktop Software CD-ROM is inserted into your computers CD-ROM drive.

• Press the power button to turn on your Meazura™ and perform a HotSync operationfollowing the instructions in step 4 to commence the driver install for your Meazura™.

• Follow all instructions on your PC and your Meazura™.

2. Connect

Figure 1

Figure 2a Figure 2b

Figure 3

Figure 4

PC SetupTo communicate between the Meazura™ and your PC, you must install‘Palm Desktop’ located on your CD-ROM included with your kit.1. Exit all programs, including those that may be running in the taskbar.2. Insert the Meazura™ Software CD into your CD-ROM drive.3. The install menu should appear automatically. If it doesn’t then

navigate to ‘install_menu.exe’ located on your CD-ROM usingWindows Explorer.

4. Follow the on-screen instruction for installing ‘Palm Desktop’.

USB Connection Serial Connection

• Connect your AC adaptor to the bottom of your communications cable (as pictured belowin figure 4).

• Connect the communications cable to the comms connector located at the bottom of yourMeazura™ (as pictured below in figure 4).

• Ensure your connection setup is the same as pictured in figure 3 left to commence charging.

WARNING: For safety reasons, ensure the Meazura™ iscompletely dry before using the electrical charger.

(Charging time varies depending on battery level)

5. Calibration

7. Contrast/Backlight

4. HotSync®

6. Resetting

All Content Copyright © 2004 Aceeca Limited - All Rights Reserved. Aceeca, Meazura, MEZ1000 and RDA are all trademarks of Aceeca Limited. Palm OS, HotSync,Graffiti and the Palm Powered logo are registered trademarks and Palm Powered is a trademark of Palm Trademark Holding Company, LLC. and are used byAceeca Limited under express license with PalmSource, Inc. All other trademarks referred to in this document are the properties of their respective owners.

QSG-MEZ1000-090204

• Ensure Palm Desktop software is installed on your computer (see step1 ‘Setup’)

• Connect the communications cable to your Meazura™ and yourcomputer as per instructions over page in step 2 (‘Connect’).

• On your Meazura™ RDA, tap on the HotSync icon (as pictured left).• Tap the large icon in the center of the screen to start the HotSync

operation.• Follow all instructions on your PC and your Meazura™.

This procedure calibrates the touch sensitive screen on your Meazura™

• Tap on the ‘Prefs’ icon• From the dropdown list, choose “Digitizer”• Follow on-screen instructions

Other preferences for setting up your handheld can be found in the dropdown list, such as “Date and Time”. To adjust these extra settings,simply tap the setting choice in dropdown list and follow the on-screeninstructions.

To turn on the backlight, press the Backlight button (pictured right)

Press and release Power and Backlight button together

Soft Reset(no loss of data)

1. Press and hold the Power and Backlight button together then release the Backlight button only2. Release the Power button when the Palm Powered logo appears3. Follow on-screen instructions

1.

2. =

Hard Reset(restores Meazura™ to factory settings)

Backlight

To adjust the contrast of the screen, hold the backlight button for 1.5 secondsto bring up the contrast slider on-screen (as pictured left).

• Use your stylus to drag the slider bar until you reach your desired contrast,then click ‘Done’.

Contrast

313 Index 313

Index

Symbols*.tbl files, 53®, RXUPilot parameters, 119

Numerics2.5 GHz, 1603-person crew, 255900 MHz, 160921.6 kHz, 178

AACEECA, 108acquiring data

CSAMT, 226MT/AMT, 289SIP, 212TDEM, 245

acquisitioncontrolling with RXUPilot, 126LED indication, 37

acquisition parametersCSAMT, 223MT/AMT, 283SIP, 209TDEM, 241

aiming directional antennas with RXUPilot, 124

air-loopcalibration, 77layout, 78pre-amplifier orientation, 261substitution for coil, 261

AL-100 air-loop, 260alligator clamps, battery, 34Ampl statistic, RXUPilot, 128AMT

electrode connections, 21signal strength, 288techniques, 250

AMTC-30 coils, 250, 284, 286analog ohmmeter, 263antennas and masts, 162apparent resistivity, filter roll-off, 61

array layoutsCSAMT, 218SIP, 200

arrays, illustrationsCSAMT, 218SIP, 201TDEM, 232

assembling antenna tripod, 169Auto modes, 181AUTO parameter, RXU-TM, 154Auto Stepping, activating on V8, 196Auto-1 mode

CPFR, 194frequency stepping pattern, 192non-pattern frequencies, 191schedule, 194TPFR, 194TTOT, 194

automatic current reduction, 195automatic formatting, Excel, 187automatic modes, 181automatic polarity correction, TDEM, 244

314 Index 314

Bband 2, 284band 3, 284band 4, 284baseline data, acquiring after

calibration, 84batteries in parallel, 33battery

alligator clamps, 34capacity, 33connecting, 33maintenance, 84V8-EX, 34voltage warning, LED indication, 39

bayonet-lock connectors, 18Bentonite, 264binary format, converting schedule

files, 188bipolar waveforms, 183blank row, inserting in spreadsheet, 52Box Cal OK, 72Box In Progress, 73Box No Cal, 72box spreadsheet, 55By schedule, file close time, 82

Ccable

excess E-line, 258parallel batteries, 33

Cagniard, 7CAL directory, 72, 74, 133, 143Calc disk required button, 289Calculate Coord button

CSAMT, 222SIP, 208

calculator, magnetic declination, 298

calibration, 150air-loop sensors, 77air-loop, tools required, 77cancelling, 79cancelling, RXU-3E, 135cancelling, RXU-TM or CMU-1, 150CMU-1, 145coil sensors, 74duration, 74, 255equipment, 254instrument file name, 72, 133, 143instrument, tools required, 73, 133, 143programming, 71RXU-3E, 132RXU-TM, 143sensors

file name, 74layout, 75tools required, 74

sunlight and, 74temperature, 72, 133, 143using RXUPilot, 116viewing results, 80

calibration failure, LED indication, 39cancelling calibration, 79capacity, battery, 33capital cost, 252changing calculated co-ordinates,

SIP, 209changing location, SIP, 214

315 Index 315

channel spreadsheetCSAMT, 221SIP, 207TDEM, 238

channels, specifications, 300checklist

E-line, 272equipment, sample, 309final site, 277sensor, 274

CLB file name, 72, 133, 143clock status, LED indication, 41clock, RXUPilot, 115clocking and synchronization,

specifications, 300CMU-1, 141

calibrating, 145maximum current, 142setting up, 151

Coil Cal OK, 72Coil In Progress, 76Coil No Cal, 72coils

AMTC-30, 250, 284, 286MTC-50, 250, 286

combining instrument types, 285Comma Separated Values (CSV)

files, 186comment text, 280common operations, 17

communication content and schedule, radio, 164

CompactFlash cardinstalling and removing, 29not installed, LED indication, 39

compass, handheld at site centre, 269compensating

obstructed dipole, 257rotating the site, 258slope, 259

component separation, 260configurations, radio, 160connecting

battery, 33electrodes, 20system components, 18V8-EX, 34

connectionselectrodes for MT/AMT, 21order of, 33specifications, 301

contact resistance, see resistancecontinuous update, RXUPilot, 128Controlled Source Audiofrequency

Magnetotellurics, 217corner frequency

feedback, 62high pass filter, 66

correcting layout errors, 262cost, capital and operating, 252

coupling, 60setting, 66SIP, 210, 224, 286vertical sensor and E-lines, 260

CPFR, 155in Auto-1 mode, 194

creating a frequency schedule file, 186CRMX, 196CSAMT, 217

acquiring data, 226array layouts, 218channel spreadsheet, 221setting up, 219

CSV files, 186current

roll-off in Auto-1 mode, 195current sensor, CMU-1, 143

Ddata processing, 266Data record

end time, 288start time, 288

data storage and transfer, specifications, 301

Data Type, setting, 286data, controlling logging, 81date format, 288declination, see magnetic declinationdepth of investigation, TDEM, 235

316 Index 316

difficulties, E-line, 257digital voltmeter, 263digits, significant

in auto modes, 178specifying frequencies, 178

dipoleobstructed, 257voltage, 264

dipole-dipole array setupSIP, 203

directional antennas, 163aiming with RXUPilot, 124

disk space low, LED indication, 39documentation, handheld terminals, 108driller’s mud, 264, 271duration of soundings, 250

Eediting spreadsheets, 51electric channels, setting up RXU-3E, 138electric fences, 256electrical characteristics, measuring, 270

electrodesconnecting, 20, ??–22connecting to instrument, 269connections for MT/AMT, 21faulty, 263identifying with E-line knots, 269installing, 23lead-chloride in, 84salt water ratio, 23testing for faults, 84, 271

elevation, RXUPilot, 115E-line

adjusting for difficulties, 257checklist, 272landmark alignment, 268length, 256setup, 267

Encryption Key, RXUPilot, 124ensuring quality data, 83entering magnetic channels information,

site setup, 282entering survey information in site

setup, 280entering telluric channels information,

site setup, 281

equipmentcalibrating, 254collecting, 278installation time, 253inventory and inspection, 255maintenance, 84protection, 264retrieval, 265, 277storage and handling, 83

equipment checklist, sample, 309error

Frequency Stepping Table, 196Out of IR Range, 114phase shift, 61

error, phase shift, 62errors

layout, 262errors and warnings, LED indications, 39evaluating sites, 253Ex, defined, 257Excel, 186excess cable, 258excitation loop, 77exploration, 3exporting data, 266external connections, specifications, 301Ey, defined, 257

FF1 Menu key, 50

317 Index 317

factors affecting radio communication, 166

FAT, FAT16, FAT32, 32FCMX, 155, 196fences, electric, 256FEND, 155fields

text, 51File close time, 82file duration, 81file names, schedule files, 97, 187filtering, 60filtering and noise, specifications, 300format

CompactFlash card, 32data records, 303

format, date and time UTC, 288formatting a CF card, 32FPOC, 155Freq statistic, RXUPilot, 128FreqTabl.exe, 83frequencies

valid and invalid, 196

frequencyderivation, 178ranges, 283ranges, specifications, 300recommended frequencies (table), 179sampling, illustration, 283schedule files, 186setting, 186significant digits, 178stepping pattern, 192

frequency rangesAMT and MT, 250specifications, 300

frequency steppingCSAMT, 225TDEM, 243

Frequency Stepping Tablered highlight, 196

frequency stepping, RXU-TM, 154frequency stepping, SIP setup, 211FRQ parameters, frequency

stepping, 155FRQ0–FRQ9 in Auto-1 mode, 190

Ggain margin, radio, 168gain setting

CMU-1, 100, 156MT, AMT, 55, 287

gain, adjusting, 227, 246

gain, setting, 286Generate Frequency Stepping Table

utility, 83global positioning system, see GPSGPS

antenna, connecting, 24ensuring lock, 275handheld locator, 256LED indications, 36lock, defined, 264testing receivers with landmarks, 84

gradient array setupSIP, 205

Graffiti, 108keyboard instead of, 110

graphs, low pass filter, 61grid, north reference, 281grid, survey, 252

HHand Era, 108HGNC, CMU-1 gain parameter, 156High frequency record start time, 288high pass filter, 66Hx, Hy, Hz, defined, 260

Iidling

LED indications, 38IERS, 178

318 Index 318

iInverse array setupSIP, 205

incrementing the station position, 282induction loop, 259Industrial, Scientific, and Medical

band, 160infrared port, 110inserting rows in spreadsheets, 52installation time, 253installing and connecting system

components, 18installing PC software, 10installing whip antenna, 173instrument

calibration, 255powering, 275setting up, 275shutting down, 278

interface, V8, navigating, 46International Earth Rotation and

Reference Systems Service, 178interpreting data, 266inventory, equipment, 255IR port, 110ISM, 160

Kkeyboard, instead of Graffiti, 110

Llate time apparent resistivity (TDEM),

equation, 234latest detectable signal (table),

TDEM, 235latest detectable signal, TDEM, 233latitude, RXUPilot, 115layout errors, correcting, 262layout sheet, sample, 305lead-chloride, 84, 256leap seconds, 178LED indications, 35–46

battery voltage warning, 39calibration failure, 39clock status, 41CompactFlash not installed, 39disk space low, 39examples, 43mode, 41new sequence, 38–46original sequence, 36satellite lock, 40saturated records, 39summary, 42system error, 40using new sequence, 45

Len/Area, TDEM, 239line frequency filter, 66loading setup or startup files, 53

locking-ring connectors, handling, 18longitude, RXUPilot, 115long-term soundings, batteries, 33loop orientation, TDEM, 233loop, induction, 259low pass filter, 61low pass filter graphs, 61LP Filter, 61

Mmagnetic declination

and site rotation, 258Internet resources, 298

magnetic signal, variation with distance, 251

magnetic vs. telluric deployments, 251maintenance, equipment, 84map

topographical, 252map, time zone, 293mast

installing antenna, 172masts and antennas, 162maximum current, CMU-1, 142Maximum Slaves, RXUPilot, 123measuring

AC and DC potentials, 271electrical characteristics, 270

Meazura terminal, 108documentation, 108

319 Index 319

mechanical and environmental specifications, 302

meters, analog vs. digital, 263Microsoft™ Excel, 186mode, LED indication, 41modes

automatic, 181changing, 210

Modifying calculated co-ordinatesCSAMT, 223TDEM, 240

modifying calculated co-ordinates, SIP, 209

monitoring, 251Mstr Rng/Brng, RXUPilot, 124MSTRLAT, 164MSTRLNG, 164MT

electrode connections, 21MT techniques, 250MTC-30 coil, 260MTC-50 coils, 250, 260, 286

NNetwork Addr, RXUPilot, 124Network Status, RXUPilot, 123network, radio, 159Next Site button

CSAMT, 223TDEM, 240

Next Site button, SIP, 209noise, variation with distance, 251noise, wind, 253, 259north reference, 280Notepad, 186NTFS, 32Number of Wnd, TDEM, 244

Oobstructed dipole, 257ohmmeter, analog, 263omni-directional antenna installation

mast, 172tripod, 170

omni-directional antennas, 163operating and monitoring RXU-TM, 154operating cost, 252operating RXU-3E, 139operating temperature for

calibration, 72, 133, 143operations, common, 17orientation, sensor, 261Out of IR Range error, 114output

phase, 178

PPalm OS, 108PalmPilot, 108parameter-based frequency

stepping, 155path loss, radio, 167pattern, frequency-stepping, 192PC requirements, 83PC software, installing, 10, 83PDA, 108permissions, 253phase, 178

leap seconds effect, 178phase shift error, 61, 62Phse statistic, RXUPilot, 128ping, 165planning, 252polarity, in TDEM, 233pole-dipole array setup

SIP, 203pole-pole array setup

SIP, 203power levels, radio, 166power, specifications, 301pre-amplifier orientation (air-loop), 261processing data, 266productivity, 255pulling, survey direction, 205pushing, survey direction, 205

Qquality control (quick start reference), 14quality data, ensuring, 83quick start reference, 9–16

320 Index 320

Rradio

antenna, 162communication content and

schedule, 164factors affecting communication, 166gain margin, 168mast, 162operating RXU, 173operating V8, 174path loss, 167receiver gain, 167receiver sensitivity, 167setting up communication, 169system gain, 166transmitter gain, 167tripod assembly, 169

radio communication, 159RXU-3E, 135RXU-TM, 150setting up with RXUPilot, 122

radio configurations, 160Radio Encryption Key, 162radio master bearing and distance,

V8, 164Radio master latitude and longitude,

V8, 163Radio Network Address, 161Radio Type, 160Radio Unit Address, 161Radio’s Transmit Power, 162rain

and instrument, 256and sensors, 262

ramp length, TDEM, 237receiver gain, radio, 167receiver sensitivity, radio, 167recommended frequencies (table), 179record formats, 303recordkeeping, 255red highlight, Frequency Stepping

Table, 196related products, specifications, 303remote channels, acquiring with RXU-

3E, 136remote reference, 251remote site, distance, 251Remotes, network quality, RXUPilot, 125repeating electrical measurements, 278

requirements, survey, 85resending results, radio network, 166resistance

and low pass filter, 61measuring, 263reducing, 264

resistivity, apparent, filter roll-off, 61resolution, specifications, 300retrieving equipment, 277Rho statistic, RXUPilot, 128rolloff corner frequency, 196rolloff in apparent resistivity, 61rotating the site, 258rows, spreadsheet, adding and

deleting, 52RQST parameter, RXU-TM, 154RXU radio, operating, 173RXU-3E, 131

calibrating, 132operating and monitoring, 139remote channels, 136setting up electric channels, 138shutting down, 132starting, 132

321 Index 321

RXUPilot, 107, 111address, 114aiming directional antennas, 124Ampl statistic, 128continuous update, 128controlling acquisition, 126Encryption Key, 124Freq statistic, 128GPS, 115launching, 111maximum slaves, 123Mstr Rng/Brng, 124Network Addr, 124network status, 123Phse statistic, 128radio communication, 122remotes and network quality, 125Rho statistic, 128SnCh statistic, 128station statistics, 127Time statistic, 128Tx Power, 124updating display, 113

RXU-TM, 141AUTO parameter, 154calibrating, 143frequency stepping, 154operating and monitoring, 154radio communication, 150RQST parameter, 154setting up, 151

Ssalt water ratio, 23, 268sample rates, 284sampling parameters, 288sampling rates, 285sampling, specifications, 300satellite lock, LED indication, 40saturated records

cause, 257saturated records, LED indication, 39Save command, 52saving data files, 81saving settings, 52saving settings files, 53saving startup files, 53scalar layout, CSAMT, 218schedule

equipment, 253

schedule filesconverting to binary format, 188creating, 186examining, 189naming, 97, 187

schedule, Auto-1 mode, 194Schlumberger array setup

SIP, 205scrolling statistics, RXUPilot

RXUPilotscrolling statistics, 129

selecting a frequency-stepping pattern, Auto-1 mode, 192

sensitivity, CMU-1, 142sensors

AMTC-30, 250, 284, 286calibration, 255checklist, 274connecting, 273installing air-loop, 28installing horizontal, 27installing vertical, 27MTC-50, 250, 286orientation, 261orienting, 27setting up, 273

separate vs. shared electrodes, 20separation, components, 260setting acquisition times, 287setting gain, 286

322 Index 322

setting sampling parameters, 288setting up

radio communication, 169RXU-TM, CMU-1 and transmitter, 151SIP acquisition, 202

setting up survey sites, 255settings files, 53settings, saving, 52Setup.exe, 83shared vs. separate electrodes, 20shutdown, LED indications, 38shutting down an instrument, 278shutting down the RXU-3E, 132shutting down the V8, 278signal polarity in TDEM, 233signal strength, AMT, 288significant digits (specifying

frequencies), 178significant digits in auto modes, 178SIP, 199

acquiring data, 212changing location, 214

SIP acquisition, setting up, 202site setup, MT/AMT, 279sites, setting up, 255slope, 259SnCh statistic, RXUPilot, 128

software, installing on PC, 10software, PC, 83sounding, duration, 250specifications

channels, 300clocking and synchronization, 300data storage and transfer, 301external connections, 301file types and logical record

formats, 303filtering and noise, 300mechanical and environmental, 302power, 301related products, 303sample resolution, 300sampling, 300system, 299

specifying non-pattern frequencies, Auto-1 mode, 191

Spectral Induced Polarization, 199spreadsheet, 186spreadsheets, editing, 51S-shape, excess cable, 259Stack result file log, 81stacked waveforms, 250stacked waveforms, saving, 81Standby mode, 285

startup, LED indications, 36, 38STARTUP.TBL

defined, 254static electricity and CF cards, 32station statistics, viewing with

RXUPilot, 127Statistics file log, 81steps in a typical survey, 252Stop Calibration, 80storage space required, 289storage, equipment, 83summary, LED indications, 42survey

grid, 252requirements, 85site, setting up, 266typical steps, 252

survey direction, pushing vs. pulling, 205Symbol Technologies, 108Symbol terminal

documentation, 108synchronization, phase, 178system error, LED indication, 40system gain, radio, 166

TTCP/IP, 160

323 Index 323

TDEM, 231channel spreadsheet, 238depth of investigation, 235late time apparent resistivity,

equation, 234latest detectable signal, 233Len/Area, 239loop orientation, 233Number of Wnd, 244polarity correction, 244polarity of signal, 233ramp length, 237setting up, 235Tx Loop Length, 238Tx Loop Turns, 237

TDMA, 160techniques

MT and AMT, 250telluric lines, setting up, 256telluric vs. magnetic deployments, 251TEM, 231temperature and calibration, 72, 133, 143testing electrodes, 84text, typing, 51Tikhonov, 7Time Domain Electromagnetics, 231time format, 288time series, saving, 81time slot, 283Time slot length, 289

Time statistic, RXUPilot, 128time to install, 253time zone map, 293topographical map, 252toxic material (electrodes), 84TPFR, 155TPFR in Auto-1 mode, 194traffic and data quality, 260Transient Electromagnetics, 231transmitted LF current, 196transmitter

setting up, 151transmitter gain, radio, 167trigonometry, 259tripod, assembling, 169TTOT, 155TTOT in Auto-1 mode, 194Tx Loop Length, TDEM, 238Tx Loop Turns, TDEM, 237Tx Power, RXUPilot, 124

Uunipolar waveforms, 184unit Address, RXUPilot, 123Update cell, box spreadsheet, 165user interface, V8, navigating, 46UTC, 115UTC, format, 288

VV5-2000 sampling schedule, MTU, 285V8

navigating the user interface, 46radio, operating, 174

V8-EXchanging battery, 34connecting, 34

vector layout, CSAMT, 218verifying location, 266vertical coil, 260VLF filter, 61voltage, dipole, 264voltmeter, digital, 263

Wwaveform

bipolar, 183code, 186phase, 178unipolar, 184

Waveform file log, 81waveforms, stacked, 250Wenner array setup

SIP, 205WFRM, 155whip antenna

installing, 173whip antennas, 163

324 Index 324

wind noise, 259

Documents

•V8 Multifunction Receiver •RXU-3 Receiver User Guide •RXU ...System 2000.net User Guide •V8 Multifunction Receiver •RXU-3 Receiver •RXU-TM Transmitter Monitor Version