Operation Manual - Michigan Technological University

SmartSeis Exploration

Seismograph

26325-01 Rev. C

Operation Manual

Copyright 8 March 2000

GEOMETRICS, INC. 2190 Fortune Drive, San Jose, CA 95131 USA

Phone 408-954-0522, Fax: 408-954-0902 E-mail: [email protected]

SmartSeis™ Seismograph Owner’s Registration Copy this page, fill in the information, and mail it to Geometrics when you receive this instrument and again whenever the operator of this instrument changes so that we can provide updates to the system software and this manual. Users Name ______________________________ Telephone __________________________ Company ________________________________ Fax ________________________________ Address _________________________________ E-mail _____________________________ __________________________________ Date Received _______________________ __________________________________ Serial Number _______________________ First Registration New User Country _________________________________ Change of Address

SmartSeis™ Operating Manual Page i-1 Introduction

Introduction

The SmartSeis is unlike any earlier seismograph. It is easy to use and it gives you answers in the field; features made possible by an internal computer programmed to help you solve your problems in looking beneath the surface. New users will be pleased to find a tutorial which may be viewed when the seismograph is turned on. A menu bar makes it easy to set up the instrument to take and display your data. The menus include an option for "standard settings" which will be adequate for any initial refraction survey. Use these first to avoid grappling with unfamiliar concepts or choices like "sample rate" and "display gain". After you gain more experience, you can re-visit these concepts and comfortably adapt the instrument as your surveys become more complex. Surprisingly, you will find that the SmartSeis combines simplicity of use with remarkable improvements in capability. The SmartSeis, with its 16-bit precision and 100-dB dynamic range, is a high-performance exploration seismograph, applicable to reflection, refraction, borehole and other specialized seismic surveys. To expand on these capabilities, the system stores its data on either floppy disk or hard disk. The recording media are DOS compatible, and may be read on any DOS-compatible computer equipped with the same storage device. The computer built in is equivalent to an IBM AT computer with 80386sx microprocessor. If you purchased the computer port option, it may also be accessed with an external keyboard. Depending on your level of experience, you may wish to proceed directly to Chapter 2 for an abbreviated set of instructions (designed for experienced users), or start with Chapter 1 (which provides an expanded tutorial). Appendix A contains a detailed explanation of the menus; while the remaining appendices provide supplementary and reference information. The SmartSeis Seismograph is a software controlled device which will receive periodic enhancements. Thus, it is likely that the menus and operating instructions in this manual may differ in minor respects from those on your instrument. As a general rule, operating menus will be self-explanatory and this will not cause any inconvenience or confusion. There may be a "README" file on the system disk containing updated information. It is absolutely essential that we maintain a record of SmartSeis users so that we can provide you with periodic updates of this manual and the system operating software. Copy the user's registration form and send it to us when you take possession of the instrument and whenever a new user takes responsibility for the SmartSeis Seismograph. Please include comments on the instrument and suggestions for improvements in this manual.

SmartSeis™ Operating Manual Page 1-1 Complete Operating Instructions

Chapter 1. Complete Operating Instructions This chapter is written for less experienced, or new users of exploration seismographs, but not with the intent of teaching fundamental geophysics. However, the system has a tutorial which includes basic principles. This tutorial is available when the system is turned on, offered as a menu selection. There are instructions included to print the tutorial for convenience. Besides the tutorial, the operator should read the application literature sent with the instrument, as well as standard textbooks on geophysics1. This manual will focus on the hardware, its use, and a few things not found in textbooks. You should also read Appendix A which explains operation of the menus, and Appendix B which provides details on the actual hardware: seismograph, geophones, cables, etc. If you consider yourself an experienced user of modern exploration seismographs, you may wish to go directly to Chapter 2, which contains a condensed set of operating instructions. For first time use, keep things simple. In fact, practice first in a comfortable office to gain thorough familiarity with the menus and equipment. Then, the first survey should be done close to home, with a sledgehammer source, and short geophone spread (say 10 ft or 5 meters between geophones). This section will be written with this setup assumed, and the operator can extrapolate this experience to more complex surveys and those using explosive sources. Preparation Before going to the field, see that paper is loaded in the printer. Open the case, then the front panel (press the two latches on either side) and look at the paper supply. If necessary, load paper, using the instructions inside the front panel lid. You will need a supply of 1.4-Mbyte, 3.5-inch floppy disks (these are the type labeled HD or high density, not DD or double density) You can format these disks on a DOS-compatible desktop computer or with the SmartSeis, or you can buy disks already formatted. Formatting prepares the disks for recording data. The SmartSeis will format disks in the field, but it's not a good way to expend field time and battery power. Instructions for formatting disks on the SmartSeis will be found in Appendix A in the FILE-FORMAT section. Setup Unpack the system and gather your accessories. You will need a 12-volt battery if one was not purchased with the system. Since the SmartSeis S12 only draws about 22 amps (or 32 amps

1For example, Exploration Geophysics of the Shallow Subsurface, by H. Robert Burger, 1992, published by Prentice Hall, ISBN 0-13-296773-1.


for the SmartSeis S24), a medium capacity (say 20 to 30 amp-hour) battery should be sufficient for a day in the field. The SmartSeis will normally be operated vertically; it is rain resistant in this position, and the display is readily viewable. Do not leave the instrument exposed in a heavy rain. Place the SmartSeis up on a reasonably flat surface and remove the cover. Spread the geophone cable in a line. Plant (by pressing the spike into the ground) a geophone by each connector (called a takeout) on the cable. The geophone connectors will have a method to encourage proper polarity (such as wide and narrow color-coded clips) connections. Connect the geophones to their connectors, and the geophone cable to the seismograph. If you are using a 24-channel SmartSeis R24, you will locate the seismograph in the center of the line and use two geophone cables and 24 geophones. Connect the 12-volt battery with the red clip to positive and black clip to the negative lead. If the connections are reversed, it will not damage the instrument, but it will not function. Operation Turn on the switch near the power connector. One of the light-emitting-diodes on the front panel should light, indicating the battery voltage. Note and remember which LED lights for a fully charged battery. As the battery charge is expended, the voltage will decrease and different LED's will light. The transition will be particularly fast in the last few minutes of operation. The voltage indicator will provide advance warning of battery discharge, as well as an aid in troubleshooting power problems Wait several seconds while the system powers up, conducts its internal tests and loads the seismic software. After the power up cycle, the screen should display a message or a set of seismic traces. If the screen is blank or faint, adjust the display contrast with the two arrow keys just above the battery level indicator. The display may be completely blank until the contrast is adjusted. There is a backlight for the screen, which may be turned on or off, depending on which gives the best display in the ambient lighting conditions. The backlight on-off control is in the Display menu discussed below. The screen will display a menu with the option of reading the tutorial, proceeding with instrument setup, or using the prior setup.

To read the tutorial, just press the ENTER key when the "Tutorial Setup" is selected. You may print a paper copy of the tutorial using the directions provided in the tutorial. COMPLETE SETUP will take you directly to the menu used to select the operating parameters

TUTORIAL SETUP COMPLETE SETUP USE LAST SETTINGS


of the seismograph. Several of the menus have a QUICK SETUP option at the top of the list. These choices will be adequate for most refraction surveys, and are a good place to start.

Once you have used the system, you will use the USE LAST SETTINGS option. That means that the controls are set as they were when the instrument was last used, as though your seismograph had mechanical switches. It is not necessary to actually select this menu item, just pressing the CLR key will turn off this menu and use the last settings. Geometry The term geometry is used to describe the locations of the geophones and the seismic energy source. Since seismic data processing requires knowing the locations of these items, their coordinates can be recorded with the data. The line geometry is also used by the ANALYZE functions, which you will see later can give you answers right in the field. The system may have already asked you for the distance between geophones as part of the power-up sequence. You also need to set the shot location. Press the MENU key. A menu bar will appear on the screen with several choices in different categories. One of the menu selections (DO_SURVEY) will be highlighted in reverse video, and a secondary menu will be displayed below it. One of the secondary items (INSPECT ARRIVALS) will be shown in reverse video. This secondary menu will be used routinely during actual surveys, and thus it always appears first for your convenience. However, before starting to survey, you need to set up the system. When you first use your seismograph, position the cursor over the OTHER position. Set the clock and calendar for your time zone, and set the units to meters or feet. Do this by positioning the cursor over the item in the list, or press the matching number key. Follow the directions on the screen to change the settings. If in doubt, refer the OTHER section in Appendix A. Now set the line geometry. Position the cursor over GEOMETRY. Start with the QUICK SETUP by pressing ENTER with the reverse video cursor over that position, or by pressing the number 0. That will set the geometry to the default settings, including setting the mode to refraction. Next, set the phone interval (if needed), and go to the phone and shot locations menu. This menu requires actual linear coordinates for the shotpoint and geophones, but it is easy to set by exception. Point the cursor at the shot coordinate and enter the correct value (or use the default). If you don't have a coordinate, then assign an arbitrary shot coordinate which will at least be valid for all the shot points related to this particular geophone spread, and preferably for the

GEOMETRY ACQUISITION FILE DISPLAY DO_SURVEY ANSWERS OTHER


entire survey line. Similarly, set the shot offset or any geophone location. If the distances between the geophones are not equal, set these as appropriate. Follow the directions in the menu or refer to Appendix A for further assistance. SHOT INTERVAL is only used for reflection surveys, you may ignore this function temporarily. Acquire Data In seismic data acquisition, electrical signals from the geophones are amplified, digitized, and stored in the seismograph's memory. The variables which affect the process are selected in the ACQUISITION Menu. Wrong choices of acquisition parameters can be corrected by clearing the memory and repeating the shot. If you are using a hammer source, and summing multiple impacts, most of these settings should not be changed between blows. Thus, the seismograph will not allow you to change those parameters when data is in the memory. The memory must first be erased. Use the arrow keys to point the cursor at the ERASE command and press ENTER. This will erase any data in memory (it may already be erased). Next, use the arrow keys to move the reverse video cursor to the ACQUISITION position, displaying the menu used to set the acquisition parameters. Position the cursor over the QUICK ACQ SETUP command and press ENTER. This will set the acquisition parameters to a commonly used set of default values. Except for variations in the sample rate and record length, these are the basic settings for routine refraction surveys, and they should be adequate for most surveys. Later on, as you gain more experience, you might choose different settings for unusual surveys. Engage the noise monitor by selecting NOISE DISPLAY in the DO_SURVEY menu. In the NOISE DISPLAY mode, signals from the geophones are used to wiggle the traces on the screen. Use the up and down arrow keys to adjust the noise monitor sensitivity, until small excursions are visible on the traces. These trace excursions represent the background vibrations sensed by each geophone. The screen will display a set of moving traces, writing the noise record on the screen. Stomp the ground and you should see a noise burst on the traces representing the geophones closest to you. If there are two people present, one can walk the line while the other observes the footsteps on the screen. This noise display is a useful diagnostic tool. You can confirm that your cable and geophones are working properly, identify noise problems, and usually schedule your shot during quiet periods. Let the seismic noise settle a little, and look at the relative amplitudes of each trace on the noise monitor display. If the geophones are all connected and properly planted, and if the cables are good, all traces should look about the same. Unusually small or large excursions on any trace are indicative of some problem that should be investigated. Disconnect a geophone to see the effect of a problem.


The level of background noise can be measured with the scale factor displayed on the screen just above traces 1 and 2, and noted in the observer's log as a quantitative measure of background noise. Your next step is to generate the seismic wave and record it on the instrument. Use a metal plate (called a striker plate) as the impact point for the hammer. Place it on the ground near the end of the string of geophones, separated by the distance set in the GEOMETRY menu (or, position the plate and set the shot offset to the distance from the striker plate to the near geophone). Attach the hammer switch to the hammer, taping it to the top edge of the handle near the head with stretchy electrical tape. Tape the wire to the handle near the hammer switch, and again near the end of the handle. Connect the hammer switch to the start connector on the seismograph. Since working with the hammer will probably trigger the seismograph, clear the memory (in the DO SURVEY menu) again. The hammer blow should be timed for quiet periods (when background seismic vibrations decrease) as monitored by the noise display. (The SmartSeis can be triggered only when the display is in "noise display" or "trace display"; you can prevent accidental triggers by selecting any screen with a menu displayed). Advise anyone in the area to stand still and not talk while recording data. Hit the striker plate to create a seismic impulse and trigger the seismograph. The word SAMPLING on the top line will temporarily be displayed in reverse video, indicating that the system was triggered. The digitized record is stored in the seismograph memory, and the computer is processing the data display. Data Display After a few seconds, the noise monitor record will disappear and a seismic record will appear on the screen (the data may not look right yet, perhaps there will be only straight lines, or wildly overlapping traces). The Display Menu is used to control how the data looks on the screen. The display functions may be changed at any time, since they do not affect the original data stored in memory, only the way it looks on the screen (and the paper plot). Press the MENU key and move the cursor to the DISPLAY menu. Select QUICK DISPLAY SETUP and press ENTER. This will set the display parameters to a set of popular default values. Press CLEAR to remove the menu from the screen and expose the traces. You should see a seismic record on the screen. The record can be scrolled up or down on the screen by pressing the up and down arrow keys. You can time specific events on the record by using any of the three timing lines on the display. Press the MENU key and the reverse video cursor will be positioned on the INSPECT ARRIVALS command. Press ENTER. The seismograph will automatically adjust the traces, pick the first arrivals (putting a marker on each trace) and position the traces so that the first breaks are on the screen.


There should be a collection of traces with excursions representing the vibrations at each geophone. The trace for the geophone nearest the impact point should have clear, early arrivals. First arrivals on traces from geophones further away should occur later and later in time. Since the instrument is set to the refraction mode, you will be offered the option of manually editing the first break picks and saving these numbers on the active disk drive. Remember that you should have the values in the geometry menu properly entered as part of this stored information. It may be necessary to go to the DISPLAY menu and adjust the individual trace sizes to make the picks easier to see and edit. At this point, you may wish to experiment a little with the display functions to change the look of the record and to gain familiarity with the system. The trace size adjustments control the excursions of the individual traces on the screen. If necessary, use the TRACE SIZE ADJUST: INDIVIDUAL function to adjust the appearance of the display (see Appendix A in you need directions). TIME SCALE will stretch the waveforms on the screen, so that the first arrivals are easier to pick, or compress them so that more of the record is visible on the screen. Examination of the entire record should also show surface waves and perhaps signals from the sound of the hammer striking the plate (see Figure 1 for an example). Use the up and down arrow keys to scroll the display on the screen if necessary. Print Make a paper copy by using the PRINT command in the DO SURVEY menu. To stretch or

Figure 1, Example seismic record, shown in wiggle-trace format and compressed time scale.


compress the printed record, use the PRINT TIME SCALE command in the DISPLAY menu before printing. The NORMAL, EXPAND and COMPRESS functions change the time scale of the record on the printer. These change the character of the seismic record, and the best choice will depend on a particular data set and the type of information displayed. Expanding or compressing the record can compensate for less than optimum choice of sample rate or record length. Experiment with these functions to see how they affect the character of the display. On the SmartSeis, the print and display scales are independent, providing flexibility in use. Notice the trace size multipliers above each trace. The numbers are different, with smaller numbers for those traces near the impact point. Traces away from the impact point will have larger trace size numbers. The trace size number is related to the amplification applied to the original data to display the traces. Thus, a small signal (like that from the more distant geophones) will require more amplification to make the excursions a usable size. The numbers are in decibels, or dB, and they change in steps of 3 dB from 0 to 99. Each 3 dB step is an increase of 1.414 times the previous value; 6 dB is 2 times. Thus, the trace size increments in a logarithmic manner, providing a very wide range of adjustment. Reducing the trace size decreases the excursions by .707 for –3 dB and 2 for –6 dB. As a normal rule, you need not concern yourself with these numbers, but they are diagnostic of certain problems. For example, if a trace is "dead" (shows no excursions) and the trace size value is small, that means that the trace size is turned down too small. If the number is large (say 99 dB), that means the signal is very small, perhaps from a bad geophone or other cause. As a learning exercise, you can compare the relative strength of the vibrations on each trace. Use the TRACE SIZE control on INDIVIDUAL and adjust each number to the same value. Then, use ADJUST ALL to increase or decrease all the traces simultaneously until the display is scaled to the best value. The near traces will have very large excursions and the far traces will be straight lines. In this mode, it is easy to judge the attenuation of the seismic signal with distance from the impact point. Make a copy if desired, then use the AUTO ADJUST and INDIVIDUAL trace size options to return the traces to a normalized display. Signal Enhancement The distant traces may be noisy. A noisy seismic trace is caused when extraneous vibrations are mixed with the signal, sometimes making it difficult to identify the first arrivals. These vibrations come from wind, vehicles, airplanes, and people. Because the signal on the geophones furthest from the seismic source are quite small, seismic noise is normally more of a problem on the far traces. When working with explosive sources, this is not generally a problem. If the signals are too weak, you just use more dynamite the next time. That is not the case with a sledgehammer (and other mechanical sources), you can only hit the ground with a certain amount of energy. To extend the depth penetration attainable with a sledgehammer, the SmartSeis can add signals


from multiple hammer blows. This process is usually called "signal enhancement" or "summing" or "stacking". The record is saved in the memory, and each time the ground is hit, the new data is added to the old sum, and the signal grows. Ambient noise is random, and it does not increase as much, so the "signal-to-noise" ratio improves as you strike the ground repeatedly. In practice, the noise increases as the square root of the number of blows, while the signal increases linearly. Thus, the improvement is proportional to the square root of the number of impacts. Try summing. Hit the striker plate again with the hammer. The record should grow larger as two records are now stacked into the memory. Further impacts should cause the traces to continue to grow. Traces that were noisy will still be noisy, but a larger seismic signal will be superimposed on the record. Using the trace size adjustments will shrink the traces back near their original size, and there should be much less noise now. First arrivals should be more distinct and easier to pick, especially on those traces distant from the energy source. Although the SmartSeis is designed to stack thousands of hammer blows without problems, there is a practical limit to the improvement available from signal enhancement, usually around 10 to 20 blows. Freeze FREEZE is used to lock in the data on individual channels. This stops the selected channels from stacking or erasing. Freeze is often useful when working in noisy conditions where many hammer impacts are needed to produce a usable record. Commonly, some traces will have good first breaks and others will be noisy (random chance dictates that some channels will be bad). Use freeze to save the good traces, then focus on the noisy weak channels individually or in small groups. Freeze is also used in specialized surveys, like "Optimum Window" reflections (where you collect data on only one channel at a time) and borehole shear wave studies (where you might activate two channels while hitting one end of a plank, then two others while you hit the other end, then two others while you hit the top). To try this function, return to the DO SURVEY menu, select FREEZE, them SOME. Use the arrow keys to freeze some of the channels (see Appendix A for detailed instructions). The channel numbers on the frozen traces will be displayed in reverse video. Clear the memory. Notice that the frozen channels remained on the screen. Hit the ground a few times and observe that the frozen channels do not change while the normal channels will change, growing with each impact. Unfreeze all the channels by selecting FREEZE in the DO_SURVEY menu, then "NONE" in the sub-menu. Clear the memory with the ERASE function. Other display modes


The traces can be displayed on the screen several different types. The basic mode is wiggly lines, each representing the motion of the ground at a geophone. This is the classic form of a seismogram, and is called "wiggle trace" (or wriggle trace) as shown in Figure 1. Wiggle trace is a good mode for getting an overview of the record, but less useful than the other modes for most purposes. Once seismographs made the transition from analog to digital instruments, data was processed on computers. Interpreters found that if you shaded the positive trace excursions black, it was easier to see reflections in the record. The SmartSeis offers this option, called "variable area" or VAR AREA in the display menu. An example is shown in Figure 2. Variable area is generally better for reflection surveys. Notice however, that the variable area shading turns much of the record solid black, obscuring portions of the individual traces. This suggests another option, which has been called "shaded". In shaded, the positive excursions are shaded grey instead of black, and you can see individual traces even when they pass through the shaded portion. Choose variable area or shaded for reflection surveys, depending on which works best for an individual recording. In refraction surveys, the first arrival of the wave at the geophone is the major event. In either variable area or wiggle trace, adjacent traces can swing over and obscure the first arrivals. To solve this problem, there is another mode called "clipped". In this mode, the traces are stopped just before they get halfway to the next trace, and a flat top replaces the normal swing. No trace can interfere with viewing another, so this mode is preferred for picking first arrivals for refraction surveys. The traces look

Figure 2, Seiamic record display in Variable Area format.

Figure 3. Record with data displayed in "clipped wiggle".The trace display gain has been increased to sharpen the first arrivals for better "picking".


strange, and you lose the character of the later arrivals, but you don't care, the information you want to see is clearly visible, as in Figure 3. "Clipped" is available in combination with wiggle trace, variable area or shading. Although "Clipped" is a better form for picking refraction records, its tendency to obscure the character of the wave makes it difficult to use. To really see the seismic picture, you need the whole waveform, with background noise, first arrivals, sound waves, and surface waves displayed. Seeing the whole picture allows you to predict the location of the desired first arrivals almost exactly, and you should work with normal wiggle trace first, adjusting the trace size for the best image. Then, you can switch to the clipped format to eliminate overlap between traces. It will be very helpful to have the data stored on floppy disk, even though you may have a pickable paper record in the field. Experiment with these options. Hit the ground with the hammer to produce a new record on the screen. Change the display by switching the TYPE to each of the other combinations. Observe the effect on the trace display. Print a copy if desired. AGC


Until now, the display was in fixed gain, which means that the trace size scale factor on a particular trace is constant throughout the length of the record (though the scale factor on individual traces may be different). Notice that each trace contains a quiet early portion, a large signal as the vibrations pass the geophone, and then a quiet portion near the end. For many applications (particularly reflection surveys) you might wish to use a different gain at different times in the record. The automatic gain control (AGC) performs this function, increasing or decreasing the trace size to keep the excursions at some reasonable value throughout the record. The particular type of AGC used in the SmartSeis is called "digital AGC". The average signal in a section of the trace, called a "window", is used to adjust the trace size (larger or smaller) for the data sample in the middle of the window time period. Then, the window is advanced slightly and the adjustment repeated for the next data sample. Digital AGC is able to look ahead in time, see a large signal coming, turn the trace size down in advance, and properly display large first arrivals. Look at the record in Figure 4. The very early portion of the record looks noisy on the far traces. This is normal, since the AGC increases the trace size until something shows, even if it's only background noise. Then, as the window advances to include the first arrivals, the gain is decreased in anticipation. The process continues throughout the record. The length of the window (in data samples) can be selected by the operator to fit the data set. For very shallow reflection surveys, with high frequency signals, the time should be relatively short. For deep reflections, or if you choose to use AGC on refraction surveys, use longer time windows. As a general rule, adopting a standard number of samples (say 250) will work for most cases, correcting automatically when the sample interval is changed. Turn the AGC on, setting the window length to 250. Adjust the trace size (you always will need to adjust the trace size when switching between AGC and Fixed Gain). The appearance of the wave will be quite different than in the previous experiment. Identification of events in the record now depends on the character of the wave and comparisons to adjacent traces (rather than on amplitude). Clear the memory and stack a few impacts with AGC on. Notice that much less adjustment is required of the trace size with AGC operating. Turn off the AGC and readjust the trace sizes.

Sample of AGC data display

Figure Unavailable

Figure 4, Data display with AGC.


Remember that AGC, like the rest of the DISPLAY menu items, has no affect on the original data stored in memory, only on how it looks when displayed and plotted. AGC is an advanced function, normally only used for reflection surveys, and new users should used fixed gain trace display. Once familiar with basic data acquisition and display, the operator should experiment with some enhancements, described in the following section. Use of the filters Filters are like the tone control on a music system. Different frequencies (such as bass and treble sounds) can be boosted or attenuated to affect the sound. Likewise, the filters in the SmartSeis can attenuate low or high frequencies in the seismic record. The seismic record will contain many different signals: refractions, reflections, surface waves, vibrations from traffic or wind, and other interference. Most of these are considered "noise" and are undesirable. Some noise signals are different in frequency than the desired signals, and filters may be used to improve the visibility of the desired signals. In particular, noise from a source some distance away tends to be lower in frequency than seismic data (because the earth carries the low frequency signals for long distances). Some signals may be considered noise, even though they are not random. The prime example is surface waves, which will grow with every hammer blow, but which can obscure useful reflection arrivals. Surface waves are always lower in frequency than shallow reflections, and you can use a lowcut filter to reduce them, letting the reflections appear. Noise from wind may be either high frequencies (from wind blowing on the geophones) or low frequencies (from wind blowing on trees or buildings, which then push on the ground). Different types of filters can be used to reduce either type of noise. The SmartSeis offers two sets of filters: acquisition and display. The acquisition filters are improved "real-time" digital filters which operate on the incoming data to the system just like traditional analog filters. When data is acquired with acquisition filters, their effect becomes part of the record stored in memory. The display filters on the other hand, are temporary. They operate on the data after it is stored in memory, and the type and corner frequencies can be changed to examine the effect of different filters on the stored data. When the display filters are used, the filtered data is displayed on the screen and a paper copy can be plotted, but the original data is held in memory. If the record is saved on a disk, the original raw data is saved, not the filtered result. This allows the user to select a different set of filters later when the data is processed or read back into the SmartSeis for analysis. It is generally better to use less filtering when acquiring data, and more when displaying data, to preserve the option for later changes during analysis.


Lowcut filters are used to remove low-frequency signals (like surface waves, and noise from distant traffic). Notch filters are used to reject interference from power lines. Highcut filters attenuate higher frequencies, such as wind noise or nearby machinery. Each filter has an effective frequency, called the corner frequency, which can be selected in the menu. Lowcut filters attenuate frequencies below the corner, and highcut filters attenuate frequencies above the corner frequency. Notch filters attenuate frequencies near their frequency, passing those above or below. To experiment with the display filters, return to the DISPLAY menu and select LOWCUT 50 HZ. Optimize the trace display and print a copy. Repeat the experiment with other, higher frequency, lowcut filter settings. Compare the records from each filter (including the one made earlier with no filter) to see the effect of the lowcut filter. If there is noise from a low frequency source, it should get progressively smaller as higher frequency filters are used. The first arrivals should grow more distinct, and then later fade away again as you pass into the frequency range where they are also filtered out. There may be a range of filter settings where reflections are visible on the record. The low frequency surface waves should disappear when higher frequency lowcut filters are used. Figure 5 shows a record displayed with a double lowcut filter. Using the same filter twice doubles the attenuation slope from 24 dB/octave to 48 dB/octave. This is the same survey line used for the previous examples; note that some of the low-frequency surface waves have been removed and some possible reflection events are visible in the data at around 100 milliseconds. Figure 5, Data plotted with double lowcut filter.


Try the same experiment with the notch filters. These will be less dramatic in their effect on the record and changes may not be visible at all unless there is some power line noise present. Remember that ideally they will not change the character of the seismic record (although there is always some change in the signal from removing 50 or 60 Hz information). Since 3-phase power lines also radiate at three times the fundamental frequency, 150 and 180 Hz notch filters are also provided. Repeating the experiment with the highcut filters should show some reduction in high frequencies, particularly at 250 Hz. This may be evidenced by rounding of first breaks or other effects. You will need to choose between acquisition and display filters. Acquisition filters have the disadvantage of permanence, but the advantage of eliminating so-called edge effects at the beginning and end of the record. In general, when a notch filter is required, it is better to select one in the acquisition menu. Using Preview for Discretionary Stack Preview lets the operator inspect each new record before stacking it into memory. Commonly, noise is transient; cars pass by, gusts of wind blow, so some individual records are better than others. When operating at greater distances between the energy source and the far geophones, or when working in areas with troublesome noise bursts, you can use preview to control which records are stacked. Turn the filters to OUT. Select PREVIEW in the STACK MODE Menu. Clear the memory and hit the ground with the hammer. After a few moments, the screen will display a seismic record, with a message in the corner of the screen advising the operator that this is preview data. The record may be accepted for stacking into memory (by pressing ENTER), or rejected (by pressing CLEAR). Press ENTER to stack the data. Try a few more times, selecting in each case. Try an intentionally noisy shot by moving your body or having someone walk down the geophone spread as you hit the ground. The most significant advantage of PREVIEW occurs when working in marginal conditions with say 10 or 20 hammer blows per shotpoint. After hitting the ground 19 times, the whole record can be lost if a car goes by during the 20th stack. With PREVIEW, this problem can be eliminated. Note that a similar function, UNSTACK, is available in the DO SURVEY menu. UNSTACK will subtract the most recent record from memory. Return STACK MODE to Autostack.


Using Delay Normally, the seismograph begins recording data instantly when the source triggers. The delay function is provided to postpone the start of the record by a selected time. This is applicable to surveys where there is a substantial distance between the shotpoint and the nearest geophone, and where there is no usable information in the early part of the record. One example might be velocity logging of deep boreholes. The delay can also be used to increase the effective record length by shooting sequential records with and without a delay and then merging the files. To test the delay, take a sample record as was done earlier. Print a copy. Then, enter a delay equivalent to some point prior to a recognizable portion of the record. Repeat the shot with the delay and compare the two records. Notice that the record made with the delay has not recorded the early portion of the record, but has appended some additional time to the record. The timing line times (and annotated time lines on the plotted record) are automatically adjusted for the delay values, so times picked on the record are referenced to shot time. Delay can also be set to a negative number, which means that the record will display some data prior to the actual trigger. This is helpful when using an energy source which is difficult to time precisely, such as a weight drop, or an air gun. One of the seismic channels can be connected to the trigger signal or to a motion sensor near the source to record the signal. Routinely using a little negative delay will help the automatic first break picking program do a better job. Set the delay back to -10 Using negative stack polarity The SmartSeis normally adds a new record into memory. It will also subtract. This polarity reversal is provided for the enhancement of shear waves, a special type of survey. Shear wave surveys are conducted by using a directional source which impacts perpendicular to the axis of the survey line (horizontal geophones are generally used). For confirmation, the direction of impact of the source is reversed, which creates shear waves of the opposite polarity. The SmartSeis stack polarity can be reversed at the same time, so that the shear waves will enhance and P-waves tend to cancel, providing an optional method of conducting shear wave surveys in difficult conditions. Since the principles involved are not important in learning to operate the SmartSeis, an actual shear wave survey should be deferred until a need exists. To test the process, try stacking a hammer blow in the normal mode, then invert the polarity and stack again. The seismic waveforms should tend to cancel, leaving just noise on the record.


Negative stack polarity may also be used to invert, or reverse the polarity of the record. If you prefer your first breaks to move up instead of down, or vice versa. Reducing the number of acquisition channels The number of channels in use may be reduced when not needed. In borehole surveys, it is common to use only three geophones (or even one). Reducing the number of channels limits the amount of memory required, so that more records may be stored on a single disk. To change the number of channels, use the ACTIVE CHANNELS menu. A list of channels will appear; use the arrow keys to select and de-activate the unused channels, referring to Appendix A if necessary. Storing data If you used a seismograph before, chances are that your result was a paper plot which you took home, picked the arrivals, analyzed, and interpreted. If that is the case, you know that records which looked fine in the field suddenly develop poor first arrivals. Perhaps even the location was uncertain. The SmartSeis will save the digital records on a disk. Once saved, it can be read back into memory, or read and displayed on a personal computer. This can be extremely useful, even for ordinary refraction surveys, since the records plotted in the field are never optimum and often difficult to pick. Plotting the records again in the office, picking them from the screen or an optimized paper plot, is a great improvement. Automatic refraction analysis on the computer is an even greater benefit. Of course, digital recording and processing is required for reflection surveys. As with other operating procedures, this is simple with the SmartSeis, although experience operating DOS compatible computers is helpful in understanding drive selection and directories. Insert a disk in the 3.5-inch drive behind the side cover. Be sure that the disk is not write protected, by sliding the tab to cover the hole. Engage the Menu; position the Cursor over FILE. Check the CHANGE DRIVE status. If necessary, set to Drive A:. Return the acquisition parameters to the initial settings used earlier and acquire a record. Look at the record on the screen (and print a copy if desired). Position the cursor over the DO SURVEY menu and select SAVE. Press ENTER. If the disk is not formatted, a "disk error" message will appear. Move the cursor to the FORMAT command in the FILE menu and press ENTER to format the disk. Follow the commands on the screen and wait several seconds for the "format complete" message. Then, try saving the file.


When the file is saved, a file saved message will appear on the screen. The message in the top right corner of the screen will change from "UNSAVED STACKED DATA" to "SAVED AS FILE xxx". Clear the memory, and observe the blank traces characteristic of a cleared memory. Move the cursor back to the FILE menu and select READ. A list of available files will appear on the screen (there may be only one file at this point, but eventually there will be several files on the disk). Position the cursor over the file number just saved and press ENTER. The disk drive will hum again, retrieve the data, and it will display on the screen. Compare it with the previous record. Remember that you can still use the options in the Display menu to change the way the data looks or even filter the records to enhance the specific events of interest. You also have the option of storing the data on the internal hard disk (Drive D:) instead of the floppy. The hard disk is quite a bit faster, and is more convenient in the field. Use of directories and the other disk operations are discussed in Appendix A. At this point, you should know how to acquire data, save it on disk, and read the data back. You should also be quite familiar with the use of the system menus at this point. Remember to set your floppy data disks to "write protect" when full. Slide the write protect tab to the open position, leaving the hole open. If you try to save data on a disk which is "write protected", the screen will display some sort of disk error message. The hard disk may also be used to store data. In general, it will be faster, more convenient, and immune to dust. You will need to copy the files to floppies later. The hard disk is drive D:, which can be selected in the FILE menu. Answers The Answers menus is used to analyze the seismic data. Programs are provided to provide a fairly complete seismic refraction solution, including a geologic interpretation with layer depths and velocities. A proper seismic refraction interpretation should have at least two records, one with the source at each end of the line. Better detail and deeper information can be obtained by also locating the source well off either end of the line and in the center. For each shot, the INSPECT ARRIVALS function will pick the first breaks and save the data on disk. Be sure that the line geometry is properly entered for each shotpoint. To help you remember, the SmartSeis will prompt you for geometry data at appropriate intervals. Once the first breaks are saved, the Answers menu has functions to draw the time-distance graphs and plot the interpreted section on the plotter. The complete procedure is described in Appendix A. in the section describing the ANSWERS menu.


There are additional functions to analyze reflection data and linear velocities, also described in Appendix A. While these programs will not provide final seismic sections, they should assist the user greatly in knowing he has good quality data before leaving the field. Conclusion By now, you should appreciate that the SmartSeis is an extremely powerful and easy to use seismograph. Only a portion of the features have been exercised, and you should continue familiarization by reading the appendices and conducting further field experiments. Try different choices in the Acquisition and other menus to see the effect. As a general rule, the SmartSeis is very forgiving, and will gather the highest quality data possible with a minimum of effort in the field. If you have conducted surveys before, you will quickly learn to appreciate the advantage of not having to set the gain controls for every refraction shot. Of course, the SmartSeis is capable of shallow reflection surveys. You are encouraged to explore these possibilities further. Geometrics can offer advice, short courses, and application notes to assist you.

SmartSeis™ Operating Manual Page 2-1 Condensed Operating Instructions

Chapter 2. Condensed operating instructions This section of the manual is provided for users who are experienced in the use of seismic equipment. Every effort has been made to make the operation of the SmartSeis simple and self-explanatory, and you may be able operate the system by just reading this introductory material. You should acquaint yourself with the rest of the manual at your convenience. System Setup Unpack the system and gather your accessories. You will need a 12-volt battery if you did not receive one with the system. Since the SmartSeis S12 only draws about 22 amps (or about 32 amps for the SmartSeis S24), a medium capacity (say 20 to 30 amp-hour) battery should be sufficient for a day in the field. Connect the battery pack, with the red clip to positive and black clip to the negative lead. If the connections are reversed, it will not damage the instrument, but it will not work. Connect the geophone cables, geophones, and energy source. Switch on the instrument with the switch near the power connector. One of the light-emitting-diodes on the battery level indicator should light. Wait several seconds while the system powers up, conducts its internal tests and loads its software. After the power up cycle, the screen should display a message or a set of seismic traces. If the screen is blank or faint, adjust the display contrast with the two arrow keys just above the battery level indicator. The liquid crystal display and keypad are used to operate the system. The seismic record is displayed on the screen, with operating menus overlaid when used to control the instrument. The display consists of four message lines above a set of vertical seismic traces. The first two lines list the acquisition parameters and other status messages. The next two list the channel numbers and the trace size scale factor in decibels. There are also three horizontal cursor lines across the screen, annotated with times in milliseconds. The information lines should be self-explanatory. Further information may be found in Appendix A or Chapter 1, Detailed Operating Instructions. Menu Operation The SmartSeis operation is through an interactive set of menus and sub-menus. These are engaged by pressing the MENU key, and making choices with the arrow keys, ENTER, and CLR. In general, use the arrow keys to move around in the menus, the ENTER key to make a selection, and the CLR (clear) key to exit from menus or escape without making changes. Avoid the tendency to exit some menus (like FREEZE) with the CLR key instead of ENTER. In that case, the selected choices are not entered.


When MENU is pressed, a set of menus appears on the screen:

One of the main menu choices (DO_SURVEY) will be selected, shown in reverse video, and a secondary menu displayed below on the screen. Use the left and right arrows to move between menu choices, and the secondary menu will change depending on which item of the main menu is selected. Use the up and down arrows to select items on the secondary menus. Work your way through the list and examine each set of menus. You can also select a menu item by pressing the key for the number next to the item in the menu. This is faster than pointing with the reverse video cursor, and for repetitive operations in routine surveys, you will soon memorize the numbers corresponding to the function. The secondary menus may either be action items (e.g. PRINT, NOISE DISPLAY) or they may be names for third level (tertiary) menus (e.g. FILTER, TRACE SIZE). In either case, the action or the tertiary menu is selected with the ENTER key. If you press ENTER while PRINT is selected, the seismograph will print a copy of the seismic record. Try selecting PRINT and printing a copy of the record. Load paper if necessary, using the instructions inside the panel. Experiment with the menus and explore the function of each. Since this chapter is for experienced users, and since the menus of the SmartSeis are generally self-explanatory, obvious features will not be discussed here. Refer to Appendix A for detailed information about any menu item that is not clear. Some are unique to the SmartSeis and will require investigation. After you are familiar with the menus and their structure, you should be able to operate the system. There are some subtleties, listed below: 1. When the seismic record is displayed, and there are no menus on the screen, the up and

down arrow keys will scroll the data on the display. The three annotated time lines on the display can be used to time events.

2. The SmartSeis will only trigger when the screen is in trace display or noise display

modes. When a menu is on the screen, the trigger is disabled. This feature can be used to prevent false triggers.

3. While in the noise display, the noise monitor sensitivity is set with the up and down

arrow keys. The same gain is used on all channels. The sensitivity will be displayed on the screen (top left, line 4), so that the operator can log ambient noise in millivolts. If



you know the sensitivity of the geophones, you can convert noise level in volts into seismic motion levels.

The noise monitor is also the geophone test. If any geophone (or cable) is open, shorted, or has a stuck coil, its trace on the noise channel should be noticeably smaller than the other channels.Some problems may be indicated by excessive signal, perhaps an open or leaky conductor near a power line for instance. In general, this geophone test will be much more diagnostic than a simple continuity/leakage test.

4. There are two sets of signal filters available. The filters in the ACQUISITION menu

operate on the incoming data, just like analog filters. Once data is acquired with these filters, the process is permanent, and filtered data is stored in memory (and will be saved on disk).

The filters in the DISPLAY menu are post-acquisition filters which only affect the data shown on the display and printed on the plotter. The original raw data is held in memory and saved on disk. As a general rule, it is better to acquire your data with a wider bandwidth, then filter it later. This gives you more information content and flexibility in processing.

The SmartSeis has digital anti-alias filters (except at the 32¼ microsecond sample rate). The corner frequency is selected when the sample interval is set, and the phase response is selected when the survey mode is set (see Appendix A). So, anti-alias filter operation is automatic.

5. SAMPLE INTERVAL and RECORD LENGTH are interdependent parameters on the

SmartSeis. To allow use of less than the maximum memory, there is a menu option to select just a portion of the available memory. Set the sample interval first, then record length. Changing the sample rate will affect the record duration but not the number of samples in a record.

6. Many acquisition parameters cannot be changed with data in memory. Clear the memory

first before changing those parameters that affect how data is acquired (e.g. sample rate, filters, record length, etc.). Parameters which may be changed include freeze, stack mode, and stack polarity.

When a record is read from disk, the acquisition parameters displayed on the top of the LCD screen will reflect those read from the header, not the instrument settings. However, the parameters listed in the secondary menus will continue to reflect the current instrument settings. This is particularly significant in the GEOMETRY menu which contains the line geometry. To find the line geometry parameters which were stored on a disk file, it is necessary to print a copy of the record and read the values listed in the print header.


7. When saving a file, the system will assign a default file name, one digit higher than the

last file saved. If a new name is selected, that will become the new base name.

The SmartSeis will also allow the use of Directories as with any DOS computer. You may assign directories to the project, the day, and even the line if desired. Once a directory is selected (using the Directory menu options), the files will be saved in that directory. Since a directory is established on each individual disk, their use on the 3.5-inch floppies should be avoided. Swapping disks may lead to directory errors.

A directory can have a maximum of 100 files (shots). If an attempt is made to store more than 100 files in a directory, the system will automatically create a new directory one number higher.

8. Under the GEOMETRY menu are entries for line geometry and other file header

information. It is good field practice to make these entries, and they are required for a number of operations, including all the ANSWER programs and for saving or printing files in the refraction mode. See Appendix A. for an explanation of these parameters.

9. The OTHER menu includes a choice of units, meters or feet, used in the ANSWER

programs, plus a clock and calendar. Set these parameters to your local standard. 10. The ANSWERS menu contains several geophysical analysis programs used for quality

control in the field. Experiment with these if you wish. A complete list and detailed instructions are in Appendix A. Note before you start that most of the programs require that accurate information be entered for line geometry in the GEOMETRY menu.

Acquire data Go to the GEOMETRY MENU and set those parameters to reflect the survey line. Clear the memory in the DO SURVEY menu. Select the ACQUISITION menu and set the acquisition parameters for the line: sample rate, record length, filter settings, etc. Engage the NOISE DISPLAY (found in the DO SURVEY menu). Raise or lower the sensitivity by pressing the up or down arrow keys. The screen should display the noise envelope on each of the active channels, continuously updating. Check to see that all the traces are functional, thus testing the geophones and cables. The background noise level will vary with the situation. Stomp on the ground and watch the noise display vary. Operate the energy source to trigger the seismograph. The noise monitor display will disappear, and be replaced by the seismic record.


Examine the record Select the DISPLAY menu and adjust the display parameters for the desired record display. Trace Size includes an automatic selection, usually a good place to start to get some usable data on the screen. Other choices include variable area/wiggle trace modes, digital filter functions, AGC, time scale, trace size, and channels displayed. Since you can observe the effect of each change, little explanation is required. You may need to readjust the trace size whenever changing between AGC and fixed gain displays. AGC has the effect of keeping trace amplitude relatively the same for the entire record, whereas fixed gain gives a more familiar display with large first arrivals and smaller later waveforms. Try an AGC window length of 200 samples as a first choice. Print a copy (in the DO_SURVEY menu). Change the printer scale if the physical length of the record is too long or too short (see PRINT TIME SCALE in the DISPLAY menu). If the record is noisy, and it is difficult to recognize the significant arrivals, you may wish to repeat the energy source and stack additional shots. Note that stacking in the AGC mode does not increase trace size as in a conventional seismograph, but the data should become more noise free. Save the data The SAVE file command, which commands the system to save the seismic record onto the default disk drive, is located in the DO_SURVEY menu. The remaining disk drive commands are located in the FILE menu. You can save files on either Drive A: (the 32-inch floppy) or Drive D: (the internal hard disk). To use a floppy, check to see that the default drive is A:, insert a formatted disk into the disk drive, and press SAVE. If the disk is unformatted, the system will prompt you, then use the FORMAT command to format the disk. To use the hard disk, select Drive D: and make a sub-directory if desired. The shot and geophone group locations (set in the GEOMETRY menu) will be saved with the data file. Read that section of Appendix A for an explanation of these variables. When saving a file, the system will suggest a number for the file name, listed in the DO_SURVEY menu. Press ENTER to use the suggested name or, (if you want to change) select a new name-number in the FILE menu. The data will be saved under that selected file name. The next time you save a file, the system will suggest a name one number higher. Since a file name can have 8 digits, you can easily incorporate additional information as part of the name (such as the survey line, or date, or project). Then, it becomes easy to sort the records with standard DOS commands.


The seismic record will be saved with the extension .DAT, indicating a data file. Related files (such as first breaks) will be saved with the same name but a different extension. It is unlikely that the system will save the data incorrectly, without providing an error message. However, you can check by first clearing the memory, then reading the same file from disk using the READ option in the FILE menu. It is not necessary to clear the data from memory first, but it may be reassuring. Once the operating parameters are set, the commands used to acquire data are all located in the DO_SURVEY menu, which is also the active menu selected by the MENU key. This grouping in sequence of routine commands will expedite actual surveys. If the SURVEY MODE is set to REFRACTION, the INSPECT ARRIVALS command will automatically position the traces on the screen so that the first arrivals show. Then, the system will pick the first breaks automatically. You have an option to adjust the picks manually, then save the picks as a file. As the process is repeated for the same spread with different shot points, additional picks are saved for the other shots. The ANSWERS menu will read this data and draw a Time-Distance Plot, and then, after the layers are assigned, plot a geologic cross section. This concludes the experienced user operation section. It is assumed that the reader will exercise the system and learn the subtleties of the menu through experimentation. There is a significant amount of material not discussed in this section which is felt to be obvious to an experienced user, but no doubt some subjects were not covered in adequate depth. For additional information, read Chapter 2, Appendix A, and Appendix B.

SmartSeis™ Operating Manual Page A-1 Appendix A, Menus

Appendix A. Interactive Menus This section describes the display, keyboard, and interactive menu. The menu section is organized in a glossary style so that individual sections may be used alone to explain menu items in detail. The Display A backlit, high-contrast, liquid-crystal display is used to display the seismic data. It is VGA compatible, composed of a matrix of dots 640 pixels wide and 480 pixels high. The top rows of pixels are reserved for message lines showing the acquisition parameters, system status, the channel numbers, and trace amplitudes. The remaining area is reserved for displaying the seismic data. Depending on the time scale in use, portions of the record may not fit on the screen at any one time. The up and down arrow keys may be used to scroll the data on the screen. There are also three timing lines on the screen. These are labeled to show the relative amount of

time displayed, and to allow picking the arrival times of specific events. The first two lines of the Header contain the following information. (xx.xx will be some numerical value depending on the parameters selected.):

SAMPLING x.xx ms LENGTH xxxx ms DELAY xxxx ms [data message] Acquisition Filters Display Filters AGC [length] STACK [type] STACK xxx 1 2 3 4 5 6 7 8 9 10 11 12 | | | | | | | | | | | | 00.0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 100.0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 200.0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |


SAMPLING x.xx is the data acquisition sampling interval (in microseconds). The word "sampling" will be displayed in reverse video when the system is triggered, and return to normal after the new data is displayed. LENGTH xxxx is the record length (in milliseconds). The SmartSeis allows the use of all or part of the available memory, so the record duration will depend on the combination of sample rate and memory length in use. DELAY xxxx is the delay in the start of the record (in milliseconds) after the trigger signal, or if negative, the amount of data prior to the trigger signal. [ data message ] is a message describing the status or type of data displayed on the screen, for example:

MEMORY CLEAR indicates the memory has been cleared.

UNSAVED STACKED DATA is seismic data stacked into the memory (but not saved on disk).

SAVED AS XXXX.DAT indicates the stacked data has been saved on disk (in file XXXX.DAT).

READ FROM XXXX.DAT indicates data read from disk (from file XXXX.DAT).

UNSAVED PREVIEW DATA indicates the data on the screen is new seismic data to be rejected or accepted by the operator.

ACQUISITION FILTERS are the type and frequency settings of the filters used during data acquisition.

DISPLAY FILTERS are the type and frequency settings of the filters used to display the data.

AGC [length] will be the status of the Automatic Gain Control function in the trace display. [length] will indicate the AGC window length in samples.

STACK MODE indicates the type of stacking, either AUTO (automatic) or PREVIEW (which allows the operator to examine a new data set before stacking it to memory) or REPLACE (which will automatically replace the data with a new record).

STACK xxx is the total number of times data was stacked into memory since last cleared.


The remaining two lines in the display header show the channel numbers and the relative trace size. Frozen (protected) channels are shown in reverse video. Relative trace sizes are labeled in decibels. Relative trace amplitudes are accurately displayed, so that absolute amplitude comparisons can be made when the traces are displayed in fixed gain (as opposed to AGC, or automatic gain control). The Keyboard The keyboard has 22 keys, including numbers 0 through 9, MENU, ENTER, CLR (clear), "-" (hyphen or minus), "." (decimal point), 4 arrow keys, a key with the propeller logo, and a pair of keys for controlling the display contrast. When the data is displayed on the screen (without the menu), the up and down arrow keys will scroll the data on the screen. This allows viewing the entire record when the time scale is expanded beyond the screen, and will position specific portions of the record on the cursor lines (for timing event arrivals).

The MENU key is used to select the operating menu.

The Arrow keys are used to position the cursor among menu options on the screen. The left arrow key "<<" can also be used as a backspace to delete the last digit when entering a string of numbers.

CLR is used to back out of the menu or to recover from errors.

ENTER is used to make a selection after positioning the cursor or after keying in a number.

ABA is used to designate a negative number or to designate a range of numbers, i.e. 1-12 (for numbers 1 through 12).

A•@ (decimal point or period) is used as a decimal point or to select items from a list.

The "logo" key is reserved for future enhancements.

The contrast keys adjust the display.

External Keyboard The seismograph may also be operated from an external computer-style keyboard of the type used on IBM AT-compatible (not PC or XT), desktop computers. Just plug the keyboard into the connector provided. The keyboard equivalent for the MENU key is F1. The Esc (escape) key is


used for CLR. With an alphanumeric keyboard, files may be named with letters as well as numbers. The F10 key is used to exit the seismic program to DOS. See Appendix D for information on using the computer, operating in DOS, and re-loading the seismic program.


The Menus When the MENU key is pressed, the display will show a list of menus.

One of the selections will be highlighted in reverse video. Below this line, overlaying the data display, will be a box containing secondary menu selections. The selections will correspond to the highlighted main menu item. There may be a single selection shown, or a long list. Some selections are execution statements, meaning that an action will be performed if ENTER is pressed while the selected item is highlighted. Other selections will cause another menu to be displayed, or a request for a number to be entered, or suggestions for further action. In operation, the menu system is quite easy to use. The secondary menu items are numbered. You can also select an item by pressing the corresponding number key instead of moving the cursor. Pressing the number key to select a menu item will be much faster when conducting actual surveys, especially after the operator has learned the numbers. GEOMETRY menus are used to record the locations of the geophones and the energy source. ACQUISITION menus control the data gathering parameters (such as sample interval, record length, filters). FILE menus control the saving and reading of data files onto disk. DISPLAY menus control the way the data is displayed on the screen and plotted. DO_SURVEY contains the functions normally used to acquire, display, and analyze data in a production mode. ANSWERS menus are used to run the field quality control software programs to analyze the data. OTHER menus are used for general operating and test functions. Experiment with the system. The complete menu structure is listed on the following pages. Many secondary menus have a status indication which identifies the current setting. The current settings in the following examples are representative. The actual menus will display many other alternatives.



GEOMETRY

Geometry is a collection of menus used to annotate the seismic data with the locations of the geophones and seismic source. The SEG-2 standard for seismic DOS files provides space in the header for 3-dimensional coordinates (X, Y, and Z) for the energy source and each geophone group. The information in the Geometry menu is optional, and surveys may be conducted without reference to this menu. However, its use is highly recommended as this information is essential when using the ANSWERS functions which depend on line geometry. Some interpretation packages also use this information for automated processing. This information will be attached to the data when the file is saved to disk. If a file is read from memory, the menu values on the LCD display will continue to indicate the current instrument settings, not the data read from disk. However, the information read from the disk file can be printed on the paper records. Proper use of these capabilities will label each file with the shot geometry and source location. The QUICK GEOMETRY SETUP option will set default values for the location coordinates.


0 QUICK GEOMETRY SETUP 1 SURVEY MODE ........REFRACTION 2 LINE NUMBER..............00-00 3 PHONE INTERVAL...........10.00 4 SET PHONE & SHOT LOCATIONS 5 SHOT INTERVAL...............10


SURVEY MODE

Survey mode will affect how the coordinates are adjusted after a file is saved. When Survey Mode is selected, a menu box appears:

Position the reverse video cursor over the desired mode and press ENTER.

REFLECTION MODE In a CDP reflection survey, it is common to physically move the shot point and the geophones by the same distance each shot. If the system is set to reflection mode, the coordinates in the line geometry are incremented (or decremented) by the SHOT INTERVAL value each time a file is saved. The anti-alias filter is set to a "linear phase" response in the reflection mode. REFRACTION MODE In a refraction survey, the geophone spread stays in one position for several shots with the shot in different locations. When the SmartSeis is set to refraction mode, line geometry is updated manually my setting a new SHOT LOCATION each time. The anti-alias filter is set to a "zero phase" response in the refraction mode. OTHER MODE In the other mode, line geometry behaves like the refraction mode, but the anti-alias filter is set to linear phase as in reflection mode. Differences in the behavior of the two types of anti-alias filters will not be important to the average user.



REFLECTION REFRACTION OTHER


LINE NUMBER

Used to store an arbitrary line number in the header. Optional. When selected, a message appears:

ENTER LINE NO: 00–00 Key in the desired number and press ENTER. Punctuation marks may be used, e.g. 12-76. Note that a line number can also be included as part of the file name or as a directory. The later choices will be very useful when handling files on the computer during processing, as standard DOS routines (such as copy 123*.DAT) are simple and convenient ways to copy and move selected files around.




PHONE INTERVAL

Phone Interval is the distance between geophones or groups of geophones in meters or feet. When selected, a message appears: ENTER PHONE SPACING 10 Key in the distance between geophones and press ENTER.




SET PHONE & SHOT LOCATIONS

When SET PHONE & SHOT LOCATIONS is selected, a menu box appears:

This is a map of the geophones and shot point locations, with coordinates listed. One of the numbers will be in reverse video. The arrow keys will move the reverse video cursor around the map. If the cursor is moved past the limits of the shot map, the display will scroll to show more of the line. To change any of the numbers, just position the cursor over it, key in a new number, and press enter or any arrow key except <<. The shot point and position numbers are intended to be absolute co-ordinates, but you may adopt relative coordinates by picking a point for the reference. The message in the box will change with cursor position. Alternate messages are:

– KEY REVERSES DIRECTION UP KEY FOR SHOTPOINT, DOWN FOR PHONE LOCATION



|----| 5.00 * V ••• V 1 12 105.00 210.00 SHOT POINT IS 100.00 CHANNEL 1 2 3 4 INTERVAL 5.00 10.00 10.00 POSITION 105.00 110.00 120.00 130.00 USE LEFT/RIGHT KEYS TO SELECT PHONE THEN ENTER NEW PHONE LOCATION PUSH CLR TO ABORT


When in the INTERVAL row, the – key will flip the geophone spread over so that channel 12 is on the left and channel 1 on the right side of the box. However, reverse spreads may confuse the SIPQC refraction analysis program. Experiment with this menu to gain familiarity. You will notice that the distance intervals between geophones are filled in with the number you entered earlier. If any of the geophone separations are different, use the arrow keys to position the cursor over that number and enter the correct value. Next, assign coordinates to one of the geophones. You should know the absolute location of at least one of the geophones, or if not, assign a location. Position the cursor over the position of the known geophone and enter the value. Notice that as geophone intervals or positions are changed, the other numbers in the map will adjust automatically, giving you a visual picture of the line geometry. If the position numbers increment in the wrong direction for your spread, press the "-" key to flip the line over, then adjust the coordinates again. Now, position the cursor over the shot point location and enter the correct value for the shot point coordinate. This should complete your setup. The top lines in the window will provide a visual representation of the line and shotpoint. Look at this map and see if it corresponds to the actual placement of the geophones (v) and shotpoint (*).


SHOT INTERVAL

Shot Interval is the physical distance between subsequent shot points. It is normally only applicable to reflection surveys. When selected, a message box appears:

Key in the distance between sequential shot points and press ENTER. When a record is saved on disk, the coordinates of the geophones and shotpoint are also saved in the file header. Then, if the survey mode is set to REFLECTION, when the next record is saved, all the coordinates will be incremented by the shot interval value. In this manner, the system will automatically update the line geometry coordinates in a CDP type reflection survey. In practice, the sequence will be interrupted eventually. In that case, just enter the correct values for the line geometry before saving the file. If the geometry changes (different group interval for example), just update the information. To prevent the coordinates from incrementing each file, enter zero for the shot interval or set the system to the refraction mode.



ENTER SHOT INTERVAL 10


ACQUISITION

This set of menus contains the acquisition parameters, those variables which affect how the data is collected. If newly acquired data is in the memory, the system will not allow you to change most of these parameters until you erase the data from memory, because stacking records with different acquisition parameters is normally invalid. For example, there is no logic in changing the sample rate between stacks. Attempting to change these parameters without clearing memory will result in an error message. Acquisition parameters are permanent in their effect on the data (unlike display parameters). You cannot change the sample interval, record length, or filters once the data is in memory or saved on disk. Fortunately, the wide dynamic range of the system and automatic gain controls makes the SmartSeis system flexible in handling variations in the survey. The QUICK ACQ SETUP option will immediately set most of the acquisition parameters to a set of default values appropriate to a refraction survey. These are chosen to be a good initial guess for most such surveys. If you are a first time user, or unsure of the proper settings, then use QUICK ACQ SETUP.


0 QUICK ACQ SETUP 1 SAMPLE INTERVAL.........500 us 2 RECORD LENGTH..........1024 ms 3 DELAY......................-10 4 FILTER 1.........LO CUT 100 HZ 5 FILTER 2...........NOTCH 60 HZ 6 STACK MODE.............PREVIEW 7 STACK POLARITY........POSITIVE 8 ACTIVE CHANNELS


SAMPLE INTERVAL

A seismic signal is continuous. When the seismograph measures this signal, the value is digitized at intervals and the resultant numbers are stored in a digital memory. The SAMPLE INTERVAL control is used to select this interval between data samples. When selected, the menu displays a list of the available sample rates in microseconds. There is a limit to the number of samples which can be stored in the memory (and a limit to the useful number of samples). The sample interval is selected to match the scale and type of the survey. The fastest sample rates will be used for short surveys in hard materials (such as rock and concrete). The slow sample rates are used for long refraction surveys and reflection surveys where events of interest arrive late in time. To set the sample interval, just position the cursor over the desired value and press ENTER. When in doubt, use the sample interval chosen by the QUICK SETUP menu.



31.25 62.5 125 250 500


RECORD LENGTH

Allows selection of the record length (time duration). The record duration is a combination of the sample interval and the size of the memory available for each channel. For example, if data were sampled at 0.1 millisecond intervals and the memory size was 1024 samples, the record duration would be 102.4 milliseconds. Because the SmartSeis has a relatively large memory, An option is provided to allow the

operator to use less than the maximum amount of memory available. Limiting the amount of memory used will save space for more files on the disk drive, and shorten the time required to stack and display a record. When this option is selected, the screen will display a choice of numbers. These are the available record lengths in milliseconds. The numbers displayed depend on the sample interval selected in the prior menu. They correspond to ¼, ½. ¾ and all the memory available. Since these values are related to the sample interval, any change of that parameter will change this record duration. Set the sample interval first, then confirm that the amount of time required is available. Specifically, you want all the events of interest to arrive before the end of the record. In refraction surveys, the last first arrival should arrive about half way through the record, which



256 512 758 1024


means that you will need about 1 millisecond for each foot distance from the energy source to the last geophone (or 3 ms per meter distance).


DELAY

Used to postpone the start of the seismic record from the time the system receives a trigger signal. For some applications, the early portion of the record will not contain usable information. Typical of these are borehole surveys, where all the geophones may be located some distance from the shot, and surveys where there is a significant offset from the first geophone. Use of the delay allows the use of less memory and/or a faster sampling rate in these cases. It can also allow effectively longer records for special situations. Data could be collected with no delay, followed by one or more records with a delay set to the end of the previous record, resulting in multiple records that can be merged together in processing to make a composite record much longer than that supported by the system's total memory. The amount of delay will be added to the cursor times on the screen and the time lines on the plotted record. Thus the timing information in the display and plotted record automatically incorporate any delay used. Key in the desired delay in milliseconds, then press ENTER. The system will also optionally display a portion of the record before the trigger. This is useful with some sources with uncertain timing. Just enter a negative number to record pre-trigger data. It also helps the first-break picking program work better, giving the near phones more history to include in the computation.

0 QUICK ACQ SETUP 1 SAMPLE INTERVAL ........ 500 us 2 RECORD LENGTH ......... 1024 ms 3 DELAY ..................... -10 4 FILTER 1 ........ LO CUT 100 HZ 5 FILTER 2 .......... NOTCH 60 HZ 6 STACK MODE ............ PREVIEW 7 STACK POLARITY ....... POSITIVE 8 ACTIVE CHANNELS


ENTER POSITIVE NUMBER FOR DELAY OR NEGATIVE NUMBER FOR PRE-TRIGGER –10 ms


FILTER 1 and 2

The SmartSeis has a set of real-time digital filters which operate on the data as it is acquired. These filters operate much like analog filters in that data is filtered before going into memory. Thus, once these filters are used, the raw data cannot be recovered. This is different than the similar filters in the Display Menu. Upon pressing ENTER, a list of available frequencies and filter types will appear: Position the cursor on the desired choice and press ENTER. OUT is used to bypass the filter for non-filtered data. This is the preferred setting for most surveys, especially since the display filter can be used for a similar purpose (the display filter can be altered and reversed, providing more flexibility in use). LC designates lowcut (or highpass) filters. Lowcut filters are commonly used to remove low frequency seismic noise (from traffic or wind in trees) to make the first arrivals relatively stronger, and also to filter out surface waves in reflection surveys. A Notch filter is a narrow band filter to reject certain frequencies, normally those of power lines. The choices are 50, 60, 150 and 180 Hz. These correspond to the power line frequencies (and the third harmonic from 3-phase power lines). Use the one appropriate to your locality. HC designates a highcut (lowpass) filter. Highcut filters reject high frequencies. They are commonly used to remove some wind noise and certain types of machinery.



OUT LO CUT 10 HZ LO CUT 15 HZ LO CUT 25 HZ LO CUT 35 HZ LO CUT 50 HZ LO CUT 70 HZ LO CUT 100 HZ LO CUT 140 HZ LO CUT 200 HZ LO CUT 280 HZ LO CUT 400 HZ NOTCH 50 HZ NOTCH 60 HZ NOTCH 150 HZ NOTCH 180 HZ HI CUT 250 HZ HI CUT 500 HZ


FILTER 2 is identical to FILTER 1. Either or both filters may be used to select the bandpass of the seismograph.


STACK MODE

Stack Mode determines the type of stacking performed, automatic or discretionary. In AUTOSTACK, each time the system is triggered (such as by a sledgehammer blow), the new data will be summed onto the old data in memory. In PREVIEW, the new data will be displayed on the screen first. The operator can inspect the data and decide to accept (stack) it. This is a useful option when working in conditions of transient, high background noise. A noisy record can be rejected (press CLR), or a good record can be accepted (press ENTER). Use of preview will slow the field operation, but is intended to prevent a transient noise burst from destroying a hard earned record. To accept some of the channels and reject others in the incoming data, turn on memory freeze (see FREEZE section) on those channels you wish to reject. In REPLACE, new data will automatically replace old data, eliminating the need to clear the memory between shots. This mode should be used with care, since any false (or real) triggers will destroy a previous record. Its principal application is in conjunction with AUTOSAVE (see AUTOSAVE menu). There is a similar function to PREVIEW in the DO SURVEY menu called UNSTACK. UNSTACK will subtract the last record summed into memory, allowing you to delete a newly stacked record. When STACKMODE is selected, the choices AUTOSTACK, PREVIEW and REPLACE are displayed. Position the cursor and press ENTER to choose.



AUTOSTACK PREVIEW REPLACE


STACK POLARITY

The SmartSeis offers the choice of adding or subtracting records. The normal application of stack polarity is in shear waves surveys. Shear waves are generated with a directional, reversible source. Reversing the source and the stack polarity at the same time will allow enhancement of shear waves and cancellation of P waves. Negative stack polarity can also be used to invert the data on the screen, so that first arrivals break "up" instead of "down" or vice versa. Position the cursor over the desired polarity and press ENTER.



NEGATIVE POSITIVE


ACTIVE CHANNELS

Used to select which channels are used. In some surveys (particularly borehole), less than the maximum number of geophones may be used. This option allows the operator to disable unused channels, reducing the amount of disk space required to store a file, and allowing room for more files on a disk. If SOME is selected, a message will appear:

Enter a channel or a range of channels separated by a hyphen. Then press the "up" arrow to select or the "down" arrow to disable

these channels. Repeat as necessary to make all your selections. AFTER MAKING THE SELECTIONS, PRESS ENTER. Exiting this menu by pressing CLR will return the system to the previous selection. The 24-channel SmartSeis operates the same except for the number of channels in the menu box.



SOME ALL

SELECT ACTIVE CHANNELS 1 2 3 4 5 6 7 8 9 10 11 12 ENTER CHANNELS OR CHANNEL RANGE (i.e. 4 – 12 ) THEN PRESS UP/DOWN KEY TO TURN SELECTED CHANNELS ON/OFF PRESS ENTER TO CONFIRM SELECTION OR CLEAR TO ABORT


FILE

This group of menus is used for retrieving data from disk and other file operations. A seismic record, once stored on a disk, is called a "file". The file operations discussed on the following pages assume that there is a disk properly loaded in the selected drive, that the correct drive is selected, and that the disk is not "write protected". Any disk drive problems will cause an error message on the screen and failure to complete the task until the problem is corrected. QUICK FILE SETUP will select a set of default parameters, and set the directory to today's date. For example, 021103 is the third directory formed on February 11.


0 QUICK FILE SETUP 1 CHANGE DRIVE...............A:\ 2 MAKE DIR 3 SET FILE NAME.........1001.DAT 4 AUTOSAVE...................OFF 5 CHANGE DIR..............A:\123 6 READ 7 TRANSFER TO FLOPPY 8 FORMAT


CHANGE DRIVE

Change Drive is used to select which drive is used for storing or reading back data (the default drive). This also selects the source drive for reading or copying files. When selected, a list of drives is displayed on the screen. Drive A: is the floppy disk and drive D: is the hard disk. The hard disk is actually partitioned into two logical disks. The C: drive partition contains the seismic program, while the D: partition is used to store data. The C: drive can not be selected by the seismograph program. Position the cursor over the desired drive and press ENTER to select a disk drive.



A: D:


MAKE DIR

Make Directory is used to create a directory or sub-directory on a disk. A disk may be split up into sections, so that groups of files may be kept in separate directories. Then, when handling the data, the number of files in a directory may be kept small for easy selection. Use of a directory system is desirable when using the hard disk, since large numbers of files can be stored. Note that a disk can contain two files with the same name if they are in different directories. Directories are normally not practical when storing data on 32-inch floppies. A directory is stored on the disk, not in the SmartSeis, and changing disks will also eliminate or confuse the directory structure, unless the same directories are installed on each disk. For seismic applications, one logical directory structure is to make a directory for each line. If the operator formats his files in the office on a desktop computer (or on the SmartSeis with the computer option using an external keyboard), the directories can be created in advance and given alphanumeric names. Directories created in the field with the seismograph keyboard must have numerical names. When MAKE DIR is selected, a message box will appear:

A suggested name for the directory will be displayed. To use this default name, press ENTER. To select a different name, key in the numbers and press ENTER.



ENTER NEW DIRECTORY NAME 123


SET FILE NAME

When a record is saved as a file on disk, it is automatically named (using numbers for the name ) one digit greater than the previously saved file. The number chosen by the seismograph will be displayed in the SAVE menu (in the DO_SURVEY group) and in this menu. The SET FILE NAME menu is used to choose another name for the file. When selected, the ENTER NEW FILE NAME message appears, along with the existing selection. Key in the new file name and press ENTER. Files can be named with up to 8 digits, which will provide room for combinations of line numbers, projects, or other systems to code the files with the name. All data files automatically receive the extension .DAT. Other files created by the system (such as first break picks) will have other extensions so that the system (and you later) can recognize the type of files on disk.



ENTER NEW FILE NAME 124


AUTOSAVE

This function will cause the system to automatically save every record to disk immediately after an acquisition. Applications include:

Marine surveys, where you fire a source repeatedly and automatically save the data.

Collecting every individual shot, where you may wish to have all the data available during processing (rather than the stacked data).

Note that the actual result is affected by the STACK MODE setting. If STACK MODE is set to AUTO or PREVIEW, the file saved will be the running sum of all shots. If STACK MODE is set to REPLACE, then each individual shot will be saved and then cleared from memory. AUTOSAVE requires some time to execute, since the data must be written to disk. Reducing the record length and the number of channels used will reduce the minimum time between shots. As a practical matter, AUTOSAVE is best used with the hard disk, which will save data much quicker and hold enough files to collect a reasonable amount of data. The status of AUTOSAVE is shown in the sub-menu as ON or OFF. It is strongly recommended that you do not use autosave unless the specific survey requires it.



ON OFF


CHANGE DIR

Change Directory is used to select a different default directory. The default directory is the one where any saved data will be placed. When READ (or other programs which offer a list of files) is selected, the list of available files will be those in the default directory selected by this menu item. When selected, the screen displays a directory tree containing the root directory and sub-directories. It will resemble this example: Where D:\ is the default drive, 123xx are directories, and 12, and 13 are sub-directories. File names do not appear on this tree. An arrow will indicate the currently active directory. Position the reverse video cursor over the desired directory and press ENTER to select the new current directory.



D: 12301

12

13

12302

12303


READ

This option is used to read a file previously stored on disk. When selected, the SmartSeis will read the disk and provide a list of the files in the current directory which have a DAT extension. Select the desired file with the cursor, then press ENTER to read the file into memory. If the disk yet it appears to be blank (there are no files listed) even though you have saved files on it, the most likely problem is that a different directory is selected other than the one where the files were saved. Files read from disk may be displayed on the screen and plotted on the plotter. The display parameters may be changed to enhance the appearance or usefulness of the record. If there is already data in memory, which was acquired by triggering the seismograph, and which has not been saved to disk, then READ will not proceed. Instead a message will appear:

SAVE OR CLEAR UNSAVED DATA BEFORE READING IN FILE PRESS ANY KEY TO CONTINUE

This interlock is provided to prevent accidental erase of a seismic record. The file on disk will read normally if the memory is clear, if the data in memory has been saved, or if the data in memory was read from a disk. The zero time trigger is disabled while the read-in file is in memory; stacking a new record to data read from disk is not permitted.




TRANSFER TO FLOPPY

This menu is used to move files from the hard disk to floppy disks. When selected, the screen will display a list of files. This list will only include the files in the default directory, and there may be other files in other directories that do not appear in this list. You must have the default drive set to D: First, format enough floppy disks to hold the files to be transferred (see remarks in FORMAT). The number of files which will fit on a floppy disk will depend on the number of channels, record format, and record length. You can determine this number by filling a disk with files and counting the number. Insert a floppy disk into the disk drive and select the files to be transferred. Position the cursor over each desired file, then mark it by pressing the decimal point (.). An asterisk (*) will appear next to each selected file. Or, press "-" to select or deselect all the files. Then press ENTER. The selected files will be moved to the floppy disk. When the floppy disk is full, the system will prompt you to replace it with another disk. If the floppy disk is "write protected", or not formatted, an error message will be displayed. As the files are saved on the floppy, they will be deleted from the hard disk. When a directory is emptied, it will be deleted. If your SmartSeis has the computer option, you can also do the file transfer in DOS, including the ability to transfer files directly to another computer using one of the popular file transfer programs like Lap Link.



1000.DAT 1001.DAT 1002.DAT USE • KEY TO SELECT/DESELECT ONE FILE USE – KEY TO SELECT/DESELECT MANY FILES ENTER KEY COMPLETES SELECTION CLR ABORTS


FORMAT

Format means to prepare a disk for use by the computer. A new floppy disk is blank magnetic material, and not usable for storing files. When a disk is formatted, information is written on the disk which directs the computer in use of the disk (space available, location of available storage, location of any files on disk, etc.). Disks may be purchased already formatted, formatted on a separate computer, or formatted on the SmartSeis. The Format process will also erase the disk, removing any seismic data files already recorded. For this reason, it is important to not format a disk with important data already written on it. The SmartSeis seismic program will actually test the disk for data, and will not proceed with the format process if there are any files on the disk. If you format disks on a separate computer, or if you format in the DOS mode, you will be able to erase seismic data. Select the menu option and press ENTER to format a disk. The format process will proceed (unless there is data on the disk). It requires a long time, typically more than 2 minutes, so do not lose patience and interrupt the process. This format command will test for data on the disk and refuse to format a non-blank disk. Thus, this format command will not erase a disk containing data files. To erase a disk containing data, use a separate computer to format the disks or (if your system has the computer option) attach a keyboard to the SmartSeis, go into DOS, and use the standard DOS format command. Be careful not to format a disk containing valuable data. Seismic files are written with the read-only attribute set, so you cannot delete individual files unless you change the attribute.




DISPLAY

The display menus contain the operations that affect the way the data is displayed on the screen and printed on the plotter. The appearance of the record has a strong effect on the information revealed in the data. For example, for refraction surveys you would prefer to use a clipped wiggle trace display, increasing the trace size to see sharp first arrivals. For reflection surveys, variable area display and small trace excursions are preferred. There are many other options (AGC, filters, etc.) to help make the data more interpretable and to emphasize the type of information desired. None of these operations affect the raw data in memory, and you can experiment with each choice and observe the visual (and printed) effect. It is usually important to save your original data on disk, so that you have the option of playing back the data on the seismograph again later. When the data is analyzed, it is always easier to see things better if there is some flexibility in the way the data is displayed. The QUICK SETUP option will choose a set of defaults for you.


0 QUICK DISPLAY SETUP 1 TYPE..................VAR AREA 2 AGC.................FIXED GAIN 3 TIME SCALE..............NORMAL 4 PRINT TIME SCALE......COMPRESS 5 TRACE SIZE 6 DISPLAY CHANNELS 7 FILTER 1...................OUT 8 FILTER 2...................OUT 9 BACKLIGHT...................ON


TYPE

Offers the choice of displaying the data in the following formats. In VAR AREA, (variable area) the positive excursions are shaded in black. This improves the operator's ability to identify reflections and other events when adjacent channels are compared. WIGGLE shows the data in the traditional wiggle trace line format, often better for picking first arrivals. SHADED is similar to variable area, except the positive excursions are shaded in grey scale instead of solid black. The traces themselves are black, and can be seen as they pass through the grey shading. "Clipping" limits the trace excursions to prevent overlap between adjacent traces. The waves will have flat tops instead of the normal curves. Clipping eliminates confusion on the record, preventing adjacent traces from obscuring the first breaks. CLIPPED AREA displays the clipped traces in variable area. CLIPPED TRACE displays the clipped traces in wiggle trace. CLIPPED SHADED displays the clipped traces in grey variable area. Use the arrow keys to position the cursor over the desired option and press ENTER.



VAR AREA WIGGLE SHADED CLIPPED AREA CLIPPED WIGGLE CLIPPED SHADED


AGC

Used to set the trace display to either fixed gain or automatic gain control. In fixed gain, the scale factor of the trace size display on each trace is constant for the entire record. Variations in amplitudes of different signals in the record are visible. For example, large surface waves will appear large on the display and plot. The scale factor for individual traces may be adjusted, and the relative trace sizes

are not fixed unless the trace sizes are intentionally set to the same value.

In AGC, the trace scale factor is adjusted continuously during the record to normalize the trace excursions regardless of the relative strength of vibrations. Note that the trace size adjustments (see below) will still affect the trace excursions. The [status] message will display FIXED GAIN, or the AGC window length in samples. Selecting FIXED GAIN sets the system to fixed gain. When AGC is selected, a message will appear:

ENTER NUMBER BETWEEN 3-512 FOR AGC WINDOW IN SAMPLES 100

It is asking the operator to select a window length, or time constant, for the AGC. An AGC system can react fast or slow, and the optimum choice will depend on the data and in particular the time length of the seismic wavelets in the data. The number entered should be in data samples, between 3 and 512. The best choice is empirically determined, but need not be particularly precise. A wide range of values will give acceptable results. Windows that are too short will distort the waveforms, those too long will obscure some reflections. The AGC algorithm in the SmartSeis is the type commonly referred to as "digital AGC", which uses data in advance of the particular sample. Thus, it will look ahead and reduce the gain before a large signal. Since only the display is affected, experiment with different displays for a particular data set to see which gives the best records. When in doubt, start with 200. To use the previously selected value, just press ENTER when the "enter size" message appears.



FIXED GAIN AGC


It will be necessary to re-adjust the trace size whenever changing between AGC and fixed gain, since AGC has a significant effect on the display.


TIME SCALE

Adjusts the time scale on the display by changing the number of data samples represented by each pixel on the liquid crystal display. For short records (that is, fewer samples), in the compressed modes, more of the record will be visible on the screen. In other time scales, considerable portions of the record will be off the screen. To see the missing portions of the record, exit the menu and use the cursor keys to scroll the display. To set the display time scale, just position the cursor over the desired choice and press ENTER.



NORMAL EXPAND COMPRESS BY 2 COMPRESS BY 4


PRINT TIME SCALE

This menu selects the amount of paper used to plot a seismic record. As with the display time scale, print time scale works by adjusting the number of dots representing a data sample. The plot can be expanded to show more information or compressed to save paper. To choose, position the cursor over the desired choice and press ENTER. The physical length of the record will vary with the record length (in samples, not time) as well as this setting, and some combinations will print very long graphs. Most analysis plots will be done on Normal and Compress by 2. Compress by 4 will be useful for quick quality control plots. Expand will be useful only on rare occasions.



NORMAL EXPAND COMPRESS BY 2 COMPRESS BY 4


TRACE SIZE

Used to adjust the size of the trace excursions on the screen and plotter. The relative amplitude scaling factors (trace sizes) are listed on line 4 of the screen header (and on the plotted record). The units are decibels, incrementing in + or - 3 dB steps. A 3 dB step is an increase of 41% or a

decrease of 29%. Two steps (6 dB) is double or one-half the original value. When the display is set to fixed gain (not

AGC), the trace excursions and trace size factor can be used to compare true amplitudes at the input. Thus, it is possible to measure attenuation and vibration levels with the SmartSeis. In AUTO SELECT, the system will automatically select the proper trace size values to display the data on the screen. With a new record, this function will quickly get to the best choice or at least close to the best choice. Only the portion of the record currently displayed on the screen affects the calculation. If the operator scrolls through the data, a different data set may be displayed on the screen with a less optimum choice. In that case, re-run AUTO SELECT. ADJUST ALL is used to increase or decrease all traces simultaneously in 3 dB steps. When activated, the menu will disappear from the screen and the trace size indicator on all the channels (on line 4 of the display header) will be in reverse video. Use the up and down arrow keys to raise or lower the trace size. Press CLR to return to the menu. INDIVIDUAL is used to adjust the size of individual traces. When activated, the menus will disappear from the screen and the trace size indicator on channel 1 will be in reverse video. Use the up and down arrow keys to raise or lower the trace size on channel 1. Then, use the left and right arrow keys to select other traces to adjust in the same manner. Press CLR to return to the menu. Whenever changing between AGC and FIXED GAIN, the trace sizes will need adjustment. Start by running AUTO SELECT.



AUTO SELECT ADJUST ALL INDIVIDUAL


DISPLAY CHANNELS

Used to select which channels are displayed on the screen (and plotted). The operator may wish to display only selected channels when using less than the maximum number available (such as in borehole surveys) or to make an individual trace easier to use (such as picking first arrivals). If SOME is selected the selection window appears. Enter a channel or a range of channels separated by a hyphen (i.e. 4-15). Then press the up arrow (to display) or the down arrow (to remove these channels from the display). Channels which will be displayed are shown in reverse video. Repeat as necessary to make all your selections. After making the selections, press ENTER to confirm your choices, and the selected channels will be displayed on the screen. If you exit this menu by pressing CLR the display will return to the prior selection. The channels selected for display will be automatically repositioned at equal distances across the screen. The 24-channel SmartSeis operates the same except for the number of channels in the menu box.



SOME ALL

SELECT DISPLAY CHANNELS FROM ACTIVE CHANNELS 1 2 3 4 5 6 7 8 9 10 11 12 ENTER CHANNEL OR CHANNEL RANGE (i.e. 4 – 12) THEN PRESS UP/DOWN KEY TO TURN SELECTED CHANNELS ON/OFF PRESS ENTER TO CONFIRM SELECTION OR CLEAR TO ABORT


FILTER 1

Used to set the digital display filter parameters: the type of filter, and corner frequencies. When selected, a list of filter types and corner frequencies are presented in a menu box. Use the up/down arrow keys to select a filter. The complete list is shown here, but the box will only display a portion at any one time, scrolling when necessary. Press ENTER to select a filter. When the order is selected, the filter will run, processing the data. Low cut (also called highpass)filters reject frequencies below the selected corner frequency. The amount of rejection depends on the setting and the frequency. These filters attenuate at 24 dB/octave. That means that when the filter is set to 100 Hz, a 50 Hz signal will be attenuated by 24 dB, or down to 1/16 of its original value. Highcut (also called lowpass) filters attenuate frequencies higher than the setting. They are used to remove high frequency noise from the signal. The highcut filters also attenuate at 24 dB/octave. Highcut filters will round off first breaks. Notch filters are used to remove power line noise, and the third harmonic of the power line noise which is radiated by 3-phase power. Some countries have 50 Hz power, others have 60 Hz power. Use whichever is appropriate to your location.



OUT LO CUT 10 HZ LO CUT 15 HZ LO CUT 25 HZ LO CUT 35 HZ LO CUT 50 HZ LO CUT 70 HZ LO CUT 100 HZ LO CUT 140 HZ LO CUT 200 HZ LO CUT 280 HZ LO CUT 400 HZ NOTCH 50 HZ NOTCH 60 HZ NOTCH 150 HZ NOTCH 180 HZ HI CUT 250 HZ HI CUT 500 HZ


FILTER 2

Filter 2's operation is identical to Filter 1's. Filter 2 is used when you want to combine two filter functions. It may be set to a different filter (for example, to combine a notch filter and lowcut filter) or it may be set to the same type of filter (to combine two lowcuts for stronger attenuation of low frequencies, for example). You may set the two types to the same frequency to double the attenuation slope. Note that the filters cannot be set to a frequency higher than the Nyquist frequency (the Nyquist frequency is equal to one-half the sample frequency, which is the reciprocal of the sample interval in microseconds).




BACKLIGHT

The LCD display has a backlight available which makes it easier to see in dim light. Whenever conditions dictate, switch the backlight by selecting ON or OFF and pressing ENTER. Avoid using the backlight in the hot sun; it will heat the display, and the screen is usually more readable with the backlight off in direct sunlight.



ON OFF


DO SURVEY

The DO SURVEY menu group contains the items required to do a field survey in a production mode. Once the parameters in the other menus have been set, this is the only menu needed. The items are arranged in the proper sequence, and not only speed the survey, but serve as a checklist or guide to the user.

GEOMETRY ACQUISITION FILE DISPLAY DO_SURVEYANSWERS OTHER

1 ERASE 2 SHOT LOCATION..............100 3 NOISE DISPLAY 4 TRACE DISPLAY 5 INSPECT ARRIVALS 6 SAVE..................1000.DAT 7 PRINT 8 FREEZE 9 ROTATE FREEZE PATTERN – UNSTACK


ERASE

The initial step is to erase data from memory. ERASE will delete an existing record from memory, preparing the system for a new one. If the data was acquired through an acquisition (as opposed to reading a file), and has not been saved on a disk, the system will provide a warning message:

UNPROTECTED DATA WILL BE LOST WHEN MEMORY IS CLEARED PRESS ENTER TO PROCEED, CLR TO ABORT

Pressing ENTER will complete the operation, erasing all data from the memory. CLR will return to the menu display without destroying the data.




SHOT LOCATION

This SHOT LOCATION menu is a duplicate of the one in the GEOMETRY menus. It is repeated here for convenience, since setting the shot location is an integral step in acquiring data (if you plan to use the ANSWERS programs). Select the menu, position the reverse video cursor over the shot location coordinate, and enter the new value. Note that the shot location will be automatically incremented by the SHOT INTERVAL value if the SURVEY MODE is set to REFLECTION. In the REFRACTION mode, the operator must enter this menu before saving or printing the record or running INSPECT ARRIVALS. This is to ensure that you are reminded to update the line geometry when necessary.




NOISE DISPLAY

Position the cursor on NOISE DISPLAY and press ENTER. A multi-channel "waterfall" display of the signal from each geophone will appear on the screen. Use the up and down arrow keys to adjust the noise display sensitivity. CLR is used to exit the noise monitor display. The seismograph may be triggered while the noise monitor display is on. It will exit the menu and display the new data record. Noise display is also used to test geophones and cables.




TRACE DISPLAY

The TRACE DISPLAY menu is used to clear the screen of menus and return the system to the trace display. CLR will often achieve the same result




INSPECT ARRIVALS

INSPECT ARRIVALS is the menu item selected when the MENU key is pressed. Press ENTER and the traces will adjust their positions to approximate the proper setting to allow examination of the relevant arrivals. It may be necessary to make adjustments of the trace sizes (in the DISPLAY menu) to make the first breaks recognizable. If the survey mode is set to REFRACTION, the system will pick the first breaks automatically, then offer an option to edit these picks and save the first break pick data on disk.




SAVE

Select this menu to save a seismic record to disk. The status message shows the name that will be assigned to the file. When ENTER is pressed, the data in the memory is immediately saved with the assigned name in the active directory on the active disk drive. Each time a file is saved, the previous name is incremented by 1. Remember that 0 is not the same as a blank, so 01, 1 and 00000001 are different file names. The file can be saved with the default name xxx.DAT. Or, the operator can select another file name, directory, or disk drive by changing the selections in the FILE menu. 3-digit DOS file extensions are automatically entered as part of the file name. Data files receive the extension ".DAT". With an external keyboard, files may be named with alpha names, and they will still increment, numerically or alphabetically, depending on the last character. When naming files, it may be convenient to include information about the project or the survey as part of the file name. If the line number is included in the name, it will simplify file handling when processing. If an attempt is made to save a file with a name already on the disk, the system will not overwrite the file. An error message will appear. There is no way to destroy a file on disk using the seismograph keyboard. It is preferable to format an adequate supply of disks before going to the field. If an attempt is made to use a blank (unformatted) disk, the system will display a warning message. In that case, go to the Format menu and format the disk. Avoid formatting disks with data in memory, since some errors will crash the system.




PRINT

PRINT is used to make a paper copy of the seismic record. When PRINT is selected in the DO SURVEY menu, press ENTER, and the system will print a paper copy of the record. During printing, a message will appear:

PUSH CLR KEY TO ABORT This is used to stop the printer before the whole record is plotted. If there is a problem with the printer, a "Printer Malfunction" message will appear on the display. This normally indicates that the printer is out of paper, or the paper is loaded incorrectly. The physical length (or scale) of the printed record can be set in the DISPLAY menu.




FREEZE

Freeze is a data protect function. When a channel or group of channels are "frozen", they are protected against further stacking and also will not erase. When working in noisy conditions, channels with good data can be "frozen" to protect them while the remaining channels receive extra effort. If FREEZE is selected, a message box will appear. If SOME is selected, the selection window appears, displaying the active channels

Enter a channel or a range of channels separated by a hyphen (i.e. 4-15). Then press the "up" arrow to freeze or the "down"

arrow to unfreeze these channels. Repeat as necessary to make all your selections. After making the selections, press ENTER. Exiting this menu by pressing CLR will return the system to the previous selection. The current status is indicated on the list of channels on line three of the display header. Frozen channels are shown in reverse video. "Freeze All" is useful for protecting data in memory from false or erroneous triggers (as will displaying a menu on the screen), and as a first step in freezing all except one channel for "Optimum Window" surveys. The 24-channel SmartSeis operates the same except for the number of channels in the menu box.



SOME ALL

SELECT FROZEN CHANNELS FROM ACTIVE CHANNELS 1 2 3 4 5 6 7 8 9 10 11 12 ENTER CHANNEL OR CHANNEL RANGE (i.e. 4 – 12) THEN PRESS UP/DOWN KEY TO TURN SELECTED CHANNELS ON/OFF PRESS ENTER TO CONFIRM SELECTION OR CLEAR TO ABORT


ROTATE FREEZE PATTERN

Once a pattern of frozen channels is established, this menu can be used to move the pattern up or down the line. The principal application is for collecting "Optimum Window" or "Common Offset Gather" reflection surveys. In this type of survey, all the channels are frozen except the first. Data is stacked into the active channel. Then channel one is frozen and channel 2 is activated. Data is acquired on channel 2 and the cycle continues. ROTATE FREEZE simplifies this operation and some others. Set up the desired freeze pattern in the ACQUISITION menu. Then, select LEFT or RIGHT and press ENTER to move the freeze patter as desired.



LEFT RIGHT


UNSTACK

UNSTACK will remove the last record stacked into memory. It is normally used when a record is stacked with an unusually large noise burst. There are no sub-menus. UNSTACK operates immediately when the "–" key is pressed or when the cursor is positioned on UNSTACK followed by ENTER.




ANSWERS

The Answers menus are used to perform geophysical analysis on the seismic data, primarily for field quality control and survey planning. The programs are used to evaluate both refraction and reflection data. Virtually all these programs use the optional line geometry information which is entered through the Geometry menu. Solving the equations requires coordinates for the shot point and the geophones. The dimensions may be either metric or english (as selected in the OTHER menu). The system makes some rationality tests on the line geometry information, and will display error messages if the numbers fail these tests, but only the operator can ensure that the numbers are correctly entered. A thorough discussion of the underlying principles of geophysics is beyond the scope of this section of the manual. Standard textbooks or the supplementary material available from Geometrics should be reviewed. Remember: The line geometry for the data you are processing must be correct or else incorrect answers will result. You can check the geometry by printing your data file and reading the data from the header, not by looking at the line geometry menu (which only reflects the current settings to be attached to the next file saved).


1 ADJUST PICKS 2 SOLVE REFRACTION 3 LINEAR VELOCITY 4 ANALYZE REFLECTOR 5 MODEL REFLECTOR 6 NMO DISPLAY 7 UNDO NMO


ADJUST PICKS

ADJUST PICKS is used to pick first arrivals for analyzing refraction data. If you have already picked the first breaks using INSPECT ARRIVALS, then you may omit this menu function. When selected, the current seismic record is displayed on the screen, with the seismograph's first arrival picks superimposed on the traces. The first trace number is highlighted in reverse video. If you want to change the first break pick on the first trace, use the up and down arrow keys to reposition the pick on the first trace. When you are satisfied with the pick on trace 1, use the left and right arrow keys to select the next trace to edit, then the up and down keys as before. Continue until the first break picks on all the traces are correct. Press ENTER and the picks will be saved in a file with the same name as the data file, but with the extension .BPK instead of .DAT.




SOLVE REFRACTION

SOLVE REFRACTION is used to generate a time-distance plot for refraction analysis, and to interpret the results. The program used is SIPQC by Rimrock Geophysics. Additional information on the full capabilities of SIPQC are available in the more detailed manual provided separately. When selected, a box appears:

These files are the first break pick files generated in the Pick Break program, identified by the extension .BPK. You must select which files to use in the refraction analysis by pointing the reverse video cursor at each desired file, then pressing the period key. An asterisk appears next to each selected file (To change your decision, press period again).

When all desired files are selected, press ENTER. A time-distance plot appears on the screen with an instruction message:

USE CURSOR KEYS TO MOVE CURSOR. PUSH 0-6 KEY TO ASSIGN LAYER PUSH "•" KEY, MOVE CURSOR, THEN PUSH 0-6 KEY FOR MULTIPLE PHONE ASSIGNMENT. PUSH ENTER FOR DEPTH PROFILE OR CLEAR TO ABORT LAYER ASSIGNMENT.

You will see one or more lines drawn on a time distance plot, with each line representing the first arrivals associated with a particular shot or hammer point. A cursor will appear on one of the points. You must assign each point on the time-distance plots to a particular sub-surface geologic layer. If you have done manual interpretation of refraction surveys, the process should come easy. The basic principle is to consider the earth as layered, with each deeper layer having a higher velocity than the one above it. The points at the bottom end of the graph (those close to the shot point) are assigned to layer 1 (unless the source is offset from the end of the line). Further up the line, you should see a point where the slope of the line changes, usually to a flatter angle. This portion of the T-D plot represents layer 2. Decide which points represent layer 1 and which points represent layer 2. As you enter a number, the cursor will jump to the next point. Just key in the appropriate number each time. If you have a 3-layer earth, you will reach another point where the slope changes again, generally flatter, and those points should be assigned to layer 3. Assign the same



LIST OF FILES 1001.DAT 1002.DAT 1003 DAT


number to the next further points until you reach the end of the line. The program will accommodate up to 6 layers. To go back and edit, use the cursor keys to point at the specific point and enter the corrected number. If you wish to reject any of the points, assign them to layer number "0". For speed and convenience, a layer can be assigned to several points with the following procedure: Pick an anchor point on a layer, press "." (the decimal point key), move the cursor to any other point on the same X-T line, and press a number key. All points between the anchor point and the cursor will be assigned that layer number. Repeat the process with the other lines in the spread. Once all the layers are selected, press ENTER. The SmartSeis will save a file with this data, with the extension .LPK. At the same time, it will call another program, SIPQC by Rimrock Geophysics, which will solve for the best answer and plot the results on the plotter. SIPQC will list the coordinates of each shotpoint and geophone, the first break times, and then list the depth beneath each geophone. Then it will draw the time-distance plot (see Figure A.1), do an interpretation of the data with each point graphed to show the scatter in the fit (Figure A.2), and finally draw a cross section annotated with velocities and dimensions (Figure A.3). These results can be inspected and interpreted to evaluate the quality of your seismic refraction survey, and to give preliminary results in the field.. SIPQC is a simplified version of the popular ray trace interpretation/modeling program SIPT2. It will operate on up to 7 shots for one or two spreads, once a file containing first arrivals and layer assignments have been created on the SmartSeis. SIPQC assumes that you have level ground, that the geophones are all in a straight line, the shots are on the ground surface and that first arrivals and layers selected are reasonable. A more accurate and complete interpretation can be obtained by using Rimrock Geophysics program SIPT2 which runs on a personal computer (or on the SmartSeis with the computer option). SIPT2 can interpret up to 5 spreads in a seismic refraction line, and the program does not assume that the shotpoints and geophones are laid out in a straight line or on a flat surface, or that shots are on the ground surface. We recommend that you use SIPT2 and auxiliary programs SIPIK, SIPIN, SIPEDT to reprocess your SmartSeis data files for a final interpretation. However, for many applications, SIPQC will provide adequate and complete results in the field. For others, SIPQC will provide enough information to confirm that you have quality data, while adjustments can still be made.


Figure 6, Time-Distance plot from SIPQC (rotated 90 degrees).


Figure 7, Depth pick from SIPQC (rotated 90 degrees).


Figure 8, Depth section from SIPQC (rotated 90 degrees).


LINEAR VELOCITY

The Linear Velocity program calculates the velocity of a linear seismic event shown on the display. The most common example would be the acoustic wave from the sound of the energy source, which travels through the air at the speed of sound. Another example might be the refractor from the water table, or a particular bedrock refractor. To run the program, the operator picks events on any two of the channels, then the program calculates the velocity of an event based on the time difference and distance between the two geophones. When linear velocity is selected, the record is displayed with the trace size number in reverse video on the first channel. Use the left and right arrow keys to move the reverse video cursor to select the initial channel to mark. Then use the up and down arrow keys to move the small pointer to the point of interest. Press ENTER to mark the first point. Use the left and right arrow keys to select the next channel to mark. Scroll up or down to position the pointer over the second point of interest. Press ENTER. A message shows:

LINEAR VELOCITY IS XXXX Press any key to return to the Main Menu.




ANALYZE REFLECTOR

Analyze Reflector is used to determine the depth and velocity of a reflection event on the record. To run the program, the operator picks events on two of the channels, then the program fills in a complete set of points across the traces. These points correspond to the hyperbolic curve characteristic of a flat reflector. The first step is to identify a suspected reflection event in the record. Position the trace display, adjust the trace sizes, and use any filters to emphasize the event. When Analyze Reflector is selected, the record is displayed with the trace size number in reverse video on the first channel. Use the left and right arrow keys to select one of the channels which clearly displays the reflector. Then use the up and down arrow keys to scroll the pointer to the event. Press ENTER to mark the first point. A second pointer will appear on an adjacent trace. Use the left and right arrow keys to select another channel to mark. Scroll up or down to position the pointer on the reflection event. Press ENTER. A series of points appears across the record and a message shows:

VELOCITY IS XXXX DEPTH IS XXXX The points drawn on the traces can be compared to the reflection event. Velocity is the average velocity to the reflector. Additional points may be picked on other channels if desired, just continue picking as before and each time the curve will be adjusted to provide the "best fit" among all the points selected.




MODEL REFLECTOR

Model Reflector is used to superimpose a synthetic reflection event on the record, based on an operator-selected velocity and depth. This model reflector can be compared to actual arrivals in the record. When Model Reflector is selected, a box appears:

If you want to use the current value for velocity, press ENTER. To make another selection, key in a new velocity and press ENTER. Another box appears:

Key in a proposed depth and press ENTER. A series of points is superimposed on the record corresponding to a reflector at the selected depth with the selected velocity. These points may be compared to the actual data to evaluate the presence of a known or suspected reflector. To change your model, repeat the sequence with different velocities or depths.



ENTER MODEL VELOCITY 3500

ENTER MODEL DEPTH 500


NMO DISPLAY

NMO Display is used to make a normal-moveout correction to the data. This will compensate for the difference in reflector arrival times at geophones with increasing offset from the shot point. Reflectors from flat horizons will become flat on the record. Note that only a single value is used for velocity, so the correction may only be valid over a limited depth range. To look at depths beyond that range may require multiple corrections. When NMO Display is selected, a box appears:

If you want to use the current value for velocity, press ENTER. To make another selection, key in a new velocity and press ENTER. The program will execute, adjusting each of the traces for the moveout correction based on the shot offset and velocity. The Menu remains on the screen to allow another choice, or press the CLR key to remove the menu from the screen. The traces displayed on the screen have been corrected. A message appears on the Status Line to indicate that the traces have the NMO correction. Press the MENU key to repeat the sequence with a different velocity. This record can be printed on the SmartSeis printer, using the normal printer commands. That provides the capability of assembling multiple records side-by-side in the field or office to make a 100% seismic section for preliminary evaluation and interpretation. UNDO NMO Undo NMO Display is used to remove the effect of the NMO correction, returning the data display to the un-processed state. It executes automatically when selected on the menu.



ENTER VELOCITY 3500


OTHER

The OTHER Menu includes some system functions. DATE To set the date, enter the day in international format (day - month - year) as numbers separated by hyphens. TIME To set the time, enter hours (in 24 hour format) then minutes, separated by hyphens as in the example on the screen. The date and time will be saved on disk as part of the file header with the data. This can be used to help identify specific records and to correlate files with field notes. TRIGGER SENSITIVITY In addition to accepting start signals from contact closures, the SmartSeis can be triggered by a voltage like that from a geophone. TRIG SENSITIVITY is used to adjust the sensitivity of the voltage detector up or down to compensate for ambient vibration levels and the source energy.


1 DATE ........................................... 6 NOV 92 2 TIME ....................................................16:42 3 TRIG SENSITIVITY ................................50 4 TRIG HOLDOFF ....................................200 5 TRIGGER 6 UNITS ................................................. FEET 7 SERIAL NUMBER ...............................1234 8 EXIT TO DOS 9 CREDITS • VERSION NUMBER..........................V1.02

ENTER NUMBER BETWEEN 1 AND 100 FOR TRIGGER SENSITIVITY. HIGHER NUMBERS ARE MORE SENSITIVE 50


TRIGGER HOLD OFF The system includes logic to prevent a double trigger in the case of hammer bounce. This is normally set to prevent a second trigger within 2 seconds of the prior one. In some cases you may wish to trigger faster or slower. The delay time may be set in the TRIGGER HOLD OFF menu. TRIGGER Used to manually trigger the instrument, for testing or recording background seismic noise. The manual trigger is almost never used to record real seismic data, since analysis depends on exactly synchronizing the seismograph with the energy source. UNITS Used to set the numbering system used in the ANSWERS programs and the SEG-2 file header to either meters or feet. When selected, a menu box appears:

Point the cursor at the preferred selection and press ENTER. SERIAL NUMBER Used to set the instrument serial number which is written in the file header with every data record. Normally, this should be set to the instrument serial number recorded on the metal tag on the instrument. When selected, a menu box appears:

Key in the number and press ENTER. EXIT TO DOS This menu selection will cause the system to exit the seismic program and go into DOS. This menu item is used to execute application programs. These are programs designed to operate on the seismic data, and may take many forms. These programs may be written by users, third-party software companies, or supplied by Geometrics. There may not be any application programs on your system. Use of these programs will normally be described in a separate manual.

ENTER NUMBER BETWEEN 0,5 AND 10 FOR TRIGGER HOLD OFF BETWEEN 0 5 AND 10 SECONDS 2

METERS FEET

ENTER SERIAL NUMBER 1234


CREDITS CREDITS will list the people at Geometrics who helped develop and manufacture the SmartSeis. The company address, telephone and fax numbers are also shown for ready reference. VERSION NUMBER Version number is the revision of the system operating software. There will be improvements and enhancements in the future, and when a new version is formally released, it is given a number. You should send in the registration card to receive future updates on the system. This is not a user-accessed menu selection, only an advisory.

SmartSeis™ Operating Manual Page B-1 Appendix B-Hardware

Appendix B. Hardware Equipment and Accessories for Operation It takes several peripheral accessories to conduct a seismic survey. Besides the seismograph, you will need a power source, geophone cables, geophones, an energy source, plus a few odds and ends. Specific items vary considerably depending on the survey. Because of the potential variations, only a minimum of the required accessories is supplied with the basic instrument. The remaining accessories may have been ordered with your system as options, or you may have intended to supply your own. Most seismographs have a high degree of interchangeability in accessories (particularly geophones and cables), and you may be using equipment you already own. The shipping documents may be checked to confirm the items supplied as standard equipment and those ordered as optional accessories. Power The SmartSeis operates from a nominal 12 volts DC. This may be a rechargeable battery pack, a standard automotive battery, 12-volt vehicle power, or an AC-powered, 12-volt DC supply. The S12 draws about 22 amperes when operating and the S24 about 32 amperes (temporarily more when the printer is running). A small power source should be sufficient (such as a 20 to 30 amp-hour sealed lead-acid battery). A general purpose power cord with clip connectors is provided with the system. Connect the seismograph to a power source with adequate capacity. It should be tightly connected, momentary loss of power will most likely destroy any data in memory and possibly interfere with disk operations. An optional 25 amp-hour rechargeable battery is available which will provide approximately one day of operation in cyclic use. The battery pack is supplied with an appropriate power cord to connect to the 3-pin Cannon plug on the seismograph. Also available with the rechargeable battery is a 110/220 volt AC-powered battery charger. Before using this charger, check and see that the proper AC mains voltage is selected on the switch. The Geometrics charger is designed to be connected continuously to the battery. The system will charge at a high rate until the battery is charged, then switch to a standby voltage. A light on the charger indicates when the rate switches to trickle charge, which also means the battery is charged. Charging will take several hours. The Energy Source Energy source, when used in a seismic context, means a source of seismic energy; something to generate elastic waves coupled into the ground. There must be a means of synchronizing the energy source with the seismograph, or more specifically, triggering the seismograph when the


energy source is activated. Energy sources come in a wide variety of explosive and mechanical types. A sledgehammer is the most common energy source. It is popular because it is lightweight, portable, low cost, repeatable, and safe. Its only serious limitation is its limited range, although it compares favorably in this respect with a number of less portable and more costly devices. Signal enhancement, or stacking seismographs (including the SmartSeis) were developed for use with a sledgehammer. The energy from several hammer blows may be stacked into memory to increase the survey depth range. The sledgehammer is synchronized by an impact-sensitive "hammer switch", taped to the handle, and connected directly to the trigger connector on the seismograph. An extension cable may be used to allow the sledgehammer to be located away from the seismograph. An aluminum or steel plate (approximately the same weight as the hammer) is placed on the ground for the hammer to impact. This "striker plate" provides more efficient coupling and more precise triggering. Explosives, such as dynamite and its derivatives, are excellent and widely used energy sources. Optional blasters, such as Geometrics' HVB-1 are available with the SmartSeis. The blaster provides power to detonate the blasting cap and sends a signal to trigger the seismograph at "zero time". Other sources which may be used with the SmartSeis include weight drops, shotgun-type devices, electro-mechanical sources, airguns, and most other types of seismic energy sources which can be synchronized in some manner with the SmartSeis. There are a number of ways to synchronize an energy source: a. If the source operates with a sharp impact, the standard hammer switch can be used

(examples: sledgehammer, shotgun, power assisted weight drop, land air gun). b. If the source is activated with electrical energy, the seismograph can usually be

synchronized with the same electrical device (examples: blasting caps, electric shotgun shells, sparker, boomer, piezoelectric transducer). Some devices have an imprecise mechanical delay and may require a device to sense the vibration or some correction (examples: marine or borehole airguns, watergun). In that case, the vibration sensor should be connected to one of the signal channels. Set the seismograph delay to a negative number to record a short portion of the record prior to the trigger. This will allow recording of the whole signature from the sensor to verify and correct for exact time zero.

c. Some sources can be synchronized by placing a standard geophone (connected to the

seismograph trigger input) near the source (examples: weight drop, explosives using a blaster without a seismic signal, explosives with chemical fuses). Obviously any source may be synchronized with this method, but the timing may be a little less precise. Since


the geophone will not be located at exactly the point of impact, there will be some delay between the impact time and the trigger. Try and keep this delay (distance) constant.

Remember that the seismograph can be triggered by a contact open as well as a closure. If you have an explosive with an imprecise detonation time (such as firecrackers, delay caps and so called "instant" blasting caps), the seismograph can be triggered by wrapping a small wire around the explosive device (connected to the start input on the seismograph), breaking contact at the time of detonation. Geophone Cables A geophone cable is a multi-conductor cable with connectors molded at intervals along the cable. The geophones will have connectors which mate with those on the cable. One common type is the wire-wrap takeout, which looks like a coil spring molded into the cable. The mating connector used on the geophone is a clip with a colored insulator. The takeouts and clips are different widths and colors to encourage the use of the same polarity each time the geophone is connected. Waterproof connectors are also available from the geophone and cable manufacturers. These are preferred in wet locations despite their higher cost and complexity. Cables for refraction surveys. There is a standard cable used for refraction surveys, consisting of 12 takeouts (geophone connections) at selected intervals. Each end has some additional slack cable and a 27-pin connector (Cannon type NK-27-21C). The cable is "double-ended", constructed so that it is reversible and identical from either end. The takeout closest to the connector is wired to pins 1 and 2, while the farthest is wired to pins 23 and 24. If the instrument is connected to the opposite end of the cable, the takeout that was previously the farthest away is now wired to pins 1 and 2 on that connector. Two of these cables are used with a 24-channel SmartSeis S24. The seismograph is located in the center of the line, and the two input connectors are wired so that the takeouts closest to the instrument are connected to channels 12 and 13. Cables for reflection surveys Reflection surveys differ in that continuous surveys are usually conducted along a line. The data is processed on a computer to produce an uninterrupted cross section. In shallow exploration, these surveys fall into two types: common offset gathers (or COG, or "Optimum Window") and common midpoint surveys (also called CMP, common depth point or CDP surveys).


Standard refraction cables are used for "optimum window" or "common offset gather" reflection surveys. CDP surveys are a little more complex. Shots are fired along a line by moving the shotpoint and geophone spread just a short distance each time (as little as 1/12 the spread length). Rather than physically moving the geophones and cables each time, two, three, or four 12-takeout refraction cables, or a special cable (called a CDP cable) is used. A rollalong switch is also required for CDP surveys. A rollalong switch is a multi-input, multi-channel switch that can select a group of geophones from a longer array, and then move that group along the ground by electrically adding new geophones on one end and dropping geophones off the other end as the shot point of the energy source is moved along the ground. The output cable of the rollalong switch will need the appropriate connectors to mate with the input connector on the seismograph. Special reels are often used to handle geophone cables, designed to hang on a person's shoulders facing front or rear. The operator can deploy or retrieve the cable conveniently. Cable reels are more useful when the total length of the cable exceeds 100 meters. Geophones The moving-coil geophone is the basic vibration sensor. The coil and its support spring make a pendulum with a natural frequency, and this is specified for all geophones. Frequency is measured in cycles-per-second, called Hertz and abbreviated Hz. The output of the geophone is reasonably flat in responding to earth vibrations with a frequency higher than the natural frequency of the geophone. The geophone is less sensitive to vibrations with frequencies lower than its natural frequency. The sensitivity decreases (or rolls off) at -12 dB/octave. Thus, for a 40-Hz geophone, the sensitivity at 20 Hz will be 1/4 the sensitivity at 40 Hz. Geophone manufacturers provide data sheets with response curves for each type geophone. The geophone is a pendulum, and left to its own devices will oscillate at its natural frequency. Internal friction will damp these oscillations somewhat, but additional damping is normally required. The published data sheets show the response curves with various levels of damping (the oscillation is shown as a peak near the natural frequency). A geophone is damped by connecting a resistor across its output terminals; the preferred resistor values are shown on the data sheet. Some seismographs have an input circuit with a low resistance, and geophones purchased for such instruments may not have damping resistors installed. The SmartSeis has a relatively high input resistance (20,000 ohms) and geophones purchased for use with the SmartSeis should be ordered from the manufacturer with the damping resistor installed (these can also be added later by soldering the proper value low-noise resistor across the terminals). An incorrectly damped geophone is not a disaster, the result is a boosted signal near the natural frequency, but proper damping is good practice. A properly damped geophone will have a lower output voltage because the resistor attenuates the signal.


The true (or desired) seismic information is generally called signal. Undesirable vibrations (from wind, vehicle traffic, airplanes, surface waves, machinery) are called noise. Improving the signal-to-noise ratio is an ongoing effort in seismic exploration. Geophone frequencies are chosen to provide adequate signals at the frequencies found in the seismic data, and preferably not at the frequencies of the noise signals (where they are different). Much noise tends to be low frequency (because low-frequency vibrations travel further through the ground). For shallow surveys, seismic signals tend to have a much higher frequency and a geophone with a natural frequency around 14 Hz is a good compromise. In shallow reflection surveys, most of the problems come from large, low-frequency surface waves. Thus, it has been common to use 100 Hz geophones to filter the surface waves. Obviously, having a wide selection of geophones available is not only inconvenient, it is quite costly. The SmartSeis seismograph, with its improved acquisition capability, can compensate for most of these problems and you can normally compromise on one good set of 14-Hz to 40-Hz wideband geophones. The seismograph's selectable lowcut filters can quickly be set in the field to the best frequency to fit the situation. Furthermore, with its 16-bit A/D converter, the SmartSeis will record data with sufficient resolution that digital filtering can be used later to extract signals from noise. Guidelines and compromises that were appropriate to 8-bit refraction seismographs do not apply to the SmartSeis. Geophone groups are sometimes used for reflection surveys. A group is a collection of geophones, wired together in series and/or parallel, connected to a single channel on the seismograph. They are spread out on the ground in an array chosen to attenuate surface waves and reinforce waves arriving vertically. Geophone groups are widely used for deep reflection surveys but are less desirable for shallow reflection surveys. The wavelengths of the surface waves are too long for practical spatial filtering with geophone groups, although using 2 or 3 phones in a small group can attenuate the effects of the sound of the shot detonating.


The SmartSeis™ Seismograph Specifications and features of the SmartSeis are described in Appendix E. Operation was discussed in Chapters 1 and 2. This section is intended to provide background information on the SmartSeis seismograph, as well as specific hardware details. Display The liquid-crystal display is easy to see in daylight. A backlight is provided to allow viewing in subdued light or nighttime. The control to turn the backlight on and off is located in the DISPLAY Menu. Some darkening of the screen may occur in hot weather and bright sunlight, caused by thermal heating. This can be compensated for by adjusting the contrast control, but it will help to shade the seismograph (always a good practice in high temperatures). Shading will be more effective if you do it before the display gets dark. Do not use the backlight in the hot sun. Printer Loading Paper To load paper into the printer, tilt open the cover (released by pressing the two latches on either side). Remove the empty reel and two plastic end plates from the retaining guides. Insert the end plates into the new paper roll and snap the new roll into the retaining guides. The paper roll should be oriented with the loose end between the printer and the paper roll, curled upward. The printer has a small lever on its front edge which clamps and releases the paper. Move it to the free position, insert the loose end into the slot in the center of the printer (see figure), and feed it through the rollers. Leave enough paper protruding to conveniently feed the loose end through the slot in the instrument case. Center the paper and move the clamp arm to the clamp position. Print a sample record. Adjust the paper if not centered. If the plotted records are blank, then check to see if the paper is upside down. Turn the paper supply reel over so it feeds into the printer the proper way. These instructions are also on the inside of the instrument panel.


Print Header The plotted record is annotated with a header which includes information about the line and the data. Examples of the Print Header appear in Chapter 1. The header will identify the source and status of the data. Raw data is identified as "UNSAVED STACKED DATA". If the data has been written to disk, the message will say "SAVED AS FILE xxxxx.DAT". Data read from a file is labeled "READ FROM FILE xxxxx.DAT". Thus, it is good practice to make paper copies of the record after saving the file to disk. Then, the copies can be matched with a particular file later. The remaining parameters listed on the print header match similar descriptors on the display and menu. The channel numbers and trace sizes are listed below the descriptors. Time lines are provided at approximately 1 cm intervals, with every tenth line accented and labeled. Thus, the physical interval between the time lines is kept at a convenient spacing for picking arrival times. Note that the Print Header is the only reliable source of line geometry and OTHER menu data retrieved from disk, since the LCD screen will display the current instrument settings, not the file information. Data Acquisition and Sampling All modern seismographs are digital. They operate by digitizing the amplified seismic signal with an analog-to-digital converter. This digital signal is then stored in a semiconductor memory, where it can be viewed on a display, plotted on a paper record, or stored on some device for later use. In digitizing, the seismic signal is broken up into different levels (or amplitudes) with a number assigned to each level. The number of bits used by the A/D converter is the measure of the number of levels. On traditional refraction seismographs, an 8-bit converter is commonly used. That means that there are 28 or 256 different levels available. Since seismic signals are either positive or negative, one bit is assigned to indicate the polarity, and the signal can range from -128 to +127 levels. A signal that is too small to make the transition between levels will not be digitized (except that noise often will add enough random signal to make the transitions happen). The signal can also be too large and exceed either -128 or +127. When that happens the reconstructed waves have flat tops and are said to be "clipped". (Clipping can also occur in the amplifier, or the memory of an 8-bit seismograph during stacking.) This is not the same as the clipping that occurs when the display is set to clipped. Generally electronic clipping can be identified as irregular distorted waveforms, not perfectly flattened ones.


In a seismograph, the amplifier gains must be adjusted to keep the signal significantly larger than the minimum quantization level, but less than the full scale value. This is not a major problem in refraction surveys, since the first arrivals are easily identified and adjustments made based on the record appearance (although there is a tendency for new users to mistakenly identify the larger surface waves as first arrivals). The principle differences between the SmartSeis seismograph and a normal refraction system are in the quality of the digitizer. The SmartSeis has a 16-bit A/D converter, which quantizes the signal in 216 steps (one part in 65536). Thus, there is extra resolution and dynamic range to allow the system to handle large and small signals simultaneously. Secondly, the floating point amplifier automatically adjusts its gain to keep the signal at close to the optimum value. The SmartSeis does not need any manual gain controls, and thus is much less prone to operator error. Substantial time is saved in field operations and setup. The amplifier gain becomes part of the digitized data. just like the exponent is part of a number written in scientific notation. Once the data is digitized, it is stored in memory in a 32-bit word. This is transparent to the user, although it is worth noting that having this many bits ensures that you will never saturate by stacking too many signals. Some instruments have an adjustment of the preamplifier gains (called "K" gains). The dynamic range of the SmartSeis is wide enough that these are not needed. The digitizing of the signal does not take place continuously, but at regular intervals, called the sampling interval or sampling rate. Practical considerations dictate that a limit be put on the total number of samples taken. The sample rate is chosen so that the total seismic record fits within the memory. The SmartSeis has a longer than normal memory, and the operator may elect to not use all the memory available. Consider a refraction line 1000 ft (300 m) long. Unless the overburden is unusually deep, there should be bedrock velocities of around 10,000 ft/sec (3,000 m/s) and the average velocity should be above 5,000 ft/sec (1,500 m/s). Thus it will take about 200 milliseconds to travel from the shotpoint to the last geophone. With a memory length of 2048 samples, a sample interval of 0.1 milliseconds will provide a record long enough to capture all the arrivals of interest. Most users will find that although 0.1 msec sampling provides more data than is necessary to accurately determine the time of the first arrivals, it is an appropriate sample rate when plotting and manually picking first arrivals on the SmartSeis printer. An experienced user employing either the SmartSeis automated first break picking software or a separate computer program would be quite happy with 1024 samples, with a sample rate selected to put the furthest geophone's first arrival at around the midpoint of the record (0.5 ms sampling would give you a total record length of 512 ms with 1024 sample memory length). It is generally quite easy in the field to repeat a shot, so feel free to experiment. It is important in refraction surveys to use a sample rate fast enough to spread the first arrivals away from the first part of the record.


Reflection surveys are different, since the important information is contained in the entire record. A longer record may be desirable, combined with faster sample rates. A good reflection record is likely to have the first arrivals close to the zero time on the plot, so that the refractions are hard to precisely "pick". One of the benefits of the SmartSeis seismograph is that the operator can afford to use a little faster sample rate or a little longer memory than needed, save the records on disk, and then pick the arrivals later with flexibility in the display and print scale factors. It is a measure of the sophistication of the SmartSeis that it is actually much easier to operate than a traditional seismograph. Triggering The SmartSeis can be triggered in a variety of ways. Almost any type of signal can be used successfully, including a contact closure, contact open, saturated NPN transistor, logic pulse, positive voltage or negative voltage. The standard hammer switch or optional blaster are preferred. When using a voltage source for the trigger, it may be necessary to adjust the trigger sensitivity. This adjustment is software controlled in the OTHER Menu. Experiment to find the best setting, using the most sensitive setting that does not result in false triggers. Any standard geophone with a suitable connector (Bendix PT06A-8-3P(SR), Geometrics part number 21-206-003) may be used for triggering. A suitable geophone with connector installed is available from Geometrics as part number 23197-01. The standard 91-meter (300-ft) hammer switch extension cable (Geometrics part number 23219-01) may be used to locate the trigger geophone away from the instrument. The sensitivity should be adjusted so that ambient vibrations from personnel or the energy source handling do not trigger the system. Locate the geophone as close as possible to the shot point to minimize timing errors (velocities in the near surface material are likely to introduce delays on the order of 1 ms/ft or 3 ms/m). Be consistent with the spacing between the geophone and shotpoint so that timing errors remain more or less constant. When using a contact open (such as breaking a wire with an explosive), remember that making the initial connection will trigger the seismograph, and the memory should be cleared before firing the shot. When interfacing external electronic devices, it is good practice to isolate the ground connection between the SmartSeis and the external device. Connecting multiple instruments to a common ground often leads to electrical interference, called a "ground loop". Consult the factory for assistance if problems appear when interfacing such devices to the SmartSeis.


Environmental Considerations The SmartSeis is specified to operate over a wide temperature range, but these limits may be exceeded in the field. Extra effort may be required when operating in very hot or cool temperatures. The following procedures should be employed if problems arise: In hot weather, shield the system from direct sunlight. Be sure and turn off the display backlight (if equipped) to help keep the display cool. Do not store disks in the sun or in closed vehicles. In cold weather, it may be necessary to wait a few minutes while the system warms up from internal heating. In extreme cold, the system can be mounted in an insulated box. Keep your spare disks in a warm place so they will be ready for use when needed. Turn on the display backlight to heat the liquid crystal display, and wrap the instrument with insulating material to retain the heat. The SmartSeis is designed for use in a light rain, but only in the vertical position. Operating in a horizontal position or in heavy wind and rain may get the interior wet and damage the instrument. Fortunately, seismic surveys are not normally conducted in such weather; the wind and rain noise obscure the seismic signal. Put your instrument in the vehicle or dry place if the rain exceeds a light mist. The SmartSeis is not designed for use in explosive atmospheres. Both the power switch and an internal relay may spark when actuated. Connector Wiring Geophone Connector The inputs from the geophones connect to a 27-pin connector manufactured by Cannon. The mating connector (used on the geophone cables) is a Cannon NK-27-21C, Geometrics part no. 21-133-027. See the table for the pin assignments. The 24-channel system has two of these connectors. The two 27-pin connectors are wired so that when two standard, double-ended spread cables are used with the system, the nearest two geophones will be fed to channels 12 and 13.


A geophone extension cable can be constructed with the above connector on one end and a Cannon NK-27-22C (Geometrics part no. 21-133-037) on the other end. Power Connector The power connector is a 3-pin connector manufactured by Cannon. The mating connector used on the power cable is a Cannon WK-3-21C (Geometrics part no. 21-133-032).

Pin Use

1 +12 volts 2 common 3 not used

Start Connector The start or trigger connector is a 3-pin connector manufactured by Bendix and others. The mating connector, used on the standard hammer switch, HVB blasters, and the hammer switch extension cable is a PT06A-8-3P(SR) (Geometrics part no. 21-206-003).

Pin Use

A Trigger input B common C not used

The other end of the hammer switch extension cable uses PT01A-8-3S(SR) (Geometrics part no. 21-207-038) wired with the same pinout.

Geophone Connector Pin Assignments 12-channel S12 24-channel S-24 (two connectors) Pin Use Use Use 1 + channel 1 + channel 13 + channel 12 2 - channel 1 - channel 13 - channel 12 3 + channel 2 + channel 14 + channel 11 4 - channel 2 - channel 14 - channel 11 5 + channel 3 + channel 15 + channel 10 6 - channel 3 - channel 15 - channel 10 7 + channel 4 + channel 16 + channel 9 8 - channel 4 - channel 16 - channel 9 9 + channel 5 + channel 17 + channel 8 10 - channel 5 - channel 17 - channel 8 11 + channel 6 + channel 18 + channel 7 12 - channel 6 - channel 18 - channel 7 13 + channel 7 + channel 19 + channel 6 14 - channel 7 - channel 19 - channel 6 15 + channel 8 + channel 20 + channel 5 16 - channel 8 - channel 20 - channel 5 17 + channel 9 + channel 21 + channel 4 18 - channel 9 - channel 21 - channel 4 19 + channel 10 + channel 22 + channel 3 20 - channel 10 - channel 22 - channel 3 21 + channel 11 + channel 23 + channel 2 22 - channel 11 - channel 23 - channel 2 23 + channel 12 + channel 24 + channel 1 24 - channel 12 - channel 24 - channel 1 25 not used not used not used 26 not used not used not used 27 ground ground ground


Maintenance and Trouble Shooting Look outside the seismograph first, most field failures are related to external devices. These can usually be corrected by the operator. Power The most common problem is power failure, normally a discharged battery. The front panel has a series of lights which constantly display the battery voltage. The lights are not dependent on the internal power supply or computer, so they will function even in case of an equipment fault. Monitor the battery voltage during field operations. When the voltage drops below 11 volts, little operating time is left and every effort should be made to complete the survey in an orderly manner. Become familiar with the pattern that the lights follow, so that you can anticipate battery discharge. A battery will deteriorate in storage unless it is charged regularly. If charged monthly, the battery pack should retain its capacity for years. A failing battery will show decreased operating life (and will charge up in less time). With the clip-type power cable, a vehicle battery can be used to operate the system. If the polarity is reversed, the system will not operate. However, the SmartSeis is protected from damage due to polarity reversal. If the system shows symptoms of power failure, check the fuse located under the front panel near the printer. Sensor problems If the geophone test shows a missing channel, check to see that the geophone is properly connected and planted in the ground. If so, try substituting a different geophone. If this does not correct the problem, then the cable is suspect. Sometimes, a cable that is faulty from one end will work properly when reversed. Trigger problems If the system will not trigger, try using the manual trigger in the test function to see if the system triggers that way. Then, try triggering with the hammer switch without the hammer switch extension cable connected. Substitution (of another hammer switch) can be used to test for a defective hammer switch. Triggering can also be tested by shorting pins A and B of the trigger connector with a small piece of wire. If that works, then the problem is generally external to the instrument.


False triggers may be caused by having the trigger sensitivity set wrong. Adjust it to a less sensitive position. If the trigger source is noisy, providing continuous trigger signals, the system may not boot properly. Either adjust the sensitivity or correct the noise problem. If problems persist, it may be necessary to add external attenuation or isolation. Internal system problems If you are comfortable working on your personal computer, (that is, installing circuit boards and disk drives), then you should be qualified to perform simple repairs on the SmartSeis. Alternatively, a local computer service center may be able to assist you with some problems in an emergency. If the system software freezes up and will not respond to the controls, try switching the power off, then on again. Use the same remedy if the system exits the seismic program and shows the DOS prompt (such as A: or C:). On rare occasions, the SmartSeis software on the hard disk may become corrupted. Symptoms include a blank display or a message on the screen after the power up sequence instead of seismic traces. If this happens, try and re-load the system software from the disk supplied with the system. If the software is corrupted, and you need to reload the software under DOS, just press 999 then ENTER when the prompt shows. Additional information may be available on the "README.DOC" file on the support disk. It is good practice to print out the contents of the "readme" and other files before you experience problems with the system. Since this manual cannot be updated as fast as the system software, the latest information is included on the support and system disk. For convenience, there are several automatic programs (called batch files, with the extension .BAT) which will print the data for you. The files are given numerical names so they can be accessed directly by the SmartSeis keyboard. Just exit to DOS in the OTHER menu, then key in the number of the name of the batch file program and press ENTER. If you have the computer option, and you are a regular user of DOS-compatible computers, you may be more comfortable connecting a standard AT keyboard to the system to explore these files. If you do not have the computer option, a keyboard connector is available by removing the instrument from its case. For repair purposes, the SmartSeis can be broken into two functional blocks. These will be called the "seismograph" and the "computer" for convenience, although they are closely integrated. The seismograph portion consists of a multipurpose omni board, and an acquisition board. These boards are of a dense, surface-mount construction and do not contain any parts which can be serviced in the field. Repair of these boards not only requires specialized training and familiarity with the details of the system, but also special tools for working on surface-mount products. Do


not try and repair either of these boards. If you have a problem, substitute a new board from your spares kit or return the unit to the factory. There is also a power supply board in the system which provides the multiple DC voltages required by the system. There are five light-emitting diodes located on the power supply to monitor the output voltages. All these lights should be on if the power supply is working properly (although the fault could be located on another board). The power supply circuit boards can be serviced by authorized Geometrics service facilities. The computer part of the system consists of selected components used in the manufacture of standard personal computers. These include the 80386SX CPU board with memory, the 32-inch disk drive, and an IDE hard drive. These components are not normally serviced, because the cost of repair exceeds their purchase price, and problems are fixed by substitution. If you purchased a standard spares kit, these components will be available for immediate replacement. Otherwise, you may be able to purchase them locally. Should you replace the hard disk, be sure and load DOS before installing the seismograph software from the support disk. The liquid crystal display, printer, and keyboard are normally serviced by replacement. They are also in the spares kit. Removing the instrument from its outer plastic case accesses most of the components. Just remove the screws in the flange and lift the unit out of the plastic case. At that point, it will be obvious how to remove and re-install the major components. You should inspect the circuit boards to ensure that they are fully inserted into their sockets and that they are properly restrained in the slots in the upper bracket. There are many cables and connectors, particularly to the multi-purpose omni card. While most of these are keyed to prevent wrong connections, be sure and make a careful drawing of each cable and its location before disconnecting them. When re-assembling, observe the proper position and orientation of each cable. The system can be operated outside the plastic case. We suggest that you turn the unit on and confirm proper operation before re-installing the SmartSeis in its case. For systems without the computer option, a standard AT keyboard can be connected to the system when it is out of its case. The plug is located on the computer mother board and a hole is provided in the sheet metal for access.

SmartSeis™ Operating Manual Page C-1 Appendix C-File Format

Appendix C. File Storage and Data Handling File Format A "file" is the data from a seismic record recorded onto the disk. The data may be from a single shot, or data stacked from a number of hammer blows or "shots". The seismic record is held in memory in the seismograph until the operator decides to write it onto the disk. When data is written to disk, it is given a file name. The term "trace" is used to refer to the data from just one channel of the seismograph. The data is stored in DOS files, a term used to describe files which can be read on IBM personal computers, IBM-compatible computers using the DOS operating system, and other types of computers which can read DOS files. The format used is SEG-2, the Standard for Seismic Data Files established by the Society of Exploration Geophysicists2. With the establishment of this standard, many data processing companies are able to read the files from the SmartSeis. Most third-party software developers have also standardized on this format. The complete standard is available from the SEG. Linear dimensions and coordinates may be either Meters or Feet, but should be consistent throughout the file. The following section describes the SEG-2 format used in the SmartSeis. File Structure The file is organized on the disk as blocks: a File Descriptor Block, followed by a sequence of Trace Descriptor Blocks and Data Blocks. The File Descriptor Block contains information common to all the traces in the file, plus it provides information required to parse the rest of the overhead data. Another name for this block is the "File Header"

Each Trace Descriptor Block provides location, format, and other information pertinent to its corresponding Data Block (containing the data from a trace). Another name for this block is "Trace Header". 2 Pullan, S. E., 1990, Recommended standard for seismic (/radar) data files in the personal computer environment: Geophysics, Vol. 55, No. 9, September 1990, pp 1260-1271

(beginning of file) FILE DESCRIPTOR BLOCK TRACE DESCRIPTOR BLOCK 1 DATA BLOCK 1 TRACE DESCRIPTOR BLOCK 2 DATA BLOCK 2 • • • • • • • • • • • • • • • • • • • • • • TRACE DESCRIPTOR BLOCK NDATA BLOCK N (end of file)


The Data Block consists of fixed point or floating point numbers as specified by their corresponding Trace Descriptor Block. This block contains the data from one channel (or one trace) of the seismograph. There is a Trace Descriptor Block for each Data Block (in other words, there is a trace header for each block of data from one trace). The blocks are arranged in numerical order. Pointers are written in the file blocks to indicate locations of the blocks with respect to the beginning of the file. Pointers are always long integers (32 bits). All addressing is to byte boundaries. All blocks start on double word (32 bit) boundaries. Integers are 16-bit numbers written low byte first to conform to the 80386 processor used in the SmartSeis. Long integers are 32-bit numbers, also written low byte first. Hexadecimal number 4547 would be written 47 45 in the file. A 32-bit (4-byte) data sample, such as 0001D340 would be written 40 D3 01 00. A typical file is shown later in an example, with interpretable characters shown in the right side column. Referring to this example will be helpful in understanding the following descriptions of the data format. File Descriptor Block The first block in the file is the File Descriptor Block. The construction of the File Descriptor Block is: This block holds information common to all traces in the file and pertaining to the structure and interpretation of the file. It consists of (i) thirty two bytes providing the block identifier, the revision number, the size of the Trace Pointer sub-block, the number of traces in this file, and the string and line terminator (ii) a Trace Pointer sub-block giving pointers to the start of each Trace Descriptor Block in the file, and (iii) followed by optional strings with

Byte 0-1 3a55 (File Descriptor Block ID) 2-3 Revision Number 4-5 Size of Trace Pointer Sub-Block (M) 6-7 Number of Traces in File (N) 8 Size of String Terminator 9 First String Terminator Character 10 Second String Terminator Character 11 Size of Line Terminator 12 First Line Terminator Character 13 Second Line Terminator Character 14-31 Reserved 32-35 Pointer to Trace Descriptor Block 1 36-39 Pointer to Trace Descriptor Block 2 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Pointer to Trace Descriptor Block N 33+M String 1 String 2 • • • • M String Z


information related to the entire file such as date, time, delay, constant, high cut filter frequency, line number, low cut filter frequency, notch filter frequency, sample interval, shot co-ordinate, shot interval, shot map, and shot offset. The File Descriptor Block ID(bytes 0 and 1 of this block and of the file) contains the integer 3a55 (in hexadecimal). This integer identifies the file as a seismic data file following this standard and identifies this block as the Record Descriptor Block (55 appears first, since it is the low byte). The File Standard Revision Number (bytes 2 and 3) appear next. Bytes 4 and 5 contain an integer giving the size of the Trace Pointer Sub-block in bytes (see below). All blocks start on double-word boundaries and are divisible by four. Bytes 6 and 7 contain the number of traces in this file. The String Terminator is one or two non-printable ASCII characters (decimal ASCII codes 0 through 31) used to separate the strings that hold the information in character string form in this (the File Descriptor) block, and the Trace Descriptor Blocks. Byte 8 is 01 (hex) and bytes 9 and 10 are 00 (hex) indicating the string terminator used by the SmartSeis is the NULL character. The Line Terminator is one or two ASCII characters used to separate the lines of text in the Notes Block. In the SmartSeis, byte 11 is 01 (size of line terminator, 01 hex), byte 12 is 0A (line terminator character), and byte 13 is 00 (hex) indicating the Line Terminator used by the SmartSeis is the Linefeed (0A) character. Bytes 14 through 31 are reserved and written as 00. The Trace Pointer Sub-block starts at byte 32, and contains pointers (unsigned long integers) to the start of each Trace Descriptor Block in the file. The length of this sub-block in bytes is specified in bytes 4 and 5, and the number of pointers (corresponding to the number of traces) contained in the sub-block is specified in bytes 6 and 7 (see above). Following the Trace Pointer Sub-block is a free format section containing strings to provide optional information common to all traces in the file (the acquisition parameters, date and time, line geometry, etc). Each string starts with an integer giving the length of the string (the offset to the next string), followed by a keyword naming the parameter in the string, followed by the value (in ASCII), and terminated by the null character string terminator (indicated in bytes 8, 9, and 10 above). A list of keywords used in the descriptor blocks will be found later in this chapter.


Trace Descriptor Block The Trace Descriptor Block contains information relative to an individual trace (seismograph channel). Each Trace Descriptor Block is followed by a Data Block containing the data for that trace. The construction of the Trace Descriptor Block is: Byte 0-1 4422 (Trace descriptor block ID) 2-3 SIZE OF THIS BLOCK IN BYTES (X) 4-7 SIZE OF FOLLOWING DATA BLOCK IN BYTES (Y) 8-11 NUMBER OF SAMPLES IN DATA BLOCK 12 DATA FORMAT CODE 13-31 RESERVED 32 STRING 1 STRING 2 • • • • • • X STRING Z The actual byte number for the start of the Trace Descriptor Block varies with the length of the Record Descriptor Block. The optional strings follow with information pertinent to that block (channel number, descaling factor, geophone group location, number of stacks, etc.). The Trace Descriptor (bytes 0 and 1) contains the integer 4422 (hex) to identify this block as a Trace Descriptor Block. The Block size (bytes 2 and 3) contains the integer giving the size of this block in bytes. The Size of Data Block (bytes 4 through 7) contains the long (32-bit) integer giving the size of the following Data Block corresponding to this Trace Descriptor Block. The Number of Samples in Data Block (bytes 8 through 11) contains the integer giving the size of the Data Block in samples. The Data Format Code (bytes 12) specifies the data format in the following data block according to the following table: Byte value Data Format 01 16-bit fixed point 02 32-bit fixed point 03 20-bit floating point (SEG convention) 04 32-bit floating point (IEEE standard) 05 64-bit floating point (IEEE standard)


The SmartSeis presently offers data recording in code 03, 20-bit floating point. The next twenty bytes (bytes 13 through 31) are a series of 00's. This space is reserved. The rest of the Trace Descriptor Block contains a series of strings. The string format and convention is the same as that used in the File Descriptor Block. Data Block A data block follows each Trace Descriptor Block. This is the data for the corresponding trace in the selected format. Except for the last trace (or a single channel record), the Data Block will be followed by the Trace Descriptor Block for the next trace. String Format The Record and Trace Descriptor Blocks contain strings that provide information about the survey or the specific trace. Each string starts with an integer giving the length of the string, followed by a keyword that names the parameter in the string, then the value (in ASCII format) corresponding to that word , and then ends with the string terminator (null character). Keywords can not have embedded spaces (use_for space, decimal ASCII code 95). The keyword and the associated data are separated by one or more spaces or tabs. To assist application program string searches, all strings are ordered alphabetically according to the keyword, and all alpha characters are uppercase. Numeric values may be decimal integers or decimal floating point numbers. Negative decimal numbers are preceded by a minus sign "-". Decimal floating point numbers may use an "E" to express the number in scientific notation. Decimal points must be followed by a numeric character. The numbers in the following list are allowable numeric expressions. Unless stated otherwise, integers must have magnitude less than 32,000 (16 bits). 12, -3, 12.657, -34.6, 1.345E24, -2.3E6, 5.6E-11, -2.0E-9 Some values like time and date are expressed in the special indicated format. Key Words Used in File Descriptor Block The File Descriptor Block normally contains the following strings. Other strings may be added later. Not all strings supported by the SEG standard are used by the SmartSeis. ACQUISITION_DATE The date the data was acquired, in dd/mmm/yyyy format. For example April 1, 1988 would be stored as 01/APR/1988.


ACQUISITION_TIME The time of day the data was acquired. The format is 24-hour time stored in hh:mm:ss format. For example 3:30PM would be stored as 15:30:00. INSTRUMENT_EG&G_GEOMETRICS_ SmartSeis [serial number] Identifies instrument used to collect the data. TRACE_SORT Identifies the trace sort. "As Acquired" is used for normal field records. UNITS [feet or meters] Identifies measuring system, e.g. feet, meters. NONE is written to designate that system does not differentiate between systems. NOTE This string appears as the last string and contains notes and parameters not defined in the standard. For the SmartSeis, the notes include the base interval, shot interval, AGC window, and display filters. Key Words Used in Trace Descriptor Blocks CHANNEL_NUMBER The channel number is a positive integer identifying the seismograph channel (or trace). DELAY The value is a floating point number expressing the time (in seconds) elapsed from the start pulse to recording the first sample in the Data Block. DESCALING_FACTOR A floating point number used to determine the true amplitude of the input signal. To convert from a data sample value to the actual input voltage (in millivolts) to the seismograph from the geophone, the formula is:

input voltage due to one shot = data point * DESCALING_FACTOR / STACK_COUNT


Notice that an individual trace is corrected for multiple hammer blows by dividing by the number of stacks, so the result is the average input voltage from a single shot. Thus, the trace header allows for different stack counts on each trace, and when selected channels are frozen they not only stop acquiring data, but the stack counter also stops. LINE_ID is the line number selected in the GEOMETRY menu. HIGH_CUT_FILTER, LOW_CUT_FILTER and NOTCH_FREQUENCY are the filters used during acquisition. RAW_RECORD is unprocessed data. RECEIVER_LOCATION is the location of the geophone group for the particular trace. It is the dimension along the line, using the same linear coordinate system as the SOURCE_LOCATION. In the file, each geophone group will have a location specified in the Trace Descriptor Block, as does the shot point in the Record Descriptor, providing that the operator has correctly entered the information in the menu during data acquisition. These locations are calculated from the line geometry data entered into the other menu. All coordinates are automatically incremented by the value entered for Shot Interval each time a file is saved. Thus, missing or duplicate files will produce errors in the group locations unless the operator is careful to reset those parameters. Note however, that use of file storage for location is optional, that the operator's log may contain the same information, and that the files may be edited later to insert of correct this information. SAMPLE_INTERVAL The value is a floating point number expressing the time between samples in seconds. SKEW is the amount of time delay between the sampling of individual channels SOURCE_LOCATION This is the location of the shot. This value is a linear coordinate specifying location along the survey line relative to some reference. May also be called "Source Location". May specify depth in a drill hole. STACK This stack count is a positive integer indicating the number of times data was stack into an individual trace. This number may be different for each channel (trace).


NOTE is used to store the display scale (trace size multiplier) chosen by the operator when examining the original data on the screen.


File Format Example Following is a listing of a typical file. The byte column lists the byte number in sequence. The right side column shows the interpreted code, where the byte corresponds to an ASCII character that can be interpreted on a standard line printer. Non-interpretable code is shown as a ".". The first Trace Descriptor Block starts at byte 0138, with the number 4422. Byte Numbers in Hexadecimal low byte first Interpreted code 0000: 55 3A 01 00 30 00 0C 00 01 00 00 01 0A 00 00 00 U:..O........... 0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0020: 38 01 00 00 74 0C 00 00 B0 17 00 00 EC 22 00 00 8...t........@.. 0030: 28 2E 00 00 64 39 00 00 A0 44 00 00 DC 4F 00 00 (...d9...D...O.. 0040: 18 5B 00 00 54 66 00 00 94 71 00 00 D4 7C 00 00 .[..Tf...q...|.. 0050: 1E 00 41 43 51 55 49 53 49 54 49 4F 4E 5F 44 41 ..ACQUISITION-DA 0060: 54 45 20 37 2F 4A 41 4E 2F 31 39 39 33 00 19 00 TE7/JAN/1 993... 0070: 41 43 51 55 49 53 49 54 49 4F 4E 5F 54 49 4D 45 ACQUISITION_TIME 0080: 20 31 36 3A 34 30 00 30 00 49 4E 53 54 52 55 4D 16:40.0.INSTRUM 0090: 45 4E 54 20 45 47 26 47 20 47 45 4F 4D 45 54 52 ENT EG&G GEOMETR 00A0: 49 43 53 20 53 6D 61 72 74 53 65 69 73 20 53 31 ICS SmartSeis Sl 00B0: 32 20 30 30 30 30 00 19 00 54 52 41 43 45 5F 53 2 0000...TRACE_S 00C0: 4F 52 54 20 41 53 5F 41 43 51 55 49 52 45 44 00 ORT AS_ACQUIRED. 00D0: 0D 00 55 4E 49 54 53 20 4E 4F 4E 45 00 58 00 4E ..UNITS NONE.X.N 00E0: 4F 54 45 20 0A 20 42 41 53 45 5F 49 4E 54 45 52 OTE . BASE_INTER 00F0: 56 41 4C 20 31 30 2E 30 30 20 0A 20 53 48 4F 54 VAL 10.00 . SHOT 0100: 5F 49 4E 54 45 52 56 41 4C 20 30 2E 30 30 20 0A -INTERVAL 0.00 . 0110: 20 41 47 43 5F 57 49 4E 44 4F 57 20 30 20 0A 20 AGC_WINDOW 0 . 0120: 44 49 53 50 4C 41 59 5F 46 49 4C 54 45 52 53 20 DISPLAY_FILTERS 0130: 30 20 30 20 0A 00 00 00 22 44 3C 01 00 0A 00 00 0 0 ....@D...... 0140: 00 04 00 00 03 00 00 00 00 00 00 00 00 00 00 00 ................ 0150: 00 00 00 00 00 00 00 00 13 00 43 48 41 4E 4E 45 ..........CHANNE 0160: 4C 5F 4E 55 4D 42 45 52 20 31 00 0F 00 44 45 4C L_NUMBER 1...DEL 0170: 41 59 20 2D 30 2E 30 31 30 00 1C 00 44 45 53 43 AY -0.010...DESC 0180: 41 4C 49 4E 47 5F 46 41 43 54 4F 52 20 30 2E 30 ALING_FACTOR 0.0 0190: 30 31 31 39 39 00 10 00 4C 49 4E 45 5F 49 44 20 01199....LINE_ID 0IA0: 30 30 2D 30 30 00 17 00 4C 4F 57 5F 43 55 54 5F 00-00...LOW_CUT_ 0IB0: 46 49 4C 54 45 52 20 31 30 20 31 32 00 14 00 4E FILTER 10 12...N 0100: 4F 54 43 48 5F 46 52 45 51 55 45 4E 43 59 20 30 OTCH_FREQUENCY 0 0ID0: 00 16 00 52 41 57 5F 52 45 43 4F 52 44 20 31 30 ...RAW_RECORD 10 0IE0: 32 34 2E 44 41 54 00 1C 00 52 45 43 45 49 56 45 24.DAT...RECEIVE 0IF0: 52 5F 4C 4F 43 41 54 49 4F 4E 20 31 31 31 36 2E R-LOCATION 1116. 0200: 30 30 00 1B 00 53 41 4D 50 4C 45 5F 49 4E 54 45 00...SAMPLE-INTE 0210: 52 56 41 4C 20 30 2E 30 30 30 31 32 35 00 11 00 RVAL 0.000125... 0220: 53 4B 45 57 20 30 2E 30 30 30 30 31 37 35 00 1A SKEW 0.0000175.. 0230: 00 53 4F 55 52 43 45 5F 4C 4F 43 41 54 49 4F 4E .SOURCE_LOCATION 0240: 20 31 30 31 35 2E 30 30 00 0A 00 53 54 41 43 4B 1015.00...STACK 0250: 20 32 00 1C 00 4E 4F 54 45 20 0A 20 44 49 53 50 2...NOTE . DISP 0260: 4C 41 59 5F 53 43 41 4C 45 20 39 39 20 0A 00 00 LAY_SCALE 99 ... 0270: 00 00 00 00 00 00 FD FF FD FF FE FF 00 00 00 00 ................ 0280: 00 00 00 00 FF FF FE FF 00 00 FF FF 01 00 01 00 ................ 0290: 00 00 00 00 FE FF FF FF FE FF FE FF 00 00 FF FF ................ 02A0: 00 00 01 00 01 00 00 00 00 00 01 00 01 00 02 00 ................ 02B0: 00 00 00 00 00 00 02 00 03 00 00 00 00 00 FF FF ................ 02C0: FF FF FF FF 00 00 FE FF FF FF 01 00 01 00 00 00 ................ 02D0: 02 00 01 00 00 00 FF FF 00 00 00 00 00 00 FF FF ................ 02E0: FF FF 00 00 00 00 01 00 00 00 FE FF 00 00 FF FF ................ 02F0: 01 00 FF FF FE FF 00 00 FF FF 00 00 FF FF 00 00 ................ 0300: 00 00 00 00 FF FF FE FF FF FF 00 00 00 00 FF FF ................ 0310: FD FF FE FF 00 00 FF FF 00 00 FF FF FE FF 00 00 ................


0320: 00 00 01 00 01 00 00 00 00 00 01 00 00 00 FE FF ................ 0330: FF FF 00 00 00 00 00 00 FF FF FF FF 00 00 FF FF ................ 0340: 00 00 00 00 01 00 00 00 00 00 00 00 01 00 01 00 ................ 0350: 00 00 00 00 FF FF FF FF 00 00 00 00 FF FF FF FF ................ 0360: 00 00 FF FF 00 00 FF FF FF FF FF FF 00 00 00 00 ................ data from trace 1 continues


Storage Capacity The number of files which can be stored on a disk drive varies with the amount of memory required for a seismic record, which of course depends on the number of channels, data format, and record length. To calculate the number of bytes required, multiply the (number of channels used) * (record length) * (number of bytes in a data word), then add some for the header information (approximately 300 bytes for the file header and Nx300 bytes for the trace headers). The record length depends on the amount of memory used, 512, 1024, 1536, or 2048 samples. The number of bytes in a data word (one sample of seismic data) is 2.5 (for 20-bit data storage format). The following table shows the number of files stored for either the floppy disk or the hard disk for different combinations of record length. If the number of channels is reduced, the capacity increases. Part of the hard disk is used for storing the seismic program. Files/ Files/ Number Record File 1.44M 40Mb of Length Size Floppy Hard Channels Samples Bytes Disk Drive

12 512 20K 70 1500 24 512 35K 40 800 12 1024 35k 40 800 24 1024 65k 20 400 12 1536 50k 25 600 24 1536 95k 15 300 12 2048 65k 20 400 24 2048 125k 10 240 Support Disks The SmartSeis comes with pre-recorded floppy disks called “Support Disks”. These include programs and data used by the system. The seismic program is included, along with sample data, and some additional files. The latest revisions to the software, format, and operating instructions will be found here. Some batch files are given names consisting of numbers, so they can be accessed from the SmartSeis keyboard. Other files may require the use of an external AT-style keyboard.


The support disk can be explored with a standard computer (with a 1.4-Mbyte, 3.5-inch drive) or on the SmartSeis. The help files will print on the SmartSeis plotter, and numerical name batch files contain the print instructions, so the seismic keyboard can control the print. It is difficult to be too specific with these instructions, as these batch files undergo frequent revisions. They may not be present on your system. Remember that you can connect a standard AT-style keyboard by removing your system from its case if you do not have the computer option. Loading the seismic program The operating software of the SmartSeis is stored on hard disk drive C:. The software is normally resident in the system and will be loaded automatically by the autoexec.bat file to configure the system as a seismograph. This software may also be loaded from drive A: in the case of a failure or, more commonly, to update the system software. To load the new software, use exit to DOS in the OTHER menu. Put the disk containing the system software in Drive A: and copy the new files to Drive C: using the numerically named batch file listed on the screen. If the seismic program is corrupted, and you cannot follow the above procedure (perhaps because the seismic program will not run, or because you have replaced the hard disk), there is an alternate procedure. Connect a standard AT keyboard as described earlier, get DOS installed and running on the system, insert the support disk in the floppy drive, and select Drive A:. Type DIR and you should see a batch file called INSTALL.BAT in the list of files. Type CD\ to switch to the root directory if you do not see this file listed. Then type INSTALL and press Enter. This file will automatically create the necessary directories and install the seismic program on the hard disk.

SmartSeis™ Operating Manual Page D-1 Appendix D-Built-in Computer

Appendix D. Using the Built-in Computer The SmartSeis contains an AT-compatible computer with an 80386SX high-performance microprocessor. If the computer option was purchased with the system, connectors are provided for an external keyboard, VGA monitor, printer, and RS-232 port. Operation is similar to any desktop IBM-compatible PC with some exceptions. Do not install performance enhancing software such as disk caches or RAM drives. These may conflict with the seismic program. The printer port is LPT1. This port also used to drives the built-in plotter. To use an external printer, disconnect the internal printer by removing the ribbon cable connector to reveal the external printer connector. This built-in plotter can also be used to print character data. It uses a different graphics interface standard than most standard dot-matrix printers, and thus is not usable on third party non-text programs unless they have specific drivers for this printer. Likewise, a standard dot-matrix printer cannot print the seismic data. Some programs (including Eavesdropper) include drivers for the SmartSeis internal printer. The quality of the data and seismic sections printed on the internal printer is excellent. The RS-232 port is COM1. The RS-232 port may be used as with any such port on a standard computer. File transfer programs, such as Laplink, can be used to transfer data to another DOS computer. A monitor connector is available for a VGA color monitor. The internal LCD screen is also VGA compatible, and may be used as well with general purpose programs. Both monitors cannot be used at the same time, because of timing differences. The decision is made automatically by the instrument during the seismograph power on sequence. If an external monitor is connected, it will be selected and the internal monitor will not function. Instructions for operating a PC-compatible computer are well beyond the scope of this manual. Anyone attempting to use this computer should be well versed in operating a standard desktop computer. The hard disk is partitioned into two logical drives, C: and D:. The D: partition is used by the program to store seismic data files. Drive C: holds the seismic program, DOS, and some related files. Some space is available on drive C: for running user programs. Print a copy of the file directory before attempting to use this space, and be prepared to reload the program from scratch from the backup copy provided with the instrument. To use the computer, connect a standard keyboard (AT type, not PC or XT) to the system. Press key F10 to exit to DOS. Run programs as with any similar computer. To return directly to the seismic program, type the name of the batch file which loads the seismic program (the name of this batch file is listed when you Exit to DOS in the OTHER menu).

SmartSeis™ Operating Manual Page D-2 Appendix D-Built-in Computer

Note that it is possible to run user programs without a standard keyboard. You can exit to DOS from the OTHER menu. To provide the capability of calling a program from the standard SmartSeis keys, programs can be given a numerical name (e.g. 1234.EXE) or you can write a batch file which calls an alpha-named program. Software developers should contact Geometrics for information on using interactive capabilities of the system. Do not install disk caches or RAM drives on your system.

SmartSeis™ Operating Manual Page E-1 Appendix E-Specifications

Appendix E. Specifications Data Acquisition: Preamplifier:

Input: Floating differential

Gain: 3X (36 dB) 2% accuracy

Differential input impedance: 20,000 ohms

Common mode input impedance: 5,000 ohms

Maximum undistorted differential input signal: 0.312 volts peak-to-peak

Input protected: against static and transient discharge. Filters: Acquisition filters:

Anti-alias filter automatically set by sample interval except none at fastest sample rate.

Selectable Lowcut, Notch or Highcut filter. Lowcut frequencies 10, 15, 25, 35, 50, 70, 100, 140, 200, 280, or 400 Hz, attenuation 24 dB/octave. Notch frequencies of 50, 60, 150 or 200 Hz. Highcut frequencies of 250, 500 or 1000 Hz.

Second filter available identical to above. Display filters:

Two display filters are available, identical to the acquisition filters. Display filters do not alter the raw data stored in memory and saved on disk.

Digitizer: 16-bit (15+sign) analog-to-digital converter, preceded by an automatic 24 dB, single-stage, gain-ranging amplifier.

Summer: Signal is summed into a 32-bit accumulator. Will also subtract for enhancement of shear waves. Maximum signal may be stacked 8000 times without saturation.

Sample intervals: selectable 31.25, 62.5, 125, 250, or 500 microseconds for all channels.

Memory size: 32-bit word per sample, 2048 samples per channel, can be reduced by menu control to 1536, 1024, or 512 samples to save disk storage space.

Record duration: 64, 128, 256, 512 or 1024 milliseconds, depending on sample interval. Length of memory in use may be restricted to ¼, 2 or ¾ of the available amount to reduce amount of data stored.

Memory freeze: selectable memory protection on individual channels to prevent erasure or further stacking.

SmartSeis™ Operating Manual Page E-2 Appendix E-Specifications

Preview: incoming data may be displayed on screen and either selected or rejected at operator's discretion to allow editing of noisy records.

Delay: start of record may be delayed from initiation by selected value from 0 to 999 milliseconds in 1 ms increments. Negative delay may be selected to display a portion of the record prior to the zero time trigger.

Trigger: System triggers from a standard hammer switch, geophone signal, saturated NPN transistor, 5-volt logic level, contact closure, contact open, or +/- voltage. Trigger voltage sensitivity adjustable from 0 to 800 millivolts.

System:

Number of Seismic Channels: 12 (in SmartSeis S12) or 24 (in SmartSeis S24).

Graphics display: liquid crystal, VGA-compatible, with 640 by 480 pixels, 11 inch (28 cm) diagonal viewing area.

Display annotation: data is annotated with acquisition parameters and time-labeled cursors.

Display parameters: data is displayed in variable area, shaded, or wiggle trace, with and without clipping, in fixed gain or AGC, with adjustments for trace amplitude and time scale.

Plotter: Paper copy of record provided by internal, 11-cm wide thermal plotter with 640 dot resolution. Record is annotated with acquisition parameters, other variables, and time lines. Time scale and trace amplitude and format adjustable, controlled by settings on display.

Noise Monitor: Multi-channel, long-persistence, oscillographic noise monitor with trace for each geophone signal. Sensitivity is adjustable with scale factor displayed on screen. Waveform envelope can be observed.

Data storage: Internal 3.5-inch floppy disk drive provides data storage on 1.44-Mbyte, DOS-compatible media. Internal 40-Mbyte hard disk for program and data storage.

Computer: Internal computer with 80386SX processor, IBM AT compatible. Available for use as computer with computer interface option, which includes outputs for an external VGA monitor, parallel printer port, standard keyboard, and RS-232 interface. Programs may be loaded on standard disk drive.

Environmental:

Temperature: operates from 0 to 50 degrees Celsius. Will operate in light rain in vertical position.

Power: External 12-volt power from rechargeable battery or other source. Operates from 10.5 to 15 volts. Current drain approximately 22 amps for SmartSeis S12 and 32 amps for SmartSeis S24.

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Operation Manual - Michigan Technological University