20003-SPE-110.1 - Underwater Module Vulcan Class Specifications

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Envirtech S.p.A . Cap. Sociale Euro 500.000 i.v.

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This document or parts of it cannot be used for scopes not authorized by Envirtech SpA that will protect its rights.

Envirtech SpAVenice, 15th March 2011

Envirtech Code: 20003-SPE-110.1

TSUNAMI WARNING SYSTEM

VULCAN CLASS

Technical Specifications of

Underwater Module
mailto:[email protected]://www.envirtech.com/http://www.envirtech.com/mailto:[email protected]


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Tsunami Warning System Code 20003-SPE-110.1

Date 15/03/2011Technical Specifications of Underwater Module VULCAN CLASS Page 2 of 17

TABLE OF CONTENTS

1 INTRODUCTION .............................................................................................................................................3

2 UM VULCAN ARCHITECTURE ....................................................................................................................3

3 UM FUNCTIONALITIES.................................................................................................................................6

4 TECHNICAL DESCRIPTION..................................................................... ....................................................8

4.1 M ECHANICAL F RAME ...................................................................................................................................9 4.2 S EISMIC S ENSOR AND D IGITIZER ..................................................................................................................9 4.3 P RESSURE S ENSOR .....................................................................................................................................12 4.4 A COUSTIC R ELEASE ...................................................................................................................................12 4.5 A COUSTIC M ODEM ....................................................................................................................................13 4.6 B ATTERY H OUSING ....................................................................................................................................13 4.7 E LECTRONIC HOUSING ...............................................................................................................................14

5 UM COMPLIANT TABLE............................................................................................................................. 16


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1 INTRODUCTION

In order to improve the monitoring capabilities of the Underwater Module, since 2005 Envirtech

developed the Vulcan Class sea bottom module integrating a seismometer, an atomic clock and

a Paroscientific high precision pressure gauge. The acquisition of high resolution pressure data

and seismic data at the same time and place, allows to discriminate the internal gravity waves from

the pressure variations generated by near seismic event. Moreover the recovery and analysis of

all data collected by the Underwater Module allows to improve the knowledge of the mechanism of

tsunami generation.

Vulcan classes devices can have different configurations: they can integrate a broad-band or

narrow band seismometer and also a hydrophone.

The configuration described in the present document is for a basic version integrating a tri-axial

seismometer for the detection of regional earthquakes in a range of about 1000 km.

The following pages provide a description of the functionalities and performances of the module.

2 UM VULCAN ARCHITECTURE

The UM Vulcan is an instrumented unit composed of a mechanical frame integrating the following

main parts:

- a high resolution pressure sensor for the accurate detection of variation of the height of the

water column;

- a three components seismometer for detection of regional earthquakes;

- an atomic clock for event synchronization;

- a mechanical release for the deployment at the seabed of the seismometer after thetouchdown of the UM;

- an high resolution digitizer with peaking algorithm for the continuous acquisition and logging

of seismic data and for the real time detection of significant seismic events;

- an electronic unit for pressure data acquisition, processing and logging: this unit integrates

a tilt sensor to verify the stability of the UM at the sea bottom and other diagnostic sensor to

verify the status of the whole system;

- a high data throughput acoustic modem for the communication with the Surface Buoy (SB);

- a battery unit to supply the electronic unit, the instruments and the acoustic modem.- the installation/recovery subsystem composed of buoyancy line, acoustic release and

ballast: this subsystem makes the UM a free fall installation and pop up recovery system.


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The components of UM are listed in the following table

Device/Component/Part Description

Ballast Composed of a squared metal block to keep the UM stable at the seabottom.

Buoyancy line A line composed of a synthetic rope and syntactic foams able to liftthe system on surface at the release of the ballast in the recoveryphase.

Beacon A device equipped with ARGOS satellite transmitter providing the

position of the UM after the recovery on surface.Mechanical Frame A light and robust metallic frame in stainless steel suitable for the

marine environment.

It integrates mechanically all the components in the present table.

Acoustic Release A mechanical release with acoustic interface to allow disconnectingthe ballast at the reception of an acoustic coded command from asurface deck unit.

Mechanical Release A mechanical release with electrical interface to allow maximumpenetration of the seismometer inside the sea bottom

Seismometer A three components seismometer (1 Vertical and 2 Horizontal) for thedetection of regional seismic events.

Seismic digitizer A high resolution digitizer (22bits @100sps) with logging capabilitiesof seismic data for 2 years. It is integrated in a titanium housing andinterfaced with the seismometer.

Atomic Clock A micro-technology low power consumption ultra-stable atomic clockfor time synchronization.

Pressure sensor High resolution (or NANO RESOLUTION) pressure sensor electricallyconnected to the Electronic Unit

Electrical Unit An electronic acquisition system integrated in a titanium canister. It is

interfaced with the seismic digitizer to get seismic diagnostic data andcompressed wave forms related to seismic events. It also embedsthe atomic clock.

Tilt Sensor An high precision tilt sensor integrated in the Electronic system

Battery Unit A primary battery pack with dedicated diagnostic electronic systemintegrated in a titanium canister

Acoustic Modem An underwater acoustic modem for the data link with the surface buoy


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Some drawings of the Vulcan basic version are reported hereinafter

Fig. 2.2 UM Drawings and Pictures

The type of mechanical frame can change with- the typology of telemetry link adopted (cable or acoustic or magneto inductive through a

mooring cable);

- the type of seismometer adopted;

- the deployment procedure of the seismometer: sometimes it is fixed on the base of the

frame, sometimes it is released at least at 1m from the UM frame.

After a detailed agreement of the requirements with the customer it is possible to define the

custom frame.


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3 UM FUNCTIONALITIES

The main functionalities provided by the UM are summarized hereinafter:

Possibility for the UM to operate in Maintenance Mode, Normal Mode, Alarm Mode ; In Normal Mode the software

o acquires, logs and process every 15 seconds the pressure data to detect events

over the normal tide signal;

o acquires from 20 tor 100 sps of the three components seismometer, detects events

and stores the data; Envirtech Property Algorithm Automatically switch in Alarm Mode in case of detection of an

event on the seismic or pressure data and automatic sending of pressure data and seismic

event wave forms (in compressed format) via acoustic link; Automatic switch to Normal Mode after 3 hours of the UM in Alarm Mode; Hourly acquisition and logging of UM Status Message composed of

o 4 averages on 15mins of the tide data;o Hourly average and standard deviations of the three seismic components, position

of the seismic masses and other diagnostic parameter of the seismic sensor.

o Seawater temperature;

o Status sensors (internal temperature, pressure and water intrusion alarm) of

Electronic housing;

o Status sensors (battery voltage and current, internal temperature, pressure and

water intrusion alarm) of Battery housing;

o Heading and Tilt sensors data. Sending in Normal Mode every 1 hour, 2 hours, 3 hours, 4 hours, 6 hours (depending on

the user settings) of the hourly UM Status Messages. Management of data request of past pressure data stream or seismic data wave forms in

compressed format. Management of request of current status data composed of

o Current Pressure;

o Seawater temperature;

o Status sensors of Electronic housing;

o Status sensors of Battery housing;

o Heading and Tilt sensors data; Management of commands to


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o

Set alarm detection threshold;o Period for sending UM Status Messages;

o Switch UM in Maintenance, Normal and Alarm mode;

o Atomic Clock synchronization Management of bi-directional acoustic link with the Surface Buoy to send messages and to

receive commands and data requests.

The installation of the UM is free fall and the recovery for maintenance and re-installation is pop-

up. This is made possible by the buoyancy line + an acoustic release + a ballast.


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4 TECHNICAL DESCRIPTION

The Envirtech UM Vulcan class is an autonomous system suitable for the real time detection of

earthquakes and perturbation on the normal tide and to discriminate real tsunami waves from

seismic waves. It can be installed up to 6000mwd in Open Ocean.

The system is composed of a robust mechanical frame in stainless steel AISI316 suitable for the

marine environment, integrating the following main parts: Three component seismometer in a titanium housing. Pressure sensor Paroscientific Digiquartz with a pressure measurement resolution better

than 1mm of H 2O in a water column of 7000m. The sensor is temperature compensated

and provides also high resolution temperature measurement (0.001C). Spread Spectrum modulation acoustic modem providing a 5000 bps bidirectional data link

with a surface modem on a relay buoy. Autonomous power supply unit composed of primary lithium battery pack, protected in

Titanium housing: this battery, used in military application, assures an operative life of 24

months with the system sending an acoustic message per hour Data Acquisition and Control system protected in Titanium housings integrating a low

power microelectronic system for the real time data acquisition and processing of the

seismic signals and the pressure data. The electronic system includes a digitizer (22 bit

@100sps) with real time synchronization via an Atomic Clock, switch board, voltage

conditioning board, heading and tilt sensor (able to measure heading, pitch and roll with a

resolution of 0.1 deg) and diagnostic board monitoring battery voltage and current, internal

pressure, temperature and water intrusion in the Titanium housings.

A recovery system relied on a buoyancy line, composed of 8 deep sea syntactic buoys andan acoustic release unlocking a metal or concrete ballast of 220kg for the recovery of the

system on surface. The acoustic release can be actuated by a dedicated deck unit with

coded commands. The electronic unit has a proper mass memory (a set of high capacity CF card) to store all

the data acquired in 24 months.

The software in the electronic system provides the following main functionalities:

The acquisition of the 3 seismic components (20 or 100 samples per seconds); The acquisition of the pressure sensor (1 sample every 15sec); The acquisition of the heading & tilt sensor; The acquisition of the diagnostic boards;


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The real time precision clock; The data storage; The real time detection of seismic events with STA/LTA algorithm; The real time detection of anomalous events on the normal tide. The following algorithms

can be implemented:

o Mofjeld Algorithm that allows to detect variations of the water column in the typical

Tsunami waves period range (2-90min);

o Innovative algorithm relied on the neural network to improve the Mofjeld Algorithm

in the detection of tsunami events.o An Envirtech property algorithm to discriminate Tsunami Waves from Seismic

Waves.

o Others algorithms on user request. Periodical transfer to the surface relay buoy (every hour or three hours) of a message

containing tide data, tilt data and diagnostic data of the system and of the seismic sensor; In case of detection of an event, alarm messages are transferred to the surface relay buoy

every few minutes. This functionality allows the rapid user validation of the collected data

and the estimation of the possible danger scenarios. The alarm messages include the high

resolution pressure data (time spaced of 15 seconds) and compressed wave forms of the

seismic data related to the detected event.

The following paragraphs detail the specification of each UM component.

4.1 Mechanical Frame

The mechanical frame can vary with the type of seismometer and the type of integration of the

seismometer. Anyway it is a robust frame in stainless steel AISI316 suitable for the corrosive deep

sea environment.

4.2 Seismic Sensor and Digitizer

The Digitizer with precision clock is an Envirtech board with the following main features.


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ENV-DIG-3-24

Device tipology Digitizer and seismic datalogger

Sizes 130mm x 110mm x 35mm

Weight 250g

Signal interfaces 4 analogue input @24bit

4 analogue input @10bit

Digital interfaces 2 serial ports RS232

1 PPS input

Static RAM memory 128kb SRAM

Mass Memory SD flash cards up to 2GB x 8

ARCHITECTURE

Processing 2 microprocessors RISC 8bit ATMEL operating at 11.0592MHz and14.7456MHz

The first processor is dedicated to the sampling and primary data bufferingand the second processor has in chard the secondary data buffering, datacompression, data storage.

Moreover the second processor manages the user command interface.

User interface Terminal VT100 with handshake protocol x-on/x-off via RS232

DATA PROCESSING

File system FAT32

Data compression Seismic standard GSE2.0 with compression CM6

Automatic triggering STA/LTA

Continuous Datalogging User Configurable

Time synchronization Time setting with GPS (TIME DATA and 1PPS) and time stability assuredby the OCXO quartz.

ADC CONVERTER

Analogue inputs Differential / Single ended (jumper selectable)

Anti-aliasing filter Single pole RC. Standard frequency 8.8Hz selectable with a capacitors set.

Input range -1V..+1V (2 V of signal range)

Input impedance 300kohm

CMRR > 144dB

Shift between sampling on analogue 0 (simultaneous sampling)


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channels

Data transfer TTL UART at 38400baud

Quartz 11.0592MHz

OCXO 0.05ppm in the range 0C..50C

POWER SUPPLY

Power voltage 8-16V

Power consumption 0.6W @12.5V

The seismic sensor usually installed is a 3 components with the following main features.

Velocity output bandwidth30 seconds 50 Hertz (Standard)1s, 2s, 10s or 60s long period options 100Hz high frequency option

Velocity output sensitivity2 400 V/ms-1 (Standard)Options for 2 1000 or 2 1600 V/ms-1Optional high-gain output ( 10)

Peak output10 V (20 V peak-to-peak)

Optional high gain sensitivity2 10000 V/ms-1 (adjustable)

Lowest spurious resonance450 Hz

Linearity> 90 dB

Cross-axis rejection2 65 dB

Electronics noise level172 dB (relative to 1m2s-4Hz-1)

It is installed on a dedicated titanium housing as shown in the following picture


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Fig 4.1 Ocean Bottom Seismometer in Titanium case

4.3 Pressure Sensor

Pressure sensor is depicted in Fig 4.2.

Fig 4.2 Paroscientific Digiquartz Pressure Sensor

Technical specifications: Range: 7000m Resolution: 0.1 ppm @ 1sample/15sec Built-in Temperature sensor.

4.4 Acoustic Release

Acoustic release is depicted in Fig 4.3


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Fig 4.3 Oceano 2500 Light Acoustic Release

Technical specifications: Super Duplex Stainless Steel Working Load Limit: 2500kg Autonomy: 6 years Depth: up to 6000m

4.5 Acoustic Modem

It is depicted in Fig. 4.4

Fig 4.4 UWM 10000 Acoustic Modem

Technical specifications: Modulation: Spread Spectrum Data rate: 5000 bps Slant range: 10000m Depth: up to 7000m

4.6 Battery Housing

It is depicted in Fig 4.4


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Fig 4.4 Titanium Battery Housing

Technical specifications: Battery pack for electronic system (14.4V 518Ah 1Amax) Status board to monitor

o Internal temperature

o Internal pressureo Water intrusion

2 battery units like this are necessary for the Vulcan class module to get a power autonomy of 2

years.

4.7 Electronic housing

It is depicted in Fig 4.5

Fig 4.5 Titanium Electronic Housing


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Technical specifications: Battery pack for acoustic link (25.2V 104Ah 5Amax) ENV-UM-ELE composed of

o CPU board

o Status board

o Switch board

o DC/DC board

An additional housing like this is foreseen in the Vulcan class module to integrate the seismicsignals digitizer and an additional battery pack (25.2V 104Ah 5Amax) for the acoustic link.


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5 UM COMPLIANT TABLE

ID Requirement Note

1 Material of the frame shall be AISI316L

2 Material of the protective housings for electronic and batteryshall be Titanium grade 5

3 The buoys of buoyancy line shall be in syntactic foam: the

use of glass sphere is not allowed4 Acoustic release of the recovery system shall be

independent by the acoustic modem for data link UM-SB

5 Primary battery for UM electronic and acoustic modem shallbe Lithium battery

6 Acoustic Modem shall provide a slant range of 10000m

7 Pressure sensor shall provide a resolution of at least 1ppmon a range of 7000m with a sampling period of 15sec

8 Electronic and battery housings shall be equipped withinternal status sensor to monitor internal pressure,temperature and water intrusion

9 The UM shall be configurable to send a normal tidemessage every N hours with N = 1,2,3,4,6. Tide shall beprovided as 15mins averaged values

10 In case of Alarm detection the UM shall send every 5 or 10minutes the raw samples spaced of 15 secs. The processshall last at least 3 hours for every alarm detection

11 Precision clock (stability o 1ppm)

12 High resolution digitizer (22 bits@100sps)

13 Seismometer with 3 components for regional earthquakedetection

14 STA/LTA algorithm in the seismic digitizer for seismicevents detection

15 Compression and decimation of seismic events wave fortransfer of useful data via acoustic link

16 Real Time Clock syncronized via Atomic Clock for absoluteseismic data time reference.


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Documents

20003-SPE-110.1 - Underwater Module Vulcan Class Specifications