24-Bit Geophysical EM Measurement System

As in seismics, technological advances in electromagnetic recording systems have emphasised the requirementfor simultaneous multi-channel data acquisition.

The Multi-Method Network Geophysical Measurement System GMS-07 is the result of over 30 years ofmetronix´s experience in the design and manufacture of electromagnetic geophysical instruments. Theelectric (E) and/or magnetic field (H) sensors are connected directly to the ADU-07 (Analog/Digital SignalConditioning Unit), which is the core unit of this system. Multiple ADU-07 units can be connected to anetwork using simple, light-weight and inexpensive network cable or Wireless LAN.

 

Each ADU-07 can be operated as a stand alone system, in a network or as part of an array in which eachunit is synchronized by its in-built GPS clock.

Features

• High data quality due to 24 Bit Analog/Digital conversion technology
• Can be operated as a stand alone or as a multi-channel network system when connecting multiple ADU-07 in a Local Area Network (LAN, WLAN)
• Multiple stand alone systems are synchronized with GPS clock accuracy
• Compatible with all metronix sensors
• Automatic unattended recording mode
• Automated system self check of ADU – 07e and sensors during set up
• Automatic input offset compensation eliminates self potential of electrodes
• Realtime display of time series and many MT parameters in online mode
• 12 V battery powered. Only a single battery is required for each ADU incl. sensors
• Compact, light-weight, ruggedized and waterproof instrument design
• Wide operating tempereture range from -40°C to +70°C

Hardware

The ADU-07e electronics are housed in a small waterproof box only 7,1kg in weight. It comprises the completecircuitry for analog signal conditioning, 24 Bit A/D conversion and data storage. A very precise GPScontrolledtime base guarantees synchronous recordings even under difficult GPS reception conditions.

The ADU-07e can be tailored according to the user´s requirements.

So the ADU contains 10 slots which can be equipped with 2 different types of A/D converter boards. A/Dconverter Type L is optimized for lower frequency recordings in a range from DC up to 500Hz while thesecond type H is optimized for high frequency recordings in a signal range from 1Hz up to 250kHz. Forinstance a broadband standard ADU-07 is equipped with 5 low-frequency and 5 high-frequency A/D converter modules. It is possible to obtain high-frequency soundings during running low-frequency recording.

 

Different types of sensors can be connected to the ADU and can even be operated in parallel. Example: Afluxgate sensor is connected for low-frequency sounding and induction coils cover the higher frequencyrange simultaneously.

Software

The ADU-07 has a built-in web server. All necessary setups to run a measurement are controlled by the webinterface and can be accessed by any web browser; no software needs to be installed on your laptop orPDA. The software MAPROS (free) performs standard and remote reference processing of the time seriesdata using robust algorithms. Online processing inside the ADU-07 with unattended data publishing on theADU’s web server is under construction.

Using an external GPS controlled transmitter the ADU-07 provides CSAMT/CSEMM recordings with realtimestacking.

Configuration Examples

Single Site Configuration

In this configuration a single ADU-07 runs either in a stand alone mode and records the data according to a time schedule pre-programmed on its internal flashdisk. For highest performance an external computer can control the ADU via the USB 2.0 interface; in the latter case incoming data is processed and displayed in real time.

Multiple Site Configuration

In this configuration several ADU-07 systems are synchronized by their built-in GPS clocks, and they record the data synchronously. A typical application for this configuration is the Remote Reference method or Array Mapping. This arrangement is used for a grid with wide-spaced recording sites where cabling is impractical or cannot be handled economically.

Network Configuration

Multiple ADUs are connected to a network by cable or WLAN. A typical example for this configuration is E-MAP or field setups, where a close-spaced station grid is required.

TECHNICAL SPECIFICATIONS
BROADBAND MAGNETOTELLURIC 10 Channels ADU-07e ALL IN ONE METHODS (MT, AMT, CSAMT, RMT)
Automatically off mode when overheated with temperature > 70oC and be automatically on again when the temperature of main unit is getting lower
Continuing to keep data on low battery mode and show the data when the main unit in on mode again (data is not loss)
Frequency Range	DC to 250 KHz (DC to 250,000 Hz)
Number of Channels	10 Channels per main unit
Bands	2 bands (LF DC-512 Hz ; HF 1 Hz – 250KHz) Sub-bands are created by digital filtering Both bands can be recorded simultaneously
A/D conversion	24 Bit (max. data rate 2048 samples/sec) LF Board 24 Bit (max. data rate 524,288 samples/sec) LF Board
Dynamic Range	>130 dB
System controller	32 bit embedded controller, Linux
Storage media	Internal compact flash up to 4 GB or more, USB devices
Test facilities	Automatic power up self test of all important system functions including sensors and display of result on the instrument. Automatic creation of log file
Calibration	Automatic calibration
E-Field connector	Input resistance >10M Ohm, ODU-G32KON-T06QP00-000 ODU S22KON-T06MPL0-4000 (E-Field cable plug)
H-field connector	Input Resistance 20 kOhm, socket ODU G32KON- T10QJ00-000 ODU S22KON-T10MJG0-7000 (H-Field cable plug)
Multipurpose connector (E/H)	Input Resistance > 10 Mohm (E), 20 kOhm (H); ODU G33KON-T30QF00-000 ODU S23KOC-T30MFG0-7000 (cable plug)
Network Connection	Standard 100 Mbit Twisted Pair, USB 1.1, 2.0 (wireless/Bluetooth)
Synchronization	GPS clock +/- 30ns to satellite reference. Station position is also determined and stored
Interfaces	Network, Magnetometers, E- Field lines 2 battery inputs, GPS antenna, USB, Wireless
Case	Ruggedized, Waterproof Polycarbonate Case
Weight	Appr. 7.1 kg
External Dimensions	400 x 330 x 170 mm
Power Consumptions	Appr. 3-5 W (LF); 12 -20 W HF @ 96kHz up to 524 kHz sample rate
Operator Temperature Range	-40°C to + 70°C
Loss of GPS Signal	Still doing measurement
Weak Battery Power	Data will be saved & secured and will be shown when unit is on
Download Data	Data can be taken during measurement
Software Processing	To be updated every year & FREE
Processing Data	Can be set up from 8 points to be 100 points (using Mapros in frequency range : 10 eo and 10 e -1
Additional Feature	E-MAP feature : with one ADU-07e and 2 satellite Box can measure 4 point in one night