3D Electromagnetic System
The V5 System 2000 uses a new approach to EM data acquisition based on multiple, rugged, lightweight, independent data acquisition units (MTUs), which are synchronized by time signals broadcast by the GPS (Global Positioning Satellite) system.
Use of 24-bit analog-to-digital converters provides wide dynamic range, simplified circuitry, and lower cost.
The V5 System 2000 is offered for the MT (Magnetotelluric), AMT (Audiofrequency MT) techniques. Future enhancements will provide data acquisition capability for other commonly used EM techniques, including Long Period Transient EM and Induced Polarization (IP).
The field configuration and spacing of the MTUs can be varied with complete flexibility, according to the requirements of the survey. No cable links are required between the boxes - an important advantage in areas with rugged topography, lakes, swamps and other access difficulties.
Where access is easier, or if required, the MTUs can be deployed at very close spacing or for continuous profiling.
The heart of the System 2000 : The MTU
The MTU is provided in 3 configurations. The MTU-2E measures 2 channels of electric field data; the MTU-3H measures 3 channels of magnetic field data; the MTU-5 combines both.
When the V5 System 2000 is used for MT, the electric field is preferably measured at a closer spacing than the magnetic field. Thus, most of the deployed units are usually MTU-2Es, with a smaller number of MTU-3Hs or MTU-5s. The MTU-2E with electric field sensors costs significantly less than the MTU-3H / MTU-5 with magnetic sensors, so that the required sampling density can be achieved at an acceptable cost.
Each MTU is configured with ample solid state memory, onboard processor and diagnostics, onboard GPS antenna and auxiliary precision timing. The solid aluminum enclosures are equipped with rugged, military style connectors.
The lightweight MTUs can be easily carried to remote locations. In the distributed (stand alone) configuration, data is retrieved by ruggedized PCs for transfer to base camp.
An important benefit of the innovative architecture of the V5 System 2000 is the light weight and extreme portability of the MTUs. All the equipment for a single 2-E measurement is easily backpacked by two field workers, reducing labor costs and permitting economical MT and other EM surveys even in remote, rugged, off-road areas.
The MTUs can be deployed without any cable links between the boxes, providing great logistic flexibility.
In reconnaissance of large areas, a multi-pass data acquisition strategy is used. The MTUs are deployed at relatively wide spacing in a first "pass" of data acquisition. If areas of interest are discovered in the first pass the MTUs can be immediately redeployed in those areas at closer spacing in the second pass to provide a higher resolution image. In this way the spatial sampling density is always optimized and cost is always minimized.
New data acquisition techniques provide far more data than previous generation equipment. New multi-site processing techniques provide better interpretation, even in noisy areas.
Data Acquisition System
One great advantage of the wireless system is the elimination of hundreds of kilograms of multiconductor cable. The wireless approach also eliminates the crosstalk that arises in multiconductor cables. Surveys proceed much more efficiently because GPS synchronization and wireless control of the transmitter permits automatic frequency stepping.
A remote Telluric Noise Cancelling reference site (TNC, upper left) improves data quality. The transmitter monitor (TMR) in the lower right also serves in this example as the master radio, relaying communications among the other instruments. Radio range depends on many variables, but even if the network is unreliable, the survey can continue. All instruments save their own data for post processing.