Our team offers several electromagnetic instrumentation solutions to ensure the most cost effect approach to data collection is performed. Our sensor platforms range from handheld to vehicle mounted. They are as follows:
GEM-2 Technical Specifications
Bandwidth : 300 Hz to 96 kHz
Frequency Domain : Single frequency or Multiple Frequencies
Sampling Rate : Selectable 30 Hz or 25 Hz
Ski : Fiberglass foam 2 kg, L 183 cm, W 12.5 cm
Coil Configuration : Coplanar
Maximum TX Moment : 3 Amp m2 at 330 Hz
Rechargeable Battery: 12 VDC
Output : Inphase and Quadrature in PPM at each frequency, Apparent conductivity and Magnetic susceptibility, Powerline amplitude
Realtime GPS input for navigation
Remote Operation Options
User Interface and Data Logger : Socket PDA
Communication : Bluetooth with the PDA and Computer or RS232
GEM-2 Survey Data Examples
Forgotten Landfill : While historical photographs showed burial activities at this site, there were no records showing the real extent of the buried waste. GEM-2 was used to map all burial trenches and to prioritize locations for remediation.
Brine Contamination at an Oil Field : The U.S. Geological Survey (USGS) conducted a GEM-2 survey to characterize shallow brine contamination at an oil field in Oklahoma. Data were collected at five frequencies from 330 Hz to 47,010 Hz . The figures below show the apparent conductivity map at 14 kHz, which define the brine concentration in 3D.
Environmental Site Characterization : A GEM-2 survey was performed for the site characterization of a former industrial plant in Binghamton, NY. The objective was to identify and delineate subsurface features associated with past site operation. The data, shown above, located buried foundations, utility pipes, fill areas, concrete pads, contaminants, and other buried objects associated with the former plant.
The system provides 2-D data display that shows ground images in real time, including flagging potential targets on the screen. The unit comes with a GPS unit at decimeter accuracy. The system can merge data from other sensors and devices on the same platform using standard serial communication lines such as Ethernet, RS232 and RS485. The GEM-3 Array consists of a large transmitter coil along its perimeter, a bucking transmitter and seven equally-spaced receiver coils along its center line. The array has the following advantages:
- Maximum possible transmitter moment for a given array size
- Broadband operation, typically 10 frequencies between 90Hz-96kHz
- Seven equally-spaced receiver channels operating simultaneously
- High-speed survey; high data density
- Easy shipping owing to its flat construction
- Ability to work as an array in which all sensors can operate simultaneously
- Immunity to noise induced by sensor motion
- Immunity to ambient environmental EM noise, and
- Increased signal-to-noise ratio (SNR) owing to the noise immunities
Swath : 210cm (7 ft)
Dimensions (variable) : 30cm x 50m x 210cm
Coil Configuration : Coaxial
Transmitter Current : 20 amp RMS max
Power Supply : 12 VDC
Frequency Range : 90 Hz to 96 kHz
Number of Frequencies : 10 – 12
Sampling Rate : 30 Hz
Output : Inphase and quad in PPM, Apparent Conductivity, Magnetic Susceptibility, Powerline Amplitude
Realtime RPS input for navigation
Remote operation options : Vehicle Towed
An example Q-sum data obtained by painting the screen over the Geophex UXO Test Site, a 10 m x 10 m area, indicated by the white square boundaries. The ground truth shown on the right shows a total of 20 seeded targets of various metal pipes and one magnetic rock (red circle to the left). The seven parallel lines indicate the ground track of the GEM- 5 array having seven receiver channels; the swath is about 2-m wide.
Example data obtained along streets in Raleigh, NC, superimposed upon an aerial photograph of the area. The survey was undertaken to detect all utility lines (water, sewer, power line, telephone and fiber optic cables) buried under the road. Faint black lines indicate the ground track of the array.