Ground ElectroMagnetics

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The GEM-2 Ski offers portability and flexibility making it the go-to multi-tool of the industry.

Because it is comfortable to carry and has a field-swappable battery, extended surveys are no problem. Its powerful transmitter and wide coil separation allow scanning to depths up to 10 meters, depending on soil conditions.  Depending on the model, it can use up to 10 simultaneous frequencies from 25 Hz to 96 kHz.

Frequency programmability allows you to tailor detection to your intended targets and environmental conditions. The frequencies can also be programmed to mimic the configuration of other instruments, possibly replacing several instruments with one GEM-2 ski. The extended frequency range also provides unique detection capabilities.

The GEM –2 is suitable for investigations in:

• Soil contamination from brine or chemicals
• Leakage from tanks or ponds
• Location of abandoned landfills and facilities
• Identification of underground structures
• Shallow geology
• Groundwater
• Precision agriculture
• Forensic investigation and archaeology
• Geotechnical education

The hand-held GEM-3 uses the same electronics and firmware as  GEM-2 ski, so its features and options are comparable. Because it is comfortable to carry and has a field-swappable battery, extended surveys are no problem.

It is available with 3 different diameters of sensing head: 30, 40 and 65 cm. The larger diameters provide more moment for greater depth penetration.Depending on the model, it can use up to 10 simultaneous frequencies from 30 Hz to 93 kHz.

The GEM-3 produces in-phase and quadrature data at each frequency. In-phase data is sensitive to earth's electrical conductivity and magnetic susceptibility. Therefore, over highly conductive and/or magnetic soil, the in-phase data is often too sensitive to sensor height to be a stable detection indicator.

The quadrature data, however, are insensitive to the height variations and, thus, provide reliable detection. The sum of all quadrature data is an excellent detection indicator in magnetic and/or conductive geology.

The GEM-3 is suitable for investigations in:

• Ferrous/non-ferrous metal detection
• Location of environmental contaminations
• Geotechnical engineering
• Soil science
• Archaeology
• Continuous EM induction spectroscopy (EMIS)

The GEM-3 configuration which is the basis of our hand-held GEM-3 instruments can be scaled up for use on a pushcart. Because the transmit coil runs around the edge of the panel, it can generate much larger moments than in the hand-held instrument. The greater moment allows it to find smaller/deeper targets. The wider size means that a single surveyor can cover large areas more quickly. The cart format also makes easy to mount a precise GPS receiver. As with all our instruments, the GPS positioning data is merged with the EM data in real time.  This photo shows a GEM-3R model with a large transmitter (1 m x 0.75 m) for deep penetration, real-time screen display on a PDA, and rugged construction for rough ground conditions. Everything, including electronics and battery, is self-contained on the cart, leaving the operator completely free of external luggage or tangled cables.      

The sensor produces in-phase and quadrature data at each frequency. In-phase data is sensitive to earth's electrical conductivity and magnetic susceptibility. Over highly conductive or magnetic soil, the in-phase data is often too sensitive to motion-induced noise to be a stable detection indicator. The quadrature data, however, are insensitive and, thus, provide reliable detection. The sum of all quadrature data, called the Q-sum, is an excellent detector in conductive or magnetic geology, with minimal false alarms.    

The GEM-3R is suitable for investigations in: Geotechnical Engineering Soil Science Archaeology Environmental Contaminations Continuous EM induction spectroscopy (EMIS) Ferrous/non-ferrous metal detection