Geophex Ltd.
30 years of excellence in EM instrumentation +1 (919) 839-8515

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Cart - GEM-3R

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 inphase and quadrature data at each frequency. Inphase data is sensitive to earth's electrical conductivity and magnetic susceptibility. Over highly conductive or magnetic soil, the inphase 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
Contact Geophex for more information

For an explanation of the GEM-2, GEM-3 and GEM-5 configurations, see the document Sensor Configurations

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Geophex Ltd.      605 Mercury street, Raleigh NC 27603 U.S.A.       Fax: +1 (919) 839-8528       Telephone: +1 (919) 839-8515