GPTX 30Wide



The MPTX-500 is a high current transmitter designed for ultra-high resolution, small Fixed-Loop, EM surveying.  It has particular application as a component of a Deep Search UXO detection system.


Conventional UXO search instruments typically have a detection depth capability of 1 - 2m and are therefore generally only suitable for locating shallow items of ordnance. However, large items such as aerial bombs may penetrate to depths which are well beyond the detection limit of conventional technologies.

This concept transmitter was developed in collaboration with the US Army Corps of Engineers (Huntsville) for unexploded ordnance detection as part of an ESTCP funded Research project.  Used in conjunction with Gap GeoPhysics’s Sub-Audio Magnetics (SAM) technology, the MPTX-500 can facilitate detection depths of up to 10m for large aerial bombs. This technology has significant application in the remediation of formerly used Defence sites or war-torn areas.


The MPTX-500 is capable of outputting up to 500A into a 40m x 40m loop.

  • up to 350 Amps in a 100m x 100m loop
  • shutoff < 40µs
  • synchronised with GPS time strobes
  • constant current and controlled current modes
  • can be operated remotely using a PDA and bluetooth communications
  • control software allows monitoring and display of all Tx functions.

The performance of the MPTX-500 can be modelled for various loop configurations using GapTxCalc.

Safety Features

The MPTX-500 has a maximum output of 90V, classing it as an Extra Low Voltage device - and thereby inherently low risk.