Canada • Singapore • India • South Africa A Neterwala Group Company

Helicopter Time-Domain EM

P-THEM is a versatile state-of-the-art time-domain helicopter-borne electromagnetic system. It features a powerful transmitter, an upgraded state of the art PC-based receiver and an advanced digital signal processing software package. It is adaptable, well suited for shallow soil mapping, ground water and/or ore-body exploration.

P-THEM comprises an 8.5 metres diameter (57 m2) transmitter loop assembly and a 3-axis receiver suspended on the tow-cable midway between the transmitter assembly and the helicopter. Power for the P-THEM system is provided by a motor generator mounted on the transmitter assembly.

P-THEM transmits a half sine wave 4ms pulse with a 400+ KNIA peak moment. It is easily transportable and rapidly deployed; typically in half-a-day.

The survey system also includes a high-sensitivity cesium magnetometer, a real-time OmniSTAR/DGPS differential navigation system, radar and barometric altimeters and an optional gammaray spectrometer with 16.8 litres of sensor.



  • Compact, focused, rigid transmitter with high spatial resolution
  • 4-turns, 8.5m diameter (57 m2 area) transmitter loop
  • 3-axis receiver midway between the transmitter assembly and the helicopter
  • Depth of penetration from 400m to 450 metres in low to moderate resistive conditions
  • Both ON-TIME and OFF-TIME measurements
  • 400,000 NIA dipole moment
  • Powered by a motor generator mounted on the transmitter assembly
  • Slow speed and good contouring, transmitter altitude of 30 metres
  • Coaxial system with symmetrical and accurate anomaly positioning (+/-1 m)
  • Full waveform recording and processing (1,500 samples per channel per half cycle)
  • 10Hz stacking integration · Unlimited customized time-channels
P-THEM profile data acquired over the Buckingham test line.