Underground Utilities

One man's "noise" is another man's "signal"!

  • SAM can be used for mapping underground utilities such as pipes and cables by channeling electrical current through the item to be mapped.
  • This technique uses the Gap LPTX – battery powered transmitter controlled by the GAP SAM-2 transmitter controller
  • The GAP TM-6 magnetometer is used to record the total magnetic intensity at 1200 samples per second.
    Navigation and positioning is performed by the TM-6’s proprietary software in combination with DGPS
  • Use of a magnetometer in built-up areas is often difficult because of electromagnetic interference from 50/60 Hz mains power
  • The bandwidth of the Cs sensor enables the magnetometer to track the alternating electromagnetic fields
  • By using a transmit frequency which is a sub-multiple of mains frequencies, mains interference can be effectively removed by signal stacking
  • The result is a clean accurate signal which is not degraded by magnetic or electromagnetic interference.
Response to underground pipe 
SAM response to a sewerage pipe at 2.5 metres depth