Technical Notes - Helicopter Electromagnetics

Electromagnetic Effects on the Magnetometer

There is sufficient separation between the EM operating frequencies and harmonics and the range of Larmor frequencies measured by the magnetometer that there is no effect on the magnetic measurement from the HEM system. Fugro Airborne Surveys has been installing the magnetometer in the centre of the HEM bird for several years, gaining the advantage of having the magnetometer as close to the ground as possible. The 8 m coil separation of the DighemV system provides the greatest possible separation between the components of the magnetic and electromagnetic system to further reduce any chance of interference.

Greg Hodges, Chief Geophysicist, 1999