Electromagnetic TDEM and FDEM techniquesof subsurface prospecting, are based on the measurement and analysis of the behaviour of electromagnetic fields induced on the ground by current pulses of a certain intensity, circulating on a coil horizontally located on the ground.
The prospecting equipment consists of a current transmitter with its power supply, a transmitting coil, the receiver of the induced fields and a digital recorder of the obtained data, which allows its later study and analysis.
Depending on which domain is being worked on, two groups of techniques can be distinguished: time domain TDEM, and frequency domainFDEM.