Dictionary:Transient electromagnetic method (TEM)

An electromagnetic method in which the waveform of the transmitted signal is a train of pulses, step-functions, ramps, or other waveforms, and measurements are made in the off-times between pulses, usually after the primary field has stopped changing. Principal advantages of transient methods over continuous-wave methods are that the primary field is not present during the measurement of the secondary field and that measurements of the secondary field as a function of time are equivalent to continuous-wave measurements over a wide frequency range. Transient methods are used for both depth sounding and continuous profiling. Also called time-domain electromagnetic method (TDEM). See Figure E-7 and Input system.