IMPROVEMENTS IN TIME-DOMAIN ELECTROMAGNETIC GEOPHYSICAL MAPPING INSTRUMENTS

摘要

In a time domain electromagnetic mapping technique of the typeusing transmitter pulses of half-sinusoidal waveform, with thehalf sinusoids being segments of a sinusoidal waveform having afrequency and corresponding to a resonant frequency of thetransmitter coil, an improved current fall time at the end ofeach pulse is obtained by forming each transmitter pulse ofplural immediately successive half sinusoids, the transmittercoil being tuned to an appropriately increased resonantfrequency relative to the pulse repetition rate. Circuits forgenerating the improved pulse waveforms are disclosed.