Why time domain?

Abstract

It is shown that the Slingram-type TEM systems that have been successful in Australian exploration in the last decade have all had magnetic moments, and sensitivities, which were one to two orders greater than those commonly used in North America. It is shown that frequency domain systems of the same sensitivity would require relative receivertransmitter alignment accuracies of better than one minute of arc which is impracticable in production geophysics. Time domain EM systems do not require such accuracy, and will become increasingly dominant in exploration throughout the world with the increasing need to explore at depth.