The nature of step and impulse TDEM systems

Abstract

Over the last few years there has been a dramatic surge of interest in time domain electromagnetic (TDEM) methods of exploration and a number of systems are in use in the world today. They are classed in two categories, on the basis of whether they measure (or their system function is) the step (eg. UTEM, West et al. 1984) or the impulse (eg. EM-37, McNeil 1982; Newmont EMP, Dickson & Boyd 1980; CRONE PEM, Crone 1975; SIROTEM, Buselli & O'Neill 1977) response of the ground.