method for detection of masses and the geological prospecting works

摘要

A primary electro magnetic field is created and directed to the zone to be prospected. The field has a waveform varying with time, and its phase and frequency components are known and are sufficient to identify the conducting mass present in the zone, these induced current set up the formation of secondary electromagnetic fields which interact with the primary field. The received signals comprise a first part whose phase and amplitude depend upon each frequency component of the secondary magnetic field and a second part which is attributable to the direct coupling with the primary electromagnetic field. Several reference waveforms are coupled in a predetermined manner to the primary field and relate to characteristic electrical responses of several different types of conducting masses. The electromagnetic signals received are compared with the reference waveforms which give optimal correlation.