ELECTROMAGNETIC SURVEYING

摘要

A submersible electromagnetic (EM) field generator (5) for seafloor electromagnetic surveying comprising an AC to DC converter (18) operable to generate a DC output from an AC input and a switching module (19) operable t o generate a waveform driving signal by selectively switching the DC output. T he EM field generator also comprises an antenna (20) that is operable to genera te an EM field in response to the waveform driving signal. This design approach of using a switched DC source allows square or rectangular wave EM signals t o be generated which have sharp transition characteristics and which are substantially independent of the AC input characteristics.