This research aims to tackle the issue of inconvenient clock synchronization in marine controlled source electromagnetic (MCSEM) operations with coaxial cables. This clock synchronization method in the manuscript that can be applied to scenarios where coaxial cables are used for MCSEM operations. We hope that in the future, MCSEM transmitters can be deployed on non-research vessels to reduce costs and broaden the scope of applications.

Current borehole receivers only measure a single parameter of the magnetic field component, which does not meet the special requirements of controlled-source electromagnetic (CSEM) methods. This study proposes a borehole electromagnetic receiver that realizes synchronous acquisition of the vertical electric field component and three-axis orthogonal magnetic field components. Results of the experiments show that our system functioned adequately and that high-quality CSEM signals were obtained.

Based on existing ocean bottom E-field (OBE) receiver specifications, including low noise levels, low power consumption, and low time drift errors, we integrated two induction coils for the magnetic sensor and a three-axis omnidirectional geophone for the seismic sensor to assemble an ultra-short baseline (USBL) transponder as the position sensor, which improved position accuracy and operational efficiency while reducing field data acquisition costs.

High-power transmitters have been playing a significant role in deep electromagnetic exploration. However, a high-power transmitter needs high-voltage support, which is a potential risk for researchers. According to the actual situation of field exploration, we designed a wireless monitoring system. The system offers two advantages, the first of which is high security; the second advantage is simple operation.

To assess the performance of the developed EM receivers, this paper presents a multifunctional waveform generator with three waveforms: 1) a wideband, low-noise electromagnetic field signal to be used for magnetotelluric, audio-magnetotelluric, and long-period magnetotelluric studies; 2) a repeating frequency sweep square waveform for CSAMT and SIP studies; and 3) a “positive-zero–negative-zero” signal that contains primary and secondary fields for time-domain-induced polarization studies.