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.

The CUGB-CS48DAS data acquisition system was primarily designed for seismic purposes. However, we tried to integrate the acquisition circuit for electrical purposes and implemented hardware improvements as well as software updates. Moreover, technology including narrow-band internet of things QC monitoring was also introduced. After a few field tests, the system was proven to be stable and easy to use and has a good application effect in engineering geology, mineral geology, and energy geology.

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.

An electromagnetic transmitter sends an electromagnetic wave to the seabed; the receiver located on the seafloor receives the electromagnetic wave which carries the information of the geosphere. In this paper, an algorithm is proposed to improve the current quality of marine electromagnetic transmitters. It has an anomaly detection function for the unstable part of the transmitting current. Our results show that the instability of transmitting-current data can cause obvious anomalies.

Complex and harsh exploration environments have put forward higher requirements for traditional geophysical exploration methods and instruments. In this study, a new distributed seismic and electrical hybrid acquisition station is developed and it can achieve high-precision hybrid acquisition of seismic and electrical data. The synchronization precision of the acquisition station is better than 200 ns and the maximum low-power data transmission speed is 16 Mbps along a 55 m cable.

The nonuniqueness of geophysical inversions, which is based on a single geophysical method, is a long–standing problem in geophysical exploration. This paper developed a distributed, multi–channel, high–precision data acquisition system. It can achieve high–precision hybrid acquisition of seismic–electrical data and monitor the real–time quality of data acquisition processes using NB–IoT technology. The equivalent input noise is 0.5 μV and the synchronization accuracy is within 200 ns.

The existing current recorder is inadequate for continuous recording, precision, bandwidth, dynamic range, and input range. A new full waveform current recorder that is ideal for measuring current signal for electrical prospecting applications is presented. The full waveform current recorder is capable of measuring current with bandwidth from DC to 10 kHz, with a power spectrum density noise floor of 10 A/rt(Hz) at 10 Hz.

The CUGB-CS48DAS data acquisition system was designed for seismic purpose at first. However, we tried to integrate the acquisition circuit and after several hardware improvements and software updates, it can be used now for seismic exploration as well as electrical prospecting. It has good application effects in engineering geology, mineral geology and energy geology, and is suitable for exploration tasks in coalfields, petroleum, minerals, earthquake monitoring and urban construction, etc.

In this study, a high-precision distributed wireless microseismic acquisition system has been designed for oil and gas exploration. The system design, which was based on the ADS1274 chip manufactured by TI, made full use of the four channels of the chip to collect vibration signals in three directions and one electrical signal, respectively. Furthermore, the acquisition system used GPS and WIFI technologies to achieve distributed wireless acquisition.

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.

We believe that our study full-waveform voltage and current recording device for MTEM transmitters makes a significant contribution to the literature because this full-waveform recording device can be used to monitor the high-power, full-waveform voltages and currents of MTEM transmitters. It has high precision, finer edge details, low noise, and other advantages. Hence, it can be used for real-time recording and transmission to the receiver for coherent demodulation.

The main contribution of our paper is the proposal of a dynamic data transmission technology of an expendable current profiler, using varnished wires as the data transmission medium. The results of both indoor and marine tests demonstrate high efficiency and accuracy for transmission distances up to 2 km. We believe that this study will be of interest to the readership because our research is of particular interest and use for scientific marine investigation.

In this study, we propose a more accurate method for calculating the current velocity from the nanovolt-scale current-induced electric field as measured using an expendable current profiler (XCP). In order to confirm the accuracy of the proposed data processing method, a sea test was performed, wherein ocean current/electric field data were collected from the sea surface to a depth of 1000  m using an XCP.