New Technologies for transient electromagnetic measurement with high performance

Theoretically, grounded-wire source electromagnetic methods can be categorized into far-source methods and near-source methods. The former have been used worldwide for many years, and the key technologies used in its equipment are mainly high-power transmitter and low-noise sensors. Due to its relatively narrow working bandwidth, its resolution capability is weak. In recent years, with the breakthrough of Short-Offset Transient Electromagnetic Method (SOTEM) in detection theory, its advantages of strong signal and wide bandwidth have been increasingly valued. For the research and development of specialized detection equipment for SOTEM, we first conducted system design by studying the characteristics of signals at different offset distances, and analyzed the technical difficulties that urgently need to be overcome. On this basis, a system with a high-bandwidth, high-current broadband transmitter and low-noise broadband receiver has been designed, the key technologies of which are ultra-high stabilized clamping voltage, low-noise hybrid amplifier, and adaptive variable damping. The performance and field tests have shown that the overall operating bandwidth of the system has increased by 2.5 times compared to existing mainstream equipment, significantly improving detection accuracy. The newly developed SOTEM equipment can provide strong support for near-source, great-depth, and high-resolution surveys.