Design scheme of a high dynamic semi-airborne transient electromagnetic receiving system based on a voltage-controlled amplifier

The semi-airborne transient electromagnetic (SATEM) technique is established to examine subsurface targets. The SATEM approach is widely used in urban underground space exploration, hydrogeological search, and deep mineral exploration. However, the strength of SATEM signals declines exponentially with the depth of detection, and the SATEM system frequently operates in high electromagnetic noise environments, directly affecting the precision of deep information interpretation. This research presents a high dynamic semi-airborne transient electromagnetic (HDSATEM) receiving system to increase the late SATEM signal intensity. This system mainly comprises a voltage-controlled amplifier (VCA) and a function generator. In addition, the VCA is modulated using the gain voltage produced by the function generator. Consequently, a simulation model has been employed to analyze various functions to compare the dynamic ranges. The actual amplification performance and signal restoration capacity are confirmed using a laboratory test. A field experiment is also carried out to evaluate the actual detection performance of the proposed system compared to standard SATEM receiving and controlled source audio-frequency magneto-telluric systems. The findings indicate that the performance improvement of the HDSATEM receiving system is more than 50% in terms of depth detection compared to that of standard SATEM receiving systems.