Design and development of a semiairborne transient electromagnetic system

The semiairborne transient electromagnetic method (SATEM) is a geophysical method that combines the advantages of high-power ground-based transmitting and efficient airborne observation. In recent years, the threshold for SATEM application has been significantly reduced through the integration of multirotor unmanned aerial vehicles and systems obtained by the simple redevelopment of existing ground-based systems. However, it is still difficult to obtain good detection results with such systems for the following specific reasons: in terms of system design, there is a lack of method for estimating the key parameters of the system, resulting in the designed system being unable to effectively meet the requirements of the SATEM method and observation scenarios; in terms of technology, there is a lack of effective means of ensuring a high signal-to-noise ratio (high-current transmitting and effective suppression of major external noise) while meeting the demand for distortion-free observation. In response to these issues, a system bandwidth estimation method based on the analysis of information-carrying capacity is developed. Based on this, solutions for large current and fast turn-off transmitter and for overcoming major external noise are provided. Through a survey located in a karst landform area, the overall application performance of the system is discussed based on the inversion results.