A Multiarray Electromagnetic Instrument for Shallow Surface Real-Time Detection

A multiarray shallow surface electromagnetic detection instrument is presented in this article. The basic module of the instrument is an array system with a single transmitter coil and five receiver coils. In order to realize a modular array system and ensure the consistency of each array, a time slice overlapping method is proposed to solve the interference problem between neighboring arrays. The work process of a single array detection system is divided into three time slices, including simultaneous transmitting and receiving, data processing, and data uploading. The simultaneous transmitting and receiving procedure of each array is carried out sequentially with no interval. The data processing and uploading procedures are overlapped. To suppress environmental noise and electromagnetic interference, a cross correlation method based on a sliding window is designed to achieve real-time data processing. A four-array electromagnetic instrument prototype is implemented. Results of the field tests show that the time slice overlapping method eliminates mutual interference. Also, the electromagnetic response of the target is highlighted. It has been demonstrated that the cross correlation analysis improves the signal-to-noise ratio (SNR).