On-time response of unexploded ordnance-like targets detection with transient electromagnetic system

Abstract

Time-domain electromagnetic induction method including on-time and off-time illumination is widely developed in unexploded ordnance (UXO) detection. The secondary field response detected in off-time is almost ineffective for targets with small size and great depth due to fast signal attenuation and low signal-to-noise ratio at late stage. In this paper, the on-time response for UXO detection with TEM system is discussed in detail. Firstly, the on-time response of a sphere is calculated theoretically and compared with the off-time response. Secondly, the transmitting circuit with four NMOS is designed to generate desired transmitting current to measure on-time response effectively. Finally, the on-time and off-time response of several targets are measured simultaneously. Results show that the late signal-to-noise ratio of on-time response is much higher and the attenuation of target with small size and iron pipe is slower than the off-time response, which is consistent with the theoretical results.