Investigation of the applicability of microphones to nonlinear acoustic mine detection

Abstract

The feasibility of using microphones to measure intermodulation effects above a buried mine is under investigation at the U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate. Acoustic mine detection techniques employ acoustic energy to excite soil and buried mines. The resultant linear and nonlinear response at the surface can then be measured using non-contacting vibrometers. Carrier signal scattering by rough surfaces, however, can limit the measurement accuracy of these vibrometers and, subsequently, successful detection of the landmine. A microphone is proposed as an alternative non-contact sensor specifically for nonlinear acoustic mine detection applications. In this scenario, distinct frequency content facilitates separation of the intermodulation effects at the surface from the acoustic excitation. Experimental results employing intermodulation effects for acoustic mine detection have been reported in the literature [Donskoy et al., J. Acoust. Soc. Am. 111, 2705–2714 (2002)]. Preliminary experimental results demonstrate the ability of microphones to sense pressure radiated from soil in the presence of realistic ground velocities. The applicability of these measurements to practical mine detection systems will also be addressed.