Acoustic–seismic detection and classification of military vehicles—developing tools for disarmament and peace-keeping

Acoustic and seismic signals of military vehicles passing between two newly-developed sensor stations separated by about 100 m distance have been measured. Five tracked and five wheeled vehicles drove with seven speeds in both directions on four lanes. Rms values rose above background at distances of several 100 m for tanks, 60–80 m for a medium truck, and 40–50 m for a light van. By processing the acoustic and seismic maxima together, tracked and wheeled vehicles were separated correctly in 94% of the passes. An algorithm for detecting lines and harmonic series in acoustic spectra worked for eight vehicles. For vehicle-type recognition, learning-vector quantisation was used, working on the relative powers of the first 15 harmonics. This was successful in 95–98% of the tracked-vehicle passes and 69–95% of the wheeled-vehicle passes. These experiences and results suggest that sensor monitoring of control lines is feasible.