Acoustic signature of an unmanned air vehicle exploitation for aircraft localisation and parameter estimation

Higher harmonics in the acoustic spectrogram of an unmanned air vehicle in-flight; as obtained from a ground-based microphone measurement, is shown to be useful for estimating the vehicle's altitude, speed and true engine revolutions per minute. Specifically, the Doppler-shifted frequency time histories derived from spectrogram contours are used in this estimation approach which is based on a least mean square error fit to an Instantaneous frequency model proposed In the literature. Benefits of employing higher harmonics -rather than the fundamental only -in the computations are brought out. The results obtained are satisfactory. A possible system configuration for automatic detection and localisation of similar aircraft is briefly discussed here.