Sound ranging of impulsive sources in air

Abstract

A passive sound ranging method based on wavefront curvature is described where the impulsive sound of a rifle firing is received at three spatially separated collinear sensors. Estimating the differential time-of-arrival (or relative time delay) of the acoustic wavefront at each pair of adjacent sensors enables the range and bearing of the source to be estimated. The temporal variability in the polar coordinates of the source is presented for real data and the system errors affecting the accuracy of the measurements are discussed. The time delay estimation technique is then applied to the passive ranging of an impulsive sound source located in the far field, where the wavefront curvature technique is no longer appropriate as the arriving wavefront is planar. For the plane-wave arrival case, the range of the sound source is estimated from the angle-of-arrival estimates at two widely spaced known locations. The source position estimated by the acoustic method is compared with the source position determined by standard surveying methods. The nonstationary behavior of the sound propagation medium leads to variability in the source localization parameters which is presented for the acoustic data collected during artillery firings.