Source localization results for airborne acoustic platforms

Acoustic sensors are being employed on airborne platforms for source localization. Under certain atmospheric conditions, airborne sensors offer a distinct advantage over ground sensors. Among other factors, the performance of airborne sensors is affected by refraction of sound signals due to vertical gradients in temperature and wind velocity. A comprehensive experiment in source localization with an aerostat-mounted acoustic system was carried out in July 2010 at Yuma Proving Ground (YPG). Acoustic sources on the ground consisted of one-pound TNT denotations and small arms firings. The height of the aerostat was approximately 1 km above the ground. In this paper, horizontal, azimuthal, and elevation errors in source localization and their statistics are studied in detail. Initially, straight-line propagation is assumed; then refraction corrections are introduced to improve source localization and decrease the errors. The corrections are based on a recently developed theory [Ostashev et al., J. Acoust. Soc. Am. (2008)] that accounts for sound refraction due to vertical profiles of temperature and wind velocity. During the 2010 YPG field test, the vertical profiles were measured only up to a height of approximately 100 m. Therefore, the European Center for Medium-range Weather Forecasts (ECMWF) is used to generate the profiles for July of 2010.