Performance Bounds on Atmospheric Acoustic Sensor Arrays Operating in a Turbulent Medium. 1. Plane-Wave Analysis

The performance bounds of an atmospheric acoustic array operating in a turbulent medium with fluctuations described by a von Karman spectrum are investigated. This treatment considers a single monochromatic source and a line- of-sight propagation path. The primary interests are in calculating the Cramer- Rao lower bounds (CRLBs) of the azimuthal and zenith angles of arrival (AOAs) and in observing how these bounds change with the introduction of additional unknowns, such as the normalized propagation distance (to wavelength), turbulence parameters, and signal-to-noise ratio (SNR). In both two and three dimensions, the CRLBs of the AOAs increase significantly for large values of the index-of-refraction variance and normalized propagation distance. For small values of the index-of-refraction variance and normalized propagation distance, the SNR is the limiting factor. For the two-dimensional treatment, the estimate of the AOA will decouple from the estimates of the other parameters with the appropriate choice of array geometry. In three dimensions, again with an appropriate choice of array geometry, the estimates of the azimuth and zenith will decouple from the estimates of the other parameters, but because of the constraints of the turbulence model, they will remain coupled to one another.Army Research Lab Adelphi Computational and Information Sciences Directorate is the author of 'Performance Bounds on Atmospheric Acoustic Sensor Arrays Operating in a Turbulent Medium. 1. Plane-Wave Analysis' with ISBN 9781423549499 and ISBN 142354949X.