Direction-finding of coherent sources via ´particle-velocity-field smoothing´

A new ´particle-velocity-field smoothing´ (PVFS) algorithm is proposed to decorrelate up to three coherent sources for azimuth-elevation direction-finding using vector-hydrophones in the underwater acoustic medium. The coherency among the incident sources would reduce the data correlation matrix´s rank to below the number of incident sources, but this proposed algorithm restores the rank by summing the individual particle-velocity-field component´s data correlation matrices. This scheme uses identically oriented underwater-acoustic vector-hydrophones, its locations may be arbitrary. Each underwater-acoustic vector-hydrophone consists of two or three collocated but orthogonally oriented velocity-hydrophones, and a pressure-hydrophone. In contrast to the customary ´spatial smoothing´ technique, this proposed PVFS algorithm does not reduce the array´s spatial aperture and does not require any ´virtual array interpolation´ even for an irregularly shaped array grid. Monte Carlo simulations verify this proposed scheme´s efficacy.