Orthogonal velocity-hydrophone ESPRIT for sonar source localization

This paper proposes a novel eigenstructure ESPRIT-based azimuth-elevation direction finding (DF) algorithm that yields closed-form estimates of multiple near-field or far-field sources' directions-of-arrival (DOA) by exploiting DOA information embedded in the sources' velocity-field, requires no a priori knowledge of signal frequencies, suffers no frequency-DOA ambiguity, automatically pairs the x-axis direction-cosines with the y-axis direction-cosines, greatly reduces hardware and computational costs, eliminates array inter-element calibration, but uses only three velocity-hydrophones (plus an optional pressure-hydrophone) and two time-delayed data sets. Velocity-hydrophone technology is well-established in the field of underwater acoustics and its inherent directionality allows it to measure separately the three Cartesian components of the incident sonar velocity-field. In one particular scenario with two closely spaced uncorrelated narrowband sources, the proposed algorithm offers a 67% savings in hydrophone hardware and 56% savings in computational costs over an array of spatially displaced pressure-hydrophones producing the same estimation performance. In another scenario where the hardware and computational costs are comparable between the proposed algorithm and the customary array of spatially displaced pressure-hydrophones, the proposed algorithm offers a 10 dB SNR advantage.