Near-field/far-field azimuth and elevation angle estimation using a singlevector hydrophone

This paper introduces a new underwater acoustic eigenstructure ESPRIT-based algorithm that yields closed-form direction-of-arrival (DOA) estimates usi ng a single vector hydrophone. A vector hydrophone is composed of two or th ree spatially co-located but orthogonally oriented velocity hydrophones plu s another optional co-located pressure hydrophone. This direction finding a lgorithm may (under most circumstances) resolve up to four uncorrelated mon ochromatic sources impinging from the near field or the far field, but it a ssumes that all signal frequencies are distinct. It requires no a priori kn owledge of the signals' frequencies, suffers no frequency-DOA ambiguity, an d pairs automatically the x-axis direction cosines with the y-axis directio n cosines. It significantly outperforms an array of spatially displaced pre ssure hydrophones of comparable array-manifold size and computational load but may involve more complex hardware. This work also derives new Cramer-Ra o bounds (CRBs) for various vector hydrophone constructions of arrival angl e estimates for the incident uncorrelated sinusoidal signals corrupted by s patio-temporally correlated additive noise.