Vector Hydrophone Array Development and its Associated DOA Estimation Algorithms

Unlike scalar pressure sensors, acoustic vector sensors measure the amplitude and phase of acoustic particle motion in a dedicated direction. An underwater acoustic particle velocity sensor provides significant operational advantages over traditional hydrophones by providing the amplitude and the three dimensional directions of the acoustic signals it senses It can improve performance with a smaller array aperture as compared to the classic scalar hydrophone array. The vector sensor array can estimate the azimuth and elevation angles of the target without left/right ambiguity that occurs in towed array scenario. Within this paper we present an approach to develop a three-axis underwater acoustic vector sensor array and its associated DOA (direction of arrival) estimation algorithm. The physical model of acoustic vector sensor array is introduced and the model is further extended for the implementation rationale with scalar pressure sensing hydrophones. The array performance, especially the array gain of the vector hydrophone array under 3D isotropic ambient noise environment is analyzed as a guideline to develop the vector hydrophone array. A seven-element vector hydrophone array is designed following the theoretical model developed. The characteristics of the vector array proves to be consistent with the theoretical analysis We further introduce the high resolution bearing estimation algorithm of the vector hydrophone array.The vector form M VDR beamforming algorithm is introduced and the performance of the vector hydrophone array and the associated beamforming algorithm are evaluated by an on site trial. The results show that the vector hydrophone array performs well in the estimation of the DOA of both azimuth and elevation of the target.