Iterative adaptive approach to DOA estimation with acoustic vector sensors

Acoustic Vector Sensors are underwater sensors that measure acoustic pressure as well as the acoustic particle velocity to estimate the acoustic intensity. The acoustic intensity, which is a vector quantity, represents the magnitude and direction of the active or propagating part of an acoustic field thus indicating the DOA(Direction of arrival) of a received signal. This paper dwells on an Iterative Adaptive Approach(IAA) for DOA and signal power estimation of underwater acoustic emissions, using a single vector sensor, which is of significance in several passive surveillance applications. The proposed IAA algorithms are robust in resolving partially correlated or coherent sources which is a known phenomenon in shallow water conditions due to multi-path. It has been observed that in case of a single vector sensor, the proposed IAA Amplitude and Phase Estimation Scheme(IAA-APES) performs better than a standard Capon beamformer even in the presence of correlated/coherent sources, the performance being measured in terms of Mean Square Angular Error (MSAE). Also another version of IAA, namely the Iterative Adaptive Approach - Maximum Likelihood (IAA-ML) estimation provides better resolution than all the other schemes.