Reduced variance distortionless response (RVDR) performance with signal mismatch

Matched field processing of underwater acoustic fields frequently involves considerable mismatch between the actual received signal and the model of the complicated propagation from various possible source locations to the receiving array. This leads to significant signal suppression in the MVDR (minimum variance distortionless response) processor. The high sidelobes of the conventional processor make it unsatisfactory. The authors examine the effectiveness of modifying the diagonal of the spatial correlation matrix. Performance in the face of mismatch is quantified. A simple parametric relationship between MUSIC, MVDR, and conventional beamforming is developed. An important feature of the proposed GDR (generalized distortionless response) approach is that the weights may be used in beamformers to produce beam output time series and are not limited to direction estimation