Matched field processing with contrast maximization

The high sidelobe level of the ambiguity surface has been a major drawback of matched field processing in ocean waveguides compared to the free space beamforming. In this paper, a contrast-maximized optimization scheme that enhances the contrast between the acoustic power output of the source region and the power output of the total region of interest is presented. The method utilizes the signal vectors determined from the contrast-maximizing formulation. Through numerical simulation and oceanic data analysis, the presented algorithm is shown to be effective in improving the contrast between the target and the averaged background sidelobe level. It was also shown that, even when the resolution of the source region in conventional matched field processing is degraded due to severe bottom attenuation, the resolution of the source is not affected in the contrast-maximized method. The same principle and method can be applied to the time-reversal processing to maintain the focal size in an ocean environment wi...