Use of Signal and Ambient Noise Coherence to Optimize Sonar System Performance

Abstract

Abstract : Acoustic transmission measurements from the 1996 ONR summer Shelfbreak PRIMER exercise [1] have shown that both acoustic signal and noise intensity levels exhibit fluctuations on the order of 20 dB, primarily due to the temporal variability of the local shallow water environment. During this on-going project, our first goal has been to relate the fluctuations in the signal and noise intensity levels, and their correlations to the relevant oceanographic features such as internal solitary waves and/or tides, shelf-break fronts, internal surface ducting, etc. Our analysis of the PRIMER data set has shown that there can be correlation between the signal and noise intensity fluctuations, and also between these fluctuations and the internal wave and tidal cycle fluctuations in the water column. Next, we plan to demonstrate that these correlations are significant in other important littoral regions. Our final goal is to develop practical methods of optimizing sonar system performance by exploiting these correlations.