Modeling of active reverberation by time delay estimation

This paper explores the statistical properties of underwater reverberation present in active sonar systems. The interference to signal processing which results from reverberation can be extensive, and is particularly acute when the boundaries (surface, bottom) of the water column are nearby. Of particular interest are situations where there may be weak targets masked by reverberation dominating the returning signal. The reverberation is represented as the output of a linear system with the transmitted signal as an input. The random nature of the reverberation is accounted for by using random parameters in the linear model, the most important of which are those parameters impacting the spatial distribution of the reverberation. Time delay estimation is used to analyze reverberant signals obtained from a sonar system operating in a shallow water environment. The statistics of the linear models obtained from these analyses are computed and discussed.