Statistical normalization of non-Rayleigh reverberation

D.A. Abraham
Oceans '97. MTS/IEEE Conference Proceedings  
Low-frequency active sonar systems operating in shallow water are primarily limited by reverberation. Reverberation is traditionally assumed to follow a Rayleigh probability distribution, from which the detector and other signal processing algorithms are developed. Experimental studies have shown that reverberation can be non-Rayleigh distributed with varying statistical character over range and bearing. In such a situation, detectors designed under a Rayleigh assumption will exhibit increased
more » ... exhibit increased and varying false alarm performance. This report develops a technique for dealing with the unknown and varying reverberation statistics by using a non-Rayleigh reverberation model to perform a statistical normalization of the background reverberation. In this manner, range-bearing images will be produced that have a constant background reverberation distribution (i.e., Rayleigh). The technique is evaluated through simulation, with particular attention to the false alarm performance, which is seen to depend on the severity of the non-Rayleighness of the reverberation and the amount of data used to estimate the parameters of the reverberation model. Application to real data has shown that a large degree of the non-stationarity of the range-bearing image can be removed by statistical normalization. Keywords: non-Rayleigh o reverberation o constant false alarm rate o normalization SACLANTCEN SR-303 References 46 Annex A -Target models in Rayleigh mixture reverberation 49 Annex B -Derivation of the EM parameter estimates for a Rayleigh mixture 51 Annex C -Mean and variance of T m 53 Annex D -Invariance of false alarm performance in Weibull reverberation using ML parameter estimates 58
doi:10.1109/oceans.1997.634415 fatcat:lnqoofrkqbekjmwjulnj4od5dq