【Title】Studies on techniques of non-Rayleigh oceanic reverberation suppression

【Author】XU Yanwei~1 ZHANG Chunhua~1 CAI Huizhi~2 LIU Yuntao~1 WANG Yongfeng~1 (1 Institute of Acoustics, Chinese Academy of Sciences Beijing 100190) (2 Beijing Zhongke Haixun Technology Co.,Ltd. Beijing 100095)

【Abstract】The sonar systems which work in shallow water environment suffer greatly from influences of oceanic noises,acoustic propagation seesaw and multipath.With shallow water environment and higher range-bearing resolution of sonar systems,there are not enough independent scatterers within a resolution cell for the central limit theorem to hold.The reverberation envelope probability density function(pdf) diverges from Rayleigh pdf.The non-Rayleigh pdf with heavier tails is complicated,and it is difficult to estimate the function parameters accurately in real time.With CFAR(Constant False Alarm Rate) processing of the reverberation envelope data,which attenuates the heavier tails data values to the estimated background power values,the data reverberation is transformed from non-Rayleigh distribution to approximately Rayleigh distribution.Since it gets rid of the interferences which affect the estimation of background power,the detector can estimate the oceanic background power level more accurately.With the rational estimation of background power level,the CFAR detection capability is better and robust.With processing of high resolution sonar data,it is shown that the proposed algorithm is efficient.