Investigation on Cancellation of Self noise induced Interference Effects in Passive Towed Array SONAR for Shallow Ocean Operations

Abstract

SONARs employ acoustic waves to detect and localise underwater targets and aid the newlinenaval forces in protecting harbour assets while augmenting constant coastal newlinesurveillance. Towed array sonars are preferred for detecting stealthy underwater targets newlinethat emit faint acoustic signals in the ocean, especially in shallow waters. However, the newlinetowing ship, being near the array, behaves as a loud target, introducing additional newlineinterfering signals to the array and severely affecting the detection and classification of newlinepotential targets by the sonar. Cancelling this underlying interference signal is a newlinechallenging task and is investigated in this work for a shallow ocean operational newlinescenario where the problem is more critical due to the multipath phenomenon. newlineFour schemes were developed for tow ship noise cancellation in shallow ocean newlineenvironments in the context of passive sonar, based on different approaches. The first newlinescheme is a spatio-temporal processing technique combined with subspace analysis. newlineTwo of the mode decomposition techniques are employed on the same problem. A newlinedeep neural network based methodology is also developed for tow ship noise newlinecancellation. newlineThe thesis is organized in seven chapters. newline