JDP_V3_N3_RP1 M. Rajeswari S. Koteswara Rao Journal on Digital Signal Processing 2322–0368 3 3 1 6 Optimum Detector, Background-Noise-Limited, FFT Based Implementation One of the most important problems in many application areas is to extract the signal of interest from background noise. In background noise, the occurrence of signal and the behaviour of signal are random. Therefore, it is reasonable to deal with the signal extraction problem using methods based on probability theory and statistical estimation. That is to say that signal detection and parameter estimation problems are statistical hypothesis testing problems in mathematical statistics. In this paper, we examine signal and noise environments encountered in active sonar using CW and LFM pulses. The optimum receiver is presented for range-Doppler-shift processing in a background-noise-limited environment. FFT based implementation for detection of CW and LFM active sonar target has been shown here. By following this method both range and Doppler resolution can be achieved. July - September 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=3589