【Title】An echo detection algorithm for underwater continuous wave active detection(2014 No.1) 

【Author】 LIU Dali;LIUYuntao;CAIHuizhi; 

【Abstract】 The model of linear frequency modulation continuous wave(LFMCW)applied in underwater detection and the method for the detection of echo signal and the estimation of target parameters were studied.By analyzing the heterodyne signal,an algorithm with the structure of heterodyne-Fractional Fourier Transform (FRFT)was proposed. To reduce the computation of searching targets in a two-dimensional FRFT result. the heterodyne signal would be processed by FRFT at a specific order,after Radon-Ambiguity Transform(RAT)was applied toccstimate the sweep rate of the signal. Simulations proved that the algorithm can eliminate the coupling phenomenon of distance and velocity of LFMCW, and estimate targets’ parameters accurately. The lake trial results showed that the processing gain of LFMCW processed by the algorithm in this paper was 13 dB better than that of the LFM processed by matched filter. The research results indicated that the algorithm applied in LFMCW underwater detection was feasible and effective, and it could estimate targets’ parameters accurately and obtain a good detection performance.