Abstract: The eanalysis of target motion in near field is difficult when the space of measurement platform is limited. A novel underwater target motion analysis (TMA) method is proposed based on the multipath structure of the ray acoustics in shallow water, A three-dimensional multipath time delay model of target in uniform speed rectilinear movement is established. The nonlinear function expression of time delay between direct sound and surface reflected sound is derived by taking the movement parameter as a variable. Based on the characteristics of typical underwater acoustic channel, the expression of channel in cepstrum domain is achieved. Then the time delay between direct sound and surface reflected sound is estimated by the homomorphic filtering technique with the ability of deconvolution.The optimal solution of the nonlinear equation is solved by combining with Levenberg-Marquardt method. The quadratic approximation correction method is proposed to decrease the influence of actual hydrological condition on parameter estimation. The simulation results show that the proposed method is practicable, and the estimation precision meets the demand of practical application.

Key words: acoustics, homomorphic filtering, multipath time delay model, cepstrum, quadratic approximation, target motion analysis