Modeling Of Underwater Distributed Target Based On FDTD And DOA Estimation

The study of underwater distributed targets is a very important issue. For distributed source, thetarget modeling method and parameter estimation algorithms based on ideal point source were nolonger trusted. In this paper, a new modeling method based on FDTD for underwater distributedsource has been proposed. The new method simplified the numerical calculation of underwateracoustic scattering field and it is suitable for underwater complex distributed target.The major work and innovation in this paper are concluded as follows:(1) Introduce a simplified model of distributed source—multi-highlights target model, andanalyze the acoustic axis distribution and the time domain waveform of the scattered echo of amulti-highlights target.(2) Introduce the classic CBF method and a decorrelation method based on Toeplitz matrixapproximation, and estimate the characteristic parameters of the multi-highlights target. Analyze thespace similarly of the target echo power spectrum, and a new method of underwater target scalerecognition based on space similarly is proposed.(3) Derivate the FDTD consistency expression in the3-D space, and derivate the FDTDrecursive equations and its matrix expressions for numerical calculation of underwater target acousticfield. A new modeling method for underwater distributed source is proposed, and simulate acousticscattering field of underwater2-D targets and3-D targets.(4) Studye on several DOA estimation methods of distributed source, including the DSPEmethod, the TLS_ESPRIT method, and a low-complexity parameter estimation method for3-D CDsources. Estimate the characteristic parameters of the2-D and3-D underwater distributed source andanalyze the RMSE of the estimation results, and a new target recognition method is proposed basedon the space features characteristic of underwater distributed source.