浅海声场时频特性与warping变换方法应用研究

The investigation of dispersion phenomena of broadband sound pulse propagation in shallow water is an important topic in underwater acoustics. Recently, a new time-frequency analysis method, Warping transform method, is used to improve the resolution of the time-frequency distribution of the measured acoustic data. And such refined knowledge of time-frequency distribution facilitates efforts to extract environmental parameters or target parameters estimation. According to the ocean environmental characteristics in our country, the waveguide dispersion characteristics in shallow water and application of warping transform method will be researched in this project, in order to apply this method to the case of modal propagation in a range-dependent shallow water environment. First, the adiabatic approximation normal mode method is used to build the theoretical model of normal mode group speed in weak range-dependent environment and predict the received acoustic vector signal temporal waveform for low frequency pulse signal in the waveguide. Second, the waveguide dispersion characteristics and the ability of the normal mode separation for warping transform method will be researched by numerical simulation and some optimal algorithm for warping transform will be established. Then, the new warping transform algorithm will be applied to extract the time-frequency distribution characteristic parameters for the sound pressure signals and particle velocity signals in the shallow water. And signal processing algorithms will be researched for target localization and ocean environmental parameters inversion. Experimental research will also be done in this project to validate the theoretical research and check the performance for different signal processing algorithms. The research of this project will be particularly emphasized to deal with acoustic vector field signal and explore new underwater acoustic signal processing method.

宽带声信号在水声波导中的频散现象是水声领域的一个重点研究课题。近来一种新的信号时频分析方法，warping变换方法，被用来提高水声信号时频分析的分辨力。提高信号时频分析中的分辨能力，将有助于提取信号中所包含的环境或目标参数信息。本项目将结合我国近海水声环境的特点，对浅海水声波导频散特性和warping变换应用方法进行深入研究，以将其推广到非水平分层介质浅海环境中。研究首先依据绝热简正波理论建立波导简正波群速度模型和低频声矢量场信号波形预报算法；其次对波导频散特性和warping变换的简正波分离能力进行仿真研究，并尝试建立优化的warping变换算法；然后在有效提取声压与质点振速信号时频特征参数的基础上，构造水中目标定位和环境参数反演的有效算法；此外，项目还将通过实验研究对理论模型和信号处理算法进行检验。项目研究将侧重于对声矢量信号的处理分析和信号处理新原理、新方法的探索。

研究浅海波导中宽带声信号的频散特性以及warping变换在分析频散特性中的应用对水下目标探测、海洋环境信息获取、海洋哺乳动物被动监测等方面具有重要意义，是水声领域的一个重点研究课题。.根据项目任务书的要求，课题组在项目执行期间建立了浅海环境下简正波宽带低频声信号频散特性理论模型以及浅海环境下声压和质点振速的时域波形预报模型；分析了浅海波导的频散特性；优化了浅海水声波导中宽带声信号频散特性的分析方法；研究了适用于实际浅海水声信道的warping变换算法以及基于warping变换的浅海波导中海洋环境参数反演算法和水下目标定位算法；总结了基于浅海波导频散特性的warping变换应用；进行了相关的海上测量实验并实现了实验数据的采集和分析处理；此外还成功地将浅海波导宽带声传播的频散特性的一般规律应用于测距、定位和反演等水声技术中，提出了两种单水听器被动测距技术和一种高分辨功率谱估计方法。此外，本课题不仅对具有半无限海底的浅海波导进行了研究，还分析了具有沉积层的弹性体海底的简正波的耦合问题以及三维抛物方程的求解问题；混响噪声场的相关性频散问题也进行了分析，促进了项目研究成果的转化应用。课题组全面完成了研究目标，相关研究成果为远距离海洋环境参数的获取和水中目标定位提供了理论支持并实现了成果转化应用。