浅海低频混响中的杂波特性研究

Ocean reverberation is defined as that portion of the sound received at a hydrophone that is scattered by the ocean boundaries or by volumetric inhomogeneities. Clutter are discrete target-like returns in ocean reverberation. It results from backscattering of abrupt changes in the bathymetric and subbottom features of the ocean, such as seamounts and faults. Clutter field is characterized by a relatively high correlation and high intensity than diffuse reverberation. According to the characteristics of shallow water area around our country, and to meet the need of far range active detection, research on low frequency clutter in non-ideal shallow water waveguide will be carried out in this project. On the base of theory and experiment work of shallow water reverberation in ideal waveguide, the low frequency clutter field expression will be gotten through Helmholtz equation. With further work on boundary condition and sound propagation Green function, low frequency clutter model in non-ideal shallow water waveguide will be proposed. Clutter intensity property, temporal and spatial correlation properties will be focused here. At last, the sea experiment data will be used to validate the clutter models proposed in this project. It is useful and important to understand the mechanism that lead to low frequency clutter in non-ideal shallow water waveguide, not only for designing more robust active signal processing algorithms, but also for realistic modeling required for training and simulation.

混响是海洋环境中粗糙界面和非均匀介质引起反向散射声波的综合，杂波是混响信号中类似目标信号的回波，由声波在空间离散分布的大尺度散射体上发生的反向散射引起，杂波声场时空相干性强，强度显著大于随时间衰减的漫散射混响强度。根据我国周边浅海海域的特点，同时考虑到当前对远程主动探测的需要，本项目拟重点研究复杂地形条件下的浅海低频杂波特性。在理想浅海波导低频混响理论和试验工作的基础上，通过Helmholtz积分方程获得浅海低频杂波声场的表达式，进一步细化海底边界条件和声场传播格林函数，建立海底山、海底断面等典型杂波源在复杂地形条件下引起的浅海低频杂波声场模型，进而研究低频杂波的强度特性和时空相干特性，掌握浅海低频混响中杂波特性的形成机理，并开展浅海低频杂波模型的海上试验验证研究。该项研究可为远程主动探测中的杂波干扰抑制和海战场环境的仿真等提供理论和方法基础。

混响是海洋环境中粗糙界面和非均匀介质引起反向散射声波的综合，杂波是混响信号中类似目标信号的回波，由声波在空间离散分布的大尺度散射体上发生的反向散射引起，杂波声场时空相干性强，强度显著大于随时间衰减的漫散射混响强度。根据我国周边浅海海域的特点，同时考虑到当前对远程主动探测的需要，本项目重点研究了复杂地形条件下的浅海低频杂波特性。在理想浅海波导低频混响理论和试验工作的基础上，通过Helmholtz积分方程获得浅海低频杂波声场的表达式，进一步细化海底边界条件和声场传播格林函数，建立了海底山典型杂波源在复杂地形条件下引起的浅海低频杂波声场模型，进而研究了低频杂波的强度特性和时空相干特性，掌握了浅海低频混响中杂波特性的形成机理，并开展了浅海低频杂波模型的海上试验验证研究。该项研究可为远程主动探测中的杂波干扰抑制和海战场环境的仿真等提供理论和方法基础。