掩埋物体的小掠角散射声场与回波信混比

Subcritical scattering field and signal-to-reverberation ratio from buried objects

探测掩埋物体的水声系统,通常是在一定距离之外以小掠角声波扫描海底的方式工作,现有的射线声学模型已不能进行系统性能预报。采用波数积分模型和等效源建模方法,将声波在介质中的传播和掩埋物体的散射场计算融为一体,可以高精度地进行各种形状物体、不同声波束和任意掩埋状态下的三维散射场计算。利用开发的声场模型,计算出了典型球壳的等效目标强度和信号混响比随频率、掠射角及掩埋深度的关系曲线。在此基础上,提出一种基于时反聚焦发射、水下移动平台接收的双基地探测设想,并采用开发的声场模型验证了其正确性。

The underwater system designed for detecting objects buried in sea-bottom often operates at large stand-off distances and insonifies the bottom with subcritical grazing angles. It is impossible to predict the performance with ray models. Combining the wavenumber integration model and virtual source approach, this paper develops a hybrid model, which can calculate the 3D scattering field accurately for buried objects with different shapes, buried status and arbitrary beam-pattern of sources. With the scattering model, the effective target strength and the signal-to-reverberation ratio are calculated for different values of frequency, grazing angle and burial depth. In addition, a bistatic system frame based on time reversal focusing is presented and validated in principle with sound field analysis, which provides a possibility of detecting the buried objects at large distance.