浅海近程混响的振荡现象*

研究浅海近程混响特性对于评估和提高主动声纳性能具有重要意义。多次浅海混响实验显示,近程混响强度存在稳定的振荡现象,脉宽基本对振荡的幅度和周期没有影响。为解释这一现象,本文基于射线理论和小斜率近似给出了浅海近程混响模型,仿真与实测数据结果基本吻合。数值仿真结果表明：海底反射声场对单站声纳接收到回声信号的贡献远小于海底近垂向大掠射角散射声场的作用；混响强度振荡现象是海底近程散射声场的多途现象造成的,并由此给出了振荡周期与海深及收发深度的关系。

Fluctuation of short-rang reverberation in shallow water

Short-rang reverberation in shallow water has an important impact on estimation and improvement of sonar performance. Previous reverberation trials in shallow water suggest that short-range reverberation exhibits a stable fluctuation phenomenon, and pulse lengths nearly have no effect on amplitude and period of fluctuation. To illustrate characteristics of short-range reverberation in shallow water, a reverberation model is proposed based on ray theory and small-slope approximation. Simulation results show in good agreement with experimental data. The results indicate that the reflecting energy from bottom is far less than the scattering energy at large grazing angle from roughness bottom interface for monostatic sonar. Moreover, fluctuation phenomenon of reverberation intensity is caused by time delay of bottom scattering energy from different rays in short range. Accordingly, relationship between period of fluctuation and depth of water, source or receiver can be determined.