深海海底声反射区多途时延差分析与近海面声源定位

Analysis of multipath time delay difference in deep ocean bottom bounce area and its application in near-surface target location

深海海底反射声工作方式下的声场主要由4条一次海底反射声线路径构成。根据4条声线路径到达接收点的时间不同,可以得到6个不同的声线到达时延差值,当声源位于近海面时,6条声线路径的时延差曲线随接收深度近似呈线性变化。本文基于虚源理论推导了海底声反射区的多途到达时延结构,给出了6条声线路径的时延差曲线随接收深度变化的近似表达式,通过分析时延差曲线与声源水平距离和深度之间的关系,提出了一种利用多途时延差估计深海海底声反射区近海面声源距离与深度的方法,仿真实验与影响因素分析验证了该原理的正确性。南海实验结果表明,当收发距离在10~33 km时,距离估计结果和深度估计结果都同实际声源距离和深度吻合较好,估计误差不超过15%,验证了该方法的有效性。

The bottom bounce areas in the first shadow zone in deep ocean are mostly contributed by four eigenrays including bottom-reflected path,surface-bottom-reflected path,bottom-surface-reflected path and surface-bottom-surface-reflected path,all of which arrive at different time with different time delay.On the basis of the time delay of four eigenrays,six arrival delay differences in deep ocean bottom bounce area can be obtained.As for a near-surface target source in deep ocean,six delay difference curves of eigenrays change approximately linearly with receiving depth.In this paper,the multipath arrival time delay structure of the bottom bounce areas in deep ocean is derived by the virtual source theory,and the approximate formulae of the time delay difference curves varying with the receiving depth are deduced.By analyzing the relationship between the time delay curves and the source range and depth,a method for source ranging and depth estimation in deep ocean bottom bounce area is proposed.The approach is demonstrated valid by the simulated data.Experimental results in the South China Sea show that when the transmitting and receiving distance is between 10 km and 30 km,the range and depth estimation results are in good agreement with the actual explosion range and depth,and the estimation error is less than 12%,which verifies the effectiveness of this method.