用于浅海有源声呐目标深度估计的匹配相位处理

Matched phase processing for active target depth estimation in shallow water

针对浅海波导中有源声呐目标深度估计问题,提出了通过单个声源发射低频宽带信号,垂直双接收水听器接收目标回波,利用宽带目标回波比值的相位特征进行匹配相位处理的方法,不仅消除了目标散射特性对有源声呐目标深度估计的影响,而且仅需计算单程的信道传递函数,运算量小,有利于实时处理的实现需求。首先通过理论推导,定义了一个隐含目标深度、且与目标散射特性无关的声场特征——单程传播向量宽带干涉结构,在Pekeris波导条件下仿真分析了简正波阶数与单程传播向量宽带干涉结构的幅度和相位的关系,发现选取较多的简正波阶数贡献的单程传播向量宽带干涉结构进行匹配相位处理可以提高目标深度估计的性能。进一步仿真分析表明,在发射信号选取一定的时间长度和带宽的条件下,利用全部阶简正波且信噪比大于-10 dB时,方法的深度估计误差在5 m之内。最后分析了信号时间长度和处理带宽对有源声呐目标深度估计性能的影响,以及海底声速、海深和声速剖面失配时方法的鲁棒性。

Aiming at active target depth estimation in shallow sea,a single sound source is used to transmit lowfrequency broadband signals,vertical dual receiving hydrophones receive target echoes,and the phase characteristics of the broadband target echo ratio are used for matched phase processing.The method not only eliminates the influence of the target scattering characteristics on the depth estimation of the active target,but also only needs to calculate the one-way sound field,and the calculation amount is small,which is conducive to the realization of real-time processing requirements.At First,through theoretical derivation,a sound field feature with implicit target depth and independent of target scattering characteristics—one-way propagation vector broadband interference structure is defined.The relationship between the order of the normal wave and its amplitude and phase is simulated and analyzed under the condition of Pekeris waveguide,and it is found that selecting more one-way propagation vector broadband interference structures contributed by the order of the normal mode can improve the performance of active target depth estimation.Furthermore,the simulations show that under the condition that the transmitted signal selects a certain time length and bandwidth,the mean error of active target depth estimation is less than 5 meters when all orders of normal mode are used and the signal-to-noise ratio is greater than-10 dB.Finally,the influence of signal time length and bandwidth on active target depth estimation performance,and the method’s robustness in case of bottom sound velocity,sea depth and sound velocity profiles mismatch are analyzed.