浅海单模入射声场目标回波特性研究

浅海环境中,目标回波受到入射和散射双向过程的信道多途影响,具有复杂的多途结构。基于相控垂直阵的单模发射技术能激发出指定的单个简正波声场,可以降低海底混响干扰,简化目标回波多途结构,为主动探测提供了一种有效手段。在信道中点声源目标回波模型基础上,采用简正波本征函数加权研究了单模声场入射下球形目标散射问题,建立了浅海单模入射声场目标回波预报模型,并利用模型对刚性球回波进行了数值计算。结果表明:总声源级相同条件下,单模发射声场与传统的点声源发射声场相比具有一定的阵发射增益,目标回波具有较高的声压级;单模入射能够消除单程多途的影响,回波结构相对简单,有利于目标的探测和识别。

Research on target echo characteristics ensonified by a single mode in shallow water

In shallow water, target echo has complex structure as a result of multipath propagation on incidence and scattering journey. Based on vertical phased linear array, single mode excitation technique can produce desired field composed of a single mode, suppress reverberation, simplify echo structure and provide an effective way of active detection. In this paper, based on target echo model ensonified by a point source, the array weighting method according to normal-mode eigenfunctions is applied to studying target scattering problem. Target echo prediction model ensonified by a single mode in shallow water has been built to analyze target echo characteristics. The results of using the model to calculate a certain sphere object''s echo numerically show that the target echo ensonified by a single mode has greater intensity comparing with the situation that target is ensonified by a point source; the single mode excitation technique can eliminate multipath interference on incidence journey, so target echo structure is straightforward relatively and favorable for target detection and identification.