当物体位于双基地声纳的收发连线附近时，由于散射信号在时频空域上受直达波的强干扰，导致常规的双基地声纳处理方法失效。然而，此时目标的前向散射信号强度比反向散射信号强度可高出20dB以上，若能够实现对直达波的抑制，就能充分利用前向散射的优势，实现对水下目标远程探测。因此，本课题拟重点研究前向散射探测中的直达波抑制技术。.本课题通过失配滤波器设计和时频分析等，深化水声信道中直达波和前向散射信号的响应特征，以此为基础，研究直达波信道响应相消和垂直阵上信道响应相关输出的直达波置零处理方法，以及基于信道中声场距离-频率相干特征的直达波广义空域滤波方法等，在抑制直达波的同时保持前向散射信号不变，最终突破水下目标前向散射远距离探测中的直达波抑制难题，为提高前向散射探测能力奠定必要的理论和方法基础。

When objects are penetrated into the source-receiver line of bistatic sonar, the forward scattering signal is interference with strong direct blast in this situation. It’s not easily detected using the traditional processing technologies for bistatic sonar. However, the scattering signal strength from forward direction is about 20dB above the backward scattering signal. If the direct blast is well suppressed, the advantage of forward scattering would be exploited fully, and the performance of underwater detection would be elevated. Hence, the direct blast suppression technologies will be investigated..In this project, the pulse compression with mismatched filter will be researched and time frequency analysis will be utilized for the waveguide response acquisitions of the direct blast and forward scattering signal. Hence, the cancelling method with the stable waveguide impulse response of direct blast, and the method with the direct blast set to be zero after the coherent processing will be researched to suppress the direct blast. The generalized spatial filtering combined with range-frequency interference pattern will also be proposed for direct blast suppression. The forward scattering signal is kept and the direct blast is suppressed. The key problems for direct blast suppression for forward scattering will be solved. These results will provide some significant theories and methods for real application.