浅海沉底小目标时的反探测研究

在浅水波导环境下,时反处理利用声场的时反聚焦特性,基于收发合置阵,将接收信号在时间上反转后,再向介质中发射回去,时反信号能量会在目标处聚焦,同时使混响降低.在接收增强的目标回波信号之后,通过多路径补偿波束形成,继续提高信混比.再将波束形成的输出与发射信号的拷贝进行相关处理,以其输出作为检验统计量进行目标检测判决,并根据到达信号的时间延迟对目标行距离进行估计.在湖上实验中,通过比较BS发射和TR发射两种情况下的混响和目标处的入射能量,发现时反处理具有抑制混响、提高信混比的能力.在实验室波导中,利用时反处理的优点进行了沉底小目标探测实验.波导实验结果表明,主动时反探测系统不仅能够有效地检测到沉底小目标,而且可以对目标进行测距.

Time reversal detection of small bottom object in oceanic shallow water

In the shallow water waveguide environment, time reversal (TR) processing based on the co-located receive and transmit array time-reversed the received signal and sent it back to the medium. The time reversal signal energy was focused on the target and reverberation was reduced. The signal-to-reverberation ratio was further improved by multipath compensation beamforming after the enhanced target echo signal was received. The beamforming output was correlated with a replica of the transmitted signal, the result of which was used to be test statistic for target detection. The time delay of signal arrival was used for target range estimation. In a lake experiment, the reverberation and focusing energy on target were compared between broad side (BS)and TR transmitting, and the result of which showed that time reversal processing had the ability of suppressing reverberation and enhancing the signal-to-reverberation ratio. In a lab waveguide, the advantage of time reversal processing was taken to detect a small bottom object. The lab waveguide experimental result showed that an active time reversal detection system not only can effectively detect a small bottom object but also measure the target range．