多输入多输出与时反联合的波导声呐有源目标定位

为了提高对浅海静止小目标的探测能力,提出了将多输入多输出和时反处理相结合的波导声呐处理框架。利用收发合置垂直阵,假设目标为点目标,每一个阵元轮流时反发射正交信号照射目标,整个阵接收对应的目标回波。当所有的阵元发射正交信号结束以后,对所有接收的目标回波数据进行分集处理,然后与时反发射驾驶向量做匹配滤波完成对目标的定位。分时发射策略克服了水声信道时延扩展和多普勒扩展导致常规多输入多输出处理接收端不同回波信号分离的困难。采用物理时反发射和数值时反接收聚焦,有助于抑制混响、提高回混比。数值仿真和波导水池实验结果表明多输入多输出时反处理较常规的有源匹配场处理以更高的精度对波导中的目标进行定位。 

Mutiple input mutiple output combined with time reversal for waveguide sonar active target localization

For improvement of detection of a small static target in shallow water environments,a waveguide sonar processing scheme is proposed based on combination of MIMO(Multiple Input Multiple Output) and TRP(Time Reversal Processing).With a point target assumption,each element of a co-located transmit-receive vertical array time-reversal transmits one of orthogonal signals to illuminate a target in turn.And the whole array is used to receive target echoes.After all orthogonal signals are transmitted,a diversity algorithm is carried out over the received data to localize a target by matched filtering the replica of the steering vector for time reversal transmission.The time-division transmission strategy is to overcome the difficulty of separation of different target echoes at receiving end in conventional MIMO processing due to time-delay spread and Doppler spread of underwater acoustic channels.Echo-to-reverberation ratio is enhanced by physical time reversal transmission and numerical time reversal reception focusing resulting in suppressing reverberation.Numerical simulations and the waveguide tank experimental results have shown that the MIMO-TR processing can localize a target in a waveguide with a higher precision than the conventional active matched field processing.