浅海小目标前向散射的非互易时反检测方法

A nonreciprocal time reversal detection method for detecting the forward scattering of the small target in shallow water

将无源非互易时反(NRTR)用于浅海小目标前向散射探测海上实验研究,提出了一种基于频域加权松弛的信道估计算法(WRELAX)和时反方法相结合的小目标探测算法(WRELAX-NRTR)。该算法采用高精度的信道响应估计实现信道的空-时匹配,利用目标引起的时反声场结构的畸变检测前向散射信号对声场的扰动实现目标探测,并通过阈值法实现目标判决。在15~30 kHz的信号频率范围内进行海上实验,数据的处理结果表明,提出的WRELAX-NRTR探测算法与传统的NRTR算法相比,环境背景的扰动幅度从10 dB减小到4 dB,从而降低了虚警率,另外该算法对海洋环境噪声、目标聚焦深度、目标穿越距离和信道动态变化等均具有良好的鲁棒性。

The strong direct wave makes difficulty to detect the forward scattering of the underwater object.The passive NonReciprocity-based Time Reversal(NRTR)technique is used for the forward scattering detection problem in this paper.A Weighted Fourier transform and RELAXation based channel estimation method(WRELAX)is combined with NRTR to improve the detection performance.The detection is achieved by detecting the variations of the acoustic filed caused by the forward scattering,the iterative threshold classifiers is applied to get the detection results.The frequency of the source signal ranges from 15 kHz to 30 kHz in the at-sea experiment.The signals gathered from experiment at sea are processed using the proposed method.Comparing with the classical NRTR detection method,the WRELAX-NRTR detection scheme decrease the background perturbations from 10 dB to 4 dB,the false alarm probability is reduced consequently.In addition,the detection is robust for the underwater noises,different source depth,crossing position and dynamic acoustic channel.