自适应直达波抑制方法在前向散射宽带信号中的应用

Application of the direct blast adaptive suppression method to the forward scattered broadband signals

介绍了前向声散射目标探测的基本原理,并提出了基于自适应滤波的直达波抑制（DBS-AF）方法。将DBS-AF方法扩展到线性调频（LFM）信号中,把信号的包络视为一种广义＂波形＂并输入自适应滤波器。利用该方法分析了湖试数据,并得到了随观测时间变化的检测输出曲线。在曲线上直达波对应了曲线的背景输出而目标引起的接收声场畸变则对应了曲线的峰值起伏。单个通道的直达波抑制效果可以达到-5 dB左右;引入去均值化预处理能够增强直达波抑制效果,再利用多通道的接收信息,直达波被抑制到-10 dB以下。影响算法性能的主要因素是训练权值时段内接收信号的起伏和信直比。

Basic principles of target detection upon forward acoustic scattering are presented. An approach of direct blast suppression （DBS-AF） based on adaptive filtering is proposed to suppress the direct blast. The DBS-AF is extended to the linear frequency modulation （LFM） signal, where the envelope of the signal is regarded as a ＂general waveform＂ and then imported into the adaptive filter. Applying the DBS-AF method to the data collected from a lake trial yields an output detection curve, in which the direct blast is mapped to the background while the acoustic field aberration is represented by the peak-value fluctuation. The inhibitory effect on single channel is about -5 dB, which is then enhanced by exploiting the mean-value removal approach as a preprocessing technique. The direct blast is further suppressed to a level of -10 dB by making full use of multi-channel receptions. The main factors affecting the performance of the algorithm are： the fluctuation degree of the receptions during the weighting vector training period and the ratio of the forward scattered signal power to that of the direct blast when the target is present.