水声信号频率对时间反转探测性能的影响

Effect of Underwater Acoustic Signal Frequency on Performance of Time Reversal Detection

针对在复杂多途浅海环境下对弱目标进行探测这一水声探测领域的研究热点,时间反转(TR)技术拥有广泛的应用前景。基于前人研究,可知利用被动时间反转(PTR)和阵列信号处理(ASP)技术相结合可以进一步提高对弱目标的检测和定位的性能。但在复杂多途浅海环境下,当信号脉宽大于门限脉宽时, TR聚焦的主峰和旁峰会产生混叠,从而导致聚焦峰能量的改变。根据以上现象,文章推导出了PTR信噪比处理增益与声源信号频率的关系,并得到结论:由于TR处理不能完全消除多径效应带来的时延扩展(镜反射之外的声线叠加),对于同一PTR检测系统,其检测性能和定位性能不仅与估计信道适配程度有关,还与声源信号的时域特性(信号频率、脉宽)相关。这一研究结果对TR通信、TR检测,尤其是信源或声源为长脉宽窄带信号的工程应用有一定参考价值。

How to detect weak targets in complex multi-path shallow sea environment has become a research hotspot in the field of underwater sound detection,in which the time reversal(TR)has broad applications.According to literature,the combination of passive time-reversal(PTR)and array signal processing(ASP)can improve the performance of the weak target detection and positioning.In complex multi-path shallow sea environment,the main peak and the side peak of TR focusing overlap when the signal pulse width is greater than the threshold.Therefore,the overlapping could have a great impact on the power of focusing peak.According to these phenomena,this paper derives the relationship between the processing gain of PTR signal-to-noise ratio and the signal frequency,and reaches a conclusion that since TR processing cannot completely avoid delay spread(overlapping of sound line beyond mirror reflection),as for the same PTR detection system,its performance of detection and positioning relates to both the matching of estimated signal channel and the features(frequency and pulse width)of sound source in time domain.This study may provide a reference for TR communication and TR detection,especially for the case where information source or sound source is the signal with large pulse-width and narrow band.