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

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.