Frequency Characteristics Analysis of Shallow Water Acoustic Channel for UUV Sonar

To improve the detection performance of underwater unmanned vehicle (UUV) sonar, the frequency charac-teristics of shallow water acoustic channel is analyzed. Shallow water acoustic channel is more complex than blue water acoustic channel. Due to multipath effect and reverberation, the propagation of acoustic wave is often deformed, result-ing in degradation in signal detection performance of sonar. The frequency characteristics of underwater acoustic chan-nel are analyzed with the data from tank experiment, lake and sea trials. Tank experiment shows the spread of signal frequency spectrum due to multipath effect. The data from lake and sea trials show that for the high-speed active sonar, the short-range reverberation is highly non-stationary, and the spread of point spectrum becomes more obvious. But the Doppler spread decreases with time. Therefore, the reverberation model algorithm based on stationarity assumption cannot be used to suppress the underwater vehicle sonar reverberation.