The Study Of Detecting Technology Of Long-distance Remote Control Underwater Acoustic Signal

With the distance of remote control (30~100Km) increasing, the relation between the effectual detection of long-distance remote control and character of channel get more closely, and the signal detection becomes more difficult. In this dissertation, based on the analysis of the time-varying character of underwater acoustic channel, the technology of acoustic signal detection is investigated and improved.The follows are the main contributions in the dissertation.1.The most prominent aspects, the effect of Multipath and time-varying character of underwater acoustic fading channel are analyzed, and the preliminary study is made on the application of time-division and frequency-division collection in underwater acoustic remote control system.2.Based on the fact that the signal after DFT is asymptolic normal distributed in frequency-domain, and the foundation of Constant False-Alarm Ratio (CFAR) detection in frequency-domain is given, then the detection-performance of CFAR and bi-threshold are analyzed, presenting interpolation algorithm of CFAR to overcome the frequency-deviation as to improve detection possibility. The technology of pre-procession and cause of Spectrum Leakage are investigated, and then the method of moving-average under the high sampling is put forward to suppress the high-frequency noise. The feasibility of detecting remote control underwater acoustic signal by High-Order Cumulant is described, and its detection performance is compared with classical Periodogram's, indicating limitation of its slice spectrum in application of detection. The effect of detection from serial and parallel transmitting acoustic signal is studied theoretically.3.Counter-display device is designed for sea test, and its program is debugged to ensure that LED can display the detection result.4.Simulated data and actual data are used to compare the performance of High-Order Cumulant with Periodogram's, and the effect of serial transmitting with parallel's, then effectiveness and reliability of various detection methods are testified.