Remote Underwater Acoustic Remote Control System Based On Spread Spectrum Technology

With the rapid exploitation of ocean and the need of national defence, underwater acoustic remote control system (especially of long-distance underwater acoustic remote control system) has received much attention recently. The underwater acoustic channel is one of adverse wireless channel. With the distance of remote control increasing, the characteristic of underwater acoustic channel becomes more complex. Signal attenuation accompanished by long-distance transmission and intersymbol interference (ISI) caused by mulitipath propagation are the main factors influencing the performance of underwater acoustic remote control systems.Because of its ability of resisting multipath interference and low probability of interception (LPI), spread spectrum techniques are important ones used in underwater acoustic communications.Spread spectrum techniques used in underwater acoustic remote control system were introduced in this paper. The development of underwater acoustic communications and characteristics of underwater acoustic channel were introduced at first. According to the requirements of underwater acoustic remote control system, a direct-sequence spread spectrum (DSSS) technique for underwater acoustic remote system is presented in this paper, which encoding signals are modulated by frequency-shift-keying (FSK) modulation (DSSS-FSK). Some key techniques of DSSS-FSK are discussed. More attentions were imposed on estimate of channel and RAKE receiving techniques for underwater acoustic remote control system. The performances of underwater acoustic remote control system were simulated with ray theory model. At last, the system's hardware designs were introduced. The process results of lake trial predicted that the long-distance underwater acoustic remote control system which based on DSSS-FSK techniques could satisfaction the requirements of underwater acoustic remote control.