一种基于DSP的实时水声跳频通信系统研究

A Real-time Frequency-hopping Communication System in Underwater Acoustic Channel Based on DSP

水声信道是一种极其复杂的时空频变信道,在进行水声通信中,必须克服强多途和大起伏等干扰.抗干扰能力强、隐蔽性好的跳频通信技术应用于水声通信领域,具有独特的优势,是近年来高稳健性水声通信技术研究中的一个热点.本文构建了一种基于DSP硬件平台的实时水声跳频通信系统,给出了系统编解码技术的实现方法.发射的帧信号由粗同步信号、细同步信号、时延信号和m序列生成的跳频信号组成,采用补零FFT的方法进行解码,提高了鉴频分辨率.通过实验室水池实验,验证了所设计系统在低信噪比条件下的可行性和稳定性.由于m序列生成的跳频图案隐蔽性强,该系统也可用于水声保密通信.

Underwater acoustic （UWA） channel is expressed as complex channel which is randomly variable in time-space-frequency. Combating the strong underwater multipath and large fluctuation is the most challenging task of an UWA communication system. Frequency-hopping （FH） communication system features its low probability of intercept and anti-interference which is widely applicated in underwater acoustic communication recently. A real-time FH communication system based on high-speed digital signal processor （DSP） was introduced in this paper. The frame of transition signal was composed of coarse and subtle synchronization,time delay signal and FH signal created by M-sequence. Fill zero FFT method was used to demodulate received signal and to improve the ability of frequency discrimination. The laboratory pool experimental results verified the good performances of the system in robustness and feasibility.