水声信道普遍存在多径效应,致使水声正交频分复用(OFDM)通信系统的同步算法经常给出误差较大甚至错误的同步点。为了完成精确的同步,本文提出一种基于恒幅度零自相关序列以及在信号开始插入两个同样训练信号的联合同步算法,系统通过粗同步和细同步两个过程完成信号开始时刻的精确定位。仿真分析和湖试结果表明,本算法能够在多径信道下准确找到信号开始时刻。
The multi-path channel brings great challenges for orthogonal frequency division system(OFDM) on underwater communication.It is difficult to get the exact time with the general synchronization method.The proposed method is arranged using the constant amplitude and zero autocorrelation(CAZAC) sequence as the fine synchronization and the SC's method as the coarse synchronization.Through the computer simulation and the lake experiment,the method is shown to be a fine synchronization of underwater OFDM both on precision of synchronization and the amount of calculation.