说明：  水声信道的时变相位起伏使得实现可靠的相位跟踪比较困难, 从而造成基于相位检测的 水声通信接收机结构复杂。提出基于FSK 调制的直接序列扩频(DSSS2 FSK) 水声通信系统。
(Underwater acoustic channel disguised bit of time to achieve reliable phase fluctuations make tracking more difficult, resulting in detection based on phase Complex acoustic communication receiver. Proposed based on direct sequence spread spectrum FSK modulation (DSSS2 FSK) acoustic communication system. )