【摘要】 针对在时变的水声信道中系统的精确同步十分困难,而传统循环移位扩频系统在没有精确同步的条件下,很难准确判决的问题,提出一种差分循环移位扩频水声通信方法.该方法采用差分方式调制,能够在系统粗同步的条件下准确解调信息;在接收端采用被动时间反转方法解调,抑制多径效应产生的影响,并降低系统的复杂度.湖上试验结果表明:所提方法在1.8km的通信距离下实现无误传输;对试验数据附加噪声和同步误差处理后,在信噪比为-8dB、同步误差为5/4移位单元情况下的误码率达到10-5.更多还原

【Abstract】 Accurate synchronization is more difficult in the time-variation channel.Conventional cyclic shift keying spread spectrum suffers performance impairment from timing errors in underwater acoustic communications.To solve this problem,a differential cyclic shift keying spread-spectrum underwater acoustic communication technique based on passive time-reversal was proposed.The proposed method requires only"coarse"synchronization at the symbol level.The passive time-reversal can suppress the inter-symbol interference caused by multipath.Lake experiment results show that the proposed method has no bit transmitting error at 1.8km range;After adding the noise collected at the test,the BER is at 10-4 when SNR is-8dB with the 5/4shift units time error.更多还原