浅海多途环境下的水声跳频通信方法

Acoustical Frequency Hopping Communication Method Resisting Multipath in Shallow Water

浅海海域强多途传输引起的码间串扰严重影响了水声通信的性能,本文采用跳频方法来抗多途和码间串扰。除了采用以往的单一滤波接收处理方法,本文还采用了一种新的接收处理方法,即前置跳频滤波接收处理方法,与其他方法不同的是在信号接收系统的混频之前增加了可控的前置跳频滤波器,可以增强抗多途和码间串扰能力,并对此方法分别采用PN码和递增序列2种跳频序列进行仿真研究。仿真结果表明,采用递增序列的前置跳频滤波接收方法使误码率大大降低。当信噪比大于10 dB,串扰信号与直达信号能量比小于0.6时,误码率可达10-4。

Intersymbol interference（ISI） due to shallow water multipath seriously influences underwater acoustical communication. To resist multipath and ISI in acoustical communication, a single filter receiving method and a new method, namely preprocessing frequency hopping filtering method, were adopted simultaneously. A controlled preprocessing frequency hopping filter was added before mixing frequencies of signal receiving system to strengthen resistance against muhipath and ISI. The method was simulated respectively on two frequency hopping sequences of PN code and increasing sequence. Simulation results show that the bit error rate（BER） can be decreased by using the increasing frequency hopping sequence. The BER reaches 10^-4when signal noise ratio（SNR） is greater than 10 dB and energy ratio of series interference signal to direct arrival signal is litter than 0.6.