加速度下的水声通信多普勒频移补偿方法  

Effective Doppler Compensation for Underwater Acoustic Communications under Relative Acceleration

作　　者：李红娟[1] 孙超[1] 

机构地区：[1]西北工业大学声学工程研究所,陕西西安710072

出　　处：《西北工业大学学报》2007年第2期181-185,共5页Journal of Northwestern Polytechnical University

基　　金：西北工业大学青年创新基金(M016207)资助

摘　　要：针对水声通信双方加速运动导致的一帧数据中每个码元的伸缩比变化,在模糊度函数的基础上提出一种多普勒频移补偿方法。通过对线性调频同步信号进行匹配滤波来估计多普勒频移的取值,根据每个码元的插值因子进行重采样后,采用带有数字锁相环路的判决反馈均衡器补偿残留频移。计算机仿真验证了该方法的有效性,将其与采用恒定插值因子的方法进行了性能对比。结果显示,该方法能够较好地补偿多普勒频移,提高接收性能。Aim. The performance of coherent acoustic communication system is adversely affected by Doppler shift resulting from relative motion of the transmitter and receiver. Existing methods of Doppler compensation^[1-5] are, in our opinion, deficient in effectiveness under relative acceleration. We now present a method believed to be effective for Doppler compensation for underwater acoustic communications. In the full paper, we explain in detail our effective method; in this abstract, we just add some pertinent remarks to listing the two topics of explanation. （1） Doppler shift in broadband communication and （2） the method of Doppler compensation under relative acceleration; in topic 2, with the help of Fig. 1 in the full paper, we point out that LFM（linear frequency modulation） chirp pilot is fed to a group of matched filters（MFs） corresponding to different Doppler shift values and that the frequency of the MF with maximum value is chosen as the output of estimated Doppler shift frequency; also in topic 2, with the help of Fig. 2, we explain how to calculate the interpolating factor of each symbol using Doppler shift; still in topic 2, with the help of Fig. 3, which shows the structure of the receiver, we explain how to use a DFE （decision feedback equalizer） with phase-locked loop （PLL） to suppress intersymbol interference （ISI） and residual Doppler errors. We performed Monte Carlo simulations on medium-range BPSK system and short-range QPSK system respectively. Simulation results are given in Figs. 5 and 6 for BPSK system and in Figs. 7 and 8 for QPSK system. Fig. 7 shows that, when the chirp signal is longer than ISI, the unusual phenomenon of the occurrence of more than one peak in the output of a MF was observed. Figs. 6 and 8 show preliminarily that, when Doppler shift difference of a data frame is higher than 0.02%, the conventional method, which uses the same interpolating factor on the whole frame of symbols, causes high bit error rate, while we can get higher receiver reliability

关 键 词：水声通信 多普勒频移 匹配滤波 插值 判决反馈均衡 锁相环路 

分 类 号：TB56[交通运输工程—水声工程]