Costas序列短波MFSK通信时频联合同步方法  

Time-frequency joint synchronization method of HF MFSK communication based on Costas sequence

作　　者：李景慧 李国军[2,3] 叶昌荣 王尊立 LI Jinghui;LI Guojun;YE Changrong;WANG Zunli(School of Communication and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,P.R.China;Laboratory of Beyond LOS Reliable Information Transmission,Chongqing University of Posts and Telecommunications,Chongqing 400065,P.R.China;School of Optoelectronic Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,P.R.China)

机构地区：[1]重庆邮电大学通信与信息工程学院,重庆400065 [2]重庆邮电大学超视距可信信息传输研究所,重庆400065 [3]重庆邮电大学光电工程学院,重庆400065

出　　处：《重庆邮电大学学报（自然科学版）》2022年第4期669-677,共9页Journal of Chongqing University of Posts and Telecommunications(Natural Science Edition)

基　　金：国家重点研发计划基金(2019YFC1511300);国家自然科学基金(61671452)。

摘　　要：针对低信噪比与强多径传播导致短波MFSK信号捕获困难、同步精度低的问题,提出一种基于Costas序列的短波MFSK信号时频联合同步方法。利用Costas序列二维图案优异的自相关特性进行信号检测与同步,将传统的滑动窗口法由时域扩展到时频域,同步获得时间和频率的估计值;为了降低计算量,给出了频偏与时延的精估计方法。仿真结果表明,与传统伪随机码(PN码)同步方法相比,提出的方法具有更好的抗噪声和抗频偏性能。在信号带宽为50 Hz、同步序列长度为1.28 s的ITU-R中纬度短波信道上,该同步方法能够达到98%的捕获率,虚警概率低于10^(-2);时间同步误差低于12 ms;频率估计误差低于1 Hz。Aiming at the problems of low signal-to-noise ratio and strong multipath propagation that cause HF MFSK signal acquisition difficulties and low synchronization accuracy,we propose a time-frequency joint synchronization method of HF MFSK signals based on Costas sequence.This method uses the excellent autocorrelation characteristics of Costas sequence two-dimensional patterns for signal detection and synchronization,and extends the traditional sliding window method from the time domain to the time-frequency domain,which can obtain time and frequency estimates simultaneously.In order to reduce the amount of calculation,a precise estimation method of frequency offset and time delay is given.The simulation results show that,compared with the traditional PN code synchronization method,the proposed method has better anti-noise and anti-frequency offset performance.On the ITU-R mid-latitude HF channel(signal bandwidth is 50 Hz,synchronization sequence length is 1.28 s),this synchronization method can achieve a capture rate of 98%,and false alarm probability is less than 10^(-2).The time synchronization error does not exceed 12 ms.The frequency estimation error is less than 1 Hz.

关 键 词：短波通信 COSTAS序列 相关特性 时频联合同步 

分 类 号：TN929[电子电信—通信与信息系统]