一种分数傅里叶域线性调频信号高精度码同步方法  

An Accurately Synchronous Method Using Chirp Signal in Fractional Fourier Domain

作　　者：温容慧[1] 沙学军[1] 张欣宇[1] 

机构地区：[1]哈尔滨工业大学通信技术研究所,哈尔滨150001

出　　处：《西安交通大学学报》2009年第4期80-84,共5页Journal of Xi'an Jiaotong University

基　　金：国家重点基础研究发展规划资助项目(2007CB310606);黑龙江省博士后基金资助项目(LBH-Z07135)

摘　　要：针对传统同步方法只能采用提高采样频率来提高同步精度的局限,提出一种分数傅里叶域高精度同步方法.该方法使用线性调频信号(Chirp信号)替代多比特余弦载波同步信号,在接收端同步信号经分数傅里叶变换后判决峰值位置,再与理论峰值位置作比较得出同步位置.通过分析影响Chirp信号分数傅里叶域峰值幅度的参数,发现峰值幅度随着同步码片数的增加而增加,从而提高了同步的精度.与传统的同步方法相比,该方法在采样率相同的条件下能获得更高的同步精度.仿真结果表明,当同步码为71、1 b,信噪比为24、dB以上时,该方法同步精度高于传统方法,并且精度迅速提高.Because of the drawback of traditional methods that improving synchronous precision can only be achieved by increasing the sampling frequency, a new method is proposed. The proposed method uses the Chirp signal, instead of cosine carrier signal, as the synchronous signal, and determines the peak location in fractional Fourier domain（FrFT） at the receiver. Then the synchronization is obtained by comparing the resulting peak location with the theoretical peak location. Through analysing the parameters that affect the amplitude of Chirp signal in FrFT domain it is found that the amplitude will increase with the increase of the number of chips, and hence increase the synchronous precision. Comparisons with traditional methods show that the proposed method has higher precision with the same sample frequency. Simulation results show that if the synchronous number is 7 or 11 bits and SNR is above 2 or 4 dB, the precision of the proposed method is higher than the traditional methods and increases rapidly.

关 键 词：同步 分数傅里叶变换 CHIRP信号 

分 类 号：TN911.3[电子电信—通信与信息系统]