基于相位差法和FRFT的Chirp信号参数估计算法  

Chirp Signal Parameter Estimation Using Phase Difference Method and Fractional Fourier Transforms

作　　者：廖烨 刘国峰 李康[1] 周文峰 LIAO Ye;LIU Guo-feng;LI Kang;ZHOU Wen-feng(School of Communication and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆邮电大学通信与信息工程学院,重庆400065

出　　处：《光通信研究》2020年第3期73-78,共6页Study on Optical Communications

基　　金：国家科技重大专项基金资助项目(2018ZX03001007-004)。

摘　　要：针对分数阶傅里叶变换(FRFT)对啁啾(Chirp)信号进行盲检测时存在运算量大的问题,文章提出一种针对Chirp信号参数估计的盲检测方法。首先利用改变窗长相位差法对Chirp信号进行粗估计,并利用最小二乘法进行拟合得到Chirp信号调频斜率粗估计值,然后通过FRFT对Chirp信号进行精细估计,并利用二分法对FRFT的阶次进行搜索,进一步降低算法的运算量。仿真结果表明,利用改变窗长相位差法和FRFT联合检测Chirp信号的方法,在低信噪比下具有较高精度的估计值,且其归一化均方误差接近克拉美罗下界,并且与FRFT穷举检测相比,极大地减少了运算量,具有很好的工程应用意义。In view of the fact that Fractional Fourier Transform(FRFT)has large computational complexities when the Chirp signals are detected blindly.This paper proposes a blind detection method for Chirp signal parameter estimation.Firstly,the Chirp signal is roughly estimated by window-length changing phase difference method and the least square method is used to fit and obtain the rough estimation value of the Chirp signal frequency modulation slope.Then,the Chirp signal is precisely estimated by FRFT,and the order of FRFT is obtained by Bisection method,which further reduces the computational complexity of the algorithm.The simulation result shows that the method of detecting the Chirp signal by using the modified window-length changing phase difference method and the FRFT at low Signal to Noise Ratio(SNR)has higher precision estimation value,and its normalization mean square error is close to Cramer-Rao lower bound.The method compared with FRFT exhaustive detection greatly reduces the computational complexity and has good engineering application significance.

关 键 词：分数阶傅里叶变换 啁啾 改变窗长相位差法 最小二乘法 二分法 

分 类 号：TN911.23[电子电信—通信与信息系统]