Chirp-Rate Resolution of Fractional Fourier Transform in Multi-component LFM Signal  

作　　者：刘锋 黄宇 陶然 王越 

机构地区：[1]School of Information Science and Technology, Beijing Institute of Technology [2]Department of Electronic Engineering, Naval Aeronautical Engineering Institute

出　　处：《Journal of Beijing Institute of Technology》2009年第1期74-78,共5页北京理工大学学报（英文版）

基　　金：Sponsored by the National Natural Science Foundation of China (60232010 ,60572094);the National Science Foundation of China for Distin-guished Young Scholars (60625104)

摘　　要：Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform （FrFT）. Then the expression of chirp-rate resolution in fractional Fourier domain （FrFD） was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What＇s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform （FrFT）. Then the expression of chirp-rate resolution in fractional Fourier domain （FrFD） was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What＇s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.

关 键 词：fractional Fourier transform（FrFT） RESOLUTION linear frequency modulation（LFM） signal chirp-rate 

分 类 号：TN911.7[电子电信—通信与信息系统]