基于分数阶傅里叶变换的线性调频信号的自适应时频滤波

兵工学报 ›› 2003, Vol. 24 ›› Issue (4): 499-503.

基于分数阶傅里叶变换的线性调频信号的自适应时频滤波

齐林，陶然，周思永,王越

北京理工大学电子工程系，北京，100081

收稿日期:2002-08-01 修回日期:2003-09-01 上线日期:2014-12-25
通讯作者: 齐林
基金资助:
国家自然科学基金资助项目(69972003)

An Adaptive Time-Frequency Filtering Method Based on Fractional Fourier Transform for Linear Frequency Modulation Signals

Qi bin, Tao Ran, Zhou Siyong, Wang Yue

Department of Electronic Engineering, Beijing Institute of Technology, Beijing, 100081

Received:2002-08-01 Revised:2003-09-01 Online:2014-12-25
Contact: Qi Lin

摘要/Abstract

摘要： 本文提出了一种基于分数阶傅里叶变换的线性调频(LFM)信号的自适应滤波方法，利用该变换等同于对信号在时频平面进行旋转这一重要特性，将混迭有噪声的信号以特定的旋转角作分数阶傅里叶变换，使得信号与噪声在变换域中的交迭达到最小;在此基础上，通过窄带通滤波器对LFIVI信号进行抽取，去除大部分的噪声能量，然后，再经过分数阶傅里叶反变换，恢复出原来的LFM信号。理论分析和仿真表明，该方法不仅可获得明显的信噪比的改善，而且具有算法简单及信号失真小等特点，和其它基于二维时频分析工具的滤波算法相比，降低了计算的复杂度，其实现更为简便。

关键词: 信息处理技术 , 时频滤波 , 线性调频信号 , 分数阶傅里叶变换

Abstract: The aim of this paper is to propose an adaptive method for Iiltering the linear FM signal em?bedded in white Gaussian noise. The idea that the fractional Fourier transform (FRFT) for a signal is e- quivalent to rotating the signal on time-frequency plane is used. First, a noisy LFM signal rotated to a cer?tain angle by the FRFT will result in the least spectrum overlap between the signal and noise in fractional Fourier domain. Then, on the basis of dechirping the LFM signal，a narrowband filter is exploited to ex?tract the signal and depress most of the noise energy. Finally, the denoised LFM signal is rotated back to the time domain using an inverse FRFT. Performance of the proposed method is seen through its simplicity in computation and in their improvement SNR. Some theoretical analysis and simulation results are included to demonstrate the validity of the method and the results have shown that remarkable improvement of SNR and tolerable signal distortion are obtained. In addition, when compared with other two-dimension time- frequency filtering algorithms, it is seen to be easy in computation and simple in implementation.

Key words: imformation processing technique , time-frequency filtering , linear frequency modulation signal , fractional Fourier transform

中图分类号:

TN 911.7

齐林，陶然，周思永,王越. 基于分数阶傅里叶变换的线性调频信号的自适应时频滤波[J]. 兵工学报, 2003, 24(4): 499-503.

Qi bin, Tao Ran, Zhou Siyong, Wang Yue. An Adaptive Time-Frequency Filtering Method Based on Fractional Fourier Transform for Linear Frequency Modulation Signals[J]. Acta Armamentarii, 2003, 24(4): 499-503.

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