基于分数阶傅里叶变换的LFM干扰抑制算法

针对利用分数阶傅里叶变换(fractional Fourier transform,FrFT)进行干扰抑制时门限阈值设定的难题,为有效抑制DS/FH系统中的线性调频(linear frequency modulated,LFM)干扰,通过深入分析DS/FH和LFM信号的FrFT性质,提出了一种新的LFM干扰抑制算法,该算法充分利用FrFT时频面坐标轴旋转性质,通过计算信号的不同阶次FrFT并搜索其峰值,确定信号最优FrFT阶次,完成对LFM干扰信号的判别,最后采用频域陷波来抑制LFM干扰。理论分析和仿真实验表明,该算法能够有效的剔除DS/FH系统中的LFM干扰信号,不需要阈值门限设定,算法具有较好的稳健性和普适性。

The Algorithm of LFM Interference Suppression Based on FrFT

The threshold value setting is a challenge when interference suppression based on frac-tional Fourier transform（FrFT） .In order to suppress the linear frequency modulated （LFM）interfer-ence of DS/FH ,a novel algorithm to suppress the LFM interference is presented by analyzing the Fr-FT properties of DS/FH signal and LFM signal .The algorithm uses the properties that FrFT is the axis rotation in the time-frequency domain .First ,calculates each order FrFT of the signal ,and sear-ches for the peak value;secondly ,determines the optimal signal FrFT order by comparing each peak value;at last ,rules out LFM interference signals and uses the frequency domain notch filter to sup-press LFM interference .Theoretical analysis and simulation experiments show that this algorithm can effectively eliminate the LFM interference signal in the DS/FH system .It doesn＆#39;t need to set the threshold and it also has better robustness and applicability .