基于分数阶傅里叶变换的LFM信号参数估计预判法

本文提出了一种基于分数阶傅里叶变换(fractional Fourier transform,FRFT)的LFM信号参数预判法,即对线性调频信号先利用FFT进行预判并粗略估计出调频系数值;根据得到的线性调频系数计算出对应的旋转角度,然后根据这个旋转角度做FRFT以找出精确的最大峰值点并精确估计出信号的各参数.理论分析与仿真结果表明该方法在保留原FRFT优点的同时,极大地减少了计算量,为单分量LFM信号的实时处理提供了可能;同时也避免了原基于FRFT(fractional Fourier transform)的二维搜索所带来的频谱伪峰干扰.

The Pre-Estimation Algorithm of Chirp Based on the Fractional Fourier Transform

This paper proposes a pre-estimation algorithm (PEA) for Linear Frequency Modulation (LFM) signal detection based on the fractional Fourier transform (FRFT),which can be used to estimate the value of chirp ratio approximately.The correspond- ing rotation angle of FRFT could be derived from this value.Then the accurate value of the maximal amplitude and some other parame- ters of the signal can be determined by using FRFT by the rotation angle.Both the theoretic analysis and Simulation results prove that comparing with the original FRFT,the PEA method can reduce the computational cost and offer the possibility of real-time signal pro- eessing for LFM signal,while keeping the advantage of original FRFT.Additionally,the PEA can avoid the disturbances from the fake peaks in the angle-frequency domain while the original FRFT method can not.