高精度LFM信号参数估计的谱校正方法

摘要

To estimate the parameters of linear frequency modulation (LFM) signal precisely in a noisy environment, a novel discrete spectrum correction method is proposed based on Radon-ambiguity transform (RAT) and fractional Fourier transform ( FRFT). This method reduces the parameter estimation to two onedimensional spectral peak searching processes, and by the spectral analysis of RAT and FRFT of LFM signal multiplied by rectangular window, the energy centrobaric correction measure is introduced in these two searching processes,which improves the estimation accuracy substantially without increasing any computing complexity. As shown in the simulation results, for the single-component LFM signal case, the correction errors of the RAT and FRFT spectral peak locations are reduced to 1. 55％ and 4. 94％ of the scanning step, which verifies the efficiency of the method%为精确估计噪声背景下线性调频(linear frequency modulation,LFM)信号的调频率和中心频率等参数,提出了一种基于Radon模糊变换(Radon-ambiguity transform,RAT)和分数阶傅里叶变换(fractional Fourier transform,FRFT)的离散谱校正估计方法.该方法将LFM信号的调频率和中心频率估计问题转化为模糊域和分数阶Fourier域上的两次一维谱峰搜索过程,并且通过对矩形窗截断的LFM信号的RAT和FRFT谱线结构分析,将能量重心谱校正法引入两次谱峰搜索过程,在不增加运算量的基础上实现了谱峰位置的超分辨率估计,较大幅度地提高了信号的参数估计精度.仿真结果显示,对于单分量LFM信号情况,该方法对信号的RAT和FRFT谱峰位置的校正误差分别降到了扫描步长的1.55%和4.94%,证明了该方法的有效性.