STFT和Zoom-FRFT联合的多分量LFM信号参数估计方法

针对传统基于分数阶傅里叶变换(FRFT)的多分量线性调频信号(MLFM)参数估计方法中计算量大,估计精度低等问题,提出了一种短时傅里叶变换(STFT)和Zoom-FRFT联合的参数估计方法.首先,利用STFT得到MLFM信号的短时傅里叶域频谱图,对其进行直线检测得到各个分量参数的粗略估计.然后,利用LFM信号在FRFT域的频谱分布特征和STFT窗函数的主瓣带宽,计算得到待估计信号在FRFT域变换阶次和频谱的分析范围;最后,在Zoom-FRFT域采用优选法对各个分量进行精估计,得到精确的变换阶次和峰值位置.仿真结果表明,该方法可以有效地对MLFM信号进行参数估计,可以根据实际需要灵活选择窗函数的宽度和细化倍数,与传统方法相比,提高参数估计精度的同时大大减小了计算量.

Mutil-Component LFM Signal Parameter Estimation Method Using STFT And Zoom-FRFT

Traditional parameter estimation methods of multi-component linear frequency modulation (MLFM) signal based on Fractional Fourier transform (FRFT) could solve neither the satisfactory precision nor the lesser computation cost. A new method, Short time Fourier transform (STFT) and Zoom-FRFT combined, is proposed in this paper. Firstly, the short-time Fourier spectrum of MLFM signal is obtained by using STFT, and the parameters coarse estimation result from the straight line detection of short-time Fourier spectrum. Then, the analysis scope of transform order and Fractional domain spectrum are calculated with the Fractional domain spectrum distribution characteristics and the main lobe bandwidth of window. Finally, the optimal order and the precise peak position are estimated by using the optimum seeking method in the Zoom-FRFT domain. The simulation results show that, compared with the traditional method, the method can improve both the parameters estimation precision and the computation cost significantly, and can flexibly choose the width of window and the refining ratio.