基于插值短时分数阶傅里叶变换-变权拟合的线性调频信号参数估计

针对低信噪比下线性调频（LFM）信号参数估计精度不高的问题，提出一种基于Rife插值短时分数阶傅里叶变换（STFRFT）-变权拟合（VWSF）方法。该方法利用STFRFT提高LFM信号的聚集性，实现对LFM信号瞬时频率的高精度估计，并通过VWSF进一步提高信号初始频率和调频率的估计精度。推导得到了初始频率和调频率估计的克拉美-罗限（CRLB），分析了信号时长、滑窗次数等因素对CRLB的影响。仿真实验及海试结果表明，相比于传统基于短时傅里叶变换的估计方法，Rife插值STFRFT-VWSF方法具有更高的LFM信号参数估计精度。

Parameter Estimation of Linear Frequency Modulation Signal Based on Interpolated Short-time Fractional Fourier Transformand Variable Weight Least Square Fitting

A Rife interpolation short-time fractional Fourier transform (STFRFT) -variable weight least square fitting (VWSF) algorithm is proposed for solving the problem of low parameter estimation accuracy of linear frequency modulation (LFM) signal under low signal-to-noise ratio (SNR). STFRFT is used to improve the aggregation of LFM signals, and the estimation accuracy of instantaneous frequency of signal is improved by VWSF, thus estimating the instantaneous frequency, initial frequency and modulation frequency of LFM signal. The Cramer-Rao lower bound (CRLB) of the signal parameters estimation is derived, and the factors affecting the estimated parameter CRLB and the variation of CRLB with it are analyzed. The simulated results show that the Rife interpolation STFRFT-VWSF algorithm has better estimation accuracy of LFM signal parameters, the parameter estimation and CRLB theoretical analysis are rational, and the feasibility of the algorithm is proven through sea test. Key