基于分数阶傅里叶变换的低信噪比线性调频信号参数快速估计算法

针对低信噪比线性调频信号参数估计精度低且运算量大的问题，该文提出一种基于高效分数阶傅里叶变换(FRFT)和分数阶频谱4阶原点矩的快速估计算法。该算法通过判断调频斜率的正负，以确定旋转阶次所在初始区间；进而应用高效FRFT获得初始旋转阶次；最终利用分数阶频谱4阶原点矩，进一步确定搜索区间和步长，实现精准搜索，从而满足参数精度的要求。实验结果表明，该算法尤其适合用于低信噪比情况下的线性调频(LFM)信号检测与参数的准确估计，而且运算量较低。

A Fast Signal Parameter Estimation Algorithm for Linear Frequency Modulation Signal under Low Signal-to-Noise Ratio Based on Fractional Fourier Transform

An algorithm based on high-efficiency FRactional Fourier Transform (FRFT) and fourth-order origin moments in the fractional-domain spectrum is proposed to estimate quickly the chirp signal at low signal-to-noise ratio. Firstly, the initial interval of the rotation order is determined by the sign of the FM slope. Then, the rotation order is estimated roughly by the efficient FRFT algorithm. Finally, the search interval and step size are determined according to the fourth-order origin moments of the spectrum in the fractional-domain. The simulation results show that the Linear Frequency Modulation (LFM) signal can be detected under low signal-to-noise ratio and the parameters of the signal can be estimated accurately using this algorithm, and the signal can be detected with a small amount of calculation.