A Fast Signal Parameter Estimation Algorithm for Linear Frequency Modulation Signal under Low Signal-to-Noise Ratio Based on Fractional Fourier Transform
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摘要: 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。
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关键词:
- 线性调频信号 /
- 高效分数阶傅里叶变换 /
- 分数阶频谱4阶原点矩 /
- 低信噪比
Abstract: 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. -
表 1 3种算法对比仿真结果
估计方法 允许阶次误差 $\hat k\left({\rm{Hz /t}} \right)$ $\hat f\left( {{\rm{Hz}}} \right)$ ${k_{{{\rm{error}}}}}\left( \% \right)$ ${f_{{{\rm{error}}}}}\left( \% \right)$ FRFT运算次数 高效FRFT算法 – 1537.2000 1580.3 53.7244 5.3565 3 FRFT 2维搜索 <0.0100 1104.0000 1511.1 10.4010 0.7417 201 FRFT 2维搜索 <0.0010 1024.6000 1501.8 2.4580 0.1214 2001 FRFT 2维搜索 <0.0001 1003.9000 1501.5 0.3950 0.1007 20001 改进搜索算法 <0.0100 940.2061 1510.2 5.9794 0.6800 7 改进搜索算法 <0.0010 993.1624 1501.1 0.6838 0.0754 20 改进搜索算法 <0.0001 1002.3000 1500.8 0.2281 0.0531 43 -
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