基于FRFT的线性调频多径信号分离算法

Separation of multi-path LFM signals based on fractional Fourier transform

在高空接收从海上发射的雷达信号时,由于海面的反射作用,信号将会出现多径效应。多径效应会造成信号的衰落,导致信号检测性能和参数估计精度的损失。该文针对线性调频雷达信号,利用分数阶Fourier变换(FRFT)的时频聚集特性,提出了基于极坐标的一维邻域搜索算法,从而实现线性调频多径信号的快速分离。仿真结果表明:该算法能够将分离多径之后的信干比较分离多径之前提高75 dB,将分离多径后中心频率估计的均方根误差降低到分离多径前的25%以下,并具有较快的搜索速度,从而能够较好地抑制多径传播对接收线性调频信号的影响。

Reflections off of the ocean surface leads to multi-path effects when receiving radar signals from high altitude space. The multi-path effects lead to signal fading and the loss of signal detection performance and parameter estimation accuracy. This paper focuses on multi-path separation for a linear frequency modulated （LFM） signal based on fractional Fourier transform （FRFT）. The method uses time-frequency clustering of the LFM signals by incorporating a 1-D neighborhood search algorithm based on polar coordinates. Simulations show that the algorithm improves the signal-to-interfertnce ratio by 75 dB and reduces the root mean square error of the center frequency estimation by over 75% after separation of the multi-path signals. The algorithm has a high search speed and achieves effective mitigation of multi-path effects on LFM signals.