联合调频率拐点与FrFT的多分量LFM干扰抑制方法

Multi-component LFM interference suppression method based on chirp rate turning point and FrFT

针对单天线卫星导航接收机在抑制多分量线性调频(LFM)干扰过程中信噪比损失较大的问题,提出了一种联合调频率拐点信息与分数阶傅里叶变换(FrFT)的多分量LFM干扰抑制方法。首先,分析LFM干扰信号时域差分数据的模值在单周期内的单调性和周期起止点的非连续性;然后,采用奇异值分解(SVD)对差分结果进行重构以估计干扰调频率拐点区间;进而,选取干扰单个周期中心区域进行FrFT最优阶数搜索与噪声能量估计;最后,在分数阶傅里叶域剔除干扰成分并在时域去除残余干扰。实验结果表明:所提方法能够在干噪比大于10 dB时提升输出信干噪比与捕获效果。

The single-antenna satellite navigation receiver has a large loss of signal-to-noise ratio in the process of suppressing multi-component Linear Frequency Modulation(LFM)interference.To solve this problem,a multi-component LFM interference suppression method is proposed based on the chirp rate turning point and Fractional Fourier Transforml(FrFT).Firstly,the monotonicity of the modulo value of the time-domain differential data of the LFM interference signal in a single cycle and the discontinuity of the value at the start and end points of the cycle are analyzed.Secondly,the difference results are reconstructed by Singular Value Decomposition(SVD)to estimate the chirp rate turning point interval of the LFM frequency.Then,the center area of a single period of interference is selected for FrFT optimal order search and noise energy estimation.Finally,the interference components and the residual interference in the fractional Fourier domain and the time domain are removed,respectively.Simulation results show that the proposed method can improve the output signal-to-interference-to-noise ratio and capture effect when the interference-to-noise ratio is greater than 10 dB.