利用分数阶Fourier变换抑制高频地波雷达中线性调频干扰

高频地波雷达(HFGWR)受到严重的射频干扰影响。单频射频干扰在接收信号中体现为高强度的线性调频信号，从而污染所有距离元。为抑制射频干扰，通过分析其频率特征，使用分数阶傅里叶变换（FRFT）将原始信号转换到分数阶傅里叶域，对射频干扰对应的谱峰置零，达到抑制干扰的目的。该方法的优点在于抑制射频干扰的同时无损干扰位置处的回波信号，无需重构信号。实测数据分析表明：FRFT不仅能有效抑制射频干扰，信噪比提高可达10 dB以上，而且其计算复杂度较小，满足雷达实时工作要求。

Linear frequency modulated interference suppression using FRFT for HF ground wave radars

High frequency(HF) ground wave radar(HFGWR) system is severly affected by radio-frequency interference(RFI). Single frequency RFI behaves as high-amplitude signal under the mechanism of linear frequency modulation(LFM) and consequently pollutes signal in all range cells. For suppressing RFI,by analyzing its frequency characteristics,fractional Fourier transform(FRFT) is used to convert the original signal into fractional Fourier domain and RFI peaks are set to zero. The advantage of this approach is that it can suppress RFI without losing echo signal at the location of RFI and does no need to reconstruct signal. Analysis of measured data shows that FRFT can effectively suppress RFI and improve signal-to-noise ratio(SNR) more than 10 dB,while its low computing complexity is able to meet the real-time processing requirement of radar system.