【作者】 邓巍；

【导师】 文必洋；

【作者基本信息】 武汉大学 ， 电路与系统， 2004， 硕士

【摘要】 本文研究了线性调频体制的高频地波雷达的射频干扰(RFI)抑制问题，分析了RFI的基本特点及其表现形式，建立了相应的干扰模型。在抑制干扰的方法上，分别提出了检测-剔除-插值的时域处理方法和基于动目标显示(MTI)技术的多普勒域处理方法，从不同的角度对RFI进行抑制。 检测-剔除-插值的时域处理方法在雷达信号的一个采样周期内进行，利用了RFI在一个周期中的瞬时性和奇异性的特点。首先通过Wigner-Ville分布和小波变换检测出RFI所在的位置并对被RFI污染的采样点进行剔除，然后根据雷达正常回波的特点，利用AR模型的方法预测恢复被零陷的采样点，以消除由于零陷引起的附加距离旁瓣。这一方法适宜处理干扰程度较轻的情况，在干扰很严重的情况下，将由于有用信息损失过大而难以奏效。 为了处理干扰程度较严重的情况，本文引入了多普勒域的MTI滤波方法。利用RFI在多普勒谱上表现出很强的距离相关性的特点，通过将含噪回波的自协方差矩阵分解为信号子空间和噪声子空间，回波数据对信号子空间进行投影来滤除RFI。 对雷达实测数据的处理表明上述方法是有效的，平均信噪比改善达10dB左右。更多还原

【Abstract】 Radio Frequency Interference (RFI) can greatly degrade the performance of High-Frequency GWR. In this paper, methods of suppressing RFI in HF GWR are studied. By analyzing the characteristic of RFI, the model of interference is established, and two methods are presented to process RFI. One is a detect-eliminate-interpolate method processed in time domain, the other is a MTI filtering method processed in Doppler domain.Since RFI presents instantaneous and singularity characteristics in a sampling period of HF GWR, a detect-eliminate-interpolate method is presented. Firstly those sampling points when RFI performing are detected via Wigner-Ville Distribution(WVD) and Wavelet transformation, and then they are set to zero. To reduce the range sidelobe caused by notch window, AR model based interpolation is utilized. When RFI is relatively weak, this method performs well. But when RFI becomes strong, this method will invalidate due to useful signal energy’s losing.The MTI filtering method is based on the fact that RFI represents strong pertinence along range bins in Doppler spectrum. By separate covariance matrix of received signal into signal-space and noise-space, RFI is suppressed while sea echoes and target echoes are reserved.Computer simulation and experiment prove that these methods are valid. Average SNR improvement can be about 10dB.更多还原