GST时频滤波SAR射频干扰抑制算法

RFI Suppression Algorithm for SAR Based on GST Time-Frequency Filtering

空间中存在的射频干扰(Radio Frequency Interference,RFI)会污染合成孔径雷达(Synthetic Aperture Radar,SAR)的回波数据,进而影响成像质量以及基于图像的应用。本文针对RFI的特点,提出了一种基于广义S变换(Generalized S Transform,GST)时频滤波的干扰抑制算法。该算法首先利用配对样本T检验对存在干扰的回波数据进行检测并标记,然后对被标记的回波数据的实部与虚部分别进行处理:将数据变换到广义S变换域,逐条对时间窗内的数据进行子空间滤波完成干扰抑制,接着把干扰抑制后的数据反变换到时域并与未标记信号组成新的纯净回波数据集,最后利用成像算法进行成像处理得到清晰的SAR图像。所提出算法可以在有效抑制SAR数据中射频干扰的同时,减少处理过程中有用信号的损失,实验结果验证了算法的有效性。

Radio frequency interference(RFI)in space can contaminate the echo data of synthetic aperture radar(SAR),which in turn affects the SAR image quality and SAR image-based applications.According to the characteristics of RFI,an interference suppression algorithm based on generalized S transform(GST)time-frequency filtering is proposed in this article.In the algorithm,the echo data with interference are recognized and labeled accurately by using paired-samples T test in the first place.Then the real and imaginary parts of the labeled echo data can be dealt with separately as follow:the pending data are transformed into the generalized S transform domain.And in this domain,to complete interference suppression,the subspace filtering method is employed for instantaneous data in each time window one by one.After that,the data after processing are transformed back into the time domain by inverse transform and then formed a new clean echo data set with unlabeled signals.Finally,a clear SAR image can be obtained by using SAR imaging algorithm.The algorithm can suppress RFI in SAR data effectively and reduce the loss of the useful signal during the processing at the same time.The experimental results also verify the effectiveness of the algorithm.