Detection and suppression of narrow band RFI for synthetic aperture radar imaging

Radio frequency interference (RFI) is becoming more and more frequently, which makes it an important issue in SAR imaging. RFI presented in synthetic aperture radar either on purpose or inadvertent will distort the useful SAR echoes, thus degrade the SAR image quality. To resolve this issue, a long time study was carried out to study the characteristic of the RFI through the RFI-affected spaceborne and airborne SAR data. Based on the narrow band nature of RFI, this paper proposes a new process which contains both RFI detection and RFI suppression. A useful subband spectral kurtosis detector is first used to detect RFI, and then its results are used for RFI suppression. The proposed process has two advantages: one is the economization on the compute time for unnecessary interference suppression when no RFI existed; the other is improving the performance of the suppression method with knowing the exact position where RFI is. Moreover, the previous RFI suppression method—subband spectral cancelation (SSC) is supplemented and perfected. The subband division step is also elaborated detail in this paper. The experiment results show that the subband spectral kurtosis detector exhibits good performance in recognizing both weak and narrow-band RFI. In addition, the validity of the SSC method with subband spectral kurtosis detector is also validated on the real SAR echoes.