Least-Square Estimation of FM Rates for Removing LFM Interference in SAR Images

Ground and spaceborne radars can cause severe linear-frequency modulation (LFM) interference in space borne synthetic aperture radar (SAR) imagery. To address this problem, it is important to develop an efficient algorithm for LFM interference suppression in SAR images. For this purpose, in this paper we first propose a fast estimator for retrieving the frequency-modulation (FM) rates of the LFM interference based on least-square estimation. Then, we develop a spectral focusing-based algorithm for removing LFM interference using the estimated FM rates. Real-data and simulation experiments show that the proposed algorithm can accurately estimate the FM rates and effectively remove LFM interference signatures in interferometric wide-swath single-look-complex images.