Ultrawideband Mutual RFI Mitigation Between SAR Satellites: From the Perspective of European Sentinel-1A

In the data processing of spaceborne synthetic aperture radar (SAR), radio frequency interference (RFI) will seriously affect amplitude, phase, and other information, thereby deteriorating image quality. Mutual RFI (MRFI) between spaceborne SAR satellites is a typical terrain scattered wave interference, and it usually has long duration and large bandwidth, which brings huge challenges to interference mitigation. From the perspective of the European Sentinel-1A (S-1A), the ultrawideband MRFI characteristics from different SAR satellites in the C-band are studied and analyzed in this article. In order to mitigate the impact of ultrawideband MRFI on SAR data, an effective solution is proposed, including two steps. The first is a novel out-of-band spectrum energy (OSE) detection method, which has the ability to detect MRFI with high accuracy. Meanwhile, the second is an improved version of eigen-subspace projection (ESP), namely, 2-D dynamic threshold ESP (2DDT-ESP) method, which can better deal with complex spatial scene changes and obtain higher precision MRFI mitigation effects. The conditions for the proper use of the above methods are discussed in this article. Comparative experiments with other methods based on simulated SAR data and three sets of S-1A level-0 raw measured data are conducted, in which the experimental measured dataset is contaminated by MRFI from different sources, including Radarsat-2 (RS-2), Gaofen-3 (GF-3), and Radarsat Constellation Mission (RCM). The final processed results verify the effectiveness and superiority of the proposed approach.