Digital Beamforming Based RFI Extraction for an On-Ground Correction of Synthetic Aperture Radar Data

Abstract

Radar remote sensing instruments have played an increasingly important role in understanding Earth and its dynamic processes. Their operational frequencies are predetermined based on the physical properties that are to be retrieved. Simultaneously, the use of their allocated frequency bands in P- to C-band by other services has increased. A reliable mitigation of Radio Frequency Interference (RFI) is therefore critical for future Earth observation missions.New space-borne multi-channel Synthetic Aperture Radar (SAR) instruments are capable of Digital Beamforming (DBF). Each receive channel is recorded individually to form the digital antenna pattern after data acquisition. This opens up new opportunities for spatial RFI filtering. Unfortunately, this approach requires significant processing power on board the satellite as it is unfeasible to downlink the increased data volume. This paper presents a new method based on auxiliary beams that relaxes the requirement for the on-board processing power and only affects the downlinked data volume minimally. The information measured with the auxiliary beam can be used for an on-ground RFI correction.