Hybrid Passive-Active Approach for Interference Mitigation in Spaceborne SAR

Abstract

With the advent of large commercial constellations carrying synthetic aperture radars (SAR), the problem of radio frequency interference (RFI) between different SAR satellites will soon arise due to the shared use of spectrum. Such interference manifests as distortion and artificial artifacts which reduce the quality of SAR images. This paper proposes a novel approach to tackle the interference problem by exploiting the RFI signal as an additional source of illumination acting as a bistatic radar transmitter. As such, rather than treating the RFI as an adversarial signal that needs to be suppressed, we benefit from this signal to further improve the acquired image quality, where the primary image is generated based on the satellite's own signal as a typical active monostatic source. In order to evaluate this approach, we first lay the geometry and signal model including the required sensor architecture that leverage the well-structured SAR waveform. Then, we present the required modifications to typical SAR signal processing workflow such that both monostatic and bistatic images are overlapped. Results based on realistic signal emulation are then shown for a typical interference scenario where the proposed hybrid approach demonstrates excellent potential to tackle SAR RFI problems.