Characterization and Mitigation of Radio Frequency Interference Signatures in L-Band LuTan-1 InSAR System: First Results and Assessment

The LuTan-1 satellite is the first Chinese, L-band, distributed, spaceborne interferometric synthetic aperture radar (InSAR) mission. However, the presence of radio frequency interference (RFI) in the L-band poses a significant threat to obtaining a high-quality digital elevation model (DEM) and deformation monitoring. This paper provides a first investigation and assessment of the RFI issues in the operational LuTan-1 InSAR system. The RFI environments are analyzed from the status of frequency allocation. The mathematical model of interference in InSAR image pairs is derived and discussed the variation of interferometry coherence under different imaging modes. Furthermore, this paper proposes an automatic processing pipeline of RFI detection and mitigation for the LuTan-1 ground processing system, which is efficient for dealing with massive images without tuning hyperparameters. Extensive experimental results on diverse scenes in LuTan-1 real measured data with different RFI cases are provided, including the single-pass, repeat-pass, and full polarization modes. Experimental results verify that the proposed detection and mitigation scheme could effectively eliminate the RFI artifacts, enhance the image quality, and improve the interferometric coherence. The proposed RFI detection and mitigation scheme has been successfully incorporated into the LuTan-1 ground processing pipeline.