Analysis of Radio Frequency Interference Detection Algorithms in the Angular Domain for SMOS

Radio frequency interference (RFI) detection techniques have different challenges and opportunities for interferometric radiometers such as the Microwave Imaging Radiometer using Aperture Synthesis on the Soil Moisture and Ocean Salinity (SMOS) mission. SMOS does not have highly oversampled temporal resolution or subband filters for oversampled spectral resolution, as do other radiometers with enhanced RFI detection capabilities. It does, however, have multisampled angular resolution in the sense that a single location is viewed from many different angles of incidence. This paper compares and contrasts RFI detection algorithms that use measurements made at a variety of different levels of SMOS signal processing, including the visibility domain, brightness temperature spatial domain, and brightness temperature angular domain. The angular domain detection algorithm, in particular, is developed and characterized in detail. Examples of the algorithms applied to cases with RFI (to assess detection skill) and without RFI (to assess false-alarm behavior) are considered.