RFI Mitigation/Excision techniques

Radio frequency interference (RFI) is increasingly affecting radio astronomy research. A few years ago, active research to investigate the possibility of observing in the presence of interference using RFI mitigation techniques was initiated. In this paper, I briefly discuss four RFI mitigation/excision projects. These projects are: (1) A technique to suppress double sideband amplitude modulated interference using which I show that an astronomical signal in the presence of a DSB interference can be observed with a signal-to-noise ratio a factor of 2 less compared to observations if the RFI were not present. (2) Techniques to suppress interference due to synchronization signals in composite video signals are presented. A combination of noise-free modeling of the synchronization signals and adaptive filtering is used for suppressing the interference. (3) Design techniques to minimize spurious pick-up at the analog input of an Analog-to-digital converter are discussed. (4) Spectral RFI excision using a spectral channel weighting scheme and its application to Green Bank Telescope observations are also presented.