Correlations of Spectral Intensity Fluctuations: Application to RFI mitigation
Avinash A. Deshpande, Arecibo Observatory/NAIC and Raman Research Institute
This paper describes a technique involving correlations between fluctuations in spectral intensities. When applied to intensity data available as a function of time and frequency, the result can be viewed in form of a correlation map, wherein the temporal correlation between fluctuations in every possible pair of spectral channels is represented. Such a correlation map, in addition to serving as a useful diagnostic tool for the measuring system itself, offers a wealth of information on spectral channels affected by RFI and inter-modulation, if any. Although such estimations are inherently less sensitive as compared to those from voltage-correlations, the technique promises much broader applicability given that the necessary intensity data are more commonly available. The strengths and weaknesses of this technique relevant to RFI mitigation are discussed, and are illustrated with real-life examples. An extension of such an analysis to polarization data is explored, and the results are discussed.