RFI detection by automated feature extraction and statistical analysis

Abstract

In this paper we present an interference detection toolbox consisting of a high dynamic range Digital Fast-Fourier-Transform spectrometer (DFFT, based on FPGA-technology) and data analysis software for automated radio frequency interference (RFI) detection. The DFFT spectrometer allows high speed data storage of spectra on time scales of less than a second. The high dynamic range of the device assures constant calibration even during extremely powerful RFI events. The software uses an algorithm which performs a two-dimensional baseline fit in the time-frequency domain, searching automatically for RFI signals superposed on the spectral data. We demonstrate, that the software operates successfully on computer-generated RFI data as well as on real DFFT data recorded at the Effelsberg 100-m telescope. At 21-cm wavelength RFI signals can be identified down to the 4-sigma level. A statistical analysis of all RFI events detected in our observational data revealed that: (1) mean signal strength is comparable to the astronomical line emission of the Milky Way, (2) interferences are polarised, (3) electronic devices in the neighbourhood of the telescope contribute significantly to the RFI radiation. We also show that the radiometer equation is no longer fulfilled in presence of RFI signals.

12 pages, 16 figures, accepted for publication in Astron. Notes

References in corpus (4)

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• Radio Frequency Interference Mitigation based on the ArPLS and SumThreshold Method
• A new approach to mitigation of radio frequency interference in interferometric data
• A LOFAR RFI detection pipeline and its first results
• A FPGA-based Fast Converging Digital Adaptive Filter for Real-time RFI Mitigation on Ground Based Radio Telescopes
• Two procedures to flag radio frequency interference in the UV plane
• Interference detection in gaussian noise
• The Robustness of Least-Squares Frequency Switching (LSFS)
• Data reduction strategy of the Effelsberg-Bonn HI Survey (EBHIS)