Jan-Willem W. Steeb, David B. Davidson and Stefan J. Wijnholds, "Mitigation of Non-Narrowband Radio Frequency Interference," URSI Atlantic Radio Science Conference (AT-RASC), Gran Canaria (Spain), 28 May - 1 June 2018.
The rapid development and implementation of wireless communication standards put increasing pressure on spectrum allocation and therefore threatens the efficacy of radio astronomy. For example, digital audio broadcasting (DAB) is a wide-bandwidth broadcast technology that is now being implemented and has spectrum allocated in the L band. A DAB signal using a 192 kbit/s codec requires 0.260 MHz per audio programme, which is slightly larger than the standard sub-band width of the Low Frequency Array LOFAR (0.195 MHz). We demonstrate that standard narrowband subspace subtraction methods may provide insufficient suppression of such signals. We therefore propose two algorithms that take into account the nonnarrowband nature of these signals. An experimental demonstration of the proposed algorithms both yielded an increase of approximately 2 times in the amount of bandwidth per channel that can be processed when compared to conventional narrowband techniques (for the same attenuation of the RFI signal). The performance of the two methods are identical for LOFAR station configurations with bandwidths between 763 Hz to 195 kHz.
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