Investigation of Spatial and Temporal RFI Events Distribution within the Swiss Airspace

Maurizio Scaramuzza, Marc Troller, Marc Bertschi, Heinz Leibundgut

Abstract:	Airplanes and helicopters operating under Instrument Flight Rules(IFR) increasingly rely on GNSS as a primary means of navigation. Hence, GNSS has become an essential as well as safety critical element within the aviation system. As GNSS signals only have low power at the receiver antenna, interfering these signals is relatively simple and also possible with low power signals. This is why stringent requirements are laid down by International Civil Aviation Organization (ICAO) and other organizations on the use of the GNSS Signal in Space (SIS). Due to the nature of low power Radio Frequency Interference (RFI) signals, the zone of influence is often limited to a radius of a few hundred meters to kilometers. In addition, a receiver bound to the earth surface might not be affected by a close RFI source due to signal obstructions such as buildings or terrain. This fact makes it more difficult to detect and locate RFI through ground-based systems. The situation of an aerial vehicle is different in the sense, that the probability of RFI exposure is higher when flying close to the terrain. This downside can be exploited to an advantage with focus on RFI detection. In [1] a new method was presented on how the RFI situation can be assessed over a large region and during a long period. The advantage of applying this detection method on helicopters during daily missions is, that a large area such as the entire country of Switzerland, is covered. Over 20’000 hours of flight data within the period of 2014 to 2018 were recorded and investigated on the presence of RFI. This unique dataset allows to assess the probability of RFI exposure of helicopters in Switzerland. Furthermore, due to the extension of the assessed area, dependencies between RFI exposure and terrain structure, i.e. flatland to mountainous region, is analyzed. Analogously, dependencies of RFI exposures on infrastructures are derived. Based on the large amount of data RFI events against time of day and day of week are assessed.
Published in:	Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019 Hyatt Regency Miami Miami, Florida
Pages:	1392 - 1400
Cite this article:	Scaramuzza, Maurizio, Troller, Marc, Bertschi, Marc, Leibundgut, Heinz, "Investigation of Spatial and Temporal RFI Events Distribution within the Swiss Airspace," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 1392-1400. https://doi.org/10.33012/2019.16905
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