Analysis of air traffic control systems interference impact on Galileo aeronautics receivers

A GNSS receiver (GPS, Galileo) operating in a civil aircraft is exposed to the signals transmitted from ATC (air traffic control) surveillance sensors, aeronautical navigation systems and other non-aeronautical systems. The present study aims to investigate Galileo E5/L5 in-band and out-of-band interference due to some ATC systems (primary and secondary radars, and VOR, DME, ILS, and TACAN Navaids), in terms of SNR and accuracy degradation. We performed the analysis through both a theoretical approach and a simulations activity. Through the theoretical approach, we analyzed the interference effects expressing the results in terms of SNR degradation as a function of the aircraft-ATC systems distance. We discovered that if the GNSS receiver is covered within 3 dB beam width by the ATC system antenna, the interference in not negligible. For this reason, we analyzed the pulse blanking mitigation technique that is able to blank the interference with a negligible GNSS SNR degradation. In addition, exploiting the CNIT (National Interuniversity Telecommunication Consortium) Galileo simulator, opportunely modified, we analyzed the effects of the radar/Navaids interferences in terms of degradation of Galileo positioning accuracy, either with and without the mitigation process. The simulation activity has been performed considering a scenario closer to a real one, of an aircraft approaching Roma-Fiumicino airport. Both the theoretical analysis and the simulation activity is highlighted and the DME system effects on Galileo receivers could be disruptive without the application of the mitigation technique. The latter technique blanks all the interference effects with a simple algorithm and a limited increase in receiver complexity.