Approach, landing, take-off… many air travel manoeuvres we are familiar with depend on Global Navigation Satellite Systems (GNSS) to be successfully carried out. Yet GNSS can be subject to interferences, namely jamming, which can seriously degrade positioning accuracy, and spoofing, which can generate false position information. Both can have serious repercussions in terms of air traffic accuracy and even safety. With this situation in mind, the GATEMAN project set out to define and evaluate how these interferences could be effectively mitigated. GATEMAN was funded within the framework of the SESAR Joint Undertaking, a public-private partnership set up to modernise Europe’s air traffic management system. By designing an innovative threats management approach, the team behind GATEMAN developed a system designed to keep aircraft GNSS navigation running despite jamming and spoofing interferences.
Ground Control to Major Tom
As head of aeronautical systems, Luis Alvarez Antón, explains: “Our approach would keep aircraft GNSS navigation operative or – failing that – enable aircraft to use alternative positioning technology (such as 5G) to help them carry out GNSS-based flight procedures.” A whole range of measures was proposed, including filtering out threatening signals from the genuine GNSS signal, detecting the presence of interferences as well as the ability to revert to other means of positioning. Perhaps most important, GATEMAN would enable aircraft to accurately determine the location of the interference’s source, leaving competent authorities to neutralise the threat. In practice, jamming or spoofing signals would be detected by each individual aircraft by processing the signals received by their GNSS antennae. Two concepts were put forward to help locate the position of the interference signal emitter. The first, the autonomous concept, sees each aircraft calculating the location of the emitter. Secondly, the collaborative concept allows each aircraft to send information to a central ground facility that then calculates the emitter location with a higher accuracy.
No need to break the bank
“One of the goals of the GATEMAN project was to propose a solution that would involve minimal changes to the typical equipment and antennae layout of transport aircraft,” Alvarez Antón says. Currently, every transport aircraft mounts two GNSS antennae on top of the fuselage, and the GATEMAN concept only requires the addition of a third GNSS antennae to function. New avionics equipment would nevertheless have to be installed in order to process the signals received by the three GNSS antennae. Resorting to 5G as an alternative means of navigation is also cost-effective, as Alvarez Antón notes: “It minimises the need for the deployment of additional ground infrastructure to be funded by Air Navigation Service Providers (ANSPs) or other aviation stakeholders.”
The sky’s the limit
Conducting live experiments in the open field is complicated, not least because the generation of jamming and spoofing signals is illegal and requires authorisation from a government agency. Fortunately for the GATEMAN team, they were able to count on the cooperation of Spanish authorities to help them carry out their tests. With this part of the project under wraps since December 2019, the project is now on the lookout for new sources of funding to continue their research efforts.
GATEMAN, air navigation, GNSS, interference, aviation