The impact of uninformed RF interference on GBAS and potential mitigations

RF interference (RFI) has been and will continue to be a significant worry for GNSS users. This paper introduces several different types of RFI, categorizes them based upon the intent (if any) of the RFI transmitter, and then examines a relatively new and growing source of RFI: Personal Privacy Devices (PPDs) that aim to prevent people and vehicles from being tracked by GNSS within a limited area. Unfortunately, signals from PPDs are not well-controlled and can interfere with GNSS receivers several hundred meters away. The impact of PPDs on the GBAS reference station site at Newark Airport, New Jersey and the WAAS reference station at Leesburg, Virginia are illustrated. While GBAS ground station monitoring prevents PPDs from posing a significant integrity threat, PPDs can force the sudden loss of service and thus harm continuity and availability. The hardware and software modifications made to the Newark GBAS installation to reduce this impact are described, and the future benefits of more-flexible ground-station siting and GNSS modernization are also identified.