Real-Time Characterization of the Collins GNSS RFI Mitigation Techniques in Flight and Lab Environments

Nowadays, commercial aeronautical GNSS receivers are more and more exposed to Radio Frequency Interference (RFI) threats from GNSS Jammers and Spoofers. Worldwide reports from air navigation service providers and Collins customers have confirmed that commercial airborne GNSS receiver products have been exposed to both jamming and spoofing. On commercial aircraft, GNSS receiver outputs are usually integrated or cross monitored with other navigation sensors such as IRS, DME etc. The type of integration and cross-monitoring varies based on the aircraft navigation system architecture. However, in many cases the GNSS receiver outputs are used directly by on-board aircraft systems. A case in point is the direct use of GNSS position outputs by aircraft transponders. Even in integrated systems there is still a need to validate that the raw GNSS measurements being provided to these systems are not impacted by Spoofers. In 2023 there was a particular increase in the number of jamming and spoofing incidents reported by commercial aircraft. A previous paper [14] by the same authors described the GNSS RFI mitigation techniques to be introduced in Collins Commercial Airborne receivers. That paper focused specifically on two techniques under development that will be incorporated via a field loadable software update to the Collins GLU-2100 multi-mode receiver. The first method, Receiver Autonomous Signal Authentication (RASA), uses the known characteristics of the GNSS receiver oscillator to detect if the received signals are from a Spoofer. A second technique, Staggered Examination of Non-Trusted Receiver Information (SENTRI), uses the inertial sensor data already available from the aircraft’s IRS/INS, to monitor the coherence between fully blended, partially blended and unblended solutions such as pure GNSS, pure inertial (INS) navigation solutions or tightly coupled inertial GNSS hybrid solutions without augmentation. SENTRI further allows the computation of position integrity levels (HPL and VPL) in the presence of GNSS spoofers. In this paper the advances made in those previously presented algorithms will be first presented and the overall receiver architecture will be described. Further the real-time characterization of those techniques in flight and lab test environments will be provided. The paper will describe in detail, the test methodology and environment that was developed by Collins to enable the generation of different types of Spoofers during real-time Flight and road tests in a repeatable fashion. Different classes of spoofers as defined in the DFMC MOPS ED-259B will be used to further characterize the receiver. A detailed discussion of the extensive flight test campaigns and their results will be provided. The paper will compare the behavior of the Collins RFI resilient receiver against other state-of-the-art GNSS receivers in flight and lab test environments.