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Session B6: Aviation and Aeronautics

GNSS Radio Frequency Interference Mitigation in Collins Commercial Airborne Receivers
Angelo Joseph, Joseph Griggs, Patrick Bartolone, Bernard Schnaufer, Huan Phan, Vikram Malhotra, Collins Aerospace
Date/Time: Friday, Sep. 15, 2:35 p.m.

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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. The advent of modernized dual-frequency and multi-constellation signals which include features such as higher signal power, FEC encoding, pilot signals and navigation message authentication will improve the availability and integrity of GNSS receiver in the presence of RFI. To be further resilient to the various types of RFI threats, the airborne GNSS receiver will need to perform additional receiver-based detection/mitigation techniques and should be able to determine position integrity in the presence of spoofers. This paper aims to present the solutions envisaged by Collins Aerospace to improve the resilience of its equipment (such as the GLU-2100 multi-mode receiver) to RFI threats such as jammers and spoofers. This paper focuses 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. The paper will describe the overall RFI mitigation architecture that is implemented on the GLU-2100. Further, the paper will provide a brief description of the RASA and SENTRI algorithms, followed by results from both simulation and real-world tests. Finally, the limitations of the algorithms will also be provided.

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