Implementation and Evaluation of GPS/GLONASS RAIM

Natasha Norris, Frank van Graas, Eric Vinande

Abstract:	Current aviation primarily utilizes the GPS constellation for aircraft navigation; however, the aviation community plans to utilize additional GNSS constellations as more constellations become available with guaranteed performance standards. As a result, multi-constellation airborne navigation requires changes to Receiver Autonomous Integrity Monitoring (RAIM), first approved for aviation in 1992 [1], based on Minimum Operational Performance Standards (MOPS) developed by RTCA, Inc. [2]. RAIM utilizes redundant signals to detect a single-satellite fault, and it may exclude the malfunctioning satellite from the navigation solution using Fault Detection and Exclusion (FDE) methods. The probabilities, detection thresholds and performance of RAIM are designed to support en route, terminal and lateral navigation (LNAV) phases of flight with GPS. Recently, RTCA, Inc. published MOPS for the use of two satellite constellations, GPS and GLONASS, for en route, terminal, and LNAV phases of flight [3]. Though airborne navigation may benefit in terms of accuracy, continuity, integrity, and availability from multi-constellation navigation, it comes at the cost of an increased number of fault modes and resulting algorithm complexity. This paper proposes a fault detection and exclusion algorithm for a combined GPS and GLONASS position solution. GPS and GLONASS signals collected during flight testing are used to demonstrate the performance of the algorithm for en route, terminal, and LNAV phases of flight. The algorithm implements the integrity requirements outlined in the GPS/GLONASS MOPS [3] using the principles of the solution separation method [4]. The algorithm is tested against multiple simulated faults associated with multi-constellation navigation. New developments in this paper include a logic diagram to process the seven fault modes for the GPS/GLONASS solution, as well as an implementation of the solution separation method to handle multiple fault modes.
Published in:	Proceedings of the 2019 International Technical Meeting of The Institute of Navigation January 28 - 31, 2019 Hyatt Regency Reston Reston, Virginia
Pages:	802 - 815
Cite this article:	Norris, Natasha, van Graas, Frank, Vinande, Eric, "Implementation and Evaluation of GPS/GLONASS RAIM," Proceedings of the 2019 International Technical Meeting of The Institute of Navigation, Reston, Virginia, January 2019, pp. 802-815. https://doi.org/10.33012/2019.16725
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