Fault Detection and Exclusion Performance Using GPS and GLONASS

Karen Van Dyke

Abstract:	As the world transitions to GNSS for air navigation, issues of availability, reliability, and integrity need to be addressed. This paper examines a hybrid GPS/GLONASS system as a potential solution for these three critical issues. RTCA SC-1 59 is currently in the process of developing minimum operational performance standards (MOPS) for a GPS-based primary air navigation system. Working Group 5 of this committee has developed a baseline fault detection and exclmion (FDE) algorithm. However, since the algorithm performance parameters must be stringent for a system to serve as the primary means of navigation, GPS alone will not be able to satisfy the availability requirement. This is true even when all 24 satellites are operational and, of course, there will be periods of time when satellites are taken out of service for maintenance. Therefore, an augmentation to the system is required. Working Group 1 of RTCA SC-159 has been examining the use of GLONASS as an augmentation to GPS. /u&ysis of the baseline FDE algorithm has been performed to determine if a combined GPS/GLONASS system could sat@ availability requirements for a primary air navigation system. The results presented in this paper are based on work performed in support of the RTCA SC-159 GPS/GLONASS working group. These results demonstrate a substantial improvement in the availabiLity of integrity, even if only a partial GLONASS constellation were to be available. Satellites are removed from both constellations in order to simulate operation under worst case conditions. It appears that an integrated GPS/GLONASS system could meet the availability requirement for a primary means air navigation system, even when there are a munber of satellites out of setice. Availability results are provided for tieanic, domestic en route, terminal, and nonprecision approach phases of flight.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	241 - 250
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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