GLONASS: As Good As It Should Be?

Elizabeth Rooney, Andrew Last

Abstract:	GLONASS system performance will be assessed on two levels: availability and integrity. The system has a num-ber of limitations although many of these are outside the control of the GLONASS system, for example funding problems and the structure of the regional ground seg-ment. However, this paper will discuss failures of the system to meet expected levels of service within these in-herent constraints. An analysis of the system availability, both before and after the latest launch in December 1998, will be carried out and the dramatic impact of the new satellites on the system's performance will be illustrated. Predictions will be made on the future availability of the GLONASS sys-tem taking into account the expected lifetimes of the cur-rent operational satellites. System integrity relies on Notice Advisories to GLONASS Users (NAGUs) to notify users of satellite outages and other events that have an impact on the sys-tem's availability. These notices have been used to derive availability figures for individual GLONASS satellites. In addition, it will be shown that NAGU reporting is not as reliable as it should be. Most NAGUs take the form of Advisories that inform the user of an outage after it has occurred. On rare occasions satellite outages have been forecast in advance. It will be shown that these forecast outages are associated with sat-ellite eclipses and could be a manifestation of a design flaw on GLONASS satellites.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1363 - 1368
Cite this article:	Rooney, Elizabeth, Last, Andrew, "GLONASS: As Good As It Should Be?," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1363-1368.
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