GLONASS Operations, 1999-2000

Gerald L. Cook and Elie Accad

Abstract:	Difficulties facing the GLONASS constellation continued to grow this year as six satellites were decommissioned. Presently, ten satellites of the 24-satellite constellation are listed operational, but only eight of those are transmitting. Only one launch has taken place in the last 4½ years, and seven of the ten satellites listed operational are over their design lifetime. The trend of the aging constellation is toward poorer accuracy and availability. Decreased maintenance may contribute to the trend. Frequent data dropouts (satellite message data zeroed out), and occasional integrity lapses (bad satellite marked healthy) continue to plague the system. Based on almanac data there may have been ground segment software upgrades installed in late December to prepare for the Y2K rollover. On 1 January 2000, two of the satellites transmitted incorrect ephemeris data for a number of hours while marked healthy. The incorrect data caused user range errors of thousands of kilometers. This apparent Y2K problem was solved by the next day.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	366 - 367
Cite this article:	Cook, Gerald L., Accad, Elie, "GLONASS Operations, 1999-2000," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 366-367.
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