Visibility and Geometry of Combined Constellations GPS with Health in Question, GLONASS and Galileo

Jacek Januszewski

Abstract:	fully operational with 29 satellites, Russian GLONASS system is not fully operational (16 satellites only), European Galileo system will be operational most likely in 2013. As there is very real possibility that in 2010 the old GPS satellites, block IIa in particular, begin to fail, and the number of GLONASS satellites will increase in 2010, the knowledge of visibility and geometry of these two systems and additionally of Galileo is very important for all users. That’s why the distributions (in per cent) of the number of satellites visible at different latitudes for different masking elevation angles and the distributions of GDOP coefficient at latitudes 50–60O for each number of GPS, GLONASS and Galileo satellites from interval [22,29], [18,24] and [24,30] respectively are presented in this paper. Additionally the minimal, maximal and weighted mean number of satellites of two systems (SI and SII), visible above Hmin, the distributions of the differences lSI – lSII for 6 selected constellations of two systems – 2 Galileo/GPS (30 & 30 and 24 & 22 satellites respectively), 2 GLONASS/GPS (24 & 30 and 24 & 22 satellites respectively) and 2 GLONASS/Galileo (24 & 30 and 18 & 24 satellites respectively) for different Hmin at different latitudes are showed. For Hmin = 5O the reduction of the number of GPS and Galileo satellites to 22 and 24 respectively allows to obtain 3D position at each latitude, in the case of GLONASS system it’s possible at latitudes greater than 50O only. In combined constellation of two systems the possibility of fix position for Hmin greater than 5O depends on the number of satellites of these systems and user’s latitude. I. INTROD
Published in:	Proceedings of the 2010 International Technical Meeting of The Institute of Navigation January 25 - 27, 2010 Catamaran Resort Hotel San Diego, CA
Pages:	1082 - 1094
Cite this article:	Januszewski, Jacek, "Visibility and Geometry of Combined Constellations GPS with Health in Question, GLONASS and Galileo," Proceedings of the 2010 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2010, pp. 1082-1094.
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