A Comprehensive Trade Study on GPS Constellation Size and Number of Orbit Planes

P.D. Massatt, F.E. Fritzen, S.R. Scuro, K.M. O'Neill

Abstract:	The paper summarizes the results of several analyses performed by The Aerospace Corporation to assess the effect of constellation size and number of orbit planes (3 or 6) on GPS performance. Some of the trades include constellations varying in size from 21 to 36 satellites in both 3 and 6 orbit planes with up to 3 satellite failures. Other trades have focused primarily on 27- and 30- satellite constellations in both 3 and 6 orbit planes with failures up to two satellites. The measures of effectiveness include availability of accuracy, robustness of the constellation to satellite failure and downtime, and constellation management flexibility. These metrics are examined for their impacts on a variety of users, including users in urban environments, in mountainous terrain, and in foliage. The measures of effectiveness are also examined for military aviation users, civil aviation users, users relying upon Receiver Augmented Integrity Monitoring (RAIM) for integrity, and high accuracy users that perform in-receiver estimation of troposphere delay. The analyses include constellation management and replenishment issues, such as the ability of the constellations to support launching two satellites from a single booster (dual manifest), and the impact that a transition from six orbit planes to three orbit planes could have on user performance during the transition. This study was conducted in response to inquiries made by the GPS Independent Review Team and was sponsored by the Air Force Global Positioning Systems Wing of the Air Force Space & Missile Systems Center.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2139 - 2150
Cite this article:	Massatt, P.D., Fritzen, F.E., Scuro, S.R., O'Neill, K.M., "A Comprehensive Trade Study on GPS Constellation Size and Number of Orbit Planes," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2139-2150.
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