Evaluation of GPS Architecture for High Altitude Spaceborne Users

Thomas D. Powell, William A. Feess and Michael D. Menn

Abstract:	Future spaceborne applications of GPS will include an increasing number of users at altitudes above the GPS con-stellation. A number of space segment architecture changes have been suggested to enhance performance for this class of user. This study examines the effects of various GPS satellite architectures and user processing options on the ac-curacy of high altitude orbit determination using GPS. It is part of a larger effort to establish the value and cost of sug-gested GPS upgrades. Error analyses of high altitude GPS users were con-ducted via Monte Carlo simulation. Several GPS broad-cast antenna configurations and user clock choices were ex-amined. The GPS antennas considered were the II-A main beam, II-R main beam, UHF crosslink (or widened main beam), and an omnidirectional back-side antenna combined with either the II-A or II-R main beam. The user clocks simulated were a standard crystal, an improved crystal and a standard atomic clock. Each antenna option was consid-ered in combination with each simulated user clock. In ad-dition, the impact of various propagation model simplifica-tions were examined. Each scenario was evaluated using position error statistics from the simulated onboard Kalman filter. The goal of this study is to assess the potential navigation performance of future GEO users of GPS under a number of optional enhancements to the GPS satellites and user equip-ment.
Published in:	Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998) June 1 - 3, 1998 The Adams Mark Hotel Denver, CO
Pages:	157 - 165
Cite this article:	Powell, Thomas D., Feess, William A., Menn, Michael D., "Evaluation of GPS Architecture for High Altitude Spaceborne Users," Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998), Denver, CO, June 1998, pp. 157-165.
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