A Study of Real Time Orbit Determination for the Extreme Ultraviolet Explorer

Kenn Gold, Willy Bertiger, Tom Yunck, Sien Wu, Ron Muellerschoen, George Born and Kristine Larson

Abstract:	A single frequency GPS receiver was launched with the Extreme Ultraviolet Explorer (EUVE) mission in the summer of 1992. The low altitude of the EUVE, the placement of dual antennas directly on the spacecraft body, and the Ll-only capability of the flight receiver allowed a unique opportunity to investigate error sources affecting real-time GPS spacecraft navigation and the level of accuracy obtainable. GPS data sets from several different periods were processed at the Jet Propulsion Laboratory with the GIPSY-OASIS II data analysis software. Data from EUVE and from a global network of Rogue and Turbo Rogue GPS receivers were processed together to eliminate the effects of selective availability and reduce other errors. Methods for removing ionosphere delay error from the single frequency data -and for reducing the effects of dynamic model error were also used to provide differen- tial GPS-based orbit solutions for EUVE, which are accurate to the meter level. In addition, orbit solutions were generated with a simulated real-time strategy and compared to the precise differential solutions. The real-time solutions used only the GPS data from the EUVE flight receiver, were gener- ated with simplified dynamical models for EUVE, and were not smoothed. Data were analyzed from periods with and without SA active. Different estimation strategies and techniques were developed that resulted in orbits that agree with the reference solutions to lo-15 m rms even in the presence of SA. Real time filtering scenarios involving single frequency ionosphere calibration techniques, and reduced dynamic filtering strategies were investigated. Reduced dynamic techniques were used to minimize errors resulting from the simplified EUVE dynamical models, such as the high frequency errors arising from gravity field truncation. Solutions were generated with various stochastic attributes for the EUVE clock, and with other parameters used to reduce the effects of SA.
Published in:	Proceedings of the 1994 National Technical Meeting of The Institute of Navigation January 24 - 26, 1994 Catamaran Resort Hotel San Diego, CA
Pages:	625 - 634
Cite this article:	Gold, Kenn, Bertiger, Willy, Yunck, Tom, Wu, Sien, Muellerschoen, Ron, Born, George, Larson, Kristine, "A Study of Real Time Orbit Determination for the Extreme Ultraviolet Explorer," Proceedings of the 1994 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1994, pp. 625-634.
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