Single Frequency GPS Orbit Determination For Low Earth Orbitors

Willy Bertiger and Sien-Chong Wu

Abstract:	A number of missions in the future are planning to use GPS for precision orbit determination. Cost considerations and receiver availability make single frequency GPS receivers attractive if the orbit accuracy requirements can be met. To put a real bound on orbit accuracy at a 700 km altitude, GPS data from the GPS/MET experiment on MicroLab I are processed as single frequency data. The GPS/MET experiment has a flight TurboRogue receiver on-board making dual-frequency GPS measurements at an altitude of 715 km. The antenna is not zenith pointing, but points off to the side. Orbits computed with the dual-frequency data have an RMS component accuracy of better than 5 cm in the radial and cross track components and better than 10 cm in the along track component as indicated by orbit overlaps and can be used as truth orbits for evaluating the single-frequency determined orbits. Single- frequency orbits for GPS/MET have an accuracy of better than 25 cm in radial and cross track components and better than 70 cm in the along track component. GPS/MET is not completely representative of all the possible flight scenarios. Its observing geometry is probably poorer and the data set selected was taken close to a minimum solar cycle resulting in less drag and lower ionosphere errors. Some of these other conditions are examined with covariance and simulation analyses. At the 700 km altitude, covariance and simulation show that orbital accuracy at the 20 cm level in radial and cross track components and 50 cm in along track is obtainable with a 10 channel single frequency receiver.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	463 - 473
Cite this article:	Bertiger, Willy, Wu, Sien-Chong, "Single Frequency GPS Orbit Determination For Low Earth Orbitors," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 463-473.
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