User Range Error and Frequency Standard Performance for the First Block II Satellite

Bruce R. Hermann, M. Wendel Gouldman, Everett R. Swift

Abstract:	Performance testing of the first Block II satellite (NAV14/PRN14) of the Global Positioning System began on 20 March 1989. The Naval Surface Warfare Center computed User Range Errors (URE) for NAV14/PRN14 based on broadcast messages and tracking data collected at six globally distributed sites: the five dedicated GPS tracking sites operated by the Defense Mapping Agency and the GPS tracking site at Dahlgren, Virginia. The URE computations provide a means of quantifying the quality of the broadcast ephemeris and clock. Excepting the periods immediately following orbit maneuvers, the results of the URE show that the broadcast ephemeris and clock prediction for NAV14/PRN14 were within the limits required by Operational Control Segment specifications. The frequency standard stability for the first GPS Block If satellite is analyzed by computing Allan variances, based on the precise clock file estimates generated at the Naval Surface Warfare Center for distribution by the Defense Mapping Agency. Hourly estimates of the offsets between satellite time and GPS time are computed along with the precise orbits. Though the clock estimates are generated in independent overlapping eight­ day fits, they can be joined together to produce a satellite clock performance history of indefinite length.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	21 - 27
Cite this article:	Hermann, Bruce R., Gouldman, M. Wendel, Swift, Everett R., "User Range Error and Frequency Standard Performance for the First Block II Satellite," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 21-27.
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