ON-ORBIT FREQUENCY STABILITY ANALYSIS OF GPS NAVSTAR CESIUM AND RUBIDIUM CLOCKS

Thomas B. McCaskill, James A. Buisson, Tammy J. Hogan

Abstract: Naval Research Laboratory (NRL) on orbit analysis of GPS NAVSTAR cesium and rubidium clocks has been performed using a three-year database that extended from 1 Jan., 1986 to $1 Dec., 1988. The NAVSTAR clock offset measurements were computed from pseudo-range data observed using a single frequency GPS receiver. Time and frequency inputs were derived from the U.S. Naval Observatory (USNO) time ensemble, Orbital data was obtained from the NAVSTAR broadcast ephemeris. A key feature of the NRL NAVSTAR clock analysis is the capability to analyze phase and frequency discontinuties, solve for the discontinuity, and correct the clock data. This feature was developed primarily as a means to solve and correct for the NAVSTAR time or frequency adjustments that are required to keep NAVSTAR clock time close to GPS time. Discontinuties are analyzed to find both the amount, and the probable cause for the break. This feature makes possible the use of sample times of 100-days or more, and the analysis of data to identify and model long term clock, system, and environmental effects. Results for this NAVSTAR clock analysis will include the presentation of clock offset, frequency offset, and aging as a function of time.
Published in: Proceedings of the 21th Annual Precise Time and Time Interval Systems and Applications Meeting
November 28 - 30, 1989
Sheraton Hotel
Redondo Beach, California
Pages: 239 - 258
Cite this article: McCaskill, Thomas B., Buisson, James A., Hogan, Tammy J., "ON-ORBIT FREQUENCY STABILITY ANALYSIS OF GPS NAVSTAR CESIUM AND RUBIDIUM CLOCKS," Proceedings of the 21th Annual Precise Time and Time Interval Systems and Applications Meeting, Redondo Beach, California, November 1989, pp. 239-258.
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