On-Orbit GPS RAFS Lamplight Variations: Statistics of Lamplight Jumps

Valerio Formichella, James Camparo, Patrizia Tavella

Abstract: In the rubidium atomic frequency standard (RAFS), an rf-discharge lamp produces the device’s atomic signal. As a consequence of the light-shift effect, variations in the lamplight’s intensity result in variations in the RAFS’ output frequency. While the basic physics of the light-shift is reasonably well understood, the temporal variations in the lamp’s light intensity are not. Here, we describe our analyses of lamplight intensity jumps occurring for the RAFS onboard GPS-IIR satellites. Briefly, we find that lamplight intensity jumps correspond to a compound Poisson process. The magnitude of the jumps appears to be a mean-zero random process with a family-wide standard deviation of 0.1%. The time between jumps corresponds to a Poisson process, and there appear to be two timescales associated with the jumps: a “fast” timescale, with a mean time between jumps of 7 days, and a “slow” timescale with a mean time between jumps of 180 days.
Published in: Proceedings of the 48th Annual Precise Time and Time Interval Systems and Applications Meeting
January 30 - 2, 2017
Hyatt Regency Monterey
Monterey, California
Pages: 291 - 298
Cite this article: Formichella, Valerio, Camparo, James, Tavella, Patrizia, "On-Orbit GPS RAFS Lamplight Variations: Statistics of Lamplight Jumps," Proceedings of the 48th Annual Precise Time and Time Interval Systems and Applications Meeting, Monterey, California, January 2017, pp. 291-298. https://doi.org/10.33012/2017.14972
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