Further Test Results for Prototype GPS Rubidium Clocks

T.J. Lynch and W.J. Riley

Abstract:	This paper presents the results of further stability and qualification-level environmental tests on two prototype rubidium frequency standards for the GPS navigation satellite program. One unit was subjected to a 140-day thermovac stability retest that confirmed the efficacy of two improvements that reduce frequency drift and frequency and light intensity fluctuations. I The observed drift was -1.4 x 10^-14/day and the stability was 6 x 10^-14 at 10^5 seconds. This was accomplished by using an absorption cell made from glass having low helium permeability and a lamp having a lower (normal) rubidium fill. The other unit was successfully subjected to qualification levels of thermal, mechanical and EMI retesting. Several electrical, high temperature, and mechanical problems associated with the ovenized crystal oscillator were corrected. Improved design and filtering 1 of the control/monitor cable and power supply satisfactorily resolved several EMI problems.
Published in:	Proceedings of the 17th Annual Precise Time and Time Interval Systems and Applications Meeting December 3 - 5, 1985 DuPont Plaza Hotel Washington, DC
Pages:	145 - 156
Cite this article:	Lynch, T.J., Riley, W.J., "Further Test Results for Prototype GPS Rubidium Clocks," Proceedings of the 17th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1985, pp. 145-156.
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