Locking a Rubidium Oscillator to a Remote Time Scale Using Real-Time Common-View GPS Measurements

Michael A. Lombardi and Aaron P. Dahlen

Abstract:	This paper introduces a new device, a prototype common-view disciplined oscillator (CVDO) that can be locked to a reference time scale through the use of real-time common-view GPS measurements. A Proportional-Integral-Derivative (PID) controller is used to discipline the oscillator. The PID controller obtains real-time common-view GPS measurements from the Internet at 10-minute intervals, and provides steering corrections to a rubidium oscillator through a serial interface. In principle, the rubidium oscillator can be locked to any time scale that makes real-time common-view data available. The paper describes the theory of operation of the prototype CVDO, including a description of the PID controller software. It then presents measurements obtained from a CVDO locked to UTC (NIST), the time scale maintained at the National Institute of Standards and Technology (NIST) in Boulder, Colorado. The paper also describes how a CVDO can emulate other time scales. Results are presented where a CVDO prototype is locked to a time scale located outside of the United States, and then UTC (NIST) is compared to both the original time scale and to the time scale emulator. The paper concludes by discussing some possible applications of CVDOs in metrological and telecommunication areas.
Published in:	Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 4, 2008 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	527 - 542
Cite this article:	Lombardi, Michael A., Dahlen, Aaron P., "Locking a Rubidium Oscillator to a Remote Time Scale Using Real-Time Common-View GPS Measurements," Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 2008, pp. 527-542.
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