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



Michael A. Lombardi, A.P. Dahlem


This paper introduces a new device, a prototype common-view disciplined oscillator (CVDO) that can be locked to a remote 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 standard serial interface. In principle, the rubidium oscillator can be locked to any time scale that makes real-time common-view data available on the Internet. 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, and 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.
Proceedings Title
Proc. 2008 PTTI Conf.
Conference Dates
December 1-4, 2008
Conference Location
Reston, VA


common-view, disciplined oscillator, time scale, traceability


Lombardi, M. and Dahlem, A. (2008), Locking a Rubidium Oscillator to a Remote Time Scale Using Real-Time Common-View GPS Measurements, Proc. 2008 PTTI Conf., Reston, VA, [online], (Accessed April 15, 2024)
Created December 1, 2008, Updated February 19, 2017