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A NIST Disciplined Oscillator



Michael A. Lombardi


The National Institute of Standards and Technology (NIST) now offers a service that provides customers with an oscillator locked to UTC(NIST), the United States national standard for frequency and time. A NIST disciplined oscillator (NISTDO) works by utilizing both the Internet and common-view observations of Global Positioning System (GPS) satellites, and can serve as the primary frequency and time standard for a calibration or metrology laboratory. NISTDOs are directly referenced to the Coordinated Universal Time scale kept at NIST, known as UTC(NIST). This makes it easy for laboratories to establish traceability to the International System (SI) directly through NIST. Customers are provided with standard frequency outputs of 5 MHz and/or 10 MHz, as well as 1 pulse per second timing outputs. These outputs provide time accurate to within about ±20 ns (peak-to-peak variation) with respect to UTC(NIST) and provide frequency with an uncertainty near 5 × 10-14 when averaged over a 24-hour interval. This paper discusses the theory of operation of the NISTDO, and demonstrates the accuracy and stability of the device over both short and long time intervals.
Proceedings Title
21st Century Innovations in Metrology
Conference Dates
July 25-29, 2010
Conference Location
Providence, RI
Conference Title
Proc. 2010 NCSLI International Workshop and Symposium


disciplined oscillator, GPS, Internet, time scale, time transfer


Lombardi, M. (2010), A NIST Disciplined Oscillator, 21st Century Innovations in Metrology, Providence, RI, [online], (Accessed May 26, 2024)


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Created July 26, 2010, Updated February 19, 2017