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The Use of GPS Disciplined Oscillators as Primary Frequency Standards for Calibration Laboratories



Michael A. Lombardi


Many calibration and testing facilities now employ a Global Positioning System disciplined oscillator (GPSDO) as their primary frequency standard. GPSDOs have the advantage of being much less expensive than cesium oscillators, and in theory, serve as "self-calibrating" standards that should not require adjustment or calibration. This makes them an attractive choice for many laboratories. However, there are some performance characteristics that make a GPSDO less suitable for some applications than a cesium. This paper explores the use of GPSDOs in calibration laboratories. It discusses how GPSDOs work, how measurement traceability can be established with a GPSDO, and how their performance can vary significantly from model to model. It also discusses possible GPSDO failure modes, and why a calibration laboratory needs to be able to verify whether or not a GPSDO is working properly.
Proceedings Title
Proc. NCSLI Conf.
Conference Dates
August 3-7, 2008
Conference Location
Orlando, FL


calibration, frequency, GPS, traceability, uncertainty


Lombardi, M. (2008), The Use of GPS Disciplined Oscillators as Primary Frequency Standards for Calibration Laboratories, Proc. NCSLI Conf., Orlando, FL, [online], (Accessed April 12, 2024)
Created August 4, 2008, Updated February 17, 2017