Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

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



Michael A. Lombardi


An increasing number of calibration and metrology laboratories now employ a Global Positioning System disciplined oscillator (GPSDO) as their primary standard for frequency. GPSDOs have the advantage of costing much less than cesium oscillators, and serve as "self-calibrating" standards that should not require adjustment or calibration. These attributes make them an attractive choice for many laboratories. However, a few of their characteristics can make a GPSDO less suitable than a cesium oscillator for some applications. 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 must be able to verify whether or not a GPSDO is working properly.
Measure: The Journal of Measurement Science


calibration, frequency, GPS, traceability, uncertainty
Created September 1, 2008, Updated February 17, 2017