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NIST GPS Data Archive
The Global Positioning System (GPS) is a radionavigation system that is available worldwide. GPS signals are broadcast from a constellation of 24 or more earth orbiting satellites. Because the GPS signals are derived from atomic frequency standards on board each satellite, they are widely used as a reference for time synchronization and frequency calibration. NIST provides this archive so that you can quickly check the frequency and time status of the GPS satellites on any given date.
NIST continuously monitors the GPS signals from Boulder, Colorado by comparing the frequency standard onboard each satellite to the NIST frequency standard. Many applications rely on GPS receivers that provide a 1 pulse per second (pps) timing output, or a frequency output, such as 5 or 10 MHz, that is disciplined to agree with the GPS signal. GPS disciplined oscillators can be used to establish traceability to the national time and frequency standards maintained by NIST, and the data available here can help support claims of measurement traceability.
To view the data, simply select the month, day, and year, and then click the "Get Data" button. The archive is only updated once every 24 hours, so data are not available for today's date. Data from the previous day are added to the archive at about 1600 UTC.
The following papers contain more information about GPS measurements and establishing measurement traceability to NIST: