NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Thomas P. Heavner, Stephan E. Barlow, Marc A. Weiss, Neil Ashby, Steven R. Jefferts
Abstract
NIST is in an initial phase of developing a prototype laser-cooled atomic frequency standard (AFS) for potential use in a future GPS system. The expected fractional frequency stability or Allan deviation, ςy(τ), will be 2x10-13 at one second, improving as the square-root of the averaging time to 7x10-16 at one day. This corresponds to an expected time dispersion of 0.060 ns at one day, or 0.02 m of user range error (URE). We discuss design and development process underway at NIST, as well as capabilities enabled by this AFS in GPS.
Heavner, T.
, Barlow, S.
, Weiss, M.
, Ashby, N.
and Jefferts, S.
(2011),
A Laser-Cooled Frequency Standard for GPS, Proceedings of the ION GNSS 2011 Conference, Portland, OR
(Accessed October 10, 2025)