You are here: Home / USNO / Precise Time / TWSTT / Calibration Services
The USNO websites,,,,,, and are undergoing modernization efforts. The expected completion of the work and the estimated return of service is the first half of 2022, subject to change due to potential impacts of COVID-19.

Calibration Services

The USNO provides precise and accurate calibration services to remote users around the world. The services can range anywhere from a portable clock trip to setting up a mobile two-way satellite time transfer earth station and connecting directly to the frequency reference to be measured.

For more information on our precise and accurate operational two-way time transfer systems please contact us through our contact pages.  Select "TWSTT" as your subject in the contact form.

Pictured below is one of the USNO's portable earth stations.  The system is completely independent of external sources and includes an on-board cesium frequency standard.


TWSTT Calibration SUV


USNO Master Clock Time
Javascript must be Enabled