The U. S. Naval Observatory is charged with maintaining the DoD reference for Precise Time and Time Interval (PTTI).  That reference is UTC(USNO).

USNO Master Clock

The DoD common time reference is the U.S. Naval Observatory Master Clock.  It is generated at USNO in Washington, D.C. and at the Alternate Master Clock Facility at Schriever AFB in Colorado.

GPS

USNO monitors the GPS constellation and provides system timingoffsets to 2SOPS, timing data for individual GPS satellites, and timetransfer services using GPS.

Computer Display Clocks

USNO servers provide a wide variety of web-based time synchronizationproducts including embedded web clocks to display UTC(USNO) on otherweb pages.

TWSTT

The highest precision and accuracy in time dissemination is providedthrough Two-Way Satellite Time Transfer (TWSTT).  USNO providesoperational time transfer and calibration services for TWSTT.

Telephone Time

USNO provides both voice announcements of the time, and services to synchronize systems over telephone modems.

NTP

Network Time Protocol (NTP) is an Internet standard that enables client computers to synchronize to USNO.  NTP runs as a client program on a computer.