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ABOUT US
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Naval Oceanography One Pager
End of Year Graphic 2022
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Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
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International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
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United States Naval Observatory
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Home
Our Commands
United States Naval Observatory
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
ABOUT US
Mission & Vision
History
Naval Oceanography One Pager
End of Year Graphic 2022
LEADERSHIP
Commander
Technical Director
Command Master Chief
All Leadership
OUR COMMANDS
Naval Oceanographic Office
Fleet Numerical Meteorology & Oceanography Center
United States Naval Observatory
News from the Naval Observatory
Earth Orientation Department
Precise Time Department
The USNO Master Clock
The USNO Master Clock
Time Dissemination at the USNO
USNO Alternate Master Clock (AMC)
Cesium Atomic Clocks
Hydrogen Masers at the USNO
Rubidium Fountain Clocks
USNO Time Scales
International Time Scales and the BIPM
Definitions of Systems of Time
Global Positioning System
Global Positioning System Overview
USNO GPS Data Categories Explanation
CGGTTS Data Format
USNO GPS Time Transfer
Leap Seconds
GPS Information: SA, DGPS, Leap Seconds, etc.
GPS Week Number Rollover
GPS Timing Data and Information
USNO Format Explanation
USNO Computer Display Clocks
Two-Way Satellite Time Transfer (TWSTT)
Telephone Time
Network Time Protocol (NTP)
US Eastern Time Zone NTP Servers
US Mountain Time Zone Servers
DoD Customer Servers
Astronomical Applications Department
Celestial Reference Frame Department
Senior Enlisted Advisor
Careers at the USNO
Naval Oceanography Operations Command
Fleet Weather Center - Norfolk
National Ice Center
Fleet Weather Center - San Diego
Joint Typhoon Warning Center
Naval Oceanography Anti-Submarine Warfare Center
Navy DoD Supercomputing Resource Center
PRESS ROOM
News Stories
Photo Gallery
Video Gallery
Public Use of Limitations
CONTACT US
USNO Alternate Master Clock (AMC)
The U.S. Naval Observatory Alternate Master Clock (USNO AMC) is located at Schriever Space Force Base near Colorado Springs, Colorado, on the same site as the
Global Positioning System (GPS)
Master Control Station.
The USNO AMC is a facility which was designed and implemented to better fulfill our responsibilities for providing the best quality and most precise time to the Department of Defense and the nation. The USNO AMC is capable of independent performance of the basic USNO Washington, DC, timing mission in any event requiring it to perform autonomously. The stated requirement at full operational status is to keep the USNO AMC within 2 to 3 nanoseconds of our primary Master Clock at the USNO in Washington, DC. The full operational specifications have been fulfilled since MJD 50250 (15 June 1996).
This installation houses three
hydrogen masers
,
twelve
cesium-beam
frequency standards, two
rubidium fountain clocks
, their associated measurement and distribution systems, and several GPS time transfer receiver systems. Although the purpose of the AMC is to provide precise time in the event of a catastrophic failure of the USNO Master Clock in Washington, DC, its role has expanded to include providing precise time to the
Global Positioning System
operated from Schriever AFB.
Synchronization to the Washington Master Clock, at the nanosecond (billionth of a second) level, is achieved via
Two Way Satellite Time Transfer
.
The AMC is also providing time over the Internet using
Network Time Protocol
, over
modems
, and by
telephone voice announcer
.
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