Public access:The easiest method to access standard time is to listen to the news on radio. National radio news programs set their clocks to the transmissions from the National Institutes of Standards and Technology. U.S. Government atomic clocks are available to the public at <http://nist.time.gov/>; with a time-of day display accurate to about 0.3S. They also provide downloads of a program to set your computer's clock via the internet or a modem. If you lack a radio or computer, the clocks are also available by phone at 1-303-499-7111 (WWV) or 1-808-335-4363 (WWVH). GPS satellites each have a Caesium atomic clock on-board, rated from clocks on the ground. The time available on a GPS unit is exact, and some instrument-quality GPS units can serve as local time standards. The NIST clocks are also available on longwave radio, station WWVB at 60KHz (binary coded decimal only) at 30,000W, and by shortwave radio stations WWV (Fort Collins Colorado) and WWVH (Kekepa on Kauai, Hawaii) at 2.5, 5, 10 and 15 Mhz at 20,000W and 10,000W respectively. The variety of frequencies helps reception no matter what the ionospheric weather. A binary coded decimal transmission is made once per second, and on the shortwave stations, a computerized voice announcement is made every ten seconds. The radio frequencies are set by the clocks and are a precision standard, useful for adjusting receivers. The shortwave broadcast information also includes standard time intervals, UT1 time corrections, geophysical alerts (e.g. tsunami warnings), marine storm warnings, and Global Positioning System (GPS) status reports. |
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Below two sections are largely U.S.-centric. Public access:The easiest method to access standard time is to listen to the news on radio. National radio news programs set their clocks to the transmissions from the National Institutes of Standards and Technology. U.S. Government atomic clocks are available to the public at <http://nist.time.gov/>; with a time-of day display accurate to about 0.3S. They also provide downloads of a program to set your computer's clock via the internet or a modem. If you lack a radio or computer, the clocks are also available by phone at 1-303-499-7111 (WWV) or 1-808-335-4363 (WWVH). GPS satellites each have a Caesium atomic clock on-board, rated from clocks on the ground. The time available on a GPS unit is exact, and some instrument-quality GPS units can serve as local time standards. The NIST clocks are also available on longwave radio, station WWVB at 60KHz (binary coded decimal only) at 30,000W, and by shortwave radio stations WWV (Fort Collins Colorado) and WWVH (Kekepa on Kauai, Hawaii) at 2.5, 5, 10 and 15 Mhz at 20,000W and 10,000W respectively. The variety of frequencies helps reception no matter what the ionospheric weather. A binary coded decimal transmission is made once per second, and on the shortwave stations, a computerized voice announcement is made every ten seconds. The radio frequencies are set by the clocks and are a precision standard, useful for adjusting receivers. The shortwave broadcast information also includes standard time intervals, UT1 time corrections, geophysical alerts (e.g. tsunami warnings), marine storm warnings, and Global Positioning System (GPS) status reports. |
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