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WWV Transmitter Building (2002 or earlier) WWV's 15 MHz antenna WWV is a shortwave ("high frequency" or HF) radio station, located near Fort Collins, Colorado.It has broadcast a continuous time signal since 1945, and implements United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, 20, and 25 MHz. [1]
WWVB's Colorado location makes the signal weakest on the U.S. east coast, where urban density also produces considerable interference. In 2009, NIST raised the possibility of adding a second time code transmitter, on the east coast, to improve signal reception there and provide a certain amount of robustness to the overall system should weather or other causes render one transmitter site ...
An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels . Electron states in an atom are associated with different energy levels, and in transitions between such states they interact with a very specific frequency of electromagnetic radiation .
A modern LF radio-controlled clock. A radio clock or radio-controlled clock (RCC), and often colloquially (and incorrectly [1]) referred to as an "atomic clock", is a type of quartz clock or watch that is automatically synchronized to a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock.
The signal, also known as the MSF signal (and formerly the Rugby clock), is broadcast at a highly accurate frequency of 60 kHz and can be received throughout the UK, and in much of northern and western Europe. The signal's carrier frequency is maintained at 60 kHz to within 2 parts in 10 12, controlled by caesium atomic clocks at the radio ...
Caesium Beam Atomic Clock [18] [19] Cs Hong Kong Observatory; Tsim Sha Tsui, Hong Kong ... 5 × 10 −13: National Standard Time and Frequency Laboratory; Taoyuan, ...
Time signals were generated from the observatory's own pendulum clocks. The transmitter oscillators were condenser-tuned and so frequency stability was not high until quartz crystal control was implemented in 1933. In 1938, the call was changed to CHU, operating on frequencies of 3.33, 7.335 and 14.67 MHz, at a transmitter power of only 10 W.
Radio time signal stations broadcast the time in both audible and machine-readable time code form that can be used as references for radio clocks and radio-controlled watches. Typically, they use a national or regional longwave digital signal; for example, station WWVB in the U.S. .