La Crosse Technology WS-9210U User Manual
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ABOUT WWVB (Radio Controlled Time)
The NIST (National Institute of Standards and Technology—Time and Frequency Division)
WWVB radio station is located in Ft. Collins, Colorado and transmits the exact time signal
continuously throughout the United States at 60 kHz. The signal can be received up to 2, 000
miles away through the internal antenna in the weather station. However, due to the nature of
the earth’s ionosphere, reception is very limited during daylight hours. The weather station
will search for a signal every night when reception is best. The WWVB radio station derives
its signal from the NIST Atomic clock in Boulder, Colorado. A team of atomic physicists is
continually measuring every second, of every day, to an accuracy of ten billionths of a second
per day. These physicists have created an international standard measuring a second as
9,192,631,770 vibrations of a Cesium-133 atom in a vacuum.
For more information on WWVB and the atomic clock please see the NIST website at
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm.