11
WWVB RADIO CONTROLLED TIME
The NIST radio station, WWVB, 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 atomic clock. However, due to the
nature of the Earth’s Ionosphere, reception is very limited during daylight hours. The atomic
clock 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 continually measures every second of every day to an accuracy of ten billionths of a
second a 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. This atomic clock regulates
the WWVB transmitter.
Once the outdoor temperature is displayed on the atomic clock, the WWVB tower icon in the
clock display will start flashing in the top center of the LCD. This indicates that the clock has
detected a radio signal and is trying to receive it. When the time code is received, the WWVB
tower becomes permanently lit and the time will be displayed.
If the tower icon flashes, but does not set the time or the WWVB tower does not appear at all,
then please take note of the following:
•
Recommended distance to any interfering sources like computer monitors or TV sets is
a minimum of 6 feet.
•
Within ferro-concrete rooms (basements, superstructures), the received signal is
naturally weakened. In extreme cases, please place the unit close to a window and/ or
point its front or back towards the Fort Collins, Colorado, transmitter.
•
During nighttime, the atmospheric disturbances are usually less severe and reception is
possible in most cases. A single daily reception is adequate to keep the accuracy
deviation below 1 second.
Note:
In case the atomic clock is not able to detect the WWVB-signal (disturbances, transmitting
distance, etc.), the time can be manually set (please refer to notes on
Manual time setting
) .
