9
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.
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 (2 meters).
•
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
).
MOON PHASE
The moon phases appear in the middle of the lower LCD. There are 12 visible Moon Phases that
will show in the LCD:
