5
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 Projection Alarm.
However, due to the nature of the Earth’s
Ionosphere, reception is very limited during daylight hours. The Projection Alarm 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 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.
WWVB Reception Icon
The icon
with full signal strength will appear on screen in front of the date when the
reception of atomic time is successful.
The tower icon will show solid when the display has received the WWVB signal.
No tower icon displayed. The display was unable to receive a signal at this time.
Reposition the display for better signal reception or try again at bedtime.
The display will start searching at UTC: 07:00 and if no reception on the first attempt
they will try again at 08:00, 09:00 and 10:00. Each attempt will be at least 2 minutes and the most will
be 10 minutes.
If there is no signal or too much interference, the receiver will only be on for 2 minutes.
If the signal is good, it may catch a signal in ABOUT 2-3 minutes.
If the signal is marginal it will try to catch a signal for up to 10 minutes.
IMPORTANT:
When operating on A/C power, the backlight, projection and USB charging port will
turn off while the Projection Alarm searches for the WWVB signal, to avoid interference. The backlight
and projection will return after the 2-10 minute search (which occurs during the late night or early
morning hours). Then the USB charging port will resume working.
Note:
In case the Projection Alarm is not able to detect the WWVB-signal (disturbances, transmitting
distance, etc.), the time may be manually set.
Manual Signal Search
In normal mode, hold the RCC button until the reception icon appears to force a search of the WWVB
signal. The WWVB icon will flash during the search. If this icon disappears after the 2 minute search,
the radio time signal is not available at the moment.
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, etc.), 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.
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 Projection Alarm is not able to detect the WWVB-signal (disturbances, transmitting
distance, etc.), the time and date can be manually set (
see “
program menu
”).
Function Buttons
SNOOZE/LIGHT/HI/LOW/OFF (TOP)
