3
INVENTORY OF CONTENTS
1) WT-5720 projection alarm
2) AC
adapter/transformer
3) Instruction manual and warranty card.
ADDITIONAL EQUIPMENT (not included)
1) Two fresh 1.5V AA batteries (optional for projection alarm)
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 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 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 about WWVB please see the NIST
website at http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
