4
G
LOSSARY OF COMMON TERMS
NIST
*
The National Institute of Standards and Technology maintains the primary frequency
standard for the United States. The NIST also coordinates the United States time and
frequency standards with other world standards. The NIST provides time and
frequency services for United States clientele.
WWVB
*
The WWVB is an AM radio station in Ft. Collins, Colorado, managed by the NIST.
The WWVB’s function is to broadcast time-of-day information derived from the NIST
atomic clock, located in Boulder, Colorado.
ATOMIC CLOCK
*
An atomic clock is an extremely accurate time device measuring time by the
movements of electrons in cesium atoms.
The NIST atomic clock is one of the most
precise clocks in the world, accurate to 10 billionths of one second. The NIST’s
atomic clock contributes to the international group of clocks calculating the
Coordinated Universal Time (UTC)—the official world time.
RADIO-CONTROLLED TIME
*
A radio-controlled time device is often confused with an atomic clock. However, a
radio-controlled time device receives its time information
from
the atomic clock each
day through an internal antenna. The radio-controlled time device searches for an
exact time signal every night when the signal from the WWVB is the strongest. The
signal can be received up to 2,000 miles away through a radio controlled time device.
LCD
“LCD” is an acronym for ”Liquid Crystal Display”. This is a common type of display
screen used in televisions, computers, watches, and digital clocks.
LED
“LED” is an acronym for “Light-Emitting Diode”. This type of light is used to illuminate
a variety of displays such as a digital clock or watch.
CELSIUS (°C)
Celsius is metric system’s unit of measurement used to calculate temperature.
FAHRENHEIT (°F)
Fahrenheit is the common unit of measurement used to calculate temperature the
United States.
*For more information regarding the NIST, WWVB, atomic clocks, and radio-
controlled time, please visit the NIST official website:
http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
