WWV is the callsign of NIST's shortwave radio station located in Fort Collins, Colorado. WWV's main function is the continuous dissemination of official U.S. Government time signals. The station broadcasts simultaneously on five distinct frequencies: 2.5 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. These carrier frequencies, as well as the time signals, are derived from a set of atomic clocks located at the transmitter site, which themselves are traceable to NIST's primary frequency standard in Boulder, Colorado using such techniques as GPS common-view observations. WWV is partnered with radio station WWVH, located in Hawaii. Onsite with WWV in Fort Collins, Colorado is also radio station WWVB, which operates on the low frequency of 60 kHz. In broadcasting and radio communication, a callsign or call sign (also call letters) is a unique designation for a transmitting station. ... As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ... A Grundig Shortwave receiver Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at... Horsetooth Rock, atop Horsetooth Mountain, is often used as a symbol of Fort Collins Fort Collins, situated on the Cache la Poudre River, is the largest city and county seat of Larimer County, Colorado. ... A radio clock is a clock that is synchronized by a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... Carrier frequency is the fundamental frequency used in both amplitude modulation and frequency modulation i. ... Atomic clock Chip-Scale Atomic Clock Unveiled by NIST An atomic clock is a type of clock that uses an atomic resonance frequency standard as its counter. ... Pearl Street Mall in Downtown Boulder Boulder (40n01, 105w16 MST) is a city located in Boulder County, Colorado, USA. As of the 2000 census, the city had a total population of 94,673. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... WWVH is the callsign of NISTs shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii. ... State nickname: The Aloha State Other U.S. States Capital Honolulu Largest city Honolulu Governor Linda Lingle Official languages Hawaiian and English Area 28,337 km² (43rd)  - Land 16,649 km²  - Water 11,672 km² (41. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ... Low Frequency or LF (sometimes called longwave) refers to Radio Frequencies (RF) in the range of 30-300 kHz. ... A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ...

WWV is the oldest continuously-operating radio station in the United States, first going on the air in May of 1920, approximately six months before the launch of KDKA. The station was formerly located in Greenbelt, Maryland, on land which now is part of NASA's Goddard Space Flight Center. WWV moved to its present location at Fort Collins on December 1, 1966, allowing better reception of its signal throughout the continental United States. This article is about the month of May. ... 1920 is a leap year starting on Thursday (link will take you to calendar) Events January January 7 - Forces of Russian White admiral Kolchak surrender in Krasnoyarsk. ... KDKA AM is a U.S. class A clear channel AM radio station located in Pittsburgh, Pennsylvania that operates on 1020 kHz. ... For other uses of the word Greenbelt, see Greenbelt (disambiguation). ... State nickname: Old Line State; Free State Other U.S. States Capital Annapolis Largest city Baltimore Governor Robert L. Ehrlich Official languages English Area 32,160 km² (42nd)  - Land 25,338 km²  - Water 6,968 km² (21%) Population (2000)  - Population 5,296,486 (19th)  - Density 165 /km² (5th) Admission into... The National Aeronautics and Space Administration (NASA) (established 1958) is the government agency responsible for the United States of Americas space program and long-term general aerospace research. ... NASAs Goddard Space Flight Center, located in Greenbelt, Maryland, is a major space science laboratory. ... December 1 is the 335th (in leap years the 336th) day of the year in the Gregorian calendar. ... 1966 was a common year starting on Saturday (the link is to a full 1966 calendar). ...

Broadcast format

WWV transmits the exact time-of-day in two ways at the same time. The first method is through voice announcements made every minute, each followed by a long beep that serves as the "on-time marker" for each announcement. These long beeps are also used to mark off standard intervals of one minute, and are usually tones of 1000 Hz, except for the top of the hour, when a 1500 Hz tone is used. The second method of transmitting the time-of-day is through a continuously-transmitted sub-audible digital time code, which also carries extra information such as whether or not Daylight Saving Time is in effect, and when the next leap second will occur. The voice announcements (made in a male voice to distinguish from WWVH in Hawaii) are useful for people manually setting clocks, while the digital time codes can be used by radio-controlled clocks. The transmitted time is given in Coordinated Universal Time (UTC). WWV also "ticks" each second (except at 29 and 59 seconds past the minute, the omissions used to encode the standard interval of thirty seconds), to allow for accurate manual synchronization. Between seconds one and sixteen inclusive past the minute, the current difference between UTC and UT1 is transmitted by doubling some of the once-per-second ticks. The absolute value of this difference, in tenths of a second, is determined by the number of doubled ticks. If the doubled ticks are between seconds one and eight inclusive past the minute, UT1 is ahead of UTC. If the doubled ticks fall between seconds nine and sixteen inclusive, UT1 is behind UTC. Timecode is also the title of a 2000 film directed by Mike Figgis which was shot in one continuous take. ... Daylight saving time (also called DST, or Summer Time) is the portion of the year in which a regions local time is advanced by (usually) one hour from its standard official time. ... A leap second is a one-second adjustment to civil time in order to keep it close to the mean solar time. ... WWVH is the callsign of NISTs shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii. ... A radio clock is a clock that is synchronized by a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... Coordinated Universal Time or UTC, also sometimes referred to as Zulu time, is an atomic realization of Universal Time or Greenwich mean time, the astronomical basis for civil time. ... UTC also stands for the University of Tennessee at Chattanooga Coordinated Universal Time or UTC, also sometimes referred to as Zulu time, the basis for civil time, differs by an integral number of seconds from atomic time and a fractional number of seconds from UT1. ... Universal Time (UT) is a timescale based on the rotation of the Earth. ...

In most minutes of the hour, WWV transmits standard audio frequencies of 500 and 600 Hz, switching between the two frequencies each minute. These two frequencies are used to synchronize 50 Hz and 60 Hz electrical power supplies respectively. WWV also transmits a 440 Hz tone (a pitch commonly used in music for the note A above middle C) every hour at two minutes past, except for the first hour of the UTC day. Since the 440 Hz tone is only transmitted once per hour, many chart recorders may use this tone to mark off each hour of the day, and likewise, the omission of the 440 Hz tone once per day can be used to mark off each twenty-four hour period. In music, pitch is the perception of the frequency of a note. ... In music, the term middle C refers to the pitch-class C located between the staves of the grand staff. ...

WWV's broadcasts are not limited to time-of-day and standard time intervals. At 8, 9 and 10 minutes past the hour, WWV stops transmitting its standard audio frequencies to broadcast regular high-seas weather warnings. At 14 and 15 minutes past the hour, reports relating to the health of the U.S. Department of Defense's GPS service are transmitted. And at 18 minutes past the hour, a special "geophysical alert" report is transmitted, containing information on solar activity and shortwave radio propagation conditions. No audio tones are transmitted from WWV between 43 and 51 minutes inclusive past the hour.

A radio clock is a clock that is synchronized by a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... BPM is the Peoples Republic of Chinas national time signal service, operated by the Chinese Academy of Sciences. ... CHU is the callsign of a shortwave radio station in Ottawa, Ontario, Canada (exact location - 45 1747N, 75 4522W), operated by the Institute for National Measurement Standards of the National Research Council of Canada. ... DCF77 is a longwave time signal radio station. ... JJY is the callsign of a longwave time signal radio station similar to WWVB. The station is located in Japan, operated by a branch of the Japanese government known as the National Institute of Information and Communications Technology. ... The MSF time signal is a broadcast from the VLF transmitter Rugby near Rugby, Warwickshire based on time standards maintained by the British National Physical Laboratory. ... RWM is the callsign of a shortwave radio station in Moscow, Russia. ... VNG was Australias national time signal service, and operated on 2500, 5000, 8638, 12984, and 16000 kHz. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ... WWVH is the callsign of NISTs shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii. ... YVTO is the callsign of the official time signal from the Juan Manuel Cagigal Naval Observatory in Caracas, Venezuela. ...

External links

• NIST: Time and frequency division (http://www.boulder.nist.gov/timefreq/)