WWVB

NIST Time & Frequency Service
TypeTime station
Country
United States
Ownership
OwnerNational Institute of Standards and Technology
History
Launch dateJuly 1956 (under experimental license KK2XEI)
July 4, 1963 (as WWVB)
Coverage
AvailabilityCanada, United States, Mexico
Links
Website"WWVB home page". NIST. March 2010.

WWVB is a longwave time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST).[1] Most radio-controlled clocks in North America[2] use WWVB's transmissions to set the correct time.

The normal signal transmitted from WWVB is 70 kW ERP and uses a 60 kHz carrier wave yielding a frequency uncertainty of less than 1 part in 1012. The time code signal is derived from a set of atomic clocks located at the site, and transmitted using the IRIG "H" format and modulated onto the carrier wave using pulse-width modulation and amplitude-shift keying at one bit per second. A single complete frame of time code begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute, and other information as of the beginning of the minute.

WWVB is co-located with WWV, a time signal station that broadcasts in both voice and time code on multiple shortwave radio frequencies. WWVB is not an acronym or abbreviation but a call sign for the radio station.

While most time signals encode the local time of the broadcasting nation, the United States spans multiple time zones, so WWVB broadcasts the time in Coordinated Universal Time (UTC). Radio-controlled clocks can then apply time zone and daylight saving time offsets as needed to display local time.[3] The time used in the broadcast is set by the NIST Time Scale, known as UTC(NIST). This time scale is the calculated average time of an ensemble of master clocks, themselves calibrated by the NIST-F1 and NIST-F2 cesium fountain atomic clocks.[4]

In 2011, NIST estimated the number of radio clocks and wristwatches equipped with a WWVB receiver at over 50 million.[5]

WWVB, along with NIST's shortwave time code-and-announcement stations WWV and WWVH, were proposed for defunding and elimination in the 2019 NIST budget.[6] However, the final 2019 NIST budget preserved funding for the three stations.[7]

At midnight on April 7, 2024, WWVB's south antenna was disabled due to damage sustained during high winds. WWVB then transmitted exclusively from the north antenna, at a reduced power of 30kW. On May 20, 2024, NIST announced that the necessary replacement parts were being manufactured and shipped, with expected service restoration at the end of September 2024. As of October 10, 2024, WWVB was back to operating at full power.[8]

NIST Time Signal Station Services[9]
Station Year
in service 		Year out
of service 		Radio
frequencies 		Audio
frequencies 		Musical
pitch 		Time
intervals 		Time
signals 		UT2
correction 		Propagation
forecasts 		Geophysical
alerts
WWV 1923 ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
WWVH 1948 ✔ ✔ ✔ ✔ ✔ ✔ ✔
WWVB 1963 ✔ ✔ ✔ ✔
WWVL 1963 1972 ✔
  1. ^ "NIST Radio Station WWVB". NIST. March 2010. Archived from the original on 21 May 2024. Retrieved 1 June 2024.
  2. ^ "Help with WWVB Radio Controlled Clocks - Where They Work". National Institute of Standards and Technology. February 11, 2010. Archived from the original on March 17, 2020. Retrieved March 23, 2020.
  3. ^ "WWVB Radio-Controlled Clocks". National Institute of Standards and Technology. 5 March 2012. Archived from the original on 21 May 2012. Retrieved 21 May 2012.
  4. ^ Lombardi, Michael A. (March 2010). "How Accurate is a Radio Controlled Clock?" (PDF). Horological Journal. 152 (3). The British Horological Institute, Limited: 108–111. Archived (PDF) from the original on 7 January 2021. Retrieved 3 August 2016.
  5. ^ "All Time, All the Time: Improving NIST Radio". NIST. October 3, 2011. Archived from the original on August 12, 2016. Retrieved July 13, 2017.
  6. ^ "NIST Budget Request". NIST. 9 February 2018. Archived from the original on 20 August 2018. Retrieved 21 June 2018.
  7. ^ "FY 2019 NIST budget looks good for time stations". The SWLing Post. 15 February 2019. Archived from the original on 25 February 2019. Retrieved 24 February 2019.
  8. ^ "Radio Station WWVB". NIST. July 4, 2024.
  9. ^ "NBS Miscellaneous Publication 236 (1967 edition): NBS Standard Frequency and Time Services" (PDF). Archived (PDF) from the original on May 17, 2017. Retrieved April 11, 2018.