A Brief History of NIST Radio Broadcasts of Time and Frequency Signals
(Updated 6/13/2001)
Transmitter site of WWVB/Ft. Collins, CO
(Courtesy of NIST Website)
- December 1922, preliminary transmissions of standard frequencies in the shortwave band were made from the NBS Washington site to about 30 observers within 1000 miles of Washington. The WWV call letters were assigned in 1919.
- March 1923, WWV began transmitting signals on a regular schedule from Washington.
- January 1931, standard WWV frequency transmissions were begun from a new location at College Park, Maryland.
- December 1932, the College Park WWV transmitter was moved to a 25 acre site at the Experimental Farm of the Department of Agriculture at Beltsville, Md.
- November 1940, station WWV was almost entirely destroyed by fire of an undetermined origin. With salvaged and additional equipment, the station was back on the air in five days and continued operation from that site for several years.
- January 1943, WWV was moved to a new site in Greenbelt, Maryland about three miles south of the Beltsville Research Station.
- February 1944, Transmissions on WWV's 2.5 MHz frequency commenced to serve the population nearest to the Maryland site.
- December 1946, WWV commenced transmissions on the frequencies of 20, 25, 30 and 35 MHz.
- November 1948, NBS initiated standard frequency broadcasts in the shortwave band from WWVH located at Kihei on the island of Maui, Territory of Hawaii.
- January 1, 1950, WWV began voice time announcements (in Eastern Time) at 5 minute intervals. This would be the normal until July, 1971.
- January 1953, WWV discontinued operations on the 30 and 35 MHz frequencies.
- July 1956, experimental station KK2XEI (later WWVB) began standard frequency broadcasts in the LF region (60 kHz) from the NBS Boulder site.
- April 1960, scheduled operation began on the 20 kHz standard frequency station WWVL at an interim site at Sunset in Four Mile Canyon near Boulder.
- July 1963, station WWVB was moved to a site just north of Fort Collins, Colorado.
- August 1963, station WWVL moved from Sunset to the site near Fort Collins.
- December 1, 1966, station WWV ceased operation at its Maryland site and began broadcasting from the site near Fort Collins at exactly 0000 UTC.
- Early 1967, WWV began announcing the time in Greenwich Mean Time. Prior to that, (since the move to Colorado), it was in Mountain Time.
- July 1, 1971, WWVH was relocated from the island of Maui to the island of Kauai (also in Hawaii). The station had been severely damaged by a hurricane in 1970. In addition, the time format of WWV and WWVH was changed to every minute as compared to the 5 minute format that was in place for many years.
- July 1972, broadcasts from station WWVL were discontinued.
- April 1977, WWV broadcasts on 20 and 25 MHz and WWVH on 20 MHz were discontinued due to adverse propagation on those frequencies and economic conditions at the time.
- October 1978, WWV broadcasts on 20 MHz were re-instated due to improved propagation on that frequency as a result of higher sunspot levels. The 20 MHz service is still in operation to this day.
- Broadcasts continue today from Colorado and Kauai. Shortwave broadcasts are at 2.5, 5, 10, and 15 MHz for both WWV and WWVH and at 20 MHz for WWV only. Time announcements on WWV are done by a male voice and on WWVH with a female voice. The time is announced on WWVH at 45 seconds past the minute and at 53 seconds past the minute on WWV. Many times both WWV and WWVH can be heard at the same time due to propagation changes.
- Aside from standard frequencies, WWV and WWVH broadcasts now include time of day (both voice and digital code), astronomical time corrections, marine weather alerts, geophysical alerts, and status information for GPS systems. The low frequency broadcasts of WWVB at 60 kHz involve only a digital time code, but the carrier frequency is referenced to the NIST frequency standard.
Information as provided from the National Institute of Standards and Technology Website
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