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Known in the hobby as Time Signals or an STF, these stations are WWV from Ft. Collins, Colorado and WWVH in Kauai, Hawaii. Many listeners use STFs for checking the performance of their equipment and are invaluable as a means to synchronize station clocks to UTC. Dxers also use them to check propagation and reception paths or quality, and the receiver‛s frequency accuracy.
While WWV and WWVH broadcast 24 hours a day, other world time stations may broadcast for a few hours or only on certain days of the week. Additional world time stations broadcast their identifications in morse-code, while others may be heard as only a 'beep' or 'pip' signal. CHU in Ottawa, Canada, uses continuous voice transmissions in English and French to identify their time signal transmissions. Additional stations are located in Argentina, Belarus, China, Ecuador, France, Germany, Japan, South Korea, Kyrgyzstan, Russia, Switzerland, Taiwan, United Kingdom and Venezuela.
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For station frequencies and broadcasting hours, refer to the 2008 edition of World Radio TV Handbook.
(Source: Gayle Van Horn/QSL Report-Monitoring Times Feb. 2008)