From Wikipedia: WWV is the call sign of the United States National Institute of Standards and Technology's (NIST) HF ("shortwave") radio station near Fort Collins, Colorado. WWV continuously transmits official U.S. Government frequency and time signals on 2.5, 5, 10, 15 and 20 MHz. These carrier frequencies and time signals are controlled by local atomic clocks traceable to NIST's primary standard in Boulder, Colorado by GPS common view observations and other time transfer methods. NIST also operates the very similar radio station WWVH in Kauai, Hawaii. WWV and WWVH make recorded announcements; since they share frequencies, WWV uses a male voice to distinguish itself from WWVH, which uses a female voice. They also make other recorded announcements of general interest, e.g., the GPS satellite constellation status and severe oceanic weather warnings. WWV shares its site near Fort Collins with radio station WWVB that transmits carrier and time code (no voice) on 60 kHz in the low frequency (LF) band.
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