Wwvb

WWVB

WWVB is a NIST time signal radio station near Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks in most of North America use to synchronize themselves. The 70 kW signal transmitted from WWVB is a continuous 60 kHz carrier wave, the frequency of which is derived from a set of atomic clocks located at the transmitter site, yielding a frequency uncertainty of less than 1 part in 1012. A one-bit-per-second time code, which is based on the IRIG "H" time code format and derived from the same set of atomic clocks, is then modulated onto the carrier wave using pulse width modulation and amplitude-shift keying. 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.