WWVB

WWVB is a time signal radio station operated by the National Institute of Standards and Technology (NIST) continuously broadcasts digital time codes on a 60 kHz carrier which serves as a stable frequency reference. The WWVB broadcasts are used by millions of people throughout North America to synchronize consumer electronic products like wall clocks, clock radios and wristwatches. The 70 kW ERP 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.

Since October 29, 2012, NIST Radio Station WWVB has been broadcasting a phase modulated (PM) time code that has been added to the legacy AM/pulse-width-modulation signal. This enhancement to the broadcast provides significantly improved performance in new products that are designed to receive it. Existing radio-controlled clocks and watches are not affected by this enhancement and continue to work as before.