Pending Changes in the WWVB Radio Signal Affects Precision Frequency and Timing Reference
A change in the WWVB signal is being considered to reduce the impact of electro-magnetic interference for improved reception for consumer-grade clocks and watches. Why does this matter? This change also affects the operation of precise time and frequency standards whose receivers are based on phase-locked loops, such as Spectracom WWVB receivers (all long discontinued), so these products will not operate as intended.
WWVB is a radio station operated by the National Institute of Standards and Technology in Ft. Collins, Colorado to transmit a time and frequency standard over a low frequency signal. Spectracom manufactured WWVB receivers as a traceable source for frequency standards and/or a time references (master clocks) for automatic synchronization of electronic equipment and computers; virtually any time-sensitive or frequency-stable device. The signal is also used to synchronize clocks and watches.
Despite increases in signal strength over the years, electro-magnetic interference affects the reliability of WWVB reception. A new protocol based on phase-modulation can improve signal reception and is backwards compatible with consumer-grade clocks and watches. However, Spectracom receivers will not function once the WWVB signal has changed.
Since GPS has long been the current standard for traceablility in precision timing applications, there are no current, or recently discontinued Spectracom products this will affect. However, there are much older generation time & frequency references and master clocks that will no longer receive the WWVB signal when the change is permanently implemented (expected around mid summer 2012).
If you are currently operating one of these models listed below, it will no longer operate as intended as a result of the WWVB signal change: