Changes in the WWVB Radio Signal Affects Precision Frequency and Timing Reference and is Now Permanent.
A change in the WWVB signal has been implemented to reduce the impact of electro-magnetic interference for improved reception for consumer-grade clocks and watches. 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 (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 are now no longer synchronizing to the WWVB signal.
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:
- 8160 Frequency Standard Receiver/Oscillator
- 8161 Frequency Standard Receiver/Oscillator
- 8163 WWVB Receiver/Phase Comparator
- 8164 Ageless Master Oscillator
- 8165 Ageless Master Oscillator
- 8170 Synchronized Clock
- 8171 Synchronized Clock
- 8182 NetClock/2 Master Clock
Typically these models have front panel indicator LEDs to show sync status. Any unit in current use will be indicating "out-of-sync" status (for at least most of the time). These models will also typically continue to provide synchronization data and will indicate "out-of-sync" within the message (if the data format provides for it) however it is dependent on the synchronization client/slave to act on this message. These models did have alarm contact closures to indicate "out-of-sync" to external devices, but experience tells us they are rarely hooked up to drive audible or visual alarms. And these models existed before it was common to use email or network protocols to signal alerts.
Contact Spectracom (tel +1-585-321-5800 or email firstname.lastname@example.org) to help assess your current need for precise time and frequency. In almost all cases, we can offer a drop-in replacement that uses a GPS receiver to provide the same signals as you currently use from the obsolete models.