Consumer Clock Signal Change Could Affect Discontinued Precision Timing Receivers (4/9/12)
A change in the radio station WWVB signal is being considered to reduce the impact of electromagnetic 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 — all are discontinued — so these products will not operate as intended.
WWVB is a radio station operated by the National Institute of Standards and Technology (NIST) in Ft. Collins, Colo., 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. 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 backward compatible with consumer-grade clocks and watches. However, Spectracom receivers will not function once the WWVB signal has changed.
Because GPS has long been the current standard for traceability in precision timing applications, there are no current, or recently discontinued Spectracom products that will be affected. However, there are much older generation time and frequency references and master clocks that will no longer receive the WWVB signal when the change is permanently implemented, expected around mid-2012.
The models listed below 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
Spectracom officials said that in almost all instances, the company can offer a drop-in replacement that uses a GPS receiver to provide the same signals as the obsolete models. Visit http://www.spectracomcorp.com for more information. For more information on NIST radio station WWVB, click here.
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