Hi John,
Thank you very much for the clarification.
Best regards,
David McGaw N1HAC
Dartmouth College
Dept. of Physics and Astronomy
On 9/26/12 2:29 PM, John Lowe wrote:
Dear Time-Nuts Forum,
In an attempt to quiet the discussion that has started, I will take
the unusual step and address this forum.
NIST is providing full disclosure of the WWVB PM format. There are no
hidden bits or protocols. We will continue to be entirely forthcoming
with the WWVB broadcast both in its content and its schedule. All
information is available and will continue to be available at:
http://www.nist.gov/pml/div688/grp40/wwvb.cfm
NIST has never been in the business of developing, designing or
producing receiver designs. We provide the format and allow our users
to create designs as they see fit. Individuals are invited to design
receivers based on the format provided.
We have taken great care to preserve the existing AM format of the
WWVB transmission. We expect the vast majority of AM envelope-type
receivers will continue to operate as designed and will detect the
Time-of-Day. Unfortunately, there are devices out there that detected
the phase of the carrier through a Phase-Locked-Loop. These devices
will no longer function as designed. There are methods of creating an
interface to recover the signal for these devices, some of which have
been discussed and presented in this forum. It is an unfortunate
consequence of improving the reception capability of our broadcast
that this segment of our loyal user base are so adversely affected.
The decision to proceed was not taken lightly, but in the end it was
decided that the improvement in reception capability (especially along
the JJY interference prone East Coast) outweighed the loss of use of
existing PLL devices.
It should be noted that the carrier-phase information is still there
and will provide the same level of reference calibration capability as
it always has, it just must be extracted in a new way. Maybe this
change will prompt a commercial enterprise to develop a new WWVB
frequency reference device as there has been no commercially produced
frequency reference devices manufactured or supported in some time.
I have given much effort in being available to answer questions and
provide information concerning this transition and I will continue to
be available to help. I hope this response to this forum aids in that
effort.
Regards,
John Lowe
WWVB Broadcast Manager
NIST Time and Frequency Division
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