[time-nuts] WWVB

J. Forster jfor at quikus.com
Sat Feb 23 09:37:43 EST 2013


So, if you use phase-tracking hardware, it's good for three more weeks.

Wonderful...  not.  :((

LORAN-C all over again!

-John

=================


> On Fri, Feb 22, 2013 at 06:01:46PM -0500, paul swed wrote:
>> Donald from what I have been seeing they are consistent.
>
>> But there is a 1 hour period up around 1 or 2 pm est that
>> they go back to the old modulation and that allows time
>> clocks to lock.
>
> Just for information here (from their web page):
>
> Since October 29, 2012 at 1500 UTC (9:00 AM MDT), NIST
> Radio Station WWVB has been broadcasting a phase modulation
> (PM) time code protocol that has been added to the legacy
> AM/pulse-width-modulation signal.
>
> This enhancement to the broadcast, which has been tested
> throughout 2012, 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.
>
> Disciplined oscillator products that track and lock to the
> 60 kHz WWVB carrier and were designed to work as frequency
> standards, will not work with the PM signal and will now
> become obsolete.
>
> A few radio controlled clocks that used information from the
> carrier – specifically the Spectracom NetClock and receivers
> manufactured by True Time during the 1970s and 1980s – will
> no longer be able to read the time code and will also be
> obsolete.
>
> To allow users of these receivers to migrate to new products,
> the plan for implementing the new modulation protocol
> includes a transition period that will extend until at least
> March 21, 2013.
>
> During the transition period, the PM signal will be turned
> off for 30 minutes twice per day, at noon and midnight
> Mountain Standard Time (MST), allowing carrier tracking
> receivers to temporarily acquire the legacy signal.
>
> HTC,
> Herbert
>
>> At least thats what the spectracom 8170 does. Then it says
>> its locked for a very long time even though it isn't.
>
>> Regards
>> Paul
>> WB8TSL
>
>> On Fri, Feb 22, 2013 at 3:35 PM, Donald Henderickx
>> <wa9ylp at sandprairie.net>wrote:
>
>>> Is wwvb consistent in the testing of there modulation scheme?I find
>>> that
>>> My Spectracom 8182  will stay in time sync for several days,and then
>>> loose
>>> it for five or six hours. Is any one else experiencing this?
>>> I am thinking of trying my kinemetrics/truetime 60-TF to see if it
>>> might
>>> function.
>>> Don Henderickx
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