[time-nuts] WWVB

[Herbert Poetzl]

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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