[time-nuts] WWVB Clocks don't sync anymore (revisited)
paulswedb at gmail.com
Wed Mar 20 14:00:36 EDT 2013
Well I have lost 2 sharps one a while ago and now another that had been
working well until dst. Yes they are 4-5 years old but the xtals aren't all
that sharp and the gain in the TRF is pretty significant such that the xtal
can be off frequency and still work.
But the odd thing is there is an antenna symbol and it saying it did sync.
On Wed, Mar 20, 2013 at 1:28 PM, Eric Williams <wd6cmu at earthlink.net> wrote:
> I also have a SkyScan clock that is claiming to be synced to WWVB, but is
> slowly drifting off. I've replaced the battery and it synced at least once
> after DST conversion, Two other WWVB clocks are working as they should.
> On Tue, Mar 19, 2013 at 1:55 PM, Clint Turner <turner at ussc.com> wrote:
> > A few weeks ago I posted a question/comment about some of my WWVB-based
> > "Atomic" clocks no longer setting themselves properly. These two clocks,
> > SkyScan #86716, would show the symbol indicating that they had set
> > themselves, but their time was drifting away from UTC. Interestingly,
> > *would* set themselves exactly once upon installation of the battery, but
> > never again.
> > Since that time, I've done a bit of digging around.
> > The first suspicion was that, perhaps, the NIST had fudged a bit in the
> > WWVB timecode recently, so I manually decoded a few frames and analyzed
> > them: Nothing suspicious there.
> > The next question was if the addition of the BPSK somehow skewed the
> > timing of the TRF's AGC/threshold - but logically, this didn't make sense
> > since the clock *did* set itself exactly ONCE - and it wouldn't have been
> > able to do this at all were this the case. Out of curiosity I poked
> > on the board and found the trace containing the time code and found that
> > despite the BPSK, its timing was exactly as it should have been: No
> > surprise there.
> > This left the clock itself, so I did what any other Time Nut would do: I
> > built a WWVB simulator.
> > Initially, I set it to a 2010 date - a time that I knew that the clock
> > worked properly. I had two clocks: One that I'd just reset by pulling
> > replacing the battery while the other had been "stuck" for a few weeks,
> > resetting itself nightly as it should. I put both of these in the
> > loops from my WWVB simulator and over the next few days, the recently
> > re-set clock happily synchronized itself while the other one with the
> > date was still "stuck." I then reset that clock and it, too, behaved
> > itself from then on.
> > I then reset the clock on the simulator to a February 2013 date and time.
> > Initially, both clocks reset themselves to the current time and date at
> > their next midnight, but after that, they got "stuck", never resetting
> > themselves at "night" again.
> > So, it appears to be a problem with "Broken Sand" (e.g. a silicon
> > For the morbidly curious, I have documented my efforts here:
> The initial testing
> > http://ka7oei.blogspot.com/**2013/03/yes-nist-did-break-**
> > bunch-of-radio.html<
> The testing with the WWVB simulator
> > 73,
> > Clint
> > KA7OEI
> > ______________________________**_________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/**
> > mailman/listinfo/time-nuts<
> > and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
More information about the time-nuts