Have you tried to put BPSK through a narrow band filter and looked at the envelope at the output?
-John ========== > Hi > > Also consider that some of these receivers use a narrowband crystal filter > in front of the IC. I doubt they spend a ton of money on the components, > so > that may not be the world's best crystal in terms of aging. If it ages far > enough the receiver simply goes deaf. If it ages a bit less than that, it > slices off one sideband much more than the other. That's likely to do all > sorts of odd things to it's ability to ignore phase modulation. > > Bob > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Herbert Poetzl > Sent: Wednesday, March 20, 2013 10:58 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] WWVB Clocks don't sync anymore (revisited) > > On Wed, Mar 20, 2013 at 02:34:19AM -0400, Bill S wrote: > >> Interestingly, I have three timepieces that will no longer >> synch to wwvb.Two Radio Shack digital clocks and a Casio >> wristwatch that I've worn for a couple of years and was always >> pretty much dead on. Like Paul, I have an analog Lacrosse clock >> that is running correctly. Nothing I've tried will make the >> other clocks synch. > > Maybe this is related to the phase modulation time code > protocol used by WWVB since October 29th, 2012. > > Their website also states that clocks using information > from the carrier will no longer work, and that during the > transition period (at least March 21st 2013), the PM > signal will be turned for for 30 minutes twice a day > (noon and midnight MST) so maybe check if the clocks > sync then? > > best, > Herbert > > http://www.nist.gov/pml/div688/grp40/wwvb.cfm > >> Bill_S W2FMA > >> On 3/19/2013 5:29 PM, paul swed wrote: >> >>> Funny you bring this up. I am just noticing a sharp clock that >>> I always use and it has been accurate. But it did not flip >>> with the time change this time and though it says its locked >>> its off by 45 seconds slow. Yet a lacross clock across the >>> room seems to be on second wise but never flipped with the >>> time change. As I say its just becoming apparent. Regards Paul >>> WB8TSL > >>> On Tue, Mar 19, 2013 at 4:55 PM, Clint Turner >>> <[email protected]> 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, they *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 around 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 and replacing the battery while the >>>> other had been "stuck" for a few weeks, not resetting itself >>>> nightly as it should. I put both of these in the coupling >>>> 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 2013 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 problem). > >>>> For the morbidly curious, I have documented my efforts here: > >>>> http://ka7oei.blogspot.com/**2013/02/did-nist-break-bunch-**o >>>> f-radio.html<http://ka7oei.blogspot.com/2013/02/did-nist-brea >>>> k-bunch-of-radio.html>- The initial testing > >>>> http://ka7oei.blogspot.com/**2013/03/yes-nist-did-break-** >>>> bunch-of-radio.html<http://ka7oei.blogspot.com/2013/03/yes-ni >>>> st-did-break-bunch-of-radio.html>- The testing with the WWVB >>>> simulator > >>>> 73, > >>>> Clint KA7OEI > >>>> ______________________________**_________________ >>>> time-nuts mailing list -- [email protected] To >>>> unsubscribe, go to https://www.febo.com/cgi-bin/** >>>> mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailm >>>> an/listinfo/time-nuts> and follow the instructions there. > >>> _______________________________________________ time-nuts >>> mailing list -- [email protected] To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and >>> follow the instructions there. > >> _______________________________________________ time-nuts >> mailing list -- [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and >> follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
