Paul, Given the long evolution of the project, and the fact that even at the end, classic receivers like the hp 117A and Tracor 599 still won't work with a remodulator -- can you revisit the synchronous decoding idea I suggested?
That is, if the local receiver has a pretty good idea of UTC to begin with (via telephone, radio, smartphone, internet, GPS, etc.), plus a rough idea of the propagation delay, then you can use the published new time code format to *predict* when the 180 degree phase shifts will occur. Then using that information you simply *preemptively* invert the antenna signal polarity at the 1 Hz level. That way any legacy code or phase receivers continue to work -- because both the 1 Hz AM subcode comes through and the 60 kHz carrier appears almost perfectly intact. The "converter" would simply sit between the unmodified antenna and the unmodified receiver. I realize the catch-22 in this; if you don't already know the time you can't decode the time. True, and I agree this is not a desert island solution. However, the truth is more like: if you know the approximate time, then you get a NIST-traceable 60 kHz carrier. And all your old carrier tracking gear will continue to work. For fun, under microprocessor control, you could slide it forward or back a few milliseconds to learn the actual propagation delay as a function of time of day. For extra credit, you can also put back the hourly 45 degree phase shift. /tvb ----- Original Message ----- From: "paul swed" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Sunday, June 29, 2014 12:30 PM Subject: Re: [time-nuts] Dephasing WWVB > The phase jumps are a killer and I assure you if a simple approach like > limiters multipliers would work and I have done everyone of them that would > have been the answer. > Ya know it just can't be that hard. Guess what it actually is that hard. > Darn, but that is the cost of learning. Nothings for free. > There has to have been a reason that all the clever none work receivers > went to the trouble of PLLs and such. They were pretty smart engineers. > Regards > Paul > WB8TSL > > > > On Sun, Jun 29, 2014 at 2:24 PM, Alex Pummer <[email protected]> wrote: > >> thank you for that info, 2kHz bandwidth is a big problem for me, since a >> very strong -- approx 20dB above the desired -- and not so stabile carrier >> is just 700 Hz away --upward -- from the desired 60kHz, a to narrow >> bandwidth is also a problem since it converts the phase modulation into >> amplitude modulation -- the filter has to change the phase, for 180° phase >> change it needs approx two times the Q times period time....that "trick " >> makes the "atomic clocks" with crystal filter also crazy., the "see" some >> unexpected characters >> Apropos atomic clocks, there is no usable available chip on the market >> which would work.... >> Question, what was the goal to introduce that new modulation schema? Since >> the new modulation scheme caused more trouble than usable result, could it >> happen, that it will disappear? >> 73 >> Alex >> >> >> On 6/29/2014 10:08 AM, John Reed wrote: >> >>> Thanks Paul. I thought that this would be a simple project. But, I'm >>> seeing that random phase jump problem on every method I've tried so far. >>> My first attempt was a 2N2222 that would go into saturation on the plus >>> cycle, then into a flip-flop. I ended up with the phase problem on the 60 >>> KHz output. Then I tried using a pulse generator into a flip-flop. Same >>> problem. The puzzling thing is the 120 KHz output from the 2N2222 or pulse >>> generator look fine, but the 50 KHz output of the flip-flop is not. >>> >>> By the way, my 5 section synchronous filter is an LC with op-amps between >>> each stage to bring the gain up for the squaring chip. It has a 2 KHz -6 >>> dB bandwidth at 60 KHz. >>> >>> John >>> >>> -----Original Message----- From: paul swed >>> Sent: Sunday, June 29, 2014 9:34 AM >>> To: Discussion of precise time and frequency measurement >>> Subject: Re: [time-nuts] Dephasing WWVB >>> >>> John welcome to time nuts. This won't be a super long post have other >>> things to do. >>> Search for d-psk-r and you can see a few of my exploits. Summation. "It >>> ain't easy". >>> It appears to be really easy unless you are far away like the east coast. >>> Then the propagation gods enter into the picture along with the 60 KHz >>> station in England that shows up most nights. >>> The simplest of approaches was indeed the old doubling trick and the many >>> flavors of it. I built most along with regenerative dividers and other >>> trickery. Fact is it simply drops a count and that flips the phase quite >>> annoying. >>> I finally created two approaches. One specifically for spectracom devices >>> essentially adding a third mixer and checking for the flip. Works but >>> requires internal hacking of the spectracom. >>> The other pretty much a freestanding receiever using a classic costas loop >>> approach. All details were released to time nuts over a year ago. >>> My next stab is more of a digital approach using the STM discovery board. >>> Have to say I seem to get lost in some of the basics of getting all of the >>> crazy registers set. >>> However its value is it can run very very fast. So you can do some nice >>> sampling. >>> Regards >>> Paul >>> WB8TSL >>> >>> >>> On Sat, Jun 28, 2014 at 5:38 PM, Charles Steinmetz <[email protected] >>> > >>> wrote: >>> >>> John wrote: >>>> >>>> I discovered an article on the web that uses an AD835 multiplier chip to >>>> >>>>> square the WWVB signal * * *. I built a five section synchronous >>>>> filter >>>>> tuned to 60 KHz to get rid of interference and its output feeds the 835 >>>>> chip. This all works fine. * * * the 599J won't tune that high so I >>>>> have to divide this 120 KHz frequency by 2. * * * I've tried to >>>>> generate a pulse train from the 120 KHz signal and then use a flip-flop >>>>> to >>>>> divide the frequency. This does not work well. Apparently generating >>>>> the >>>>> pulse train picks up noise and I end up with a 60 KHz signal with >>>>> fluctuating phase. Now I'm trying to get a Miller frequency divider >>>>> working >>>>> >>>>> >>>> Why are you trying to generate pulses, rather than just squaring >>>> (clipping) the output of the 835 in a saturated amplifier? Pulses have >>>> less energy and therefore higher noise. All you need is a >>>> signal-conditioning squarer matched to the level coming out of the 835 >>>> (see >>>> Bruce Griffith's pages at <ko4bb.com> for ideas, as well as the Wenzel >>>> site and any number of illustrations in Experimental Methods in RF Design >>>> -- for example, both Figures 5-46 and 4-45 show complete simple squarers >>>> with FF dividers). Even a CMOS gate biased to half-voltage should work >>>> fine. I like the NC7SZ74 Dflop for the divider. Half of a 74HC74 works >>>> fine, too. >>>> >>>> This should be the kind of thing you throw together in 15 minutes and it >>>> works first time. >>>> >>>> Best regards, >>>> >>>> Charles >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> 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. _______________________________________________ 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.
