[time-nuts] WWVB d-psk-r down conversion method

[paul swed]

Update
Have received the 5.9904 MHz xtals and when put into a circuit can easily
be tuned to 5.99000 Mhz div by 100 = 59.900 Khz and creates the 100 Hz
output. I need to figure out the correct injection setting for the SA612
mixer and in general the correct  and reasonable system settings.
But it looks pretty good I can easily see the phase shifts and do not need
a big complicated HP 3335 generator.
Regards
Paul
WB8TSL

On Tue, Sep 23, 2014 at 8:23 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> If the idea is to decode in software in order to “de-psk” with a switch,
> then things are indeed easier.
>
> My *guess* is that the loops in most WWVB systems are tolerant of noise
> bursts already. If not, they would have a hard time with the normal RX
> environment. There are a number of ways to build a PLL and make that
> happen, even with long time constants involved. They probably used one or
> more of the common approaches.
>
> So here’s a plan:
>
> 10 MHz / 168 = 59.532xxxx KHz
>
> 168 is 8 x 7 x 3. That’s two 4 bit programable divider chips and a divide
> by 8. With 10 MHz in, it does not have to be very fast. There are (cheap)
> CPU chips that will do it on a PWM output. If it’s DIP packages, one
> 74AC161’s should do the job for the programable sections. You would need a
> NAND gate for each of the programable sections as well. The divide by two’s
> can be done several ways. I’d put one at the tail end and the other two at
> the front end.
>
> The 467 Hz note is slow enough to be pretty easy to process with a simple
> CPU.
>
> Bob
>
>
>
> On Sep 23, 2014, at 11:54 AM, paul swed <paulswedb at gmail.com> wrote:
>
> > Wow. What 8 hours can do for responses.
> >
> > Great comments and appreciated. A piece of the puzzle appears to have
> > gotten lost from the start of the process.
> >
> > This down converter system. Only detects phase change. It is not intended
> > to be a phase locked oscillator system that replicates what the old
> radios
> > have.
> >
> > Its output flips a signal path to invert or not invert the incoming wwvb
> > signal that feeds the old radios.
> > There is no need for an instantaneous response in the flip circuit. .3-.5
> > seconds seems fine for the old radios. Want to see if I can get down to
> > .1-.2 sec.
> >
> > Pretty sure from what I have seen so far there is no need to lock the LO
> > nor must it be some precise offset of 100 Hz or anything else.
> > In watching this on a scope with a stable local 100 Hz reference not
> locked
> > to anything. The phase changes were obvious and useful.
> >
> > One of the comments in the thread was that you could use a good local
> > reference and adjust for the LO drift. I do believe thats the case. I am
> > pretty good at dividing in decades. ;-) But getting ahead of the other
> > criteria. Simple as possible.
> > OK time to fix the HP3335a that failed. Lost my LO for the moment.
> >
> > Regards
> > Paul.
> > WB8TSL
> >
> >
> >
> > On Tue, Sep 23, 2014 at 7:37 AM, Bob Camp <kb8tq at n1k.org> wrote:
> >
> >> Hi
> >>
> >> Actually stability isn’t the main problem with the progamables. The
> issue
> >> is usually phase noise ad spurs. Often they use odd multi modulo divides
> >> rather than a PLL. That gives them a low cost chip, but the output
> spectrum
> >> is pretty poor. Figuring out if you have a “bad one” or not is tough
> from
> >> many data sheets. It’s rare that cheap XO’s come with phase noise and
> spur
> >> plots.
> >>
> >> Bob
> >>
> >> On Sep 23, 2014, at 12:04 AM, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> >>
> >>>
> >>> paulswedb at gmail.com said:
> >>>> Did try lots of frequencies and divider math to come up with a simple
> LO
> >>>> scheme for 61 or 59 KHz. Messy.
> >>>
> >>> There are companies that will make a crystal or oscillator at any
> >> frequency
> >>> you want at a not silly price.  Delivery is not overnight.
> >>>
> >>> Beware: There are several companies selling instant delivery of
> >> oscillators
> >>> running at any frequency you want.  They are using a programmable PLL
> so
> >> you
> >>> won't get the stability you expect from a crystal.
> >>>
> >>> --
> >>> These are my opinions.  I hate spam.
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> 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
> >> 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
> 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
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>