[time-nuts] WWVB Dephaser Question

Sun Oct 18 07:27:13 UTC 2020

Hello Time Nuts,

FYI:  Teensy NTP server found here:
https://github.com/ddrown/teensy-ntp

73's,
John
AJ6BC

On Sat, Oct 17, 2020 at 1:16 PM paul swed <paulswedb at gmail.com> wrote:

> The teensy arrived and was easily installed in the arduino IDE. Worked
> right off the bat.
> The wiring of the A/D and the TFT display is a bit less clear. I have all
> of the details but need to go over them carefully. The teensy 4.0 is
> slightly different in the pins used as compared to the various
> documentation on the wwvb receiver. I will guess this is going to have an
> effect in the actual program.
> Regards
> Paul
> WB8TSL
>
> On Sat, Oct 17, 2020 at 12:06 PM John C. Westmoreland, P.E. <
> john at westmorelandengineering.com> wrote:
>
> > Hello Time Nuts,
> >
> > Maybe this should be added to this thread - this page is actually pretty
> > good:
> >
> > https://en.wikipedia.org/wiki/WWVB
> >
> > 73's,
> > John
> > AJ6BC
> >
> >
> > On Tue, Oct 13, 2020 at 12:50 PM John C. Westmoreland, P.E. <
> > john at westmorelandengineering.com> wrote:
> >
> > > Hello Time Nuts,
> > >
> > > Paul, I haven't gone over in fine detail of how the multipsk software
> is
> > > working - so I'd like to answer with that caveat if that's OK.
> > >
> > > I thought it was more interesting that I got anything working as far as
> > > 60kHz with my existing OpenHPSDR rig AND my default antenna.
> > > The system wasn't really designed for that - and it worked.
> > >
> > > I'll dig into some of the details and report back - since the time
> > > information is all that is needed for clock synchronization - I think
> the
> > > easiest method available is more than likely what was done.
> > >
> > > It agrees with the GPS feed from Themis - so, that's a good check.
> Also,
> > > Themis is driving the reference clock for the HPSDR rig.
> > >
> > > 73's,
> > > John
> > > AJ6BC
> > >
> > >
> > >
> > >
> > >
> > >
> > > On Tue, Oct 13, 2020 at 12:20 PM paul swed <paulswedb at gmail.com>
> wrote:
> > >
> > >> John I looked at what you sent. I assume its decoding the am time
> signal
> > >> is
> > >> that correct?
> > >>
> > >> On Tue, Oct 13, 2020 at 1:19 PM Chris Howard <chris at elfpen.com>
> wrote:
> > >>
> > >> >
> > >> > That's a fair assessment.  I'm really not very far into SDR
> > programming,
> > >> > would like to learn more.
> > >> >
> > >> > I was working with someone who gave me a way forward toward
> > >> > using the same hardware to do the BPSK demodulation, but I want
> > >> > to get his OK before I spread his stuff into this group or other
> > places.
> > >> > And I have not yet done anything with it yet myself.
> > >> >
> > >> >
> > >> > Chris
> > >> >
> > >> >
> > >> > On 10/13/20 9:06 AM, paul swed wrote:
> > >> > > The teensy is on order and downloaded the arduino plugin.
> > >> > > In looking at the code I should mention it does not appear to be a
> > I&Q
> > >> > > sampling. Just a single stream I AM sampler. Though at 60 Khz. Its
> > >> > > essentially a diode with AGC and a slicer to determine a 1 or 0.
> No
> > >> > matter
> > >> > > a good start in the world of SDR. (At least I do not see an I&Q
> > >> approach)
> > >> > > Regards
> > >> > > Paul
> > >> > >
> > >> > > On Tue, Oct 13, 2020 at 2:47 AM John C. Westmoreland, P.E. <
> > >> > > john at westmorelandengineering.com> wrote:
> > >> > >
> > >> > >> Paul,
> > >> > >>
> > >> > >> Sure - even on my OpenHPSDR system using my vertical antenna - I
> am
> > >> > almost
> > >> > >> able to decode WWVB (reliably) using the clock
> > >> > >> program from:
> > >> > >>
> > >> > >> http://f6cte.free.fr/index_anglais.htm
> > >> > >>
> > >> > >> with no changes whatsoever.  If I 'fix' the antenna - I'm sure
> > it'll
> > >> > work
> > >> > >> more reliably.
> > >> > >>
> > >> > >> Teensy is Arduino compatible - pretty sure you can use the
> > tools/libs
> > >> > >> fairly easily from Arduino - I don't have a Teensy (yet) but I
> will
> > >> > >> probably
> > >> > >> get a kit like what's outlined in Chris's post and also here for
> > the
> > >> > people
> > >> > >> that may not be in the US:
> > >> > >>
> > >> > >> https://github.com/DD4WH/Teensy-DCF77 (referenced by Chris in
> his
> > >> > post).
> > >> > >>
> > >> > >> that describes the antenna circuit in more detail.
> > >> > >>
> > >> > >> 73's,
> > >> > >> John
> > >> > >> AJ6BC
> > >> > >>
> > >> > >>
> > >> > >>
> > >> > >>
> > >> > >>
> > >> > >>
> > >> > >>
> > >> > >> On Mon, Oct 12, 2020 at 8:20 PM paul swed <paulswedb at gmail.com>
> > >> wrote:
> > >> > >>
> > >> > >>> John
> > >> > >>> I would simply use any number of receivers and grab 60 KHz out
> of
> > >> one
> > >> > or
> > >> > >>> could use the IF at 10 KHz or 1 KHz. But more fun to use 60 KHz.
> > The
> > >> > cost
> > >> > >>> on the teensy components is very reasonable.
> > >> > >>> Regards
> > >> > >>> Paul
> > >> > >>>
> > >> > >>> On Mon, Oct 12, 2020 at 7:44 PM John C. Westmoreland, P.E. <
> > >> > >>> john at westmorelandengineering.com> wrote:
> > >> > >>>
> > >> > >>>> Hello Time Nuts,
> > >> > >>>>
> > >> > >>>> Chris - maybe you can share that if that's something you can
> > share
> > >> > >> right
> > >> > >>>> now.
> > >> > >>>>
> > >> > >>>> Jim and Paul,
> > >> > >>>>
> > >> > >>>> Like Chris pointed out - on that audio board in the design he's
> > >> worked
> > >> > >>> on -
> > >> > >>>> the Line In has L and R channels - the input resistance is
> higher
> > >> than
> > >> > >>> for
> > >> > >>>> the mic input -
> > >> > >>>> but I suppose it's possible to try a BPSK implementation using
> > >> that as
> > >> > >> a
> > >> > >>>> starting point.  There's no separate gain stage for the Line In
> > >> inputs
> > >> > >>> like
> > >> > >>>> for the mic - but
> > >> > >>>> it could work - a small preamp that works with the input
> > impedance
> > >> of
> > >> > >> the
> > >> > >>>> Line In circuitry may be necessary to get a good input signal -
> > but
> > >> > >> that
> > >> > >>>> shouldn't be too hard
> > >> > >>>> to add.  Also - do the internals of that chip - the
> > >> > >>>>
> > >> > >>>> https://www.pjrc.com/teensy/SGTL5000.pdf
> > >> > >>>>
> > >> > >>>> really allow the L/R Line In channels to be treated
> > >> independently?  If
> > >> > >>> so,
> > >> > >>>> it should be good to go at least for experimentation.
> > >> > >>>>
> > >> > >>>> 73's,
> > >> > >>>> John
> > >> > >>>> AJ6BC
> > >> > >>>>
> > >> > >>>>
> > >> > >>>>
> > >> > >>>>
> > >> > >>>> On Mon, Oct 12, 2020 at 12:07 PM Chris Howard <
> chris at elfpen.com>
> > >> > >> wrote:
> > >> > >>>>> I received a good pointer about doing the BPSK implementation
> > >> > >>>>> but have just not gotten it done.
> > >> > >>>>>
> > >> > >>>>> Chris Howard
> > >> > >>>>>
> > >> > >>>>>
> > >> > >>>>>
> > >> > >>>>> On 10/12/20 11:02 AM, jimlux wrote:
> > >> > >>>>>> On 10/12/20 7:40 AM, paul swed wrote:
> > >> > >>>>>>> John really appreciate the pointer. Though it doesn't help
> > wwvb
> > >> > >> BPSK
> > >> > >>>>>>> its a
> > >> > >>>>>>> really good intro to SDR and DSP super simple. A good way to
> > get
> > >> > >>> your
> > >> > >>>>>>> feet
> > >> > >>>>>>> wet. Hmmm is there a parts order soon? :-)
> > >> > >>>>>>> Regards
> > >> > >>>>>>> Paul
> > >> > >>>>>>> WB8TSL
> > >> > >>>>>>
> > >> > >>>>>> And the teensy has plenty of space and speed to implement a
> PLL
> > >> for
> > >> > >>>>>> doing BPSK demodulation.
> > >> > >>>>>>
> > >> > >>>>>>
> > >> > >>>>>>> On Mon, Oct 12, 2020 at 10:33 AM Bob kb8tq <kb8tq at n1k.org>
> > >> wrote:
> > >> > >>>>>>>
> > >> > >>>>>>>> Hi
> > >> > >>>>>>>>
> > >> > >>>>>>>> The “ideal” antenna solenoid would be a bit longer ( say 2
> X
> > to
> > >> > >> 5X
> > >> > >>> ).
> > >> > >>>>>>>> The turns should be spaced apart by a few percent of the
> > >> length.
> > >> > >>>>>>>> ( so turns over 30 or so … not so much …).
> > >> > >>>>>>>>
> > >> > >>>>>>>> How much better is “ideal” compared to “just get it done?”.
> > At
> > >> > >>> least
> > >> > >>>>>>>> from the stories that are told, it is significant. Since
> all
> > >> > >> these
> > >> > >>>>>>>> antennas
> > >> > >>>>>>>> are very small (so non-ideal) it’s a bit of a snail race.
> > >> > >>>>>>>>
> > >> > >>>>>>>> Bob
> > >> > >>>>>>>>
> > >> > >>>>>>>>> On Oct 12, 2020, at 3:42 AM, John C. Westmoreland, P.E. <
> > >> > >>>>>>>> john at westmorelandengineering.com> wrote:
> > >> > >>>>>>>>> Paul,
> > >> > >>>>>>>>>
> > >> > >>>>>>>>> Doesn't the post by Chris Howard above appear to be a
> > >> good/great
> > >> > >>>>>>>>> starting
> > >> > >>>>>>>>> point?
> > >> > >>>>>>>>> Seems like that approach could be extended.
> > >> > >>>>>>>>>
> > >> > >>>>>>>>> https://github.com/chris-elfpen/Teensy4WWVBsdr
> > >> > >>>>>>>>>
> > >> > >>>>>>>>> 73's,
> > >> > >>>>>>>>> John
> > >> > >>>>>>>>> AJ6BC
> > >> > >>>>>>>>>
> > >> > >>>>>>>>>
> > >> > >>>>>> _______________________________________________
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