[time-nuts] WWVB Dephaser Question

paul swed paulswedb at gmail.com
Sat Oct 24 22:53:25 UTC 2020 

Antenna and filtering are not a problem for me. I use the 10' X 10' square
loop and about 800' of wire with a cap to resonate at 60 KHz and then a
preamp really to drive 140' of coax. Currently using a modified KD2BD
receiver frontend but using a 350 Hz xtal filter. Yes indeed that hamfest
find was amazing.

Looks like you have to build a costa loop SDR. Looked at lots of documents.
My first question to the group.
Can a single incoming sample be converted to I & Q through math. I sort of
think so. The original sample might be I and then use math to make Q. That
would save an entire analog chain. The teensy has a single chain for mic
level input. Though it does feed left and right channels. Granted there are
two audio chains at line level.

The teensy has a NCO that can create a quadrature output. The alternate
would be to use that to drive analog switches as a multiplier to form I & Q
samples.
Regards
Paul
WB8TSL

On Sat, Oct 24, 2020 at 2:05 PM John C. Westmoreland, P.E. <
john at westmorelandengineering.com> wrote:

> Hello Time Nuts and Paul Again,
>
> Paul - Have you thought about adding a 2nd audio board for the orthogonal
> antenna?:
>
> https://www.pjrc.com/store/teensy3_audio.html
>
> I think adding a 2nd audio board could work for this possibly - of course
> with the correct antenna set up.
>
> Note the setup they have further down that page for 4-channel audio
> (Quad).  I think something similar could
> work for BPSK.
>
> 73's,
> John
> AJ6BC
>
>
>
> On Fri, Oct 23, 2020 at 8:34 PM John C. Westmoreland, P.E. <
> john at westmorelandengineering.com> wrote:
>
> > Hello Time Nuts and Paul,
> >
> > Glad to hear you're making progress - of course, as Chris Howard
> mentioned
> > earlier - it's all based on this as a starting point:
> >
> > https://github.com/DD4WH/Teensy-DCF77
> >
> > and Chris' work is here:
> >
> > https://github.com/chris-elfpen/Teensy4WWVBsdr
> >
> > Those sites are good to look at and review as well.
> >
> > I still think some work will be needed to get a good signal in on the
> Line
> > In channel.
> >
> > 73's,
> > John
> > AJ6BC
> >
> >
> > On Fri, Oct 23, 2020 at 6:45 PM paul swed <paulswedb at gmail.com> wrote:
> >
> >> John I was looking for a lot of things around BPSK and SDR and more.
> >> Had not hit this repository yet. But it has the piles of functions that
> >> would be useful. I noted it had a I & Q oscillator. So maybe the way
> this
> >> all works is you grab these functions and line them up. In looking at
> the
> >> wwvb SDR for AM mentioned here by Chris thats what I had started to
> >> understand.
> >> Really slowly getting the barest grasp on what a project might look
> like.
> >> With respect to the wwvb AM SDR receiver it does not look like any of
> the
> >> code would be used for solving the BPSK problem. That is not throwing
> >> stones by the way. It did nicely prove that a signal could come in and
> be
> >> processed through numbers of steps. It does work.
> >> My next step is to keep learning and then start to tinker with some of
> the
> >> modules in this library or even simpler the audio library for the pjrc
> >> shield. Audio in digitise and then back out. Much like the super simple
> >> arduino blinky program you have to start someplace.
> >> Regards
> >> Paul
> >> WB8TSL
> >>
> >> On Fri, Oct 23, 2020 at 7:55 PM John C. Westmoreland, P.E. <
> >> john at westmorelandengineering.com> wrote:
> >>
> >> > Hello Time Nuts,
> >> >
> >> > The code that has been previously discussed in this thread is posted
> >> here,
> >> > in case some of you didn't know and could be wondering about it:
> >> >
> >> > https://github.com/chipaudette/OpenAudio_ArduinoLibrary
> >> >
> >> > It's for the Teensy boards and WWV(B/H) SDR.
> >> >
> >> > 73's,
> >> > John
> >> > AJ6BC
> >> >
> >> > On Sun, Oct 18, 2020 at 12:27 AM John C. Westmoreland, P.E. <
> >> > john at westmorelandengineering.com> wrote:
> >> >
> >> > > 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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