[time-nuts] WWVB Dephaser Question

Tue Oct 13 15:21:53 UTC 2020

Hello Time Nuts,

Thanks Graham - I will check that - sounds like it's something I'll do.

Paul - you're off to a good start - I will probably order that as well.

I did get my set up to decode WWVB somewhat reliably - or maybe it was just
good conditions in the last 24 hrs:

WWVB-Decode-OpenHPSDR-MultiPSK-CLK
<http://www.westmorelandengineering.com/WWVB/wwvbSyncOpenHPSDRmultipskclk.jpg>

73's,
John
AJ6BC

On Tue, Oct 13, 2020 at 7:46 AM paul swed <paulswedb at gmail.com> 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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