[time-nuts] WWVB teensy BPSK early experiments

Wed Nov 4 18:19:47 UTC 2020

Nope never seen it. Its as if the display is writing vertically and
horizontally.

On Wed, Nov 4, 2020 at 11:55 AM John C. Westmoreland, P.E. <
john at westmorelandengineering.com> wrote:

> Paul/Chris,
>
> Also - in addition to the white screen, I get this sometimes after running
> for a while - have you guys seen this?
>
>
> https://user-images.githubusercontent.com/2308903/98118247-cd4c7b00-1e5f-11eb-8510-aa1ed0beba52.jpg
>
> 73's,
> John
> AJ6BC
>
>
> On Wed, Nov 4, 2020 at 1:44 AM John C. Westmoreland, P.E. <
> john at westmorelandengineering.com> wrote:
>
> > Paul,
> >
> > Thanks for the info.  I took some good measurements on the signal coming
> > in on one of the small ferrite antennas when the signal was fairly OK - I
> > measured
> > 4-9 uV.  I haven't done this same measurement yet on the antenna I'm
> > testing on - I didn't think I could be over driving the mic input but
> > that's a possibility.  Also, I haven't done a great job in assembling
> this
> > project - I need to neaten things up and maybe encase in a housing
> > that will reject RFI, etc.
> >
> > Thanks for mentioning this.  I have ordered one of those nice antennas
> > from Stormwise but I'm still waiting to receive it.
> >
> > 73's,
> > John
> > AJ6BC
> >
> >
> >
> >
> > On Tue, Nov 3, 2020 at 12:13 PM paul swed <paulswedb at gmail.com> wrote:
> >
> >> By the way thats leads. A typo.
> >> It just hit me I had to cut the signal down so that the signal graph was
> >> in
> >> the middle.
> >> On the large antenna thats a 330K resistor to a 100K pot.
> >> For the wwvb simulator its simply the 100K pot turned up about 2/3rds of
> >> the way. The simulator is something like 60 uv out.
> >> Maybe you have a overdrive issue.
> >> Regards
> >> Paul.
> >>
> >> On Tue, Nov 3, 2020 at 9:49 AM paul swed <paulswedb at gmail.com> wrote:
> >>
> >> > John
> >> > Yes I have used Chris's code to decode the wwvb AM timecode. I am in
> >> > Boston so just about as far away as you can get. Though maybe Florida
> is
> >> > further. But Boston is in more of a null from wwvb.
> >> > Granted the antenna is a tuned 10' X 10' 800 ft of wire loop and
> preamp
> >> > mentioned numerous times on time-nuts. It reliably during the day
> >> delivers
> >> > 100 uv at the end of the coax.
> >> > I found the teensy wwvb sdr really worked best during the day. With
> >> > respect to power for the antenna its just a power inserter I built, 8
> Mh
> >> > choke, 100 ohm resistor, .47 uf coupling cap to the teensy. No magic
> at
> >> all.
> >> > One very serious issue with the teensy is that the audio module must
> be
> >> > directly stacked on to the cpu. I originally used 3" leeds those
> little
> >> > jumpers. It makes a mess of the clock signals.
> >> > Regards
> >> > Paul.
> >> >
> >> > On Mon, Nov 2, 2020 at 10:55 PM John C. Westmoreland, P.E. <
> >> > john at westmorelandengineering.com> wrote:
> >> >
> >> >> Paul,
> >> >>
> >> >> Have you successfully decoded WWVB with Chris's code?
> >> >>
> >> >> I haven't gotten that to work.
> >> >>
> >> >> I'm using the same antenna set up I've used that works with the
> >> multipsk
> >> >> Clock program to decode WWVB that will decode fairly reliably as long
> >> as
> >> >> atmospheric conditions are favorable.
> >> >>
> >> >> Note, if using the Arduino IDE and you're connected to a PC; it will
> >> >> sometimes set the clock on the TFT to the PC's clock; I'm mentioning
> >> that
> >> >> since some that try this could think their set up is synced to WWVB
> >> when
> >> >> it
> >> >> actually grabbed time from the PC.  Maybe the loader from Teensy does
> >> >> that;
> >> >> I haven't looked close enough yet to know for sure what's setting
> that.
> >> >>
> >> >> Glad you're making progress with your approach.
> >> >>
> >> >> 73's,
> >> >> John
> >> >> AJ6BC
> >> >>
> >> >>
> >> >> On Mon, Nov 2, 2020, 18:20 paul swed <paulswedb at gmail.com> wrote:
> >> >>
> >> >> > John thats exactly what Chris did. Its the teensywwvb.ino. It
> decodes
> >> >> the
> >> >> > AM timecode just as the DCF code does. In fact Chris's code is
> >> derived
> >> >> from
> >> >> > the DCF code with the changes you are asking about and it works.
> >> >> Download
> >> >> > his solution and read the comments throughout. The original DCF
> >> comments
> >> >> > are in it also.
> >> >> >
> >> >> > Its the starting point for the tinkering I am doing towards a BPSK
> >> SDR.
> >> >> > Thats a big leap for me.
> >> >> > What the code gives you is the frontend gain, followed by a
> bandpass
> >> >> > filter. Multiplier that mixes the LO and incoming signal to a
> lowpass
> >> >> > filter. Then on to AM detection and AGC.
> >> >> >
> >> >> > If you don't care to install the arduino IDE with teensy extension
> >> just
> >> >> use
> >> >> > notepad ++ to look at the code. Pretty exciting.
> >> >> >
> >> >> > Regards
> >> >> > Paul
> >> >> > WB8TSL
> >> >> >
> >> >> > On Mon, Nov 2, 2020 at 8:24 PM John C. Westmoreland, P.E. <
> >> >> > john at westmorelandengineering.com> wrote:
> >> >> >
> >> >> > > Hello Time Nuts,
> >> >> > >
> >> >> > > I have a question -
> >> >> > >
> >> >> > > Has anyone been successful getting WWVB to decode using the
> example
> >> >> for
> >> >> > > DCF77 and making the changes for WWVB?
> >> >> > >
> >> >> > > Chris has his own approach - it's interesting - but on my setup
> at
> >> >> least
> >> >> > I
> >> >> > > haven't been successful with it - maybe it's my antenna - not
> sure
> >> >> just
> >> >> > > yet.
> >> >> > > Also - my screen eventually 'whites-out' after running that for a
> >> >> while -
> >> >> > > meaning - the screen goes completely white and I don't know
> what's
> >> >> doing
> >> >> > > that yet - I suppose it's a bug of some sort.
> >> >> > >
> >> >> > > But, with the DCF77 approach - it appears to identify bits OK -
> >> with
> >> >> the
> >> >> > > code having only minimal changes - so I'd like to go down that
> >> path.
> >> >> > >
> >> >> > > Note - I have a fork here - but it's debug - and not sure it's
> >> worth
> >> >> > > anything other than looking at some of the data that's being
> >> dumped.
> >> >> > > https://github.com/jwestmoreland/Teensy-DCF77
> >> >> > >
> >> >> > > For DC7FF - the AM is just 0.2ms (1) and 0.1ms (0) with no AM at
> >> the
> >> >> > minute
> >> >> > > marker, but WWVB is a little more complicated -
> >> >> > > 0.2ms (0), 0.5ms (1), and 0.8 ms (Marker) - 2 consecutive markers
> >> mark
> >> >> > the
> >> >> > > end of current minute/beginning of next minute.
> >> >> > >
> >> >> > > The DCF77 code seems to take some advantage of the signal
> >> level/timing
> >> >> > and
> >> >> > > the dimensions of the TFT display for
> >> >> > > displaying the signaling - at least that's what it appears to me
> >> right
> >> >> > now
> >> >> > > unless I'm looking at this wrong - I guess that isn't
> >> >> > > a big deal until you try to deal with the marker timing for WWVB
> -
> >> of
> >> >> > > course I could be looking at this wrong right now too.
> >> >> > >
> >> >> > > Maybe trying something like the Goertzel algorithm like KE9NS has
> >> >> done in
> >> >> > > his work with WWV is worth taking a look at too with
> >> >> > > this setup.
> >> >> > >
> >> >> > > 73's,
> >> >> > > John
> >> >> > > AJ6BC
> >> >> > >
> >> >> > >
> >> >> > >
> >> >> > >
> >> >> > >
> >> >> > > On Sun, Nov 1, 2020 at 10:50 AM Mike Feher <mfeher at eozinc.com>
> >> wrote:
> >> >> > >
> >> >> > > > Too bad I am an old retired hardware engineer and know nothing
> >> about
> >> >> > > these
> >> >> > > > new SW controlled devices. Have Fun - Regards - Mike
> >> >> > > >
> >> >> > > > Mike B. Feher, N4FS
> >> >> > > > 89 Arnold Blvd.
> >> >> > > > Howell NJ 07731
> >> >> > > > 848-245-9115
> >> >> > > >
> >> >> > > > -----Original Message-----
> >> >> > > > From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf
> Of
> >> >> paul
> >> >> > > swed
> >> >> > > > Sent: Sunday, November 1, 2020 12:48 PM
> >> >> > > > To: Discussion of precise time and frequency measurement <
> >> >> > > > time-nuts at lists.febo.com>
> >> >> > > > Subject: Re: [time-nuts] WWVB teensy BPSK early experiments
> >> >> > > >
> >> >> > > > John sent the link on the teensy wwvb AM receiver. It can
> easily
> >> be
> >> >> > > > shifted to other frequencies. Using the work Frank dcf77 and
> then
> >> >> Chris
> >> >> > > > wwvb did with the PJRC audio design tool gives quite a bit of
> >> >> insight
> >> >> > to
> >> >> > > > the work that was done.
> >> >> > > > The system assumes a sample rate of 192Khz. That limits the
> >> receive
> >> >> > range
> >> >> > > > to about 98KHz.
> >> >> > > > I have not been able to confirm the rate I am using is 192Khz
> and
> >> >> when
> >> >> > > the
> >> >> > > > set command is used its not recognized. So somethings up.
> >> >> > > > The design Chris has essentially is a microphone input with
> some
> >> 38
> >> >> db
> >> >> > of
> >> >> > > > gain feeding a bandpass filter around 60 KHz to a multiplier
> (RF
> >> >> mixer)
> >> >> > > > then a low pass filter. Chris and Franks design is much more
> than
> >> >> these
> >> >> > > few
> >> >> > > > words with spectrum display, signal level, and AGC.
> >> >> > > > So without any effort the frontend solution is sitting in the
> >> teensy
> >> >> > that
> >> >> > > > cuts out a bunch of typical wiring. Granted its not as tight as
> >> >> > discrete
> >> >> > > > components can be. But its a chunk of software code. No digi
> key
> >> >> orders
> >> >> > > for
> >> >> > > > L & Cs... :-) The output of the chain is 600 Hz audio that does
> >> >> contain
> >> >> > > the
> >> >> > > > phase changes.
> >> >> > > >
> >> >> > > > But the trick is creating the true I & Q channels. Not an issue
> >> to
> >> >> add
> >> >> > a
> >> >> > > > second multiplier and chain did that last night. But at
> >> someplace a
> >> >> 90
> >> >> > > > degree phase change or delay needs to occur.
> >> >> > > > Or as suggested a hilbert transform.
> >> >> > > > Regards
> >> >> > > > Paul
> >> >> > > > WB8TSL
> >> >> > > >
> >> >> > > >
> >> >> > > >
> >> >> > > >
> >> >> > > > _______________________________________________
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> >> >> > > >
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> >> >> > > >
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