[time-nuts] WWVB teensy BPSK early experiments

Wed Nov 4 18:20:16 UTC 2020

Did you hook the touch screen up?
I didn't as there was no reason to.

On Wed, Nov 4, 2020 at 1:19 PM paul swed <paulswedb at gmail.com> wrote:

> 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
>> >> >> > > >
>> >> >> > > >
>> >> >> > > >
>> >> >> > > >
>> >> >> > > > _______________________________________________
>> >> >> > > > time-nuts mailing list -- time-nuts at lists.febo.com
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>> >> >> > > >
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>> >> >> > > > and follow the instructions there.
>> >> >> > > >
>> >> >> > > _______________________________________________
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>> >> >> > >
>> >> >> > _______________________________________________
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>