[time-nuts] WWVB teensy BPSK early experiments

Tue Nov 3 18:41:29 UTC 2020

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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