[time-nuts] WWVB teensy BPSK early experiments

[paul swed]

No time to experiment the last few days as the weather has been great and
have to get outside stuff done. That said trying to tease apart how to
create a lockable NCO in the teensy.
Its not clear to me that I can create a sine wave oscillator and drive that
out to a pin to see stability and adjustment effects. It can be done by
mixing with another internal signal and measuring the output. But my
preference would be direct measurement.
With respect to sine and cosine. It seems a second oscillator and a third
oscillator that is 90 degrees out can be created. Supposedly these would be
locked. (To be proven)
Regards
Paul


On Sun, Nov 8, 2020 at 7:59 PM John C. Westmoreland, P.E. <
john at westmorelandengineering.com> wrote:

> Hello Graham and Fellow Time Nuts,
>
> I did what Paul had mentioned as well - and that appeared to clear up the
> immediate screen issues but I will
> insert a termination resistor as well as Graham has suggested.
>
> I looked on the PJRC forum as well - and it appears there has been a lot of
> discussion and development regarding
> the enhancement of the performance of these TFT displays - also - there's a
> beta version of the arduino libraries -
> Teensyduino 1.54 Beta #4 -
> https://forum.pjrc.com/threads/64303-Teensyduino-1-54-Beta-4 - take a look
> at that
> for those that are experimenting with this platform.
>
> As far as my current setup - in the wee hours today - the WWVB signal was
> coming in very strong - my HPSDR rig
> using the Clock tool from Multipsk was decoding every minute - the Clock
> programs' PLL was solidly locked.
>
> I noticed for the Teensy4WWVBsdr code it appeared to be in sync with WWVB -
> it was decoding either a minute or
> the hour apparently correctly - but it was shifted - meaning say for:
>
> 2:38:00 AM it decoded 2 as the minute - which was incorrect but correct for
> another time position
>
> or, for the hour it would say 8 as hour.  This makes me think obviously for
> some reason the positions are being
> shifted in an otherwise somewhat successful decode attempt.
>
> I am using the Teensy 4.1 - I need to check all of the libs to make sure
> nothing incompatible is possibly taking place.
>
> I've been informed also the antenna from Stormwise is on the way.
>
> Thanks again Graham - KE9H - for helping out on this.
>
> 73's,
> John
> AJ6BC
>
>
> On Sun, Nov 8, 2020 at 8:02 AM Graham / KE9H <ke9h.graham at gmail.com>
> wrote:
>
> > John W:
> >
> > Regarding your Teensy WWVB receiver display issues.
> > The Teensy does not have a source termination resistor on the SPI clock.
> > Add a 50 Ohm resistor (value not critical, anything from 33 to 75 will
> > work) in series with the SPI Clock signal, as physically close to the
> > Teensy as practical.
> > This totally cleared up all of my display issues.
> > https://www.analog.com/media/cn/training-seminars/tutorials/MT-097.pdf
> > Source termination resistors provide a source resistance to absorb the
> > reflection of fast edges off the slave device input, reducing all the
> > bouncing and wiggles on the rising and falling edges of signals,
> > particularly important/beneficial on clock signals.
> >
> > --- Graham
> >
> > ==
> >
> >
> > On Wed, Nov 4, 2020 at 10:55 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
> > >
> > >
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