[time-nuts] WWVB teensy BPSK early experiments

[John C. Westmoreland, P.E.]

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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