Paul: It might be easier to relegate that function to hardware. A simple TC-VCO that drives the sampling clock for the ADC and is steerable for frequency/phase lock from the CPU would allow you to build a synchronous receiver without working about locking the CPU clocking system to anything.
--- Graham == --- Graham On Mon, Nov 9, 2020 at 8:06 PM paul swed <[email protected]> wrote: > 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. < > [email protected]> 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 <[email protected]> > > 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. < > > > [email protected]> 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 > > > > > > > > > > > > To unsubscribe, go to > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > > > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
