Tom, I did most of the software development work using just the uncorrected 1PPS into TMR0 and two scaled and summed PWM outputs instead of a DAC, and the results were surprizingly good. It made a very low cost, small footprint design without the external counters and DAC. All the added extras since are just part of my continuing education.
Richard ----- Original Message ----- From: "Tom Van Baak" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Friday, July 20, 2007 5:51 PM Subject: Re: [time-nuts] Sawtooth correction with a slower TIC > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] > > > My original design used a 50 MHz TIC clock and the TMR0 > > prescaler as the phase counter giving 20ns single sample resolution > > in the prototype system. > > In this case how about making a super-simple GPSDO > and just put the uncorrected 1pps directly into TMRO. > The sawtooth jitter of an M12+ is 9 ns rms, which is just > the magnitude you need to improve on the 20 ns single > shot PIC-based TIC resolution. If you average long enough > even hanging bridges will not be a concern. > > You'd have to do some work to get fancier, but it's hard to > imagine a PIC-only GPSDO that would be simpler. > > /tvb > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
