[time-nuts] Sawtooth correction with a slower TIC

Tom Van Baak tvb at LeapSecond.com
Fri Jul 20 21:51:56 EDT 2007


> 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




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