[time-nuts] Syncing Tom's PICDivs to 1PPS

Edesio Costa e Silva time-nuts at tardis.net.br
Thu Jul 21 11:09:28 EDT 2016


Some models support synchronization to a external (PPS) reference. Take a
look at http://leapsecond.com/pic/picdiv.htm

Ed├ęsio

On Thu, Jul 21, 2016 at 10:05:15AM -0400, Scott Stobbe wrote:
> I think you will have to decided if you want both your xo (presumably 10
> MHz) and PPS to be phase aligned to UTC. No matter which way you go you
> will have propagation delay across a clock divider. If you just want your
> PPS to be on phase, you can steer your xo.
> 
> On Thu, Jul 21, 2016 at 12:11 AM, Bob Stewart <bob at evoria.net> wrote:
> 
> > For my next GPSDO board revision, I would like to include one of Tom's
> > PICDiv devices to give a much better 1PPS out than the Ublox receivers are
> > capable of.  This means that it has to be started (or slewed to be) exactly
> > on time.  So I was wondering if anyone had experimented in controlling the
> > startup of one of these PICDivs to make them in sync, and if you'd be
> > willing to share your solution before I start digging into it.  I haven't
> > yet looked at the source code for any of these devices, but it's my
> > understanding that this feature isn't provided, and is deemed to be
> > difficult due to the input divider making for a large steering step.  Even
> > a suggestion as to which of the chips would be the best candidate would be
> > much appreciated.  I'm looking for a method that's deterministic, rather
> > than starving the PICDiv of clock cycles and waiting for the 1PPS to match
> > a conveniently correct 1PPS from the Ublox.
> >
> > Bob - AE6RV
> >  -----------------------------------------------------------------
> > AE6RV.com
> >
> > GFS GPSDO list:
> > groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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