Re: [Linuxptp-users] grandmaster with an H/P 3805A GPS disciplined osc

[Miroslav L. <mli...@re...>]

On Wed, Aug 21, 2013 at 08:09:08AM +0200, Richard Cochran wrote:
> On Wed, Aug 21, 2013 at 07:47:54AM +0200, Richard Cochran wrote:
> > On Tue, Aug 20, 2013 at 02:00:05PM -0700, David Gravereaux wrote:
> > > I was wondering if I use NTPd for controlling the GPS radio with its
> > > built-in driver for it along with the PPS signal on the comport as the
> > > DCD line
> > > <http://support.ntp.org/bin/view/Support/Z3801AReceiverModifications>,
> > > would this share the same counter for PTP?
> > 
> > This setup will synchronize the Linux system time to the external
> > Z3801A box using a PPS signal. You could use ptp4l with software time
> > stamping and the 'free_running' option to serve this time to your
> > network.
> 
> But you have an Intel i210, right?
> 
> So it would be even better to feed the PPS from the Z3801A into one of
> the i210's SDP pins. (Be careful with the signal conditioning, SDP is
> CMOS directly to the chip.)

Just to list all options, if the requirement is to have the PTP slaves
well synced together, but the absolute accuracy of the PTP time
doesn't matter match, the PHC can be synchronized from the system
clock by phc2sys with a very slow PI servo and used by ptp4l without
losing hw time stamping.

e.g. phc2sys -w -c eth0 -s CLOCK_REALTIME -P 0.03 -I 0.0001

-- 
Miroslav Lichvar