[LinuxPPS] testing PPS with ktimer

[Hal V. Engel]

On Tuesday, November 09, 2010 08:49:05 am Ken MacLeod wrote:
> On Tue, Nov 9, 2010 at 2:37 AM, Udo van den Heuvel <udovdh at xs4all.nl> wrote:
> > On 2010-11-08 21:19, Ken MacLeod wrote:
> >> Did I miss something obvious? or a patch?  should ktimer work in this
> >> configuration?
> > 
> > Isn't ktimer just for testing?
> > ktimer is something different than ntpd's local clock.
> 
> Yes, ktimer is just for testing.  Like ktimer, the driver I will be
> writing will only be a PPS source, not a time source.  I wanted to
> test with ktimer first to confirm that a PPS-only source is already
> supported by ntpd.

You also need another time source so that ntp can figure out what the current 
second is.  This can be another ntp server or other supported time source that 
allow ntp to resolve the time close enough to resolve an unambitious second.

I use this when I boot over to Windows since the Windows version of ntp does 
not directly support the OnCore GPS I use only it's PPS and then external ntp 
server to resolve the second.  This takes a lot longer to sync than using the 
OnCore natively (on Linux) but it works. 

Hal