[Voyage-linux] Re: PPS kernel patches

[Mark Phillips]

You need to look at the NTP sources. These contain a kernel patch. If I
understand it correctly, GPSD and others pick up the 1PPS via the kernel
(usually connected to the DCD pin on the serial port).

They are available here ftp://ftp.kernel.org/pub/linux/daemons/ntp/PPS/
and a rough howto is available here http://etienne.favey.ch/ntp/

Thanks very much for looking at this!

Mark

On Mon, 2007-12-24 at 09:27 +0800, Kim-man 'Punky' TSE wrote:
> Hi ,
> 
> But where can I get the 1PPS patch for Linux and instruction?  As far as 
> I read gpsd documentation, it indeed support 1PPS as long as you have 
> the proper equipment.
> 
> What is the different between gpsd support for 1PPS and the 1PPS patch 
> for the time server?
> 
> Regards,
> Punky
> 
> Mark Phillips wrote:
> > Any thoughts/comments on this Punky?
> >
> >
> >
> > On Mon, 2007-12-10 at 14:33 -0500, Mark Phillips wrote:
> >   
> >> I have mine setup in a similar way but it is not a true time server in
> >> that because of the lack of a disciplining kick on a regular basis it is
> >> able to drift between time updates.
> >>
> >> The problem with NMEA time strings is that they tend to come in a
> >> cluster and not at all every second or 3 seconds or 5 seconds. They come
> >> along whenever the GPS processor has time to spit them out.
> >>
> >> The 1PPS pulse from the GPS system is not derived from the decoded data
> >> but rather is an inherant component of the GPS signal along with the
> >> 10KHz pulse and thus is more reliable.
> >>
> >> I'd still like to see a 1PPS patched kernel particularly as it would
> >> then allow for connections to things like Frequency Standards and LORAN
> >> RX's etc. Heck, one could even connect it up to the mains after a very
> >> simple signal divider (trick used on clock radios etc) is added.
> >>
> >> Mark 
> >>
> >> On Thu, 2007-12-06 at 19:24 +0800, Kim-man 'Punky' TSE wrote:
> >>     
> >>> Hi guys,
> >>>
> >>> Forget to mention, I have setup voyage attached to Garmin GPS18/USB and 
> >>> get NTP time sync'd.  Of course, this device is not PPS-capable, but it 
> >>> works without any patch to the kernel and NTP daemon.   See my blog article:
> >>>
> >>>     http://www.punknix.com/?q=node/116
> >>>
> >>> Regards,
> >>> Punky
> >>>
> >>> Mark Phillips wrote:
> >>>       
> >>>> Now I think about it, updating the gpsd package would also be useful for
> >>>> this purpose.
> >>>>
> >>>> FYI, my NTP server is running Voyage on a Neoware N3000 thin client
> >>>> (ebay $20). It has a 300MHz via processor in it as well as an IDE
> >>>> interface which is now running a CF card. The GPS RX plugs into ttyS0
> >>>> and I'm running gpspipe on ttyS1 to allow my Nixie tube clock to correct
> >>>> itself.
> >>>>
> >>>> Mark
> >>>>
> >>>> On Fri, 2007-11-30 at 05:10 +0000, Clark wrote:
> >>>>   
> >>>>         
> >>>>> Mark Phillips <g7ltt at ...> writes:
> >>>>>
> >>>>>     
> >>>>>           
> >>>>>> Hi all,
> >>>>>>
> >>>>>> Is there anywhere that I can register a feature request for adding PPS
> >>>>>> to the kernel for use in NTP apps? This would be really handy I think.
> >>>>>>
> >>>>>> Thanks
> >>>>>>
> >>>>>> Mark
> >>>>>>
> >>>>>>       
> >>>>>>             
> >>>>> I would really like that too!  
> >>>>>
> >>>>> I have been using Voyage to try to create an NTP appliance  'cause the
> >>>>> commercial ones are WAY beyond my budget!
> >>>>>
> >>>>> I appreciate the work on Voyage so far!
> >>>>>
> >>>>> Thanks!
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Voyage-linux mailing list
> >>>>> Voyage-linux at list.voyage.hk
> >>>>> http://list.voyage.hk/mailman/listinfo/voyage-linux
> >>>>>     
> >>>>>           
> >>>       
> 
> 
-- 



Mark Phillips, G7LTT/NI2O
Randolph, NJ