[ntp:questions] Bought a GPS receiver--What next?

W. D. NewsGroups at US-Webmasters.com
Mon Nov 1 19:20:41 UTC 2004


Hi Brad,

Thanks for your reply.  More...

Brad Knowles wrote:
> 
> At 4:11 AM -0600 2004-11-01, W. D. wrote:
> 
> >  He says that you need to rebuild the kernel, but others
> >  say that it's possible to get better accuracy if you don't.
> >  What's the real, full story?
> 
>         For FreeBSD, you do not need to rebuild your kernel, if you want
> refclock support in your NTP server.  The kernel should already have
> everything you need in this respect.

OK, how do I implement this?  What should I put in /etc/ntp.conf
to activate this?


 
> >  Somewhere I read that you need to load the following
> >  driver:
> >
> >     /usr/src/contrib/ntp/ntpd/refclock_oncore.c
> 
>         Right, this would be a natural part of building "ntpd", the NTP
> daemon.  It will need to be built with refclock support for the
> Oncore, which the default standard ntpd provided by FreeBSD may not
> be configured to do.

OK, what is the procedure to build-in Oncore support?  How is 
refclock_oncore.c integrated into the NTP executable programs?

 
>         Unfortunately, building the version of ntpd in the ports
> subsystem probably won't be configured for refclock support, either.
> 
>         You'll need to download the latest version from
> <http://ntp.isc.org/bin/view/Main/SoftwareDownloads>.  

I am running:

  version="ntpd 4.2.0 at 1.1161-r Tue Oct  5 23:55:53 CDT 2004 (2)"

that's the most recent version, yes?  If it's not configured
for refclock support, how do I do this?


>The tarball
> you download should give you the information you need to build and
> install your own version of ntpd that is properly built to
> incorporate refclock support for your Oncore device.

OK.  I understand that it 'should'.  I am wondering where that it
*DOES*.  I an currently looking at the HTML docs that came
with that version.  Here are some analogous pages on the Web:

Pulse-per-second (PPS) Signal Interfacing
http://www.eecis.udel.edu/~mills/ntp/html/pps.html

Motorola Oncore GPS receiver
http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver30.html

PPS Clock Discipline
http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver22.html

Debugging Reference Clock Drivers
http://www.eecis.udel.edu/~mills/ntp/html/rdebug.html

Kernel Model for Precision Timekeeping
http://www.eecis.udel.edu/~mills/ntp/html/kern.html


Also, it is suggested that I need the configuration file:

  /etc/ntp.oncoreX

What is the format of the file--what are the appropriate
commands and settings?  I don't see this documented 
fully anywhere.

Twiki pages are also inscrutable:
http://ntp.isc.org/bin/view/Support/ConfiguringMotorolaOncoreRefclocks
http://ntp.isc.org/bin/view/Support/ConfiguringNTP
http://ntp.isc.org/bin/view/Support/TestingNTPsBehavior
http://ntp.isc.org/bin/view/Support/WebOrder

I guess if I can't get satisfactory answers to these
questions, I'll just try to slog through Art Neilson's
instructions:

  http://www.wh7n.net/refclock/clock2.php

Again, does anyone know how talk to this unit to find out my 
latitude, longitude and elevation?  How many satellites
it sees?


> 
> --
> Brad Knowles, <brad at stop.mail-abuse.org>
> 
> "Those who would give up essential Liberty, to purchase a little
> temporary Safety, deserve neither Liberty nor Safety."
> 
>      -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
>      Assembly to the Governor, November 11, 1755
> 
>    SAGE member since 1995.  See <http://www.sage.org/> for more info.

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