unruh wrote:
On 2010-02-14, Dave Baxter <[email protected]> wrote:
In article <[email protected]>,
[email protected] says...
On 2010-02-14, Dave Baxter <[email protected]> wrote:
Hi All.
Been trying (again) to setup a FreeBSD GPSDNTP server, as I want to use
the currently used Win2k (With the Meinberg binary etc) box for
something else, having found that running anything else "significant" on
it, "distrubes" the NTPD system somewhat. Nothing wrong with the
Meinberg system (far from it in fact) it's just that I need that machine
to replace an older PC that has finaly expired, so as I have another
with no OS on it, I thought I'd go the FreeBSD route this time.
A good move!
Trimmed things a bit...
Hi Tom.
All that I'm trying now, I have done successfully before, but for
whatever reason it doesnt want to fly now. Not sure if my notes are
bad, DT's website, or the F-BSD docs are different now.
I *Need* PPS support, as I have an app that needs mS accruacy. See:-
http://www.dxatlas.com/Faros/ for details of what I have running, that
needs such data. Plus, for whatever reason, my ISP (Demon/Thus/C&W)
seem unable to provide a stable NTP service these days.
You do not need PPS support. Just use something like gpsd, and the shm
refclock and you will get usec accuracy (not ms accuracy).
That might be a Linux specific feature of gpsd.
Man page mentions Linux version of gpsd detecting PPS on
serial DCD line otherwise best accuracy around 10ms.
On NetBSD I've only tried gpsd + shm with GlobalSat BR-304
and that doesn't have PPS out and couldn't get anything near
10ms from it having tried with large mindist and various
fudge times. It's on my todo list to try with the Garmin
gps-18x-LVC in case the PPS DCD support is working on NetBSD
to compare with using NMEA/PPS and NMEA + ATOM drivers.
David
I have at present, a seperate Win2k machine, running the Meinberg port
of NTPD and Dave Hart's serialPPS hack. It works very well, even
surviving Windows updates and a reboots etc!
Trouble is, I want that physical PC for something else, and as I had a
"spare and empty" PC, I decided to revisit the FreeBSD version, after
all, it only took me 2 days last time to get it going.
I've been at it (trying to get FreeBSD working again) this time for over
3 weeks! And am about to lob the thing out of the window.
Install a prepackaged Linux from one of the distros. don't install X or
all of the other stuff (openoffice, firefox, etc) to keep the size down.
Then on either Linux or bsd, you could use chrony instead, and get even
better accuracy and much faster convergence, but since you already only
want ms accuracy, that might be overkill except for the faster
convergence.
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