[time-nuts] NTP IRIG config help

Jim Kusznir jkusznir at gmail.com
Mon Mar 7 19:07:42 UTC 2011


Hello:

I'm not sure if this is the right place; I've been having trouble
finding "current" info / discussions on NTP on linux.

I have a SEL 2407 clock (http://www.selinc.com/sel-2407/) that I was
trying to make more useful by providing NTP service to the university
(and others).

This clock has IRIG (modulated and "unmodulated") outputs, as well as
PPS and 10kPPS.  I know there is a linux PPS driver, but it is unclear
to me whether it works without an accompanying NEMA feed, and this GPS
does not do NEMA out.  I also haven't made the custom DB9 cable to
feed the PPS into the linux box yet.  However, I had the right
adapters and cables to feed the IRIG into the sound card, so I thought
I'd try that.

After playing with levels and such for a while, I got it to give me a
timecode = "00 ", but no other numbers after that, and it appears its
not sync'ing to it.  If I turn up the audio at all, I start getting
errors indicating overdriven IRIG, and if I unplug it, I get other
errros reported, so its clearly seeing "something" there.  However, it
never locks and shows something other than "00 " for timecode.

I had to guess on a lot of how to make it work, including cabling and
termination and the like, as it seems to be a big deficit in
documentation at a level below "extremely knowledgeable / technical"
level.

Is this the right place to ask?  If so, anyone have any pointers?  If
not, can someone direct me to a more appropriate place?

Thanks!
--Jim




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