[ntp:questions] Odd results with Oncore UT+ ref clock

Mike S mikes at flatsurface.com
Wed Feb 2 01:50:17 UTC 2011


At 08:06 PM 2/1/2011, Chris Albertson wrote...

>During those hours it would display "377" and then revert back to what 
>I posted.
>
>What I'm looking for here is advice on what to check.

Chris, I've seen similar when using an Atom (PPS) refclock linked to 
another refclock (using the "prefer" keyword) which delivers time via a 
serial character stream. The PPS is, as it should be, very accurate. 
But the serial (Trimble Thunderbolt, in this case) would bounce around 
+- quite a few ms. When they got too far apart, NTP would consider the 
pair bad (or maybe only the PPS dropped out, I can't recall).

I don't know if the monolithic Oncore driver pays any attention to 
this, but my issue was corrected by adding a "tos mindist 0.015" line 
to /etc/ntp.conf. That allows the two refclocks to be separated by up 
to 15 ms before NTP considers it a problem. 




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