[ntp:questions] Ignore one server except in extreme conditions?

A C agcarver+ntp at acarver.net
Wed Nov 16 07:17:28 UTC 2011

On 11/15/2011 22:09, Harlan Stenn wrote:
> And you are sure the PPS signal goes away when your NMEA source is no
> syncd?

I'm not talking about losing sync on the GPS.  I'm talking about 
purposefully ignoring the NMEA data because it has a lot more drift than 
the other servers so I'd like ntpd to use only PPS plus Internet when 
the Internet is available.  If the Internet ceases to be available, fall 
back to the NMEA.  Obviously if the GPS loses sync at the same time as a 
loss of the Internet connection then the clock is just going to wander 
away but would eventually come back when sync/connections are restored.

In my case, I am supplying two different refclocks with the single GPS. 
  The PPS is being fed through a serial port using the PPS refclock 
(22).  The NMEA refclock (20) data is coming from a different serial 
port with no PPS signal and the clock is not configured to us its own 
PPS routines.

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