[ntp:questions] what happens when sys.peer turns stratum 16?

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Wed Jun 2 17:31:23 UTC 2010

David J Taylor wrote:
> "Miroslav Lichvar" <mlichvar at redhat.com> wrote in message
> news:hu5osh$kc5$1 at speranza.aioe.org...
> []
>> I couldn't find a description either, but it seems to work as expected.
>> PPS is turned off when the sync is lost and turned on when a fix is
>> back. It works only when the fix status is changed, i.e. the command
>> itself doesn't change the PPS status.
>> --
>> Miroslav Lichvar
> That's good news, Miroslav, thanks for the update. I'm not sure how best
> to use that. If lock is lost for a long period then using an alternative
> source would be better, even if that means only getting (for example)
> millisecond accuracy. But if the outage is just a few minutes, I wonder
> whether the free-running PPS output might not be better than sync over
> the Internet? There may sense in leaving the PPS output running for a
> few minutes if lock is lost and the PPS is the only precision source -
> what do you think?

I have seen ntp source code which used the (measured or implied?) 
quality of the freerunning oscillator to determine how long such a 
signal should be considered valid.

Sorry, I don't remember if this was within a specific driver or in the 
mainline code. :-(


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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