[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

Chris Albertson albertson.chris at gmail.com
Tue Mar 13 18:40:36 UTC 2012

On Tue, Mar 13, 2012 at 9:52 AM, Ron Frazier (NTP)
<timekeepingntplist at c3energy.com> wrote:
> Hi all,
> I just woke up to a 50 SECOND clock error.  Prior to the error, with my PC
> locked into the GPS and the internet servers noselected, here's what my
> peerstats looked like.  Baseline is the GPS.  Colored lines are internet
> servers.
> http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg

Looks to me like that GPS, maybe lock lock and was able to "coast" on
hold over for a while then fell off a cliff.     If you have a log of
satellite  signal to noise ratios you might be able to figure out why.

The internet servers appear to be 100% reliable seeing as they all agree.

These kinds of things are why some hobbysts end up buying multiple GPS
(different brands)  Otherwise it is hard to sort out a GPS firmware
bug from a solar storm or just that there were not sats visable to
your indoor antenna for a few minutes

I think your goal is to learn about all of this so these problems are
a good thing.  No one learns much from working systems.   But if the
goal is a reliable NTP server, the pool NTP servers can't be beat
except by a good timing mode GPS, that has good self diagnostics and
PPS.  The self diagnostics part is important

Chris Albertson
Redondo Beach, California

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