Ron Frazier (NTP) wrote:
On 3/13/2012 2:40 PM, Chris Albertson wrote:
On Tue, Mar 13, 2012 at 9:52 AM, Ron Frazier (NTP)
<timekeepingntpl...@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
The link you quoted just now is not the one that bugs me so much today.
This one is the one that bugs me today, where my clock was stepped by 50
seconds for some reason.
http://dl.dropbox.com/u/9879631/drifting02b%20-%20peerstats%20insane.jpg
I'm on a text mostly system so why do you require me to use
a web browser to help you?
What is your current ntp.conf, ntpd version, operating system
and response of "ntpq -crv -p" after ntpd has had at least
a day to stabilise?
Not so long ago you posted that you had an offset within
+/- 6 ms but didn't give any evidence. Response from
"ntpq -crv -p" or better a day from peer_summary or couple
of days from loop_summary would be enough.
David
When I get the Sure board, I plan to hang it on the pc in tandem with
this GPS and compare.
Sincerely,
Ron
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