[ntp:questions] Sure serial - USB with PPS performs 16% better after Windows reboot
Ron Frazier (NTP)
timekeepingntplist at c3energy.com
Sun Mar 25 20:51:29 UTC 2012
Hi all,
I think I've discovered something very interesting. Just by chance, I
had to take the laptop computer to someone else's house the other day to
do some work. So, I shut it down and unplugged the GPS and left. When
I came back, I plugged the GPS back in and rebooted. After a while, I
checked my graphs. I found peak offsets in the 800 us range rather than
in the 1.2 ms range I had seen before. I restarted NTPD and started
another graph. After a while, saw the 1.2 ms offsets I had seen in the
past. Then, after forming a theory that the reboot may have some
effect. I rebooted again. After letting the graph run a while, I was
again seeing offsets in the 800 us range. See the graph below.
http://dl.dropbox.com/u/9879631/2012-03-24-2327-loopstats-reboot-restart-reboot.png
There are three distinct sections. First, is the beginning. Here, as
you can see, the peak offsets are approximately + .8 / - .6 ms. Then,
there is the middle. As you can see, peak offsets are approximately +
1.2 / - 1.2 ms. Then, there is the end. There are two subsections
here. In the first, the peak offsets are approximately + .8 / - .6 ms
again. In the second subsection, the peak offsets are approximately + 1
/ - .7 ms. I don't know why there is a variance between the
subsections. However, the beginning of the graph is a time just after a
reboot, the middle is a time just after an NTPD restart, and the end is
a time just after another reboot.
I can use the signal either way. I just thought this was interesting.
Anybody know what's going on?
Sincerely,
Ron
--
(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such. I don't always see new messages very quickly. If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)
Ron Frazier
timekeepingdude AT c3energy.com
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