NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Time and cel nav, a stupid question
From: Dan Allen
Date: 2008 Apr 22, 16:52 -0600
From: Dan Allen
Date: 2008 Apr 22, 16:52 -0600
On 22 Apr 2008, at 4:26 PM, Fred Hebard wrote:
> On a Mac, using time.apple.com. Just synced, and still about 50
> seconds slow.
That's very unusual. I sync lots of Macs to time.apple.com and I am
never off more than 10 or 20 milliseconds, according to the Mac
Terminal command
ntpq -c peers
which shows details of NTP servers and times. I have tweaked my /etc/
ntp.conf file so that I can query several different servers and NTP
figures everything out.
Here is a sample output of the ntpq -c peers command on my main Mac:
---
remote refid st t when poll reach delay
offset jitter
=
=
=
=
=
=
========================================================================
*clock.xmission. .GPS. 1 u 614 1024 377 24.369
-8.786 6.633
-time1.apple.com 17.106.100.13 2 u 19 256 377 38.468
-5.278 34.007
+time-b.nist.gov .ACTS. 1 u 419 256 376 88.355
8.279 27.296
+tick.usno.navy. .USNO. 1 u 255 256 377 97.773
10.332 19.811
---
It shows four different servers that I am checking in with. The
offset column is in ms and shows how far from those servers my machine
is. The delay column shows the distance in ms to these servers. The
jitter column combines errors in propagation along with absolute time
errors to come up with an overall error figure, also in ms.
Dan
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