NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Problem with Time-Server from NIST
From: Lu Abel
Date: 2011 Apr 8, 11:02 -0700
From: Lu Abel
Date: 2011 Apr 8, 11:02 -0700
Marcel:
When your web browser was displaying the incorrect time, what did it show for "time accurate to..." ??
Recently I had unhooked my DSL modem from my computer and, forgetting that I was unhooked, fired up the NIST server. When I didn't see the display I realized I was disconnected and re-connected. I got an incorrect time -- but the "accurate to" display said something like "accurate to 30 seconds" (that round-trip delay measurement got sidetracked by the unplugged cable).
As I understand it, NIST measures the round-trip delay to your computer and then advances the time display by half the measured amount to compensate for the travel display.
Your internet provider may just have had a hiccup that day.
Lu
From: Marcel Tschudin <marcel.e.tschudin@gmail.com>
To: NavList@fer3.com
Sent: Fri, April 8, 2011 5:30:54 AM
Subject: [NavList] Re: Problem with Time-Server from NIST
After some further testing: The time shown on the Web-interface corresponds now again with the synchronised computer clock. In between the difference reduced from 2s to 1s. It appears to me that the time shown on http://nist.time.gov/timezone.cgi?UTC/s/0/java doesn't seem to be reliable.
Marcel
When your web browser was displaying the incorrect time, what did it show for "time accurate to..." ??
Recently I had unhooked my DSL modem from my computer and, forgetting that I was unhooked, fired up the NIST server. When I didn't see the display I realized I was disconnected and re-connected. I got an incorrect time -- but the "accurate to" display said something like "accurate to 30 seconds" (that round-trip delay measurement got sidetracked by the unplugged cable).
As I understand it, NIST measures the round-trip delay to your computer and then advances the time display by half the measured amount to compensate for the travel display.
Your internet provider may just have had a hiccup that day.
Lu
From: Marcel Tschudin <marcel.e.tschudin@gmail.com>
To: NavList@fer3.com
Sent: Fri, April 8, 2011 5:30:54 AM
Subject: [NavList] Re: Problem with Time-Server from NIST
After some further testing: The time shown on the Web-interface corresponds now again with the synchronised computer clock. In between the difference reduced from 2s to 1s. It appears to me that the time shown on http://nist.time.gov/timezone.cgi?UTC/s/0/java doesn't seem to be reliable.
Marcel
