TELECOM Digest OnLine - Sorted: Network Time (was Re: Using Cell Phone For Frequency Calibration?)

Network Time (was Re: Using Cell Phone For Frequency Calibration?)

Koos van den Hout (koos+newsposting@kzdoos.xs4all.nl)
5 Jun 2006 19:50:37 GMT

> [TELECOM Digest Editor's Note: Or notice, for example, the setting
> of accurate clocks via the internet. I've a program here called 'Net Time'
> which constantly polls various 'time servers' around the net. When
> you set it up, one site returns data reported to have latency of .150 ms
> and another has latency of .75 ms, etc, in other words _none _ of
> them display (on my screen) -exactly- the right time. But the
> program takes a half dozen or so of these time servers, and averages
> the latencies then makes an adjustment which is as close as one can
> get apparently, to the 'correct time'

NTP (Network Time Protocol) and the associated software is a science
in itself. The round-trip latency is used in the time calculations, as
is the averaging of multiple servers to find correct servers and
outliers. With good hardware, microsecond to nanosecond accuracy is
possible.

http://www.ntp.org/ (The network time protocol project) has a lot of
information, including scientific papers.

Koos van den Hout

Camp Wireless, wireless Internet access at campsites| Koos van den Hout
http://www.camp-wireless.org/ | http://idefix.net/~koos/
PGP keyid DSS/1024 0xF0D7C263 or RSA/1024 0xCA845CB5| Fax +31-30-2817051

[TELECOM Digest Editor's Note: Thanks for mentioning this site. I went
over earlier today and selected from the 'us.pool.ntp.org' numbers for
my computer clock settings. PAT]

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