Re:Which clock to trust?

Robert G Fenske Jr (fenske@rgfpc.electro.swri.edu)
Tue, 15 Sep 1998 08:36:10 -0500 (CDT)

On Mon, 14 Sep 1998 dmbrierley@taz.dra.hmg.gb wrote:
> I've been following this thread, and I fail to see how anyone can get
> an accurate time over the Web, with uncertain delays in transmission 
> and nodes.  Either a radio signal or the 1-900 number is preferable.

	Is is quite possible to get times with 10s of milliseconds.  The
NTP (Network Time Protocol) and associated programs have a lot of research
and developement behind them to handle this kind of time transfer and
thus to properly account for variable transmission delays, local clock
jitter, and local frequency instability.  I have my office PC running an
xntp client and it usually reports offsets of less than 50 milliseconds (I
have no way to verify this though).

Robert Fenske, Jr.   rfenske@swri.edu    Sw     |The Taming the C*sm*s series:
Southwest Research Institute            /R---\  |
Signal Exploitation & Geolocation Div  | I    | |"The Martian canals were the
San Antonio,Texas USA  ph:210-522-3931  \----/  | Martians' last ditch effort."