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RE: Online atomic clock



> This recent thread caused me to wonder about the dynamic 
> nature of the internet and variable propagation delays. Does 
> anyone know the relative accuracy - at your computer - of 
> "internet" timing services as compared to "hard-wired" timing 
> services as are available in many cities in many countries?

For Internet based timekeeping, NTP is your best bet, as NTP does all it can
to compensate for propagation/packet delivery delays.  For specs, the RFC on
NTP (it'll be a heavy read :) ) will tell you the answer, but I believe the
accuracy can be surprisingly high, especially if you choose a time server
that's relatively close to you and then use full NTP (rather than SNTP) to
that server. SNTP is good for sycing between a gateway time server on your
LAN and all the other PCs, if acuracy is important.  

Unfortunately, I can't recall the exact accuracy of NTP, but I believe it's
in the order of a few milliseconds, maybe even more accurate.

Of course, if you're on dialup and are constantly saturating your link with
downloads, all bets are off. :-)
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