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RE: Online atomic clock



A good solution for NTP would be SymmTime.  We (the US Navy) do a
considerable amount of business with these folks.  They offer a free
download for your computer called SymmTime
(http://www.ntp-systems.com/symmtime.asp?engine=adwords!3230&keyword=%28Symm
time%29&match_type=).   You can use it to just sync your PC clock (and it
will show you the accuracy, too) or you can see as many time zones as you
want and you can customize the way it appears on your screen.  Pretty handy
piece of freeware.

73s,
Eric KF4OTN

 
-----Original Message-----
From: owner-AMSAT-BB@amsat.org [mailto:owner-AMSAT-BB@amsat.org] On Behalf
Of Tony Langdon (ATC)
Sent: Tuesday, September 13, 2005 6:12 PM
To: 'William B Magnusson'; 'amsat-bb'
Subject: RE: [amsat-bb] 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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