[Elecraft] accurate time

[David Woolley (E.L)]

Dick Dievendorff wrote:
> 
> 
> Recent versions of Windows (certainly XP and beyond) include an NTP client

Although it may not matter if you only want a non-resillient time source 
accurate to a few seconds, XP only contains a (broken) implementation of 
SNTP, not NTP.  Windows 2003 contains an implementation of NTP, which is 
broken out of the box (it will not work against a real NTP server, and 
will accept time from servers indicating that they don't have a valid 
time), but may be configured to be compliant, or at least less broken. 
Out of the box, these all poll too slowly for tight time control, 
although well enough for Windows Kerberos to work.

> that can synchronize with one of several NTP servers.  You right click the

NTP requires several, as much of the specification is about using 
multiple servers to detect server problems and improve the time quality.

> time in the status bar, choose "Adjust Date/Time", select the "Internet
> Time" tab, optionally provide an alternate NTP server and punch the "update

Two servers isn't enough, with true NTP, to isolate a faulty server.

> now" button.  No special NTP client code is required to get to the accuracy
> necessary for this sort of task.

However, to get accuracy of the order of the tick interval on Windows, 
you need to use the open source reference implementation of NTP, rather 
than W32Time, and to get accuracy of the order of 10s of microseconds, 
you need to use Unix and a clock with a pulse per second output.

For wristwatch and eyeball accuracy for logging W32Time may be OK, but 
not, especially out of the box, for anything that requires accurate time 
synchronisation.

-- 
David Woolley
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