Accurate time without a network connection?

Mxsmanic mxsmanic at
Tue Apr 22 14:30:33 PDT 2003

In the past I simply watched the time on the server that was to serve as my
time reference, noted the drift over a few days, then wrote a very simple
daemon that periodically skewed the time to compensate for the drift.  I was
surprised at how easy it was to get the server to stay within 1 second of
the correct time for periods of several days with this simple and crude
adjustment.  The PC clock was way off (more than six seconds a day), but it
was fairly consistently so, so with a bit of tweaking I managed to keep it
close to the correct time.

I was still happy to get the network connection back up, though.

I did look at a few radio-controlled clocks (the GPS ones were not an
option, as I have no place to put the antenna), but since I could buy
another server for the price of the cheapest among them, they were not
really a realistic option.

----- Original Message -----
From: "John Murphy" <jfm at>
To: "David Kelly" <dkelly at>
Cc: <questions at>
Sent: Tuesday, April 22, 2003 23:19
Subject: Re: Accurate time without a network connection?

> David Kelly <dkelly at> wrote:
> >Surfing has turned up a lot of information but
> >little hardware. Of most interest was use of sound card connected to
> >radio receiver for decoding the time signals. But that's a touch exotic
> >for this application. Else I'd use the $20 LCD "atomic clock" I have on
> >my wall, a $25 USB "web-cam", and some sort of OCR.
> I nearly fell off my chair laughing after reading that 'solution'!
> There's a self build method at the following URL with notes for USA users:
> I'm determined to make one (or two) myself soon.
> I think Charles Swiger gave the answer which will suit you best.
> John.
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