On Fri, 24 Jun 2005 22:19:33 -0500 Jim Adney
wrote:

On Fri, 24 Jun 2005 20:59:10 GMT Jonathan Kirwan
wrote:

I had thought that maintaining an accumulated deviation of no greater
than 1/60 sec in 6 hours is about like 24 seconds/year or 2 seconds a
month. This is 1ppm drift. Without being temperature stable, this
is not so easy, is it?

It's about one part in 13 million, so, yes, this is pretty difficult.

Oops, I'm off by one decimal place; it's more like one part in 1.3
million. This can be done with a good crystal oscillator, but it's got
to be a pretty good one, and it has to be calibrated against a real
standard.

The question remains of why one would need this degree of accuracy in
a timing function.

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Jim Adney
Madison, WI 53711 USA
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