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.
You won't do this with a straight crystal oscillator, and I don't know
if any of the GPS units actually give out a clock signal that's fast
enough to measure 1/60 of a second.

HP makes a 10 MHz ovenized crystal oscillator which is much more
stable than this, however. There is one on ebay now for about $85.
That's about as cheap as you are likely to find for this level of
precision.

Do you really need this much precision?

-
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Jim Adney
Madison, WI 53711 USA
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Once you have this precision, you need some way to reliably use it.

I always get a chuckle out of "Star Trek". They've got massive
computers calculating precise timing, trajectories etc.
but they always initiate it with an imprecise verbal command, "ENGAGE".
mike

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