[time-nuts] Some More questions

Hal Murray hmurray at suespammers.org
Thu Jan 19 20:50:42 EST 2006


> My main curiosity with the GPS is whether there are other
> stabilization methods employed that would make ovenizing moot.

I don't think so.

Basically, the signal you get out from the radio part of a GPS system has 
poor short term stability but great long term stability.  If you want good 
short term stability you need something like a crystal.  Ovens around 
crystals give you much better performance.  Of course, it all depends on how 
good you need and such, but I think an oven is pretty high on the 
price/hassle vs performance curve.

Any GPS box with a good signal out has a good crystal inside it, probably 
with an oven.

Here is a graph of GPS "position" for a non-good antenna position.
  http://www.megapathdsl.net/~hmurray/leap-second/garmin-rmc.png
To first order, 1 ft position error will be 1 ns time error.


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