Unnamed Administration sources reported that Ian A Finlay said:
I recently purchased a GPS. The manual indicates that SA has no effect on
timing. SA only affects positioning.
Err...
GPS is nothing but timing.
I'm not quite sure how you'd change "position" without timing.
Position is a function of time measurments...and a bunchamath.
The vast majority of people will not notice that their clocks
are 400 nanoseconds off. What are they going to check against?
The vast majority of people WILL notice if they hit the concrete
wall that's 400 feet past the highway exit. That's VERY easy
to check against.
Valdis Kletnieks
Operating Systems Analyst
Virginia Tech
Date: Wed, 26 Sep 2001 21:39:37 -0400 (EDT)
From: David Lesher <wb8foz@nrk.com>GPS is nothing but timing.
I'm not quite sure how you'd change "position" without timing.
Position is a function of time measurments...and a bunchamath.
Of course, the Heisenberg Uncertainty Principle states (among
other things) that "the more precisely position is determined,
the less precisely the momentum is known". As long as we're
getting technical, shall we add quantum mechanics to the
discussion? 
(I suppose that GPS breaks down as we approach the speed of
light...)
Eddy