At 10:32 AM +0100 2005-07-20, [EMAIL PROTECTED] wrote:
While I agree that GPS is the likely answer, I wasn't expecting the
ability to work inside computer rooms and basements.
It doesn't need to work in basements, etc. It only needs to keep
a record of the last location it was at when the signal faded
away. The emergency service vehicles probably can't get any closer
than that anyway.
I've been doing some reading on this subject. It seems that both
GPS and tower triangulation methods suck. For GPS, the problems are
signal acquisition and penetration in urban environments, especially
with non-dedicated handheld devices. For tower triangulation, the
problem appears to be areas with poor signal coverage where you might
only be able to barely see one tower, and where TDoA, AoA, and EOTD
aren't going to do you any good.
In either case, simply keeping the last known signal lock may
very well be one of the worst things you could do.
It seems to me that we need to use both technologies in order to
get any real hope of reasonably sustainable accuracy, either for E911
or any other location-aware technology. And I'm not convinced even
that's enough.
So, anyone want to place any bets on what's really going to happen?
--
Brad Knowles, <[EMAIL PROTECTED]>
"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
-- Benjamin Franklin (1706-1790), reply of the Pennsylvania
Assembly to the Governor, November 11, 1755
SAGE member since 1995. See <http://www.sage.org/> for more info.