George <george@nospam.invalid> wrote in
news:bvadnf8PPeVrpc7anZ2dnUVZ_uKdnZ2d@comcast.com:
> Without repeating the spammers URL they use triangulation (the
speed of
> light is a constant so you can deduce how far away you are from
a radio
> transmitter etc). It gives much coarser results than GPS. It is
at least
> something because say you bought a recent Blackberry from VZW
which
> has a real GPS built in that is disabled at VZWs request.
>
>
Impossible. Pipedream. The signal from the tower rarely comes
directly to your phone so it could be "timed" by anything.
SELLphones operate at the bottom of the microwave band and bounce
all over the place with "multipath propagation", bouncing off
buildings, cars, terrain, bridges, and every electric wire over
the street. This multipath is what used to cause your old AMPS
phone to fade in and out when you were in a poor signal area.
The direct signal either was aided by, or cancelled by, the
reflected signals, all of them. If they cancelled too much, you
lost the tower and got noise. Move 3 3/4" (1/4 wave on 800 Mhz)
and you found a "peak" signal where the reflected waves were in-
phase with the main signal.
All this bouncing about would just trash the timing of anything
trying to use timing delay for locations. These timing delays
from the longer bouncing paths limited AMPS and digital data
speeds to 1X for years until a new quadrature scheme was invented
to error correct it.
I can tell you are "within 3 miles" of a cell because that's the
footprint of the tower sector you're talking on....not because of
some electronic magic radar.....
GPS sucks when you are under some covering that causes you to
operate on reflected satellite signal for the same
reason....timing delays. Take your GPS under a metal roof but
with big windows like a restaurant with a metal roof. Watch it
wonder all over the parking lot as it receives multipath signals
from passing cars and trucks and other reflecting obstructions.
That's why....multipath. As soon as you walk back out so it can
see the birds unobstructed by the roof...it locks back on the
correct position. It's all about TIMING....microseconds,
picoseconds.
Larry
--
Isn't it ironic that the same ISPs that are telling you
you're downloads threaten their networks......
.....are testing 100Gbps TV to sell on the SAME systems?
http://tinyurl.com/27qx3v