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Thank you for taking the time to wright the below, very interesting.
Robert Q. Steinman, Ph.D.
John Stevens <[EMAIL PROTECTED]> wrote:
John Stevens <[EMAIL PROTECTED]> wrote:
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One of the primary reasons that cellphones are prohibited in aircraft is that
they (MAY) interfere with aircraft electronics. That is obvious. Just put a
cellphone near a CRT computer monitor or near an unshielded set of computer
speakers and you can either see or listen to the electromagnetic interference
that they generate. Secondarily a cellphone will step up its' power relative
to the signal that it is receiving so that these new phones can save as much
battery power as possible - so inside a commercial airliner you are in the
equivalent of a faraday cage with little openings to the "outside world".
This will make a cellphone step up its power to try and poll a cellsite so
that it can function. Now fill that faraday cage with lots of people with
cellphones and all of the possible mixing of signals bouncing around inside.
That's why they don't allow it. One person with a phone might be benign but
add 20, 30, 40 or more people to that mix and you might have a serious problem
if the right circumstances allow.
Next, add "line of sight" to the equation - cellphones are designed to connect
to the nearest "cell" that they can receive from ground level. This takes
into account obstructions like buildings, cars, hills and other natural
obstructions to your horizon. Get 4500-5500ft up in a coupe and you have
nearly unobstructed views of potentially hundreds of cell towers and the
voting system that the cell systems use can get a bit confused when you have
simultaneous access to 20+ cell sites at the same time. At 5500ft your
horizon (on a perfect day) is 97 miles away - using the general formula of
(sqrt (altitude in feet / 0.5732))=number of miles line of sight to horizon
Saying that - flying cross country in rural Georgia where the sites aren't too
close together you probably aren't hurting anything, but anywhere within or
near an urban centre you'll be causing some confusion for sure.
The old "mobile" telephones use a fixed frequency channel to communicate with
the public telephone network, the "airphones" use a combination of satellite
and fixed ground stations to relay your call into the public network. They
were designed from the get go to be in planes.
Anyway - probably WAY over explained this one. But my $.02 and my one post a
year....
John - EX CF-RGD - I MISS MY COUPE!
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Robert Q. Steinman, Ph.D.
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