Permit to use aircraft radio frequencies on ground

Gord Beaman wrote:
Roy Smith wrote:

Gord Beaman wrote:
Well, CJ, I wouldn't want you to pass up a good thing because of
incorrect info so perhaps you should check out about this
'illegal' thing. They have cell phones installed in the seat
backs of some commercial airliners for the use of passengers
(I've seen them but haven't used one) so they sure aren't
illegal,

These are not cell phones. They are attached to a ship-board
communications system which uses a satellite link (or possibly dedicated
ground stations) to patch you through to the terrestrial phone network.
Different system completely from cell phones.

Yes...dedicated ground stations...as I said Roy...actually I
believe that they utilize regular cel towers some of which are
equipped with somewhat different receiver systems...also there's
many fewer of them than regular cel service because of the
generally much longer range of the airbourne units.

I would not be surprised if they used some of the same towers, but
just because they're on a cell phone tower doesn't make them a cell
phone. Towers are a limited resource and most of them are shared by
all sorts of unrelated servics (often even direct competitors).

The terrestrial cell phone infrastructure is optimized for phones on
the surface which are either stationary or moving at relatively low
speeds (i.e. highway speed or less). The antenna coverage, cell
overlap, signal propigation patterns, and switching algorithms are all
designed around these assumptions.

Using a cell phone in an airplane not only gives the phone line of
sight to many more cells than the system was designed for, but the
high speed motion also causes it to switch from cell to cell faster
than normal. Both of these break design assumptions and degrade the
system. That's why the FCC bans cell phone use from airplanes.

Systems designed for aviation use may share some of the basic cell
system ideas (and even some of the physical infrastructure like
towers), but the ground station grid and switching algorithms are
optimized for their intended use.