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.

(Roy Smith) wrote:

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.

Of course, so what are we arguing about?...I never did claim that
they're compatible with each other...these special cell phones
are merely special cell phones...they operate just 'like' the
common cell phone in that they allow the 'customer' to move from
'cell' to 'cell' and they switch the customer to the new 'cell'
precisely as the common cell system does except at -longer
intervals- because of the wide cell tower spacing (and certainly
on different channels from the common system).

As you say, these special phones cannot use the standard cell
system because of their generic differences (mostly in range)
etc. BUT...they're cell phones nonetheless simply because they
allow the customer to move from cell to cell...which is the
reason that the word 'cell' was coined in the first place.

It's pretty easy to see the problem...a terrestrial cellphone can
almost never 'get into' more than one cell facility at a time yet
a cell phone on an aircraft can 'see' dozens of them because of
antenna height, thus creating havoc in the system...that's -why-
using the common unit on an aircraft is illegal.
--

-Gord.
(use gordon in email)

I understand that AirCell phones use the same system as regular cell
phones. There is a special antenna on the aircraft which gives a lower
power shaped transmission which cannot broadcast past the existing cell
region. Each region is made up of a network of cell phones. They may
have some dedicated frequencies or channels but they use the same
network of cell towers and regions.

(Roy Smith) writes:

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).

Well, in reality, the towers and sometimes the RF gear is owned
by a company such as American Tower, Inc. and oh yes, they stack
as many carriers as they can on one piece of iron.

(And it's more than tower space; co-location means they can share
generator backup, fiber feeds, etc..)

As for if airborne is "cellular" -- that depends on whose
definition you want to use. Is it Jill Winecooler 'cellular'?
Nope. But can it share the name? You decide.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher wrote:

(Roy Smith) writes:

Gord sed:
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).

Well, in reality, the towers and sometimes the RF gear is owned
by a company such as American Tower, Inc. and oh yes, they stack
as many carriers as they can on one piece of iron.

(And it's more than tower space; co-location means they can share
generator backup, fiber feeds, etc..)

As for if airborne is "cellular" -- that depends on whose
definition you want to use. Is it Jill Winecooler 'cellular'?
Nope. But can it share the name? You decide.

Of course...and the term is no longer 'cellular' anyway it seems,
they now seem to prefer 'Mobile phones' so I guess it's a moot
point, but ISTM that the aircraft cel system is a helluva lot
closer to the terrestrial cel system than anything else.
--

-Gord.
(use gordon in email)

On Sun, 09 Jan 2005 19:01:30 GMT, Gord Beaman
wrote:

Of course...and the term is no longer 'cellular' anyway it seems,
they now seem to prefer 'Mobile phones' so I guess it's a moot
point, but ISTM that the aircraft cel system is a helluva lot
closer to the terrestrial cel system than anything else.

The term "cellular" has a specific meaning within the FCC rules.
There is a section of the rules (I forget which one) that regulates
the "cellular service", and another section of the rules that
regulates PCS phones (the "personal communications service"). The
former is not allowed to be used in the air whereas the latter is.

A few years ago there was a company that was experimenting with ways
to use the "cellular service" from the air without bringing up too
many cells, etc. They were working with a special waiver from the
FCC. I don't know what all ever became of their work.

CJ

Cell towers do not work individually, each tower only has a few
channels of the huge amout of frequencies available. Your cell phone
simply picks the strongest available frequency. That is usually the
nearest cell tower, but if all available channels are in use that may
be the next nearest tower. There are not just cells but also regions
of cell towers, each region will use all of the available channels and
have a limited number of land lines available to it. The problem
occures when the cell phone access several regions with several towers
of the same frequency. Aircell phones have a lower power and a shaped
antenna giving a norrow beam down to the ground.