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From: rees@pisa.ifs.umich.edu (Jim Rees)
Newsgroups: comp.dcom.telecom
Subject: Re: Questions About the GTE Airfone
Message-ID: <15300@accuvax.nwu.edu>
Date: 6 Dec 90 16:56:11 GMT
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X-Telecom-Digest: Volume 10, Issue 871, Message 9 of 11


In article <15223@accuvax.nwu.edu>,  seanp%undrground@amix.
commodore.com (Sean) writes:
  
>The transmitter section of the setup is IMPRESSIVE. Everyone could
>concievably use thier phone at the same time, as there are 400
>channels available for use.

I doubt very much that the airplane is able to transmit on 400
channels, or even 56 channels, at once.

>894 - 896 MHz (5 KHz spacing). Assignment is done in the same
>manner as cellular. It picks an available frequency from what the
>ground station tells it. AM mode is used for modulation.

AM on 5KHz spacing?  Are you sure?  I would guess companded SSB, just
based on the age of the system, but I don't know.

We have now had one person claim that there is no hand-off, and
another claim that there is.  What's the real story?  Airfone
pre-dates cellular, right?