Robert Foxworth wrote:
>>They used the airphones, except in one case I think an actual cell
>>phone was used (given they were five miles away from any nearby tower
>>going at 600 MPH, it's a surprise it got through).
>>
>>The FCC is only recently permitting the use of cell phones after the
>>door closes, subject to individual airlines' preferences. It was
>>feared that the use of cell phones would mess with the plane's
>>navigation systems, and it was found that they don't (after all, they
>>fly near cell towers all the time, if cell phones were a problem the
>>cell towers should have also been screwing up their systems. They
>>haven't.).
>>
>>Steven Buehler | swbuehler@yahoo.com/steven@sanctuaryweb.org
>>
>>
>
>
>I recall reading some time ago that usage of cell phones
>on aircraft at flight level was a bad idea because the
>signal from the phone would illuminate multiple ground
>towers and the system would not know which one the
>phone would register with. Perhaps this was either
>bad info, or the system can now deal with this better. If you
>look at a tower, you'll see that the antenna elements are
>pretty big to provide high local gain, but not very tall, so that
>the boundary of each tower's coverage radius stays within
>a few miles. That's how I understand it anyway, IANAE
>(Not an Expert)
>
>
>
That is what the Altobridge is most likely for it acts as a mini tower
that then relays to the actual cell towers. But there are some reasons
they started with GSM protocol, other than the fact that is is used
widely here and almost everywhere in the EU.
But GSM is known for fast hand offs, while these handoffs are faster
with gms they are often very noticeable. Example some may recongize a
hard hadn off on ATT/Cingular/Tmobile gsm networks say when driving down
the interstate at high speed. The real challenge is CDMA phones, do to
the way they handle the handoff they use a slower handoff which is
consdier a soft handoff where you can not hear the hand off. At the
speed of a plane it will be interested how the providers handle billing
While most do not have to worry about roaming prepaid ( building a very
strong presences here in the states) and smaller reagional providers
with mid tierplans where you can be roaming by simply crossing the
street. It is very exciting how this unfolds.
>I heard stories about guys with 1-watt HT (handi-talkie)
>sets on 146 MHz in piper-cub-type aircraft, at a few thousand
>feet, keying up ham repeaters 200 miles away etc
>
>Slightly OT, I suppose ....
>
>- Bob 2239 est 2004-02-17
>
>
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