> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Nate Duehr
> Sent: Friday, December 01, 2006 4:56 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [OT] Physics denies official 9/11 report.
> 
> tachyon_1@email.com wrote:
> 
> >  The other problem that jumped out at me was the idea that 
> the people 
> > on flight 93 used their cell phones to call family members. 
> This just 
> > will not work,
> 
> I can unequivocally state that cell phones work just fine 
> from an airliner.  I can't say how I know this, since the 
> person doing it was violating both FCC and FAA rules at the 
> time of the "demonstration".
> 
> But, you seem enamored with physics, so go do the RF math.
> 
> The free-space path losses aren't that high, and depending on 
> carrier type and modulation type, the phone will capture the 
> receivers at multiple cell sites (the real reason they don't 
> want you doing it - it wastes a ton of spectrum because 
> cellular systems are RF-designed for ground-level 
> line-of-sight) from even a modestly high altitude.

The most important part of this calculation is the antenna pattern of
the cell phone tower.  It doesn't make much sense for the antennas to
radiate upward since there aren't any legal customers up there.  Here is
one WWW page that discusses the base station radiation pattern:

http://www.datasync.com/~rsf1/cell-air.htm

And a PDF file with charts made from actual field measurements:
http://www.salzburg.gv.at/Tagungsband_(27)_Giuliani_2.pdf

The first link also discusses the doppler shift due to aircraft speed.

--steve


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