Archived posting to the Leica Users Group, 2001/10/04

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Subject: RE: [Leica] Re: New Aviation Rules
From: Mark Cohen <markc@neo.binaryfaith.com>
Date: Thu, 4 Oct 2001 23:15:50 -0700 (PDT)

Yes, we in the states use GSM. PacBell (Cingular Wireless) for one.
Carriers like Sprint use CDMA, and AT&T use TDMA.

=Mark



On Fri, 5 Oct 2001, Austin Franklin wrote:

> > Re cellular phones and aircraft interference, let me clear up a few
> > misconceptions.
> >
> > GSM phones perform regular location updates and send measurement reports
> > back to the system using a crazy burst of signals at about 217Hz
> > (modulated
> > at the carrier freq). Any electrical apparatus with non-linear components
> > (e.g. a diode) will demodulate this, and here's your interferer.
>
> ANY?  Even if it's well shielded?
>
> Do we even have GSM here in the US?  I'm not sure, I only have experience
> with T/CDMA phones and systems.
>
> > And regarding the phones chewing up capacity when in the plane at
> > altitude
> > ... it just doesnt work like that. A phone in a high rise can be
> > 'heard' by
> > dozens of base stations, but it will only ever use a carrier from one of
> > them when it makes a call. The system chooses the most appropriate base
> > station, based on signal strength, quality and other parameters. Handing
> > over between cells is not an issue either.
>
> > Also, the radiation pattern from base stations is aimed towards
> > the ground,
> > not up in the air.
>
> That was my understanding also...
>
> > I hope this confuses things.
>
> You never know.
>
> Thanks!
>
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