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Re: [RFI] Blackberry interference with conference room audio systems

To: "Michael Germino" <ad6aa@sbcglobal.net>, <rfi@contesting.com>
Subject: Re: [RFI] Blackberry interference with conference room audio systems
From: "Jim P" <jvpoll@dallas.net>
Date: Mon, 21 Mar 2005 12:28:00 -0600
List-post: <mailto:rfi@contesting.com>
  "This seems to be a common problem with GSM phones."

1/2 watt from a UHF HT will produce clicks on key-up
in my PC speakers;

We used to get low rep-rate 'thhhhht' sound from our
800 MHz IS-136 TDMA phones induced in our PC
speakers all the time as well (we could also tell that
___ a phone call was coming in__ by a series of
'clicks' as the phones digitally communicated back
and forth with the MTSO several times before audibly
'ringing' the ringer) .

So, it ain't  _specific_  to GSM ...

*Any* of the over-the-air protocols/formats that
dynamically pulse the carrier will induce some sort
of pulse 'noise' this way, and, technically speaking,
GSM (and EDGE) is a TDMA (Time Division -Multiple
Access) protocol where 'calls' are (cutting to the
quick here) 'chopped-up into timeslots'.

Now, I cannot say that some eqipment isn't more
susceptible b/c of the shorter 1800 MHz wavelength
(thinking about the ' waveguide beyond cutoff ' property
now; it's the reason AM BCB signals aren't heard
going into tunnels, get weaker under steel awnings,
etc, why 2 Meter HT operaion from inside a car is
horrendous, where shorter wavelengths have the
advantage in propagating).

Jim P  /  WB5WPA  /




----- Original Message -----
From: "Michael Germino" <ad6aa@sbcglobal.net>
To: <rfi@contesting.com>
Sent: Monday, March 21, 2005 12:11 PM
Subject: Re: [RFI] Blackberry interference with conference room audio
systems


>
>
> The list should mostly be about Amateur RFI, however, I don't mind
non-amateur discussions once in a while.
>
> Mike
> AD6AA
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