[sdiy] Re: mobile phones gettin' OT but..

[John L Marshall]

It is difficult to jam cell phones. Some cell phones use CDMA (code division
multiple access). There are perhaps a dozen or more simultaneous cell
conversations on exactly the same spread sprectrum channel, greater then 1
MHz in width. Signal levels tend to be close to the noise floor.

BTW, Walsh codes are used to separate the voice channels on the spread
sprectrum channel.

Take care,
John
---------------------------------------------------------------------------
Pacific Northwest DIY Synthesizer meeting, January 18, 2003
See: www.sound-photo.com
---------------------------------------------------------------------------

----- Original Message -----
From: "Gavin" <elmystico at earthlink.net>
To: "Les Mizzell" <lesmizz at bellsouth.net>; "Blue_NINE.a"
<pennypridy at earthlink.net>
Cc: "synth diy" <synth-diy at dropmix.xs4all.nl>
Sent: Friday, November 08, 2002 4:42 PM
Subject: Re: [sdiy] Re: mobile phones gettin' OT but..


> This is really interesting, although I meant something that would hone in
on
> the transmission frequency and jam the signal or overtake it with some
> unbearable noise.  But these articles remind me of something I was hearing
> about how new movies use hidden sound and sub audio effects to create
> "emotional" reactions in viewers, anybody know anything about that?
> ----------
> >From: Les Mizzell <lesmizz at bellsouth.net>
> >To: "Blue_NINE.a" <pennypridy at earthlink.net>
> >Cc: Gavin <elmystico at earthlink.net>, Synth DIY
<synth-diy at dropmix.xs4all.nl>
> >Subject: Re: [sdiy] Re: mobile phones
> >Date: Fri, Nov 8, 2002, 5:17 AM
> >
>
> > > I tell you what I wanna make is a box that jams them or sends a nasty
> >loud
> > > noise through them when you point it at somebody talking on one.
> >
> >Uhhh....
> >
> >http://www.angelfire.com/nj/kristinashomepage/sound.html
> >
> >http://www.forteantimes.com/articles/153_sonicweapons.shtml
> >
> >http://www.freerepublic.com/focus/news/705020/posts
> >
> >http://www.freerepublic.com/focus/news/705020/posts
> >
> >http://www.nationaldefensemagazine.org/article.cfm?Id=746
> >
> >http://entropy.brni-jhu.org/europe.html
> >
> >
> >...heh
> >