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

[Richard Wentk]

At 17:26 08/11/2002 -0800, John L Marshall wrote:
>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.

http://starportuk.com/21.htm

http://www.cellular.co.za/accessories/phone_blockers/mobileblocker.htm

http://www.newhousenews.com/archive/story1a092200.html

http://www.excel-hk.com/store/default.tpl

And if you're feeling lucky:

http://www.kenneke.com/plans.html

Details of CDMA are here:

http://www.cdg.org/tech/a_ross/index.asp

Is there any reason why CDMA would keep working if you used bandpass 
filtered noise to modulate an RF oscillator -> transmitter? I'm thinking if 
you dump enough noise into every possible frequency channel the receiver is 
eventually going to lose any hope of a lock on its pseudonoise carrier.

You probably spend some time in jail too if you're caught, but hey. :)

Backtracking slightly - re: WAVS as ringtones - my Nokia 9210 can do that. 
I never use that feature though. It's just too bloody annoying. :)

Richard