It seems that Australian mobile phones are somewhat unique in that they will interfere with speakers or radios nearby - you get a tone coming through a few seconds before the phone rings.

I've noticed American phones don't do this.

Does anyone know why, how it works, and whether this phenomenon could be harnessed to make a gizmo to project said tone into the earphones of some toolbag on a bus listening to his iPod too loudly ?

 

Certainly UK phones do, it's the RF power from the transmitter in the phone interfering with the electronics - makes a mess of monitors as well (imagine what it's doing to your brain?). Presumably the transmission from your phone is a 'handshake signal', which accepts the incoming call and allows your phone to ring?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

I saw a brain surgeon interviewed on TV who said he had operated on several patients who had brain tumours behind the ear that they use for the mobile.

__________________
Len

 

Brain surgeons also remove brain tumors from patients who do not use a cell phone.

__________________
Uncle $crooge

 

True, but the surgeon felt that it is more than just coincidence that the tumours were located where they were.

I don't like the idea of high frequency RF being generated near my grey matter.

__________________
Len

 

OK, so now part II - how to simulate the same effect and "broadcast" to headphones ...

 

Use your phone!.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Baaa rubbish, the only effect RF has on your brain is heating; I'm not saying that's healthy I'm just saying it doesn't cause tumours, there's no real proof.

__________________
I also post at the following sites:
http://www.stop-microsoft.org http://www.heated-debates.com
Screen name: Aloone_Jonez

 

I live in the US, and I've heard cell phones do this many times, so it's not just an australian thing. It's pretty simple, phones put out a lot of power when they're making a connection, and it's enough to screw certain things up, such as the audio amplifiers in your speakers (or perhaps it directly affects the speaker coils themselves, though that seems less likely as it seems it would take a lot more power for any significant effect)

I've seen products sold that consisted of thick plastic stickers in the shapes of butterflies and hearts and things, with a small coil and some LED's embedded in them, that you could stick on your cell phone, and they'd light up and/or flash when the phone was making a connection/etc. Probably didn't help your reception too much

__________________
EEgeek.net

 

All phones will do this to some extent or another. It could be that you have seen the older American phones which use FM rather than Pulse Modulation. FM is a lot less prone to this effect.

Yes, the RF from the phone is rectified by the transistors in the early audio stage of the radio, the resulting rectified signal is then amplified just like any other signal in the amplifier.

In theory yes, but there are practical problems in trying to implement such a jammer.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

 

No, that wouldn't be possible to jam an IPOD's users file playback, they're not receiving RF signals. You'd have to be carrying a 50lb spool of wire and have some way of pulsing a massive current through it, basically an EMF bomb. If you could build something like that that was portable you could probably overthrow the government.

__________________

 

My phone does this all the time. What I want to know is how it does not affect its own speaker. My phones speaker also buzzes when I am talking on it unless I wrap a finger around the stubby antenna. Any ideas on that one? Its really annoying and people I talk to hear it on the other end.

 

Oh, and I forgot to mention that it is probably illegal to broadcast that signal to someones earphones. Amusing to you, but not the FCC.

 

That's interesting. I had a Verizon phone for 5 years in the US and it never did it.

 

My CDMA phones never did the speaker buzz thing. Only GSM phones seem to do it.