*#@!% AT&T speaker interference!

[Big-TDI-Guy]

A ferrite will not help you. It's due to the fact it's GSM. It's also very unlikely to be affecting your speakers - it's more likely affecting your amplifier (that drives said speakers) - and it's being driven to the speakers.

It has all to do with the way GSM transmits packets, and the frequency they use. Add to this, the fact that ATT physically has fewer towers - so a greater likelihood that your phone is transmitting at a higher power level than a carrier with MORE towers, or one that uses CDMA.

Verizon, generically speaking, is less likely to cause this, due to the inherent differences between CDMA and GSM, the fact that Verizon tends to be on more towers (requiring lower transmission power levels), and the preferred frequency band that is used.

I'm good friends with a PHD who designs mobile phone chip-sets for a living, I can get more info, if needed.

The energy level from phone radiation is a property of an inverse square. So the energy level falls rapidly with distance - so the best bet to limit this interference is to keep as far away from the speakers amplifier as possible. Increasing antenna reception (via location / rotation / moving surrounding ferrous objects) may also reduce the transmission power levels, which may help reduce induced noise.

Shielding can be a nightmare - so trying to create a faraday-cage around your amp (or other affected electronics) will not be so easy. Even so - the solution could be as simple as wrapping or placing some tinfoil around the outside of your amp. (be careful not to short it out or cause it to retain heat)

 

[yagrax]

I concur. I already tried those exact Ferrite blockers from Radio Shack. They don't work.

GSM Buzz 'solution' - You're going to laugh, and I'm no PhD., but if you put a static baggie (the kind that computer memory is wrapped in when shipped), behind your iPhone, that will knock down the GSM buzzing a lot. It will also somewhat deaded your signal strength, but you should still be able to receive phone calls. Everybody in my office that has an iPhone does this. It's an effective 'free' solution.

High-Pitched-Whine 'solution' - (not the GSM buzz) If you attach your iPhone/iPod via your car audio system, and you charge the iPhone/iPod with a 12v charger also at the same time and experience the high-pitched-whine issue (some can hear it some can't). Try putting on what is called a Ground-Loop-Isolator to eliminate the high-pitched-whine. It goes inline with the audio cables going to your car audio system from the iPhone/iPod. I believe RS sells that for around $20 or so.

You can also get shielded speakers, $$$$, or something like the $99 Sony Clock Radio which has decent sound and has no GSM Buzz and comes with a remote. Look it up on iLounge.com



Good luck, and pass this info on if it works for you.

 

[yagrax]

It ain't AT&T, because the same thing happens up here in the Great White North on Rogers. And I don't think it's the speaker wiring, I think the cell waves are acting on the speaker amplifiers directly. The cheaper the speaker, the worse it is. My Bose 2.1's hardly have it at all, but the cheap speakers on my computer at work buzz like crazy. Airplane Mode is the only real solution.

Please see my post on the 'static baggie' approach.

 

[yagrax]

Every phone can cause this interference. I've heard it CDMA phones, iDEN phones, and all GSM phones. They each produce a different tone but it's part of the fact of radio and poor shielding on cables. You could always try this tip: http://www.ipodobserver.com/story/36388

IMHO ferrites don't work. Please try the ferrites yourself and edit you post with your results (which will be to remove that link).

 

[jmpage2]

IMHO ferrites don't work. Please try the ferrites yourself and edit you post with your results (which will be to remove that link).

We install LAN CAT5e cables with ferrites on the ends on our IP telephones and they do seem to reduce the interference from GSM phones to our IP desk sets. I would say it probably depends on if the device was designed to benefit from them.

And as others are telling you it has nothing to do with AT&T and everything to do with GSM. Most electronics are extremely poorly shielded from the frequencies used for GSM and the result is a lot of interference. The iPhone sends insane amounts of data back and forth compared to most phones so you are probably noticing the problem more frequently than you would with other GSM phones.

 

[Warbrain]

IMHO ferrites don't work. Please try the ferrites yourself and edit you post with your results (which will be to remove that link).

Are you sure you placed them on the cable correctly? Thanks for your pretentious attitude.

 

[kdarling]

GSM buzz is caused by its time sharing radio. Basically, your phone's transmitter turns on/off 217 times a second as it shares allotted time slots with everyone else... for voice or data.

This causes quite a pulse as the radio power amplifier switches between off and using up to 1A of current to transmit. Other equipment can pick up the power and RF envelope pulse, and since 217 Hz and its lower harmonics are easily within hearing range, you hear a buzz.

GSM 3G is a different protocol. It's a form of CDMA, which doesn't cycle like that. So you don't get the same interference on 3G or native CDMA phones.

 

[yagrax]

Are you sure you placed them on the cable correctly? Thanks for your pretentious attitude.

You're welcome and by the way, the H in my IMHO is humble, meaning in my situation they did not work.


And yes, placed correctly, our resident phone/network expert who's also an Electrical Engineer at my Fortune 500 company helped me on this one. And they don't work for us.