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Why Your Clock Radio Is All Abuzz About iPhones
blackbearnh wrote in with a story that's not really about the iPhone, but if your office speakerphones beep like mine does, read on: "If you own an iPhone, you may have noticed that it has a distinct and very annoying effect on clock radios, computer speakers, car radios, and just about anything else with a speaker. The folks at O'Reilly Media aren't immune, so they set out to discover just what is it about iPhones that makes them such bad RF citizens. The iPhones aren't the only bad apples in the cell phone basket and there's not much you can do about the problem. We're really in an interesting time in that there has never been so many high-powered personal transmitters just wandering loose in the world."
It's not just the iPhone. It's any GSM phone. Google "GSM Buzz". Meet the "GSM Devil", which relies on this interference to tell you you're phone is about to ring. http://shop.mopodmania.net/product.sc?categoryId=1&productId=15
Maybe it's just because you guys aren't used to GSM cellphones but over here in the UK everyone recognises that noise. Anytime you put a mobile next to speakers you get that noise.
Welcome to the 1990s, America!
Nick
...everything regarding cellphones? Including, in this case, sometimes annoying side effects?
This is nothing new...especially if, on any other phone, you have also kept semi-constant GPRS connection.
PS. Rearranging speaker cables/etc. eliminates the problem anyway...
One that hath name thou can not otter
Mod parent up. Cell phones have been doing this since my old Nokia to my new Blackjack II.
Posts not to be taken literally. Almost everything is sarcasm.
Yes, speakers which are magnetically shielded to prevent affecting CRTs will also likely reject the GSM buzz.
The clock radio would only pick up the GSM buzz if the speaker was on (radio or buzzer); when it's off, no problem.
whatever happend to the label on the bottom of everything, which states that:
"This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) the device may not cause harmful interference, and (2) the device must accept any interference received, including interference that may cause undesirable operation."
obviously the folks that made my PC speakers obeyed those rules, so why is apple getting away with breaking condition 1?
The iPhone isn't operating under Part 15. It's licensed. Your cell provider holds the license from the FCC. They paid a lot of money for it; remember the spectrum auctions that raised billions. It's your speakers that have to live with the licensed world, not the other way around.
The same is true for broadcast radio, TV, police, fire, ambulance, business radios, taxi dispatchers, amateur radio, military, and even foreign licensed broadcast systems. Your speakers have to live with it.
You might try (1) using twisted pair instead of zip line to your speakers and (2) using ferrite bead clamps, a few turns wrapped around both ends of the speaker cable. But it probably won't help, as it's likely your speakers internal amplifier is picking up the signals directly, as they're cheaply made (see TOA) and poorly shielded.
It is not just GSM phones. My old RAZR had the same problem. At meeting, anytime a phone rings we get all sorts of interference with audio.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
The GSM buzzing is all GSM phones but I noticed on my iPhone that using 3G it goes away. From what I've read, the loud noise is caused by rapid turning on/off of the GSM transceiver which creates EM pulses.
As the AC pointed out it's not a magnet, it's a ferrite bead. This is a very common thing, and many cables come with one installed already. Just looking at the monitor sitting on my desk I can see a pair of beads on it's VGA cable (one at each end), and they're very common in most high end speaker systems. For cables that don't have them you can pick them up from various places in the form of snap-on cylinders which can either be directly clamped onto the cable, or alternatively you can wrap the cord around the bead once or twice before clamping it, which will hold it in place on the cable and also serves to improve the filtering slightly.
They're a very simple passive device that works by disrupting high frequency RF passing through the cord. Since any large (long) conductor can function as an antenna, most cables are really just giant antenna, so adding a ferrite bead is a really cheap and simple way to counteract this. As for interference within a speaker itself (that is, not arriving by way of the speakerwire used to hook it up) there's not much you can do other than putting a Faraday cage around the speaker, or just moving the source of noise farther away from the speaker.
Curiosity was framed, Ignorance killed the cat.
You wouldn't get interference if your television receiver wasn't a POS. We know how to design and build receivers that can operate in hostile RF environments, we just choose not to, because it's cheaper to build the POS.
Mea navis aericumbens anguillis abundat