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Why Your Clock Radio Is All Abuzz About iPhones

Posted by CmdrTaco on from the i-hate-that-sound-so-much dept.

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."

14 of 397 comments (clear)

  1. Psh by waffledoodle · · Score: 5, Funny

    As I understand it, all Apple products have a distortion field.

  2. Nothing to see here. by HeavyD14 · · Score: 5, Insightful

    It just looks like someone has never had a GSM phone before.

    1. Re:Nothing to see here. by Spazztastic · · Score: 5, Informative

      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.
    2. Re:Nothing to see here. by Midnight+Thunder · · Score: 5, Interesting

      Mod parent up. Cell phones have been doing this since my old Nokia to my new Blackjack II.

      Yup and with some computers you hear static over the speakers before the cell phone rings.

      --
      Jumpstart the tartan drive.
    3. Re:Nothing to see here. by realisticradical · · Score: 5, Funny

      You've left your cell-phone on when you fly!!! You know that it emits dangerous pilot-killer-rays!

    4. Re:Nothing to see here. by Anonymous Coward · · Score: 5, Funny

      Links are occasionally helpful.

    5. Re:Nothing to see here. by orclevegam · · Score: 5, Informative

      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.
  3. GSM Buzz by russotto · · Score: 5, Informative

    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

    1. Re:GSM Buzz by bloodninja · · Score: 5, Funny

      Meet the "GSM Devil"

      I put on my robe and wizard's hat.

      --
      Lock the wife and the dog in the boot of the car.
      Return one hour later.
      Who's happy to see you?
  4. All GSM phones do that! by Nick+Ives · · Score: 5, Informative

    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
  5. Re:the cause could be put into the summary by russotto · · Score: 5, Insightful

    Or, in other words, a 217Hz signal is amplitude modulated onto the GSM signal. Some electronic devices (like amplifiers) incidentally demodulate the 217 Hz and convert that to sound. 217Hz is well within the human audible range, thus... dutuh, dutuh, dutuh, dutuh, dutzzzzzzzz.....

    (since it's a 217 hz square wave you get lots of harmonics as well)

  6. Re:FCC Rules Part 15 by leighklotz · · Score: 5, Informative

    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.

  7. You beat me to it by jshackney · · Score: 5, Interesting

    I was going to chime in along those lines as well. This is hardly news. When the weather is ideal at departure and destination, I usually tell my pax they don't have to turn their phones off. When the weather is bad and I'm going to be shooting the ILS to minimums, the last thing I want to hear is seven or eight phones ticking in my headset from the initial approach fix to the DA.

    Some phones seem to be worse than others and it sounds like the iPhone may validate the FAA's position on cell phones.

  8. Re:the cause could be put into the summary by Anonymous Coward · · Score: 5, Funny

    ...and if you're really good you can tell the difference between a 2.5G location update, an incoming call, a GRPS attach/detach and 3G noises.

    Yes, alright, 'Getting out a bit more' is on my plan, I just didn't get around to it yet.