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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."
As I understand it, all Apple products have a distortion field.
It just looks like someone has never had a GSM phone before.
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
Reason not to get an iPhone
"The stupid neither forgive nor forget; the naive forgive and forget; the wise forgive but do not forget." -Thomas Szasz
...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
As others have said, this really is a GSM issue and not an iPhone issue. The sound I hear from my computer speakers with my iPhone is identical to what I heard from my Nokia 3610 which is about as un-iPhone as a phone can get without being better described as a rock.
Seriously - the interference sound is identical.
My only concern really is what is this doing to my neurons, rods, cones and assorted other presumably sensitive body parts. I don't care about a goofy sound coming from my computer speakers every once in a while.
I'm a big tall mofo.
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?
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)
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.
Yes, this is a pain in the butt, but as others have noted, it's nothing new. I've been having this issue since my first AT&T (formerly Cingular), i.e., GSM, phone. There is a trick to fix this though: magnets. Simply loop your speaker wire through a magnet, as this article indicates.
I was quoted out of context in my autobiography...
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.
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.
You don't quite understand the cause of the problem -- it's not that phones are transmitting on the wrong frequency or "splattering" the spectrum. It's that devices like unshielded speakers are prone to pick up interference like this from all across the spectrum, including the GSM bands.
Cell phone transmitters are much more heavily regulated than consumer electronics like clock radios.
I have seen the future, and it is inconvenient.
The US's Part 15 only applies to RF emitters; devices that don't emit RF at all, like audio amplifiers, don't need Part 15 certification. Part 15 doesn't say anything about sensitivity to interference.
The European Union, however, does regulate sensitivity to interference under the Electromagnetic Compatibility Directive. So the EU tries to address the problem.
The EU standards require a test for susceptibility to high power AM, FM, TV and airport-type radar signals. Those were viewed as the worst case when the directive was published. Electronics that's not designed for it is likely to crash when faced with a megawatt airport radar at a few hundred meters. (Remember, with most radars, the peak power is huge but the duty cycle is low.) But the EU directive doesn't address nearby TDMA sources. That's probably something the EU will have to address.
There's something to be said for spread-spectrum emitters, like WiFi and Sprint PCS phones. They have a broad enough output spectrum that they tend not to interfere with much.
...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.
when a text message arrives, older nokias beep
da-da-da daaa-daaa da-da-da
Perhaps the AT&T cellsite is further away from your location than the T-Mobile cellsite. Hence, your phone has to "talk louder" for the AT&T cell to hear it.
No cellular provider would intentionally instruct your cellphone to emit more power than required, because it would be self-defeating. Excess transmit power just means unnecessary interference to nearby cells on the same frequency. The cellular protocols provide a means for controlling the power of a handset up and down as needed to get "just the right amount" of RF energy at the cell tower's receiver.
What's that?
Hey, I think your pager is trying to tell you something...
Maybe he should be using the clock on an iPhone. ;-)
"Flyin' in just a sweet place,
Never been known to fail..."
So the poster is correct. It is a 217Hz RF pulse with about 500uS pulse width.
Cell phones use an electric field antenna which produces a high near field electric field that decays at 1/r cubed, and a propagating electromagnetic field that decays at 1/r.
It is most likely the near field electric field (capacitively coupled) that is consequently demodulated by any non linear components in your speaker amplifiers as the PA (Power Amplifier) in the phone changes power level.
Even though the electronics industry is one of the most regulated in the world with a zillion tests, there is no mandatory test for effects on electronics from near field coupling of transmitters such as mobile phones.
I had a product many years ago that passed all the regulatory tests, but would fail when put right up to a mobile phone. Adding a 47pF cap to the clk line an external EEPROM solved the problem.
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