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Why Your Clock Radio Is All Abuzz About iPhones
Posted by
CmdrTaco
on Mon Oct 27, 2008 11:00 AM
from the i-hate-that-sound-so-much dept.
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."
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Psh (Score:5, Funny)
Re:Psh (Score:4, Funny)
It's not the phones, it's the douche bag field emitted by iPhone owners.
Parent
Re:Psh (Score:5, Informative)
Parent
Re: (Score:3, Informative)
Except that when an Ipod (or other WSD) is broadcasting on channel 18, not all the signal stays inside channel 18. A lot of it spills-over into WPHL's channel 17. Think of them as the EM equivalent of harmonics of the original signal.
So you cannot place two broadcasts directly side-by-side and expect it to work. This is not a flaw of design. This is a flaw of nature. "You cannae change the laws of physics" is a favorite joke from Star Trek, but it also happens to be true. A DTV receiver cannot decode
Re: (Score:3, Insightful)
Sorry buddy, parent poster is needlessly blunt but essentially right.
There is nothing really wrong with them; they aren't really "crap". Its just that they aren't particularly special. Yet they are marketed (and usually priced) as if they were. The simple reality is that many other brands of speaker perform equally well at a considerably reduced price.
To put it into slashdot terms, Bose speakers are like Dell's line of gaming PCs. Nothing wrong with them per se; they are certainly functional enough, but the
Hi, I'm a Mac! (Score:3, Funny)
What's that?
Hey, I think your pager is trying to tell you something...
Maybe he should be using the clock on an iPhone. ;-)
Nothing to see here. (Score:5, Insightful)
Re:Nothing to see here. (Score:5, Informative)
Parent
Re:Nothing to see here. (Score:5, Interesting)
Parent
Re:Nothing to see here. (Score:5, Funny)
Parent
Re:Nothing to see here. (Score:5, Funny)
Parent
Re: (Score:3, Funny)
As long as it isn't da-da-da daaa-daaa-daaa da-da-da. :-)
Re:Nothing to see here. (Score:4, Informative)
SOS for the Morse intolerant.
Parent
Re: (Score:3, Insightful)
You beat me to it (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.
Parent
Re:Nothing to see here. (Score:4, Funny)
Yeah, to give some idea of just how non-news this is, I first noticed this effect when Slashdot was called Chips & Dips.
Parent
Re:Nothing to see here. (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.
Parent
Re: (Score:3, Informative)
It's not so much the computer as it is the speakers themselves. The long cheap unshielded speaker wires pick up GSM interference, whose lower harmonics result in that distinctive buzzing sound. The speaker wire basically acts as an antenna.
Digital speakers obviously don't suffer from this phenomenon, but they're hard to find outside of pro-audio circles and the occasional cheapo USB speaker set.
Re: (Score:3, Funny)
I have an iphone but no one's ever called me. Sigh.
Re: (Score:3, Insightful)
no, don't mod parent up, because he clearly didn't RTFA, which is quite informative and provides a lot of insight into this issue, actually:
Re:Nothing to see here. (Score:5, Informative)
Parent
Re:Nothing to see here. (Score:4, Insightful)
I don't know how this ever made it to any news source. I'm trying to remember how long ago the first time I noticed it. It's been at least 10 years. My first phone that did it was an old Nextel.
Parent
Re:Nothing to see here. (Score:4, Insightful)
Indeed. It is a well known phenomenon. I end up turning my blackberry off or leaving it in the kitchen on game/movie night because it makes all sorts of funny beeps on the surround system. I don't think people realize how powerful the transmitter in a cell phone is, and that it is not unique to iPhone.
Apple customers tend to be rather picky and vocal about any possible defect with Jobs' perfect little products.
Parent
Re: (Score:3, Informative)
Re: (Score:3, Informative)
It's not a magnet. It's ferrite.
Re:Nothing to see here. (Score:5, Informative)
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.
Parent
Re: (Score:3, Funny)
there's not much you can do other than putting a Faraday cage around the speaker,
...how about putting a Faraday cage around the phone instead?
Re: (Score:3, Insightful)
Yep... I'm relying on the subtle noise, that my *berry makes on the computer-speakers as a mail-notifier... It is, actually kind-convenient — quiet enough not to wake-up the baby, but noticeable enough not to miss an e-mail.
Re: (Score:3, Interesting)
Nope. RTFA, Part 15 devices (consumer electronics, not the phones) have the following regulations:
1) Cannot interfere with devices in a "higher priority" classification (such as a licensed transmitter)
2) Must accept interference from devices in a "higher priority" classification, such as a licensed transmitter. Cell phones are, effectively, licensed transmitter. The user themselves doesn't have the license, but the carrier does.
GSM Buzz (Score:5, Informative)
Re:GSM Buzz (Score:4, Insightful)
Correct, lots of cell phones do this. If people are noticing it more with the iPhone, it's probably because people are more likely to want to hook the iPhone into audio equipment than with other cell phones.
Parent
Re:GSM Buzz (Score:5, Funny)
Meet the "GSM Devil"
I put on my robe and wizard's hat.
Parent
All GSM phones do that! (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!
Re:All GSM phones do that! (Score:4, Funny)
Slashtip: Including a link to a silly gadget is always worth karma. Bashing the US can go either way.
Parent
Re: (Score:3, Insightful)
You insinuated that the USA is technologically inferior becase we've been living without the GSM buzz? Huh... :p
Verizon/Sprint/Alltell are the only big CDMA players left in the US afaik.
Do those people think Apple reinvented... (Score:5, Informative)
...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...
My Nokia 3610 did this also. (Score:5, Funny)
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.
FCC Rules Part 15 (Score:5, Interesting)
"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?
Re:FCC Rules Part 15 (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.
Parent
Re: (Score:3, Informative)
Leighklotz is exactly right, but it gets even worse. Even a Part 15 device, using similar modulation to the GSM phone, could likely cause interference to your speakers. I have a DECT phone, compliant with FCC Part 15, sitting next to my computer speakers, and it creates a nice buzz when it's searching for the base. That's not the phone's fault, I'm sure they're transmitting all their energy in the allowed band, but nonetheless my speakers are rectifying that RF energy and amplifying the resulting envelop
Re: (Score:3, Informative)
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.
What will twisted pair do ? Doesn't twisted pair only protect against interference when you have a balanced line [wikipedia.org] with opposite voltages going down each wire?
Read this, page 2 [audiosystemsgroup.com]:
There is a relatively easy fix for this (Score:3, Informative)
Not on 3G, EDGE only (Score:5, Informative)
What's happening in Europe? (Score:3, Interesting)
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. [conformance.co.uk] 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.
Re:the cause could be put into the summary (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)
Parent
Re:the cause could be put into the summary (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.
Parent
Re: (Score:3, Informative)
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 i
Re:Huh... (Score:5, Informative)
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.
Parent
Re: (Score:3, Informative)
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.
Re:It seems to be AT&T more than anything... (Score:5, Insightful)
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.
Parent