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June 4, 2008 7:10 AM   Subscribe

What is the purpose of this random noise my electronics are making?

I first noticed this on my Tivo. I’d be sitting around, not even watching TV, when I’d hear a short (< 2 second) burst of “morse code.” Not beeps, but sort of a muted dit-dit-doot-doot-dit-dit. This would happen about once or twice a day. I assumed the hard drive was doing some sort of self check.

Then yesterday I was in a meeting at work when I heard the exact same noise (same pattern of dits and doots, as far as I can tell) coming from one of those starfish-type speaker phones. Nobody was talking on the phone. There goes my hard drive theory. Now I’m thinking perhaps it didn’t come from the Tivo, but perhaps a speaker near the Tivo.

Last night, I heard the same thing from one of my Squeezebox players, or rather from the speakers attached to it. The player was not playing music, though both the player and speakers were powered on, or at least in stand-by.

Now that I think about it, I’m pretty sure I’ve heard this noise on other electronic devices. It's definitely a digital-type signal, as opposed to static.

What the hell is happening? Is something else causing interference? Is there a common component inside these devices that is doing this? Why is the pattern always the same? Are my electronics communicating back to the mother ship, planning the revolution?

I’d prefer a technical explanation (“These devices all use a THX1138 chip, it’s the hammerflanger module recalibrating the DRADIS.”) over a guess, and I’d love to know I’m not the only one hearing this.
posted by bondcliff to Technology (11 answers total) 1 user marked this as a favorite
Best answer: This is interference from cell phones being reproduced on a speaker.
posted by sanka at 7:13 AM on June 4, 2008

Best answer: The speakers are picking up the signal from your cell phone. If you want a good example of this, hold your phone near a radio.
posted by LolaGeek at 7:15 AM on June 4, 2008

Here's a good example of what cell phone interference sounds like. (Minus the stupid alien sound effects.)
posted by knave at 7:22 AM on June 4, 2008

Best answer: previously
posted by philomathoholic at 7:23 AM on June 4, 2008

Best answer: Sorry for the double post, an even better example.
posted by knave at 7:24 AM on June 4, 2008

Response by poster: Wow. It all seems so obvious now. I’d never heard it from my Squeezebox before because I only recently moved it, along with where I keep my cell phone, and last night they were right next to each other for the first time.

I’m also kicking myself for not searching. I (wrongly) assumed this was a unique question that nobody could have possibly asked before. Let that be a lesson to you kids out there: always search before posting, no matter how silly the question.

Just did a test here at work and, yep, the old Nokia just communicated back to the mother ship.

Thanks, everyone!
posted by bondcliff at 7:45 AM on June 4, 2008

I'm glad you asked this because I started to notice this also.
posted by unixrat at 7:45 AM on June 4, 2008

It can also be heard on the car radio just before your phone rings in GTA4.
posted by jontyjago at 8:16 AM on June 4, 2008 [1 favorite]

Big guitar amplifiers are really good at picking this up too. And the funny thing is, the noise often (maybe 50%) happens about 3 seconds before a cell phone rings. So during rehearsals, if we're talking between songs or something, when we hear 'dit dit dit --- dit dit dit" we stop and everyone checks their phones.
posted by PercussivePaul at 9:56 AM on June 4, 2008


This is a totally "known issue" with GSM technology. Not that * you * necessarily should know. But any cell phone carrier using GSM (which is pretty much all of Europe, and I believe anyone US that is not Verizon or Sprint) will cause this to occur within up to 20 feet or so of any device that typically is susceptible to emi of that kind.

About 2 years ago, my Sprint contract was up and I decided since I could, to look for a cool new phone from another carrier. While I have always been pretty satisfied with Sprint's service here in Austin in terms of sound quality, I figured "why the hell not."

Within a single week, I had switched my # between every major US cell phone carrier. To me, Sprint sounded the best. Even Verizon did not sound as good, and they are also using CDMA, I believe. In any case, it infuriated me that the GSM carriers all know this, and can get away with selling theses devices knowing that they typically cause this kind of interference.

Sure, great, your guitar amp makes a noise just before the phone rings? That's awesome, your band can tell when a call's coming in when you are rocking out. My guitarist buddy told me about this as well. But how about people who do audio work for a living? Or use any kind of typical consumer multimedia devices for any other kind of work? Yes, I could just shut off my cell phone, or keep it a few hundred yards away - but the point is that there's no notice from these companies telling people this is very likely to occur with the GSM phones, which to me is just bull.

(As an avid audio recording person, I had planned at the time to start some kind of letter writing campaign, but frankly there's way more important stuff to write letters about these days, so I didn't start )

What I was able to do, fortunately, though, was switch back to a carrier I thought at least sounded decent and didn't spit out heinous interference.


posted by bitterkitten at 12:05 PM on June 4, 2008

posted by bitterkitten at 3:05 PM on June 4 [+] [!]


Does T-Mobile use GSM? How would I find out what frequency my carrier uses? For instance, I don't experience this interference effect, ever, but some of my friends do.
posted by knave at 12:34 PM on June 4, 2008

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