Every so often our computer or car speakers will make a light beep/chirping sound. I’m almost certain this is related to our cell phones—though if no one else knows what I’m talking about I’ll chalk it up to confusing correlation with causation. But if it’s common, what is it? Why should talking, texting, surfing, etc. be silent, but an impending ring or move from cell tower to cell tower create a signal that leaks to the speakers? Also, why is it only in the car or near a computer that we hear the sound, but not around home stereo equipment?
It’s very easy to make a radio receiver. All you need is something to act like an antenna and something that conducts better in one direction than another. It turns out that just about every circuit these days has all of these elements in it. Us folks that design stuff actually spend quite a bit of our time trying to make our stuff not be a radio receiver when we don’t want it to be.
In the case of your speakers, the wires and circuit traces are acting as the antenna, the transistor input built into the integrated circuit used in the amplifier is the thing that conducts better in one direction than the other. What is worse is that this feeds directly into the input of an amplifier which takes any radio noise received and amplifies it to much more noticeable levels.
Cheaper stereos will pick up cell phone signals. You can also hear cell phone chirps on some television sets, and contrary to popular belief, cell phones really can interfere with some types of hospital equipment. You can also pick up walkie talkies, ham radios, and all sorts of other radio equipment, and other sources of radio noise like lightning bolts and neon signs. You won’t hear as much of this sort of thing on a better stereo system just because the noise filtering built into the stereo is better, but if there is enough noise even a better stereo will pick it up. Cell phones don’t transmit very much power though.
Some types of signals cause more problems than others. It depends on how concentrated the signals are around a specific radio frequency. Your speakers will form a naturally resonant circuit that will pick up some frequencies better than others. Some folks can hear chirps when texting or surfing. It all depends on how the frequencies line up with your particular radio receiver. Many folks hear occasional chirps as the cell phone and tower periodically communicate with each other just so the tower knows the phone is still in its cell.
Passive computer speakers (with the amplifier in the sound card and not in the speakers themselves) are more immune to this type of noise since it is harder for the radio noise to get coupled into the audio path before the amplifier. Amplified speakers with better shielding will pick up less noise, but will be more expensive.
electronic devices can make a lot of electronic noise (radio signals). not only data going to and from that device, if it is a digital communications device, and just what it has in its running internally (like making a display of numbers or letters).
Man I love this board!
What is the difference between the handshake (for lack of a better term) between my cell and the tower and voice/data communication between them? We hear one but not the other.
(Somewhat randomly, ECG’s post took me back to the 70’s, trying to watch cartoons as a kid and having them ruined by some yahoos with CB radios. Grrrrr!)
IF I understand that question correctly, then here it is again, rephrased: Why do my computer speakers squeak when someone is calling me, but not when I am calling someone else? And why not during the phone conversation?
And here’s a related question: Why does the pc start squeaking before the phone starts to ring? Sometimes by a good 2-3 seconds! Does it really take my phone that long to figure out that I have an incoming call?
Cell phone protocols vary. With some of them, the basic idea is that the cell phone and the tower communicate to set up the call. Part of the information that the tower gives to the phone as part of this setup is which communication channel to use. Once you start talking, the cell phone may switch to a slightly different frequency that corresponds to the communication channel selected. It could be that your speakers are more closely tuned (due to natural resonances in the circuitry) to the main channel and not some of the individual communication channels.
Some of the data protocols are also specifically designed to reduce interference. The setup may use one specific set of commands that center around certain frequencies and therefore cause more interference, but the data transfers may be a bit more spread out in the spectrum, making them less disturbing to your speakers.
The cell phone and tower periodically talk to each other. Basically, the tower says yo, still there? And the phone says yup. These will often cause periodic random chirps on your speakers.
When a call comes in, the tower starts with another hey, you still out there? type of thing and the phone says here I am! and the tower says ok, I have a call for you and the phone says ok give me the call info and the tower says here’s the info you need about the call and what communication channel you are going to use and all that stuff. Once all of that back and forth stuff is done to set up the call, then the phone finally rings.
Thanks!
The weird thing is that it’s not really so random. For example, the pc will chirp for the great majority of incoming calls, almost never for the outgoing calls, and if no one is calling me, I’ll get only one chirp per random hour of sitting at the computer. Surely the checkups you describe are happening far more often than once per hour, no? Are some of these “handshakes” more high-powered than others?
Definitely nothing random about it. At least for me it is always and only the precursor to an incoming call. More of a clickita-clickita-clickita from the speakers several seconds ahead of the ring. My laptop and car speakers both do it. Car speakers do it even with the radio off. :dubious:
Here is some discussion from many years back about it on the physics forums.
Lots of searching around and no explicit explanation, but it does seem to be unique to GSM phones and some explanations attribute the interference to the time slice protocol GSM uses to separate signals and allow multiple phones on the same channel. Also found more than one mention that the phones briefly respond at higher power to a tower “seek”. I am not an EE so I apologize if I have butchered the terminology.
Coupled together that would seem to explain whey the sound only happens, or mostly only happens prior to an incoming call. The necessary conditions existing during negotiations with the tower. And why some people think I am crazy, they probably have Verizon or some other CDMA service and have never experienced the noise.
I am still more than a bit curious why it doesn’t happen on outgoing calls. Is there something significantly different about the communication protocol with the tower on outgoing versus incoming calls?
We have two GSM phones (an iPhone and a HTC Magic) and they both make our (amplified) computer speakers chirp like crazy every few minutes, without receiving any calls. They’re set up to check e-mail (and, for the Magic, sync Google cloud stuff) over 3G, not Wi-Fi.
I also have a cheap, wired land-line phone whose earpiece will also chirp when one of these cell phones is nearby.
Oh, yes! Excellently spelled! Not a chirp at all!
Well, in our case, it’s a modulated buzzing sound on about the same frequency as a mosquito, cut up into short bursts (maybe 100 ms to 600 ms each, with about 200 ms of silence in between). It sounds a bit like a Morse code transmission in an old movie.
A way to help eliminate (or lessen) this noise is to put magnet ‘chokes’ onto your PC’s speaker wires. They’re those round bulky things you see built into the ends of most all computer peripheral cables.
Clickita-clickita-clickita is a good description of the sound GSM phones make through car stereos. My Sprint phones and those of my wife have never done this with any equipment.
Driving in the car with friends, I would say, “one of you is about to get a phone call” and sure enough, 2 seconds later, a phone would ring.
When I was googling around, almost all the recent stuff was about the iphone. With most people having your experience of intermittent but nearly continuous noise generation if left near speakers.
I have an adult cell phone. It goes “clickita-clickita-clickita-bow-wow,” and then hot girls show up to deliver pizza in their underwear.
How the pizza got in their underwear I’ll never know.