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I have recently started using my iPhone near a stereo set which picks up the radio signals from calls and 3G connections, making me very aware of when the phone emits anything.

The phone currently makes about 10-20 "wakeups" per minute, which is enough to make me place it a couple of meters away so the speakers won't pick up anything. Though this is annoying in itself, I'm more concerned about if this is normal for an iPhone. I'm always connected to a WiFi router, so if it's an app trying to get Internet access – it's doing it wrong. Each wakeup lasts for about one second but sometimes (far less often) it blasts away for two or three seconds.

Is there anything I can do to find out what's causing the activity? I don't really want to uninstall my apps one by one to find the possible villain.

Edit: To clarify, I simply want to know why it's using the 3G/EDGE connection when it really should be using the WiFi.

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3 Answers

I find that an Edge connection is much NOISIER in terms of what electronics pick up than 3g is. BTW, a low or intermittently low signal condition is liable to eat battery. When the phone tries to regain signal, it steps the antenna up to higher power. If it's doing that over and over, it can be costly to battery levels.

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This is exactly what I observe with my iPhone. Since I moved the job the iPhone no longer has 3G in the office. Exactly from that day on I can hear those noises in speakers. –  Martin Sep 12 '11 at 11:34
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I doubt very much that the speaker interference is being caused by the iphone's wireless being constantly on, but that's extremely easy to test.

Just turn off your wireless and leave your iphone next to the speakers.

If (as I suspect) you still get the speaker interference issue, then it's quite possible that you happen to be in an area where 2 or more 3g booster towers happen to "overlap" with their pattern of 3g blanket coverage.

Your phone may constantly be switching from 2 or more possible 3g signal sources, which would cause exactly that type of interference and constant polling to occur.

This same type of issue can occur if you are on the edge of a 3g signal, and the phone will constantly try to re-acquire a stronger signal.

This will also tend to suck your battery charge dry, since the phone is spending a lot more time "awake" than it should.

The only real fix is to either move to a different location (move house), or just to turn of 3g and switch your phone back to using edge in that location.

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Thanks for the input. It's not the WiFi signal that's causing the interference. The theory about several towers seems to be fitting, I'm currently located basically in the middle of a crop field where the signal strength varies between "no service" and full strength depending on time of day and the weather. It seems to be switching from 3g to edge quite often as well, I'll try to verify if that is what's making all this noise. –  jesper Aug 10 '11 at 18:21
    
I disabled WiFi and 3g. I now have full signal strength and the E is showing instead of the 3g indicator. Sadly, the phone is still making frequent transmissions. –  jesper Aug 10 '11 at 18:38
    
Sorry that I couldn't help, although you may notice (as a bonus of switching off your 3g) that your battery charge should last a lot longer now that your phone is not constantly trying to re-acquire a 3g signal. –  mrBitch Aug 10 '11 at 18:57
    
Certainly thankful for your advice! It did help me in determining that there's something else going on even with 3G off. I will consider jailbreaking to be able to view the output of top or something similar, but I guess it could also be the result of chatty towers. –  jesper Aug 10 '11 at 19:06
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Another thing to take into consideration, is that wether you are on EDGE or 3G the iPhone will be emitting frequencies on its own regardless of activity from any of your apps. The phone checks online automatically for clock syncs and many other things. This is why smart phone data packages are highly recommended, because if you don't have one and don't even use the internet on your phone you will still receive overages due to your phone using data for you. Hope this helps.

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Please read the comments to the answer from mrBitch. I'm currently in EDGE mode (with WiFi enabled again). What I hear through the speakers resembles what I hear when I know I'm using the 3G/EDGE connection for something. I have a flat rate package but that is totally off-topic. –  jesper Aug 11 '11 at 20:13
    
This isn't off topic, you stated the following... "The phone currently makes about 10-20 "wakeups" per minute, which is enough to make me place it a couple of meters away so the speakers won't pick up anything." I was simply pointing out that you shouldn't even bother deleting your apps one by one because it won't matter, the phone uses data all the time period. –  0x7fffffff Aug 11 '11 at 21:38
    
Here's why it's off topic: I don't care that it uses data all the time. I care about why it's using the 3G/EDGE connection when the WiFi connection is available. –  jesper Aug 12 '11 at 9:34
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