My neighbor is a Ham radio operator (don’t remember which frequencies are used in Germany). I sometimes can pick up the incoming radio signal. He explained to me it’s most likely the amp de-modulating the signal that is fed into the power line and my headphone cable acting as an antenna. When I first heard voices speaking I was a little freaked out for a moment I have to admit.
iPhone audio detectable with AM radio
31–40 of 68 posts
Re: iPhone audio detectable with AM radio
#32I've found that the iPhone display is quite easily detectable between 400nm and 700nm wavelengths.
Oh you...
Re: iPhone audio detectable with AM radio
#33Most likely not an FCC (EMC) issue. This sounds like direct inductive coupling from speaker D class amplifier output (or power, which would be worse, but not likely) circuit at Why it is not an issue, is that magnetic field decays really rapidly, (inversely proportional to the cube of the distance [1]) and thus is not a general concern. In fact some "secure by physics" nearby communication methods like RuBee [2] rela…
A later tweet says "I was able to hear it from 20 feet."
Re: iPhone audio detectable with AM radio
#34I can do this with my Asus laptop as well, at up to about 5 meters distance.
Re: iPhone audio detectable with AM radio
#35Meh. More fun is listening to the GPU redraw the screen and the cpu servicing interupts, both of which you can hear by holding an AM radio close to the phone.
Re: iPhone audio detectable with AM radio
#36Why does it say it's an FCC problem? What are the consequences that Apple may face?
Wirelessly transmitting devices have a lot of regulations on what they can transmit, they need to be certified by the FCC, and are not allowed to transmit in certain frequency bands beyond a certain power.
Some of the discussion here is asserting that this is just induction (i.e. a changing magnetic field causing a changing electric field in the radio, rather than the radio antenna picking up the signal). if that's the case, I'm unsure about why the radio would need to be set to a specific frequency to pick this up (is the proposed inductance in the speaker wire?). Magnetic fields drop off very quickly (with the inverse square of distance) so this is also why people are saying this would be a very short range effect.
The other options seem to be a faulty device actually emitting electromagnetic waves in the stated frequency domain, or an actual fault in general with iphones emitting at that frequency.
The last one would likely have very large consequences for apple (i.e. iphones not able to be sold in the US, and then probably most other markets with similar regulations, i.e. anywhere). Companies tend to be pretty strict on the testing of these things due to the large repercussions, which is why I assume people think it's unlikely.
What I don't know is the repercussions for apple producing some faulty devices that would broadcast EM radiation like that, can anyone fill me in on that?
Re: iPhone audio detectable with AM radio
#37Most likely not an FCC (EMC) issue. This sounds like direct inductive coupling from speaker D class amplifier output (or power, which would be worse, but not likely) circuit at Why it is not an issue, is that magnetic field decays really rapidly, (inversely proportional to the cube of the distance [1]) and thus is not a general concern. In fact some "secure by physics" nearby communication methods like RuBee [2] rela…
A later tweet says "I was able to hear it from 20 feet."
Does the range depends on the volume level? If the max volume interferes upto 20 feet, I don't think it is a big issue as anyways you are going to have interference of the sound.
Re: iPhone audio detectable with AM radio
#38It's probably by design, iPhones support magnetic-induction hearing aids, see here:
https://support.apple.com/en-us/HT202186
The are 2 standards, the old "telecoil" (direct) and the new FM loop, both operating at low frequencies...
Both work at very short ranges (inverse cube of the distance)
Re: iPhone audio detectable with AM radio
#39I've found that the iPhone display is quite easily detectable between 400nm and 700nm wavelengths.
:)
Re: iPhone audio detectable with AM radio
#40Meh. More fun is listening to the GPU redraw the screen and the cpu servicing interupts, both of which you can hear by holding an AM radio close to the phone.
For most laptops you don't even need a radio, just ears.