6 ms·
iPhone audio detectable with AM radio
- vmarius 6y agoWow. I wonder how far from the phone this signal could be detected.
- fredley 6y agoIt depends on how noisy the surroundings are. In an office block with potentially many other iPhones and sources of interference, probably not far at all. Out in a suburban or rural setting probably much further. I wonder if it'll tune into phone calls?
- erk__ 6y agoHe says in one of the comments that he was able to get a signal you could hear from around 20 feet away.
- m0xte 6y agoI suspect that’s unlikely from my own experiences on this stuff. Perhaps 20-40cm is more likely.
- eptcyka 6y agoIf you are disregarding that detail of the story, why not dismiss the author outright?
- m0xte 6y agoI am disregarding the whole thing. The author knows nothing of EMC. This is expected at close quarters.
- ponker 6y agoWhy would you assume that his experiences and yours are the same?
- m0xte 6y agoIt’s physics. There is EMC testing done on these devices. There is little opinion involved in such matters.
- murgindrag 6y agoYou've clearly never done EMC testing, if you think there's no opinion involved in such matters. You might as well say "It's software engineering. There's no opinion involved..."
- m0xte 6y agoI have, in defence sector.
- murgindrag 6y agoInteresting. I've never done defense. What was it like? In the real world (non-defense), I did this once in my life. We went to and independent testing laboratory (actually the premier / highest-regarded one) with our device. They put it outside, pointed a big antenna at it, and it didn't pass. We made some random changes (adding shielding of some kind somewhere; the lab had it on-hand). Things ... changed. Sometimes they got better. Sometimes they got worse. We didn't know whether we were changing, or simply the radiation patterns to better match the test setup. We kept making tweaks like that until it passed, and that was our final, independently lab-certified product design. If we had tested at a slightly different angle, I'm pretty sure we would not have passed. Or in a different lab. It was deep voodoo. From what the lab guys said, EMC testing almost always looks like that. I believed them. We can't really solve Maxwell's Equations in our head, and we know so little about antenna design that predicting the radiation from a complex device is not really possible. You just tweak, adding a gasket here or ferrite bead or whatever, and pray it works. Most of the small tweaks we did at the lab, but I do recall we did some larger design change (making a signal differential or something) which necessitated going to the lab a second time with a device with a new PCB.
- sgt 6y agoJust a few meters, as per the article. I'm guessing if you can't hear it on the iPhone's speaker, it won't be audible on AM radio either.
- m0xte 6y agoCorrect. Although it’s possible on older handsets with 3.5 jack that the audio amplifier in the handset itself is possible to receive. I’m not sure about lightning. But I very much doubt at the stated range. The EMC guys would be all over that.
- xt00 6y agoPretty interesting.. many class D audio amps drive at frequencies above 100-200khz, so either the odd or even harmonics of that frequency sounds like where you would get the actual audio content showing up in the audible band (not sure if it’s odd or even that would be the right one). I want to try this on some other class D speakers.
- m0xte 6y agoThis is not surprising. We’ve been using AM and FM radios to debug circuits for decades. They can pick up oscillations and instabilities. But the range is centimetres at best. So much so the antenna gets used as a fairly directional probe.
- phlhar 6y agoIn a later tweet he says the signal is pretty strong and that he could detect it from 6 feet away
- m0xte 6y agoI doubt it. That probably wouldn’t pass the EMC testing. Exaggerating I suspect to back up the claim. Really why is this a surprise when you can hear the phone blips and buzzes from the RF induced pickup on shitty hifi equipment.
- evgen 6y agoGoing to have to call bullshit on this. If it was detectable at that range then he has a faulty phone. The iPhone is classified as an emitter and so it needs to undergo rather strict FCC testing to ensure that it does not emit outside of certain frequencies and at specific power levels. The device would NEVER have been approved if it emitted at this level into bands licensed to other uses.
- jojobas 6y ago6 meters is near field in that frequency range. The emission power is possibly well below FCC limits.
- deleted 6y ago[deleted]
- whereistimbo 6y agoHe said 20 feet away https://twitter.com/doctorcube/status/1301146339561164800 https://twitter.com/doctorcube/status/1301146339561164800
- doctorshady 6y agoI'm surprised this wasn't discovered sooner. For a while, when I was working in Portland radio, there was an AM station that played recent indie releases on it. Needless to say, while it was the butt of countless hipster jokes, there was a sizable crop of people with both AM radios and iPhones on them, frequently operating at the same time.
- evgen 6y agoIt wasn't discovered because either it didn't happen or the person claiming such has a faulty device. The FCC would never allow these phones to be imported for sale if they were so sloppy in their emissions. The idea that there are millions of people out there listening to AM radio every day for hours at a time in cars and homes/offices in close proximity to iPhones but no one ever detected this before is laughable.
- SiempreViernes 6y agoArguments by appeals to authorities like the FCC, CDC, or FAA sort of work if the authority can be trusted. For the argument to be coherent that trust must have been established by a proven track record of both employing the appropriate methods correctly and showing independence of vested interests in their reporting of the results.
- evgen 6y agoApparently you have no idea what you are talking about, so you think that these sorts of arguments work when discussing FCC emission testing. The FCC does not actually run the test, they set the standards. The tests themselves are run by various labs and testing agencies that are certified to perform the tests and who would be risking a very lucrative gig for the sake of cheating on a test for a device that will be widely deployed and certainly tested by third-parties who will want to examine the device. It is possible for some mid-range device to slip through or bribe someone to pass a test, but unlikely to the point of absurdity that this would be done for something like an iPhone.
- polskibus 6y agoWhy does it say it's an FCC problem? What are the consequences that Apple may face?
- yuhong 6y agoIt would not fail FCC class B unless it is noticeable from quite a distance away.
- mijoharas 6y agoWirelessly 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?
- numpad0 6y agoIsn’t it more or less how inductive speakers[0] work? [0]: https://youtube.com/watch?v=vDrRNdgz2C8 https://youtube.com/watch?v=vDrRNdgz2C8
- IndrekR 6y agoMost 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 <100 kHz. Below 30 MHz only conducted emissions are measured (common mode emission via cable, say, forming a large antenna together with the power grid). The emitting component may be the speaker or (unshielded) output filter (for EMC compliance!) of the amplifier. 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] relay on this. [1] https://en.wikipedia.org/wiki/Near_and_far_field https://en.wikipedia.org/wiki/Near_and_far_field [2] https://en.wikipedia.org/wiki/RuBee https://en.wikipedia.org/wiki/RuBee
- 0-_-0 6y agoA later tweet says "I was able to hear it from 20 feet."
- YetAnotherNick 6y agoDoes 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.
- floatingatoll 6y agoI can hear the iPhone’s speaker from 20 feet away, too - without using AM radio technology to do so. (It’s a curse, trust me.)
- amelius 6y agoI've found that the iPhone display is quite easily detectable between 400nm and 700nm wavelengths.
- daneel_w 6y agoOh you...
- nobrains 6y ago:)
- 8K832d7tNmiQ 6y agogee, I wonder which sensors can detect at that such wavelengths.
- iso1210 6y agoOnly in a c. 170 degree arc though
- jwandborg 6y agoThat sounds way worse since it's in the frequency range of many high-powered lasers. It's also in the range of many low-power lasers, but I'm not worried about them.
- Johnythree 6y agoWoosh...
- compsciphd 6y agoAlso happens in the reverse. growing up in the shadow of WTOP[1] towers in the DC area, we used to hear WTOP in our rotary phones (between dials mostly) and even sometimes picked up in our ovens (yes, could hear the radio coming out of the oven) [1] https://en.wikipedia.org/wiki/WFED https://en.wikipedia.org/wiki/WFED it was really powerful, heck, I even remember in my youth going up to relatives in boston and being able to pick up the signal at night to listen to Oriole games in the summer.
- jakedata 6y agoThis feature was also available on the Altair 8800. http://vintagecomputer.net/browse_thread.cfm?id=720 http://vintagecomputer.net/browse_thread.cfm?id=720
- emsy 6y agoMy 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.
- abyssin 6y agoI remember picking up the conversation coming from a hot air balloon one day I was playing on the computer. I was focused on the game, and suddenly these voices start overlapping with the sounds I'm used. Today I'm not even sure it was possible. The speakers were that kind that made a noise when receiving or sending an SMS from a nearby mobile phone.
- daneel_w 6y agoI can do this with my Asus laptop as well, at up to about 5 meters distance.
- swiley 6y agoMeh. 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.
- formerly_proven 6y agoFor most laptops you don't even need a radio, just ears.
- skim_milk 6y agoI can't wait for laptops to start including the 30xx series NVidia cards in it and replace mine, because my current one is so awfully noisy. The sound of the USB circuitry in my laptop processing my mouse movements is louder than the sound of my mouse moving across the mouse pad, and when I'm moving a bunch of data around the SSD in my laptop makes as much noise as the physical hard disk it replaced! I am constantly in awe of how noisy some things that aren't supposed to be physically moving at all can be.
- commonjcb 6y agoIt's probably by design, iPhones support magnetic-induction hearing aids, see here: https://support.apple.com/en-us/HT202186 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)
- exikyut 6y agoThat is admittedly really cool. It's nice to hear that these sorts of things are just quietly included, maintained, and work well, without widespread fanfare/marketing/publicity. Hmm. I wonder how they could be practically compromised...
- KMnO4 6y agoThis reminds me of the "car recall" evaluation from Fight Club: > Take the number of vehicles in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one. However, in this case, it would be: Take the number of people who would benefit from accessibility features, A, multiply by the probability that they would buy an iPhone with these features over any other phone, B, multiply by the profit of each iPhone sale, C. A * B * C = X. If X is greater than the engineering cost to implement accessibility features, we do it. And realistically I'm sure there's some coefficient not included that equates to how likely Apple is to spend money on something just because it's good for the world (and not because they'll bring in a profit).
- gok 6y agoFWIW, the CEO somewhat infamously snapped at an activist investor: > When we work on making our devices accessible by the blind, I don’t consider the bloody ROI.
- angrygoat 6y agoExcellent that there is accessibility support, but at what range can people pick my calls up – especially with a directional antenna?
- geerlingguy 6y agoI just tested this on my iPhone XS with both an old AM radio and my SDR receiver, and neither seemed to cause any kind of signal or interference around the 930-980 KHz range. My dad, a radio engineer (who worked for one of the US' largest AM radio stations for a decade), also tested with his XR and couldn't find any signal. I'm wondering if either it is limited to the iPhone 7 and/or 8, or if the Twitter OP might have a faulty unit? Has anyone else been able to replicate the result?
- dgellow 6y agoWhat about https://twitter.com/mehdi0x61/status/1301094353050439681 https://twitter.com/mehdi0x61/status/1301094353050439681 ? > I reproduced this on iPhone 6, 8 Plus and 11 Pro, using an H probe (only happens when playing through the speaker) > In my tests, all the 3 phones broadcast on 857 KHZ (broadcast might not be the correct technical term here though) (with picture)
- floatingatoll 6y agoRetest with the hearing aid settings enabled? https://news.ycombinator.com/item?id=24363153 https://news.ycombinator.com/item?id=24363153 To activate Hearing Aid Compatibility on an iPhone with iOS 13 or later, go to Settings > Accessibility > Hearing Devices. On these iPhone models, Hearing Aid Compatibility modifies the phone’s acoustic settings to improve compatibility with hearing aids set in "T" or telecoil mode. If you have an iPhone 6 or earlier, you can activate Hearing Aid Mode. To activate Hearing Aid Mode, go to Settings > General > Accessibility. Hearing Aid Mode reduces the transmission power of the cellular radio in the GSM 1900 MHz band, which may result in decreased 2G cellular coverage.