iPhone audio detectable with AM radio
twitter.com
twitter.com
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)
Hmm. I wonder how they could be practically compromised...
> 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).
> When we work on making our devices accessible by the blind, I don’t consider the bloody ROI.
It's also in the range of many low-power lasers, but I'm not worried about them.
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/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.
But the range is centimetres at best. So much so the antenna gets used as a fairly directional probe.
Really why is this a surprise when you can hear the phone blips and buzzes from the RF induced pickup on shitty hifi equipment.
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.
The summary of the above article is that yes: if you hold the phone sufficiently far away from the measuring device the detected radiation is below the levels mandated, and if someone else tries to test the emission for themselves Apple will say they did it wrong and refuse to give any explanation of what the error might be. A bullet proof system indeed.
Try again.
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?
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.
> 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)
But I very much doubt at the stated range. The EMC guys would be all over that.
You might as well say "It's software engineering. There's no opinion involved..."
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.
We used stuff in defence sector I can’t talk about even today past saying they have specially designed facilities that rival the commercial sector and fairly capable high end 3D field mapping equipment that cost more than my house did. It was based on commercial kit from Agilent with their own software and hardware.
As for antennas, they’re not really that voodoo. I’ve built quite a few even up to 2.4GHz. I played with 10GHz as well but not successfully yet. Same for radiation. PCB traces are antennas and transmission lines. Impedance control is fun IMHO.
There are design patterns and crib sheets at most large companies that avoid such pitfalls though. Spinning another board is expensive so avoiding this sort of stuff is where your design engineers should be leveraged. Some stuff is indeed tweaking but that’s getting less these days with some of the CAD software around. But it costs real money.
I'll clarify my comment on the antenna end: If you do a standard pattern (a yagi, a quarter-length dipole, or whatnot), it's well-understood. What's deep voodoo are the radiation patterns from complex shapes. I've seen research projects where this is basically just done numerically -- a computer tries a bunch of shapes, computes their radiation patterns, and you get bizarre antennas.
EMC looks a lot more like the latter than the former. Our design had a PCB with several daughterboards, and a whole bunch of cables going in and out. That was voodoo. We'd add shielding. Emissions would go up. Or down. There was little rhyme or reason.
But in the end, we didn't break the bank. We went to the test facility twice, I think. We didn't have any sensible kit in-house, but we did have a scope with an FFT function, and we could make loops our of wire. We couldn't measure in real units, but we got a sense of when things went up and when they went down. And, I think, we had a healthy dose of luck.
I totally believe your equipment was superior than commercial. For defense, you want things like stealth and rad-hard. For us, we just want basic compliance.
I wonder if it'll tune into phone calls?
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?