To simplify, up to 7 users (+1 timeslot for signalling) share the same channel/frequency, but each of them is allowed to transmit only 1/8 of the time (even less, due to guard intervals). This basically means, that your phone transmitted for a bit over 0.5 milliseconds (577us), then waited quietly for 7 more intervals like that for other devices to transmit, then your phone transmitted again, and the affected speakers "buzzed" because of these 577ms bursts of power every 4.616 milliseconds (this causes a buzz in the frequency range we can actually hear).
That's not to say it's not using some archaic weak encryption scheme left in for backwards compatability though.
GSM uses time division multiplex, which means it shares the 8-timeslot channel with 6 more devices (7 devices + 1 signalling), meaning your phone transmits for 577us, then waits quietly for all the 7 timeslots that other devices use (so, for 4.039 milliseconds - 7x577us), and again transmits for 577us, and again waits. Bursts of power every ~4.6milliseconds make a noise that we can actually hear at a bit over 200Hz.
Good ol moto razr
That was a bad time.
Not exactly the same, but makes me reminisce the days of the iPod nano. It offered FM radio using the headphone cables as an antenna. I haven’t seen that supported anywhere since, which is a shame because I’d really like to get local stations on my phone.
I blame the French. They introduced a law that forbids radio receivers that don't support DAB radio, as a way to make the newer DAB format take off. But globally, DAB never did so phone hardware don't have it. In the EU, distribution chains often cross borders and it would be too bothersome to have models with special firmware just for France — so instead, nobody gets FM-radio.
I bought last year a DAB compatible radio for my car, only to realise that it is worse than FM :)
https://www.reddit.com/r/MotoG/comments/u2dvvp/any_current_m...
https://www.amazon.com/Ulefone-Power-Armor-13-Smartphone/dp/...
https://crgsoft.com/the-list-of-2019-smartphones-that-have-f...
That was common on phones in general. Headphones acted as antenna.
If you open the FM radio app without connecting wired headphones, it'll ask you to connect it.
This was common in Android phones as well.
My current Android phone does not have headphone jack. And I can't use FM radio (although there are services that play radio over the internet, but that isn't really the same...).
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About phones which have the capability but which are disabled, I wonder if it's because of security implications.
Where I live, the allowed frequencies were from 87 MHz to 108 MHz or something. Consumer FM radios could only be tuned in this range.
That's because on frequencies outside this range, other transmissions — for example, police transmissions — might be taking place.
The aforementioned allowed range is different in different countries.
Also, in my country long long ago (like, ≈50 years ago) you needed to get the permission of the government (via a license or something) to get a radio. You couldn't just go to a store and buy one. That changed later, however.
Now that I think about it, it might have something to do with semi-secret transmissions happening on frequencies outside the allowed range.
A friend told me it's possible to take apart the radio and tune to non-standard frequencies because in most radios the "dial" to select the allowed range really works by physically jamming the dial with another block. If you remove that block, you could keep turning that dial. Haven't tried this myself, so take that with a pinch of salt.
I had that come with a cheap motorola phone (3 years ago or so)
https://www.motorola-support.com/uk-en/?page=topic/applicati...
So not ubiquitous but not that rare either.
It was very common in previous decades because it was cheaper and allowed more room in the device (the alternative was the metal “pull to extend” antennas).
Or a clip on, something like this : https://www.cablechick.com.au/cables/ferrite-core-rfi-and-em...
https://resources.altium.com/p/how-do-ferrite-beads-work-and...
Likely cost savings combined with design considerations ("these knobs look ugly").
Second, hams are not vindictive people, and most interference issues are sorted out locally, possibly with support from the ARRL. Some sources of interference can be very hard to find.
The FCC only levies massive fines when their instructions are being ignored. They don’t play games, that’s true.
So odd.
On the other hand, instead of doing loads of research and buying new equipment, I can just connect my headphones or speakers by Bluetooth and the noise is gone.
Now I have to deal with the annoyances of Bluetooth which are not zero either. But it's a great tradeoff for me.
I have a pair of desktop speakers that have both a USB input (to an onboard DAC) and an analog input; originally, I had the USB input connected to an iMac and used the analog input to plug into my work laptop. Recently, I swapped the iMac for a Mac Studio and a Studio Display, and figured that I could just unplug the Thunderbolt cable to the display from the computer and plug it into the laptop. I kept using the analog cable, though, because I wanted to keep the speakers directly plugged into the computer rather than the hub on the display, probably due to irrational audiophile-esque superstition that this would make the sound laggy or the highs less chocolaty or whatever. (More seriously, I've heard of DACs having stuttering issues when they're run through hubs, and hey, I had the cable, right.)
And the first time I plugged the analog cable into the same laptop that I'd been using, the only difference being that the Thunderbolt cable was also plugged into it, it was terrible.
Despite the audiophile joke above, I don't mean terrible in some kind of "this cable is making the sound subjectively worse" fashion, I mean terrible in a "when no sound is playing, I can hear grinding electrical noise going BZZZZZbzzzzGRRRFTTTTgrrnkFFFFNK constantly" fashion. The problem was clearly the Thunderbolt cable, even though it wasn't involved in the audio circuit at all. It's like it had turned into its own little RF interference generator. While I only had the one Thunderbolt cable so I couldn't swap it, the interference went through two different analog cables.
(This is not as weird as hearing RF interference over one specific pair of headphones from a headphone amp when nothing was playing but only when I was using a specific USB cable running to the same outboard DAC, which also happened to me years ago.)
https://www.corning.com/optical-cables-by-corning/worldwide/...
As soon as I stand up my headphones become violently disconnected from my computer. Cables also interfere with each other and all the other items on my desk.
It's just different sets of compromises.
> Wired sound infinitely nicer sounding
There are good sounding wireless headphones and terrible sounding wired headphones. The drawbacks is that with wireless headphones you can't control the sound stack and are dependent on the manufacturer to provide high quality drivers, amplification, and digital to analog conversion all built into the device.
> much lower latency
...is an engineering problem.
> Will we ever have a day when wireless will be sufficiently low latency?
A company already markets their wireless headphones directly to musicians, which is basically the threshold of low latency you need to meet; realtime monitoring [1]. Does it accomplish what it set out to do? Not sure, but seems like it's good enough for some people.
Ultimately it comes down to exactly what I said, which is that there are tradeoffs to using wired vs. wireless headphones and one is not intrinsically better than the other. You thinking that something sounds "infinitely better" doesn't make the rest of those tradeoffs not meaningful to other people.
[1] https://aiaiai.audio/headphones/tma-2-studio-wireless-plus
Of course, it has the dongle issue which limits the usage to certain devices (Xbox and Windows in my case, I haven't tested the dongle on my Mac or Linux).
"flow of electrons in a copper wire" has little to do with the speed of a signal transmitted via electrons in a copper wire - what we care about here is propogation delay[1]. Assuming that the speed is about c in air (a bit less but whatever) and at least 0.6c in copper, and assuming a minimum threshold of say 1ms of delay being noticeable to an audiophile, then you would need a headphone cable about 450km in length to noticed the difference.
Compressed air will never get it out. It gets really compacted in there. Don't be afraid of using a needle, the port is quite rugged. Just avoid the contacts in the middle.
A high bandwidth data cables (aka wires) does introduce RF noise / EMIs. That's why ferrite bead were invented to reduce the noise.
https://en.wikipedia.org/wiki/Ferrite_bead
The reason some ethernet cable and audio cables don't have ferrite beads is because they have internal metal mesh EMI shielding. But not all cables have that.
Don't have the equipment to test or diagnose, but empirically, having moved to using balanced cabling from point of analog conversion all the way to amp input, there's no sounds coming out of my headphones that shouldn't be.
What a happy world. There's enough interference in cabling, but most time it's not enough to cause any issues. Had a case once where an AP with PoE did not work properly (started, then died, repeat) and the issue was that we had to much cable somewhere and rolled it. Interference caused issues, despite using STP and Cat. 6...
Backpacks are also a recurring offender.
Many pieces of clothing... or objects you regularly traverse, can become a wire trap.
Those objects are the bait & fishing rod, and your wires are the fish :)