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Comment by cptskippy | Hacker News Reader

The transceiver powering up is actually noisy. I had a Nokia 2100 series in the late 90s that generated enough emi to distort a CRT if it was sitting next to it.

You could hear the whine from across the room a few seconds before a call would ring through.

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Heh. Back in the 90’s in college I would keep my phone on top of the monitor I was sitting at exactly so I would see the monitor juke just before the phone connected.

People always asked how I managed to answer the phone so fast. Electromagnetic Supplementary Perception, of course.

Heh - same sort of timeframe - probably a Nokia 8210 though - I could reliably have my Apple hockey puck mouse "crash" if my phone got an incoming call while it was sitting on my desk in a loop of the usb cable for the mouse. It'd just stop working, and need unplugging/replugging to get it working again.

It was clearly electromagnetically "noisy", but I do't recall ever having heard any on my phones make any unexpected audio noise... (My old-and-abused rock concert and motorcycle weary ears probably can't get up as high as inverter whine any more though...)

We had four computers on a LAN-party that didn't have the shielding on the computer. On phonecalls, all four computers got bluescreens.

Pretty much all cellphones would do that to CTRs. They would also go directly into the audio circuits of cheap amplifiers, to the point where you could "hear" a text or call incoming before the phone made any kind of notification.

You know, that reminds me on how we don't really hear any speakers making odd noises when there's an incoming call anymore. Probably because phones operate on different frequencies nowadays.

-I presume transmit power has been lowered significantly as coverage has improved, too; your cell always transmits at the lowest level it can get a reliable connection with to preserve battery life. This should reduce interference considerably.

Also, GSM phones used TDMA (keying the transmitter on and off to occupy one of -hm- eight, I believe - time slots on a given channel.)

This is practically asking for EMC issues.

LTE, on the other hand, transmits continously (I believe - I do not work in RF engineering anymore, but try to read up on new tech every now and then.:) - much less interference-causing than the constant on/off of TDMA.

I thought LTE worked on a timeslice schedule as well. I remember hearing that was one of the problems with carrier plans to start running LTE on unlicensed spectrum, because it doesn't play nice with listen-before-talk wifi.

I still hear speakers make noises when there is an incoming call, I assume it varies by country.

In college I bought one of those antennas that lights up whenever I got a call or a text. Didn't those lights work on the same principle?

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