Itâs like a dog whistle. Itâs emblazoned on my brain. You all know what Iâm talking about. Unless youâre way too young and youâre intent on making me feel way too old. Iâm talking, of course, about the noises your dial-up modem made when hooking up to the internet back when the internet was this terrifying thing we used to âsurfâ.
The above massive image attempts to visualise every aspect of that modem noise, and also does a great job of explaining precisely what every blip and bloop meant, what it represented. I just love it.
Oona RĂ€isĂ€nen does her level best to explain, but really you should just click on the image belowâŠ
When humans talk, only one of them is usually talking while the other one listens. The telephone network exploits this fact and temporarily silences the return channel to suppress any confusing echoes of the talkerâs own voice.
Modems donât like this at all, as they can very well talk at the same time (itâs called full-duplex). The answering modem now puts on a special answer tone that will disable any echo suppression circuits on the line. The tone also has periodic âsnapsâ (180° phase transitions) that aim to disable yet another type of circuit called echo canceller.
Now the modems will list their supported modulation modes and try to find one that both know. They also probe the line with test tones to see how it responds to tones of different frequencies, and how much it attenuates the signal. They exchange their test results and decide a speed that is suitable for the line.
Be right back. Currently rocking in a nostalgic fetal ball.
The sound of the dialup, pictured [Absorbtions]
Mark Serrels is the EIC for Kotaku Australia. You can follow him on Twitter!
Republished from Kotaku Australia
