Oona Räisänen has written a thorough and engrossing article about the noises emitted by dial-up modems while they connect and handshake, and the accompanying graphic (ZOMG HUGE) is nothing short of spectacular. It would make a great full-size poster -- maybe a framed art-print.
Now the modems must address the problem of echo suppression. 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 talker's own voice.
Modems don't like this at all, as they can very well talk at the same time (it's 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 "snaps" (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.
After this, the modems will go to scrambled data. They put their data through a special scrambling formula before transmission to make its power distribution more even and to make sure there are no patterns that are suboptimal for transfer. They listen to each other sending a series of binary 1's and adjust their equalizers to optimally shape the incoming signal.
The sound of the dialup, pictured
Yahoo has released a machine-learning model called open_nsfw that is designed to distinguish not-safe-for-work images from worksafe ones. By tweaking the model and combining it with places-CNN, MIT’s scene-recognition model, Gabriel Goh created a bunch of machine-generated scenes that score high for both models — things that aren’t porn, but look porny.
I dote on fidget gadgets — soothing gizmos intended to give your hands something to keep busy with, like modern worry-beads — and while you can’t buy Chris Bathgate’s amazing machined sliders, and the Fidget Cube Kickstarter just closed, there’s still Thinkgeek’s new Jumbo Noah Fidget Toy, which looks like a lot of fun and […]
JWZ documents his adventures in bringing a 1982/3 vintage Ann Arbor Ambassador 60 terminal (a rare portrait-orientation terminal) back into service — fitting it with a Raspberry Pi and a new power-supply and getting it to boot its beautiful green-screen.
This Python Mega Course will help you learn to code by teaching you to build 10 real-world apps that each highlight a unique use of Python.Job prospects for coders are still growing steadily—and with Python being one of the most popular coding languages out there today, it’s important for job seekers to demonstrate a widespread understanding of the […]
The Atmos R2 may be bigger than the brand’s previously-released vapes, but we argue that in this case it’s definitely a good thing. A bigger heating chamber means more room for packing it full. And the bigger battery means longer, more fulfilling vape sessions. In fact, you can use the Atmos R2 for up to about 25 […]
These days, there is huge demand for ethical hackers. Companies pay these professionals to identify and remedy security holes in their networks before malicious hackers find and exploit them. What’s great about this is that if you love hacking or think you may love hacking, you can do it for a living and not as […]