signal processing

Technology Connections explains why the superheterodyne radio has its name and how mixing frequencies lets it tune stations well. It walks through the underlying wave phenomena and algebra and why the design solved a hard tuning problem.

3Blue1Brown's animated visual introduction to the Fourier Transform, showing how a signal breaks into frequency components.

Technology Connections explains why North American tail light rules, which allow red turn signals and flashing brake lights, make signals ambiguous. He argues for amber signals and cites studies showing a safety benefit.

3Blue1Brown shows how the uncertainty principle arises from Fourier transforms. A wave packet cannot be narrow in both position and frequency, so the principle is a property of waves rather than of measurement.

An MTA video on communications-based train control, the system meant to replace the New York City subway's century-old signaling. It also shows the mechanical interlocks and signals in use today.

Mike Pound explains the discrete cosine transform and how it underpins JPEG compression. It is part two of Computerphile's JPEG series.

Huygens Optics explains the Fourier transform and shows how a lens performs one optically. A DLP projector is used as a Fourier filter to do simple pattern recognition on lithographic character patterns.

Tom Scott explains for Computerphile how Unicode and UTF-8 grew out of messy older character encodings to become the web's standard. It covers why the design works and how it handles worldwide text.

Tom Scott explains why confetti and snow wreck video quality, using interframe compression and bitrate. He demonstrates it live by changing the quality on screen.

Tom Scott explains for Computerphile how floating point numbers work, why moving the binary point is fast, and why it handles money badly.

Not Just Bikes explains how Dutch traffic lights use early detection, transit priority and conflict-free design to cut waiting. The aim is to move as many people as possible rather than as many cars.

MinutePhysics explains that computers store brightness nonlinearly, so blurring and blending colors in raw RGB gives wrong, dark results. It shows why mixed colors, such as in gradients, look off.

The 8-Bit Guy covers IBM's 1981 CGA graphics system, including how composite output and artifacting produced extra colors beyond the nominal palette. He argues CGA looked better in period than it does on RGB monitors.

A short Techquickie explainer on why laptop webcams are much worse than phone cameras. It covers sensor size, image processing, and the interface differences between laptops and phones, with input from a Logitech engineer.

LGR looks at the 1988 Canon Xap Shot, a still video camera that records photos to a floppy disk as analog NTSC signal rather than digital data.

A short FoundMyFitness explainer on the trade-off between growth hormone/IGF-1 and longevity. Higher IGF-1 helps muscle and cognition, while lower levels are linked to longer lifespan and stress resistance.