Correct alpha and gamma for image processing

This is a note on the correct usage of alpha blending, pre-multiplied alpha, gamma correction, and linear colors for image processing.

Rtk Gps Project

I built a RTK-GPS gadget and wrote enough software to do basic GNS tasks such as finding distances, decoding GPS NMEA and RTCM messages, finding intersections, and doing boundary detection.

Intro to Wireless Communications

This talk is an intro to wireless communications, starting with the basic physics of EM waves and how they interact with materials, then how antennas work, then on to antenna properties and design. Next modulation schemes are discussed, showing how data is encoded and transmitted over noisy channels via modulation, spread spectrum, time and frequency division, and other methods. Noise in the form of doppler, intermodulation, and other causes is covered. Information theory (channel capacity, Shannon entropy, error correction) is covered. Finally specific protocols are analyzed under this framework: FM, NTSC, remotes, WiFi, Bluetooth, ZigBee, satellite radio, GPS, and cellular formats.

Meltdown and Modern CPU Architecture

This talk covers CPU architecture from the early days (Intel 4004) through modern designs (2018, Intel i7 and i9), with a view towards how the Meltdown and Spectre exploits were discovered. It covers virtual memory, process separation, cache issues, RAM details, pipelining and stalls, branch prediction, Moore’s law versus physics, and finally how Meltdown and Spectre are the consequence of many of these design decisions.

In the end I show the code for Meltdown along with a demo.

Making Three NOT Gates from Two

This is a hard puzzle about using two NOT gates to build three.

LZCL: An embedded compression library

Here’s an embedded compression format I designed to meet certain requirements. It’s small, fast, and efficient.