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.Read more →
The Cosmic Distance Ladder is how mankind has determined the distances to various astronomical objects, basically by deducing closer “rungs” on the ladder and using them to determine farther distances (higher rungs on the ladder).
These notes are from Terry Tao, modified by me to suit my audience and to add other topics.Read more →