ChannelSPURIOUS EMISSIONS

Sheet 3 · The series · Series 02

RF
principles

Radio rests on a small number of ideas, and most of them look hard on paper. Each episode takes one idea and draws its mathematics as it moves: a carrier, a spectrum, an arrow that turns. The aim is that you see why it works before you meet the formula. Every one uses a real signal, so you hear what the picture means.

  1. 01AMHow does a voice ride on a radio wave?Modulation21:13
  2. 02SSBWhat is left when AM drops the carrier and one sideband?Modulation3:38
  3. 03FMWhy does FM sound clean?Modulation3:37
  4. 04FM Stereo and the Capture EffectHow do two channels fit in one signal, and why does the stronger station win?Modulation3:47
  5. 05The Superheterodyne ReceiverHow does one fixed filter serve every station?Receivers2:49
  6. 06DecibelsWhat is a decibel, and why do decibels add?Measurement2:48
  7. 07Sampling and AliasingHow many samples are enough?Sampling2:36
  8. 08I/Q SignalsWhy does a software radio keep two numbers for each sample?Sampling3:22
  9. 09Filters and BandwidthWhat does a sharp filter cost?Filters2:40

Still to come

  1. 10Digital Modes: FSK and PSKIn preparation
  2. 11Noise and the Limit of a ChannelIn preparation
  3. 12Phase-Locked LoopsIn preparation

Later, in no fixed order: Antennas and Wavelength, Propagation.

Operate it in the lab: Modulation Operate it in the lab: The superheterodyne receiver
SpurEach episode leaves things out to stay short. The lab has pages where you operate the same ideas yourself.