Modulation & Encoding#

Reshaping signals to carry information. Modulation impresses information onto a carrier — shifting it in frequency, varying its amplitude, or encoding it as a pulse pattern. These techniques show up everywhere from AM radio to Class-D amplifiers to digital audio interfaces.

The boundary between “audio/signal processing” and “communications” is thin here. AM and FM are covered in this section from a signal-processing perspective; the Radio & RF section covers them in their natural habitat of antenna systems and receivers.

What This Section Covers#

• Amplitude & Frequency Modulation — Why modulation exists; AM sidebands and bandwidth; FM deviation and Carson’s rule; non-RF applications.
• Pulse-Based Encoding — PWM, PDM, and their connection to Class-D amplifiers and delta-sigma conversion.
• Digital Modulation & Data Encoding — Line codes, audio interface protocols (I2S, S/PDIF), and signal integrity on digital audio links.