This document summarizes key topics from Chapter 3 of the textbook "Principles of Electronic Communication Systems" including: amplitude modulation concepts such as modulation index, sidebands, and power calculations; single-sideband modulation advantages; and radio emission classifications. Specifically, it discusses how amplitude modulation varies the carrier amplitude based on the modulating signal, defines modulation index and percentage, explains how sidebands are generated in the frequency domain, describes power calculations and distributions, reviews benefits of single-sideband over double-sideband and amplitude modulation, and outlines international codes for classifying radio signal emissions.