# Lesson 28 — Modulation and Amplitude Modulation

<p class="block-synopsis">Why we modulate, the function multiplier, and the modulation index.</p>

**Objectives covered**

- **3.1** — I can determine the modulation index, output signal, and output signal bandwidth of an Amplitude Modulation (AM) system and assess whether the system is under-modulated, over-modulated, or fully modulated.

<div class="block-toc">
  <a class="bt-card bt-reading" href="../Block3Reading/Obj01/ECE215_B3_Obj01_Reading.html">
    <span class="bt-kind">Reading</span>
    <h4>Amplitude Modulation</h4>
    <p>The course reading for Objective 3.1.</p>
  </a>
  <a class="bt-card bt-flashcards" href="L28_Flashcards.html">
    <span class="bt-kind">Flashcards</span>
    <h4>Review deck</h4>
    <p>Key terms, equations, and ideas from this lesson, in a self-test deck.</p>
  </a>
  <a class="bt-card bt-slides" href="../_static/slides/ECE_215_Lesson28.pdf">
    <span class="bt-kind">Slides</span>
    <h4>Lesson 28 deck</h4>
    <p>The slides used in class, as a PDF.</p>
  </a>
  <a class="bt-card bt-practice" href="../downloads.html">
    <span class="bt-kind">Practice Problems</span>
    <h4>Work these before the quiz</h4>
    <p>Ungraded problems with answers, on the downloads page.</p>
  </a>
  <a class="bt-card bt-demo" href="https://usafa-ece.org/apps/modulation/" target="_blank" rel="noopener">
    <span class="bt-kind">Demo ↗</span>
    <h4>Modulation Demo</h4>
    <p>AM modulation with synchronized time and frequency-domain views.</p>
  </a>
</div>