# Lesson 4 — Pulse Radars & Ambiguity

<p class="block-synopsis">Pulsed waveforms in slow time, how pulse width and PRF trade range resolution against unambiguous range and velocity, and the invariant that ties the two ambiguities together.</p>

<div class="block-toc">
  <a class="bt-card bt-reading" href="L04_PulseRadarsAndAmbiguity_Reading.html">
    <span class="bt-kind">Reading</span>
    <h4>Pulse Radars &amp; Ambiguity</h4>
    <p>Pulse train, PW/PRI/PRF and duty cycle, range resolution, unambiguous range and velocity, and the <span class="math notranslate nohighlight">\(c\lambda/8\)</span> invariant.</p>
  </a>
  <a class="bt-card bt-flashcards" href="L04_Flashcards.html">
    <span class="bt-kind">Flashcards</span>
    <h4>Review deck</h4>
    <p>Key terms and relations from the lesson, in a self-test deck.</p>
  </a>
  <a class="bt-card bt-demo" href="L04_PRFExplorer_Demo.html">
    <span class="bt-kind">Demo</span>
    <h4>PRF Explorer</h4>
    <p>Drive PRF and pulse width, watch the pulse train, and fold a true range into its apparent range.</p>
  </a>
  <a class="bt-card" href="L04_Preflight.html">
    <span class="bt-kind">Pre-flight</span>
    <h4>Pre-flight quiz</h4>
    <p>Pre-class check, due before the lesson. Counts toward your IP grade.</p>
  </a>
</div>