# Lesson 13 — Angle of Arrival

<p class="block-synopsis">The one field in the pulse-descriptor word that says <em>where</em>, not <em>what</em> — and the hardest to measure. We compare amplitude comparison against phase interferometry, derive the interferometer relation, and resolve the accuracy–ambiguity trade with multi-baseline arrays.</p>

<div class="block-toc">
  <a class="bt-card bt-reading" href="L13_AngleOfArrival_Reading.html">
    <span class="bt-kind">Reading</span>
    <h4>Angle of Arrival</h4>
    <p>Amplitude comparison, the interferometer relation $\Delta\phi=\frac{2\pi d}{\lambda}\sin\theta$, phase wrap, and multi-baseline.</p>
  </a>
  <a class="bt-card bt-flashcards" href="L13_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="L13_AoAAccuracyExplorer_Demo.html">
    <span class="bt-kind">Demo</span>
    <h4>AoA Accuracy Explorer</h4>
    <p>Stretch the baseline to sharpen the bearing, then watch the phase wrap into ambiguity past $\lambda/2$.</p>
  </a>
  <a class="bt-card" href="L13_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>
