X.</p>
  </dd>
  <dt>Cross PM</dt>
  <dd>
  <p>Cross phase modulation amount.</p>
  <p>Horizontal (X) axis constrols Y to X modulation, and vertical (Y)
  axis controls X to Y modulation.</p>
  </dd>
  <dt>Feedback PM</dt>
  <dd>
  <p>Feedback phase modulation amount.</p>
  <p>Horizontal (X) axis constrols X to X modulation, and vertical (Y)
  axis controls Y to Y modulation.</p>
  </dd>
  </dl>
  <h3 id="filter"><a href="#filter" class="header-anchor"
  aria-hidden="true">Filter</a></h3>
  <p>Lowpass filte