an><span class="o">.</span><span class="n">T</span><span class="p">,</span> <span class="n">sfreq</span><span class="p">)</span>
  <span class="n">sp</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">DataFrame</span><span class="p">(</span><span class="n">data</span><span class="o">=</span><span class="n">np</span><span class="o">.</span><span class="n">log</span><span class="p">(</span><span class="n">Sxx</span><span class="o">.</span><span class="n">T</span><