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<section id="band-limited-oscs-py-oscillators-whose-spectrum-is-kept-under-the-nyquist-frequency">
<h1>02-band-limited-oscs.py - Oscillators whose spectrum is kept under the Nyquist frequency.<a class="headerlink" href="#band-limited-oscs-py-oscillators-whose-spectrum-is-kept-under-the-nyquist-frequency" title="Permalink to this heading">¶</a></h1>
<p>This tutorial presents an object (misnamed LFO but it’s too late
to change its name!) that implements various band-limited waveforms.
A band-limited signal is a signal that none of its partials exceeds
the nyquist frequency (sr/2).</p>
<p>The LFO object, despite its name, can be use as a standard oscillator,
with very high fundamental frequencies. At lower frequencies (below 20 Hz)
this object will give a true LFO with various shapes.</p>
<p>The “type” slider in the controller window lets choose between these
particular waveforms:</p>
<ol class="arabic simple" start="0">
<li><p>Saw up (default)</p></li>
<li><p>Saw down</p></li>
<li><p>Square</p></li>
<li><p>Triangle</p></li>
<li><p>Pulse</p></li>
<li><p>Bipolar pulse</p></li>
<li><p>Sample and hold</p></li>
<li><p>Modulated Sine</p></li>
</ol>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <a class="sphinx-codeautolink-a" href="../../api/alphabetical.html#module-pyo" title="pyo"><span class="nn">pyo</span></a> <span class="kn">import</span> <span class="o">*</span>
<span class="n">s</span> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/server.html#pyo.Server" title="pyo.lib.server.Server"><span class="n">Server</span></a><span class="p">()</span><span class="o">.</span><span class="n">boot</span><span class="p">()</span>
<span class="c1"># Sets fundamental frequency.</span>
<span class="n">freq</span> <span class="o">=</span> <span class="mf">187.5</span>
<span class="c1"># LFO applied to the `sharp` attribute</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.Sine" title="pyo.lib.generators.Sine"><span class="n">lfo</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.Sine" title="pyo.lib.generators.Sine"><span class="n">Sine</span></a><span class="p">(</span><span class="mf">0.2</span><span class="p">,</span> <span class="n">mul</span><span class="o">=</span><span class="mf">0.5</span><span class="p">,</span> <span class="n">add</span><span class="o">=</span><span class="mf">0.5</span><span class="p">)</span>
<span class="c1"># Various band-limited waveforms</span>
<span class="n">osc</span> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.LFO" title="pyo.lib.generators.LFO"><span class="n">LFO</span></a><span class="p">(</span><span class="n">freq</span><span class="o">=</span><span class="n">freq</span><span class="p">,</span> <span class="n">sharp</span><span class="o">=</span><a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.Sine" title="pyo.lib.generators.Sine"><span class="n">lfo</span></a><span class="p">,</span> <span class="n">mul</span><span class="o">=</span><span class="mf">0.4</span><span class="p">)</span><span class="o">.</span><span class="n">out</span><span class="p">()</span>
<span class="n">osc</span><span class="o">.</span><span class="n">ctrl</span><span class="p">()</span>
<span class="c1"># Displays the waveform</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Scope" title="pyo.lib.analysis.Scope"><span class="n">sc</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Scope" title="pyo.lib.analysis.Scope"><span class="n">Scope</span></a><span class="p">(</span><span class="n">osc</span><span class="p">)</span>
<span class="c1"># Displays the spectrum contents</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Spectrum" title="pyo.lib.analysis.Spectrum"><span class="n">sp</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Spectrum" title="pyo.lib.analysis.Spectrum"><span class="n">Spectrum</span></a><span class="p">(</span><span class="n">osc</span><span class="p">)</span>
<span class="n">s</span><span class="o">.</span><span class="n">gui</span><span class="p">(</span><span class="nb">locals</span><span class="p">())</span>
</pre></div>
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