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  <title>Upsampling data (LTPDA Toolbox)</title>
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  <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Upsampling data</h1>
  <hr>

  <p>
	<h2>Description</h2>
<p>
  Upsampling is the process of increasing the sampling rate of a signal. <a href="matlab:doc('ao/upsample')"><tt>Upsample</tt></a> increases the sampling rate of the input AOs by an integer factor. LTPDA <a href="matlab:doc('ao/upsample')"><tt>upsample</tt></a> overloads <tt>upsample</tt> function from Matlab Signal Processing Toolbox. This function increases the sampling rate of a signal by inserting (n-1) zeros between samples. The upsampled output has (n*input) samples. In addition, an initial phase can be specified and, thus, a delayed output of the input can be obtained by using this option.
  <br>
  <br>
  <h2>Syntax</h2>
</p>
<div class="fragment"><pre>
  <br>
    b = upsample(a, pl)
  </pre>
</div>
<h2>Parameters</h2>
<p>
  The following parameters can be set in this method:
  <ul>
    <li> <tt>N</tt> - specify the desired upsample rate </li>
    <li> <tt>phase</tt> - specify an initial phase range [0, N-1]</li>
  </ul>
</p>
<p>
  <h2>Examples</h2>
</p>
<p>
  1. Upsampling a sequence of random data at original sampling rate of 1 Hz by a factor of 10 with no initial phase.
</p>
<div class="fragment"><pre>
  <br>
    pl    = plist(<span class="string">'tsfcn'</span>, <span class="string">'randn(size(t))'</span>,<span class="string">'fs'</span>,1,<span class="string">'yunits'</span>,<span class="string">'m'</span>,<span class="string">'nsecs'</span>,100);
    x     = ao(pl);
    pl_up = plist(<span class="string">'N'</span>, 10);     <span class="comment">% increase the sampling frequency by a factor of 10</span>
    y     = upsample(x, pl_up); <span class="comment">% resample the input AO (x) to obtain the upsampled AO (y)</span>
    iplot(x, y)
  </pre>
</div>
</p>
<br>
<img src="images/upsample1.png" alt="Upsample" border="3">
<br>
<p>
  2. Upsampling a sequence of random data at original sampling rate of 1 Hz by a factor of 21 with a phase of 20 samples.
</p>
<div class="fragment"><pre>
  <br>
    pl         = plist(<span class="string">'tsfcn'</span>, <span class="string">'randn(size(t))'</span>,<span class="string">'fs'</span>,1,<span class="string">'yunits'</span>,<span class="string">'m'</span>,<span class="string">'nsecs'</span>,100);
    x          = ao(pl);
    pl_upphase = plist(<span class="string">'N'</span>, 21,<span class=string>'phase'</span>, 20); <span class="comment">% increase the sampling frequency and add phase of 20 samples to upsampled data</span>
    y          = upsample(x, pl_upphase);    <span class="comment">% resample the input AO (x) to obtain the upsampled and delayed AO (y)</span>
    iplot(x, y)
  </pre>
</div>
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<br>
<img src="images/upsample2.png" alt="Upsample" border="3">

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  <p class="copy">&copy;LTP Team</p>
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author	Daniele Nicolodi <nicolodi@science.unitn.it>
date	Wed, 07 Dec 2011 17:24:37 +0100
parents	f0afece42f48
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