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Cleanup
author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 07 Dec 2011 17:24:36 +0100 (2011-12-07)
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1 <h2>Description</h2>
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2 <p>
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3 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.
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4 <br>
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5 <br>
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6 <h2>Syntax</h2>
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7 </p>
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8 <div class="fragment"><pre>
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9 <br>
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10 b = upsample(a, pl)
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11 </pre>
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12 </div>
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13 <h2>Parameters</h2>
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14 <p>
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15 The following parameters can be set in this method:
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16 <ul>
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17 <li> <tt>N</tt> - specify the desired upsample rate </li>
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18 <li> <tt>phase</tt> - specify an initial phase range [0, N-1]</li>
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19 </ul>
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20 </p>
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21 <p>
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22 <h2>Examples</h2>
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23 </p>
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24 <p>
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25 1. Upsampling a sequence of random data at original sampling rate of 1 Hz by a factor of 10 with no initial phase.
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26 </p>
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27 <div class="fragment"><pre>
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28 <br>
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29 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);
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30 x = ao(pl);
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31 pl_up = plist(<span class="string">'N'</span>, 10); <span class="comment">% increase the sampling frequency by a factor of 10</span>
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32 y = upsample(x, pl_up); <span class="comment">% resample the input AO (x) to obtain the upsampled AO (y)</span>
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33 iplot(x, y)
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34 </pre>
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35 </div>
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36 </p>
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37 <br>
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38 <img src="images/upsample1.png" alt="Upsample" border="3">
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39 <br>
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40 <p>
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41 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.
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42 </p>
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43 <div class="fragment"><pre>
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44 <br>
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45 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);
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46 x = ao(pl);
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47 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>
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48 y = upsample(x, pl_upphase); <span class="comment">% resample the input AO (x) to obtain the upsampled and delayed AO (y)</span>
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49 iplot(x, y)
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50 </pre>
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51 </div>
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52 </p>
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53 <br>
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54 <img src="images/upsample2.png" alt="Upsample" border="3">