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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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10
11 <title>Resampling data (LTPDA Toolbox)</title>
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15 "Presents an overview of the features, system requirements, and starting the toolbox.">
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17
18 <body>
19 <a name="top_of_page" id="top_of_page"></a>
20
21 <p style="font-size:1px;">&nbsp;</p>
22
23 <table class="nav" summary="Navigation aid" border="0" width=
24 "100%" cellpadding="0" cellspacing="0">
25 <tr>
26 <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td>
27
28 <td valign="baseline" align="right"><a href=
29 "upsample.html"><img src="b_prev.gif" border="0" align=
30 "bottom" alt="Upsampling data"></a>&nbsp;&nbsp;&nbsp;<a href=
31 "interp.html"><img src="b_next.gif" border="0" align=
32 "bottom" alt="Interpolating data"></a></td>
33 </tr>
34 </table>
35
36 <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Resampling data</h1>
37 <hr>
38
39 <p>
40 <h2>Description</h2>
41 <p>
42 Resampling is the process of changing the sampling rate of data. <a href="matlab:doc('ao/resample')"><tt>Resample</tt></a>
43 changes the sampling rate of the input AOs to the desired output sampling frequency. LTPDA <a href="matlab:doc('ao/resample')"><tt>resample</tt></a> overloads <tt>resample</tt> function of Matlab Signal Processing Toolbox for AOs.
44 </p>
45 <h2>Syntax</h2>
46 <div class="fragment"><pre>
47 <br>
48 b = resample(a, pl)
49 </pre>
50 </div>
51 <h2>Parameters</h2>
52 <p> The following parameters can be set:
53 <ul>
54 <li> <tt>fsout</tt> - specify the desired output frequency (must be positive and integer)</li>
55 <li> <tt>filter</tt> - specified filter applied to the input, <tt>a</tt>, in the resampling process</li>
56 </ul>
57 </p>
58 <p>
59 <h2>Examples</h2>
60 </p>
61 <p>
62 2. Resampling a sequence of random data at original sampling rate of 1 Hz at an output sampling of 50 Hz.
63 </p>
64 <div class="fragment"><pre>
65 <br>
66 <span class="comment">% create an AO of random data with fs = 10 Hz</span>
67 pl = plist(<span class="string">'tsfcn'</span>, <span class="string">'randn(size(t))'</span>,<span class="string">'fs'</span>,1,<span class="string">'nsecs'</span>,10,<span class="string">'yunits'</span>,<span class="string">'m'</span>,<span class="string">'nsecs'</span>,100);
68 x = ao(pl);
69 y = resample(x, plist(<span class="string">'fsout'</span>, 50)); <span class="comment">% resample the input AO (x) to obtain the resampled output AO (y)</span>
70 iplot(x, y) <span class="comment">% plot original and resampled data</span>
71 </pre>
72 </div>
73 <br>
74 <br>
75 <img src="images/resample1.png" alt="Resample">
76 <br>
77 <br>
78 <br>
79 <p>
80 1. Resampling a sequence of random data at original sampling rate of 10 Hz at an output sampling of 1 Hz with
81 a filter defined by the user.
82 </p>
83 <div class="fragment"><pre>
84 <br>
85 <span class="comment">% create an AO of random data with fs = 10 Hz</span>
86 pl = plist(<span class="string">'tsfcn'</span>, <span class="string">'randn(size(t))'</span>,<span class="string">'fs'</span>,10,<span class="string">'nsecs'</span>,10,<span class="string">'yunits'</span>,<span class="string">'m'</span>);
87 x = ao(pl)
88
89 <span class="comment">% filter definition</span>
90 plfilter = plist(<span class="string">'type'</span>,<span class="string">'lowpass'</span>,<span class="string">'Win'</span>,specwin(<span class="string">'Kaiser'</span>, 10, 150),<span class="string">'order'</span>,32,<span class="string">'fs'</span>,10,<span class="string">'fc'</span>,1);
91 f = mfir(plfilter)
92
93 <span class="comment">% resampling</span>
94 pl = plist(<span class="string">'fsout'</span>, 1, <span class="string">'filter'</span>,f); <span class="comment">% define parameters list with fsout = 1 Hz and the defined filter</span>
95 y = resample(x, pl); <span class="comment">% resample the input AO (x) to obtain the resampled output AO (y)</span>
96 iplot(x, y) <span class="comment">% plot original and resampled data</span>
97 </pre>
98 </div>
99 <br>
100 <br>
101 <img src="images/resample2.png" alt="Resample" border="0">
102
103
104
105 </p>
106
107 <br>
108 <br>
109 <table class="nav" summary="Navigation aid" border="0" width=
110 "100%" cellpadding="0" cellspacing="0">
111 <tr valign="top">
112 <td align="left" width="20"><a href="upsample.html"><img src=
113 "b_prev.gif" border="0" align="bottom" alt=
114 "Upsampling data"></a>&nbsp;</td>
115
116 <td align="left">Upsampling data</td>
117
118 <td>&nbsp;</td>
119
120 <td align="right">Interpolating data</td>
121
122 <td align="right" width="20"><a href=
123 "interp.html"><img src="b_next.gif" border="0" align=
124 "bottom" alt="Interpolating data"></a></td>
125 </tr>
126 </table><br>
127
128 <p class="copy">&copy;LTP Team</p>
129 </body>
130 </html>