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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Mon, 05 Dec 2011 16:20:06 +0100
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  <title>IFO/Temperature Example - Introduction (LTPDA Toolbox)</title>
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  <p style="font-size:1px;">&nbsp;</p>

  <table class="nav" summary="Navigation aid" border="0" width=
  "100%" cellpadding="0" cellspacing="0">
    <tr>
      <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td>

      <td valign="baseline" align="right"><a href=
      "ltpda_training_topic_1_7.html"><img src="b_prev.gif" border="0" align=
      "bottom" alt="Writing LTPDA scripts"></a>&nbsp;&nbsp;&nbsp;<a href=
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      "bottom" alt="Topic 2 - Pre-processing of data"></a></td>
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  <h1 class="title"><a name="f3-12899" id="f3-12899"></a>IFO/Temperature Example - Introduction</h1>
  <hr>
  
  <p>
	<p>
  In your data pack, you will find two raw data series. These are real measurements
  of a system that looks like
</p>
<img src="images/ltpda_training_1/ifo_temp_model.png" alt="Model of the IFO/temperature system" width="600px" border="1">
<p>
  We have measured the two signals, <tt>T(t)</tt> and <tt>X(t)</tt>. The displacement input to the
  interferometer, <tt>dx(t)</tt>, is inaccessible to us, and is in fact the data we want to
  recover from the data analysis.
</p>
<br>
<br>
<h2>Reading and calibrating the interferometer data</h2>
<br>
<p>
  The interferometer data, X(t), is saved in the file <tt>ifo_temp_example/ifo_training.dat</tt>. This is a
  two-column ASCII file with the first column giving the time-stamps of the data and the second column the
  measured IFO output in radians.
</p>
<p>
  To read in the data, we can use the AO constuctor, with the set of parameters "From ASCII File". The key
  parameters are:
  <table cellspacing="0" class="body" cellpadding="2" border="0" width="80%">
    <colgroup>
      <col width="15%"/>
      <col width="35%"/>
      <col width="50%"/>
    </colgroup>
    <thead>
      <tr valign="top">
        <th class="categorylist">Key</th>
        <th class="categorylist">Value</th>
        <th class="categorylist">Description</th>
      </tr>
    </thead>
    <tbody>
      <!-- Key 'filename' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>FILENAME</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'ifo_temp_example/ifo_training.dat'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>The name of the file to read the data from.</p>
        </td>
      </tr>
      <!-- Key 'type' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>TYPE</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'tsdata'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Interpret the data in the file as time-series data.</p>
        </td>
      </tr>
      <!-- Key 'columns' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>COLUMNS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>[1 2]</p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Load the data x-y pairs from columns 1 (as x) and 2 (as y).</p>
        </td>
      </tr>
      <!-- Key 'xunits' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>XUNITS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'s'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set the units of the x-data to seconds (s).</p>
        </td>
      </tr>
      <!-- Key 'yunits' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>YUNITS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'rad'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set the units of the y-data to radians (rad).</p>
        </td>
      </tr>
      <!-- Key 'robust' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>ROBUST</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'no'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Use fast data reading for this simple file format.</p>
        </td>
      </tr>
      <!-- Key 'description' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>DESCRIPTION</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'Interferometer data'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set some text to the 'description' field of the AO.</p>
        </td>
      </tr>
    </tbody>
  </table>
</p>
<p>
  Once we've loaded the data we can calibrate it to displacement using the following
  equation:
</p>
<img src="images/ltpda_training_1/topic1/ifo_cal_factor.png" alt="Convert rad to m" width="200px" border="1">
<p>
  
  where lambda=1064nm.
</p>
<p>
  To do the calibration, you can use the method <tt>ao/scale</tt>,
  specifying the <tt>factor</tt> and the <tt>yunits</tt> of the factor
  itself. Then save the resulting time-series to disk in <tt>ifo_temp_example/ifo_disp.xml</tt>.
</p>
<p>
  A finished pipeline might look something like:
</p>
<img src="images/ltpda_training_1/topic1/ifo_cal_pipeline.png" alt="IFO calibration pipeline"  border="1">


<br>
<br>
<h2>Reading and calibrating the temperature data</h2>
<br>
<p>
  The temperature data, T(t), is saved in the file <tt>ifo_temp_example/temp_training.dat</tt>. Again, this is a
  two-column ASCII file; the first column contains the time-stamps of the data, the second column
  contains the temperature values in degrees Celsius.
</p>
<p>
  To read in the data, we can use the AO constuctor, with the set of parameters "From ASCII File". The key
  parameters are:
  <table cellspacing="0" class="body" cellpadding="2" border="0" width="80%">
    <colgroup>
      <col width="15%"/>
      <col width="35%"/>
      <col width="50%"/>
    </colgroup>
    <thead>
      <tr valign="top">
        <th class="categorylist">Key</th>
        <th class="categorylist">Value</th>
        <th class="categorylist">Description</th>
      </tr>
    </thead>
    <tbody>
      <!-- Key 'filename' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>FILENAME</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'ifo_temp_example/temp_training.dat'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>The name of the file to read the data from.</p>
        </td>
      </tr>
      <!-- Key 'type' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>TYPE</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'tsdata'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Interpret the data in the file as time-series data.</p>
        </td>
      </tr>
      <!-- Key 'columns' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>COLUMNS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>[1 2]</p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Load the data x-y pairs from columns 1 (as x) and 2 (as y).</p>
        </td>
      </tr>
      <!-- Key 'xunits' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>XUNITS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'s'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set the units of the x-data to seconds (s).</p>
        </td>
      </tr>
      <!-- Key 'yunits' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>YUNITS</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'degC'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set the units of the y-data to degrees Celsius.</p>
        </td>
      </tr>
      <!-- Key 'robust' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>ROBUST</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'no'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Use fast data reading for this simple file format.</p>
        </td>
      </tr>
      <!-- Key 'description' -->
      <tr valign="top">
        <td bgcolor="#f3f4f5">
          <p><tt>DESCRIPTION</tt></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p><span class="string">'Temperature data'</span></p>
        </td>
        <td bgcolor="#f3f4f5">
          <p>Set some text to the 'description' field of the AO.</p>
        </td>
      </tr>
    </tbody>
  </table>
</p>
<p>
  Having loaded the temperature data, we can proceed to calibrate it to Kelvin by adding
  273.15 to the data and then change the y-units. You can do this using the two AO methods:
  <br>
  <ul>
    <li><tt>offset</tt> -- to add the offset</li>
    <li><tt>setYunits</tt> -- to change the y-units of the data</li>
  </ul>
</p>
<p>
  The final step is to save this calibrated temperature data to disk as an AO XML file called
  <tt>ifo_temp_example/temp_kelvin.xml</tt>, ready for input to the next topic.
</p>
<p>
  A complete pipeline for this step might look like:
</p>
<img src="images/ltpda_training_1/topic1/temp_cal_pipeline.png" alt="Calibration pipeline for temperature data" border="1">
<p>
  <table cellspacing="0" class="note" summary="Note" cellpadding="5" border="1">
    <tr width="90%">
      <td>
        To plot the data with hours on the x-axis instead of seconds, use the <tt>iplot</tt> parameter <tt>XUNITS</tt>.
        For example:
        <div class="fragment"><pre>
            iplot(a, plist(<span class="string">'XUNITS'</span>, <span class="string">'h'</span>))
        </pre></div>
      </td>
    </tr>
  </table>
</p>

  </p>

  <br>
  <br>
  <table class="nav" summary="Navigation aid" border="0" width=
  "100%" cellpadding="0" cellspacing="0">
    <tr valign="top">
      <td align="left" width="20"><a href="ltpda_training_topic_1_7.html"><img src=
      "b_prev.gif" border="0" align="bottom" alt=
      "Writing LTPDA scripts"></a>&nbsp;</td>

      <td align="left">Writing LTPDA scripts</td>

      <td>&nbsp;</td>

      <td align="right">Topic 2 - Pre-processing of data</td>

      <td align="right" width="20"><a href=
      "ltpda_training_topic_2.html"><img src="b_next.gif" border="0" align=
      "bottom" alt="Topic 2 - Pre-processing of data"></a></td>
    </tr>
  </table><br>

  <p class="copy">&copy;LTP Team</p>
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