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author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Mon, 05 Dec 2011 16:20:06 +0100 |
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd"> <html lang="en"> <head> <meta name="generator" content= "HTML Tidy for Mac OS X (vers 1st December 2004), see www.w3.org"> <meta http-equiv="Content-Type" content= "text/html; charset=us-ascii"> <title>IFO/Temperature Example - Introduction (LTPDA Toolbox)</title> <link rel="stylesheet" href="docstyle.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.52.2"> <meta name="description" content= "Presents an overview of the features, system requirements, and starting the toolbox."> </head> <body> <a name="top_of_page" id="top_of_page"></a> <p style="font-size:1px;"> </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> <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> <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> </td> <td align="left">Writing LTPDA scripts</td> <td> </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">©LTP Team</p> </body> </html>