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author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Mon, 05 Dec 2011 18:04:34 +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>Constructor examples of the MFIR class (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= "constructor_examples_smodel.html"><img src="b_prev.gif" border="0" align= "bottom" alt="Constructor examples of the SMODEL class"></a> <a href= "constructor_examples_miir.html"><img src="b_next.gif" border="0" align= "bottom" alt="Constructor examples of the MIIR class"></a></td> </tr> </table> <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Constructor examples of the MFIR class</h1> <hr> <p> <!-- -------------------------------------------------- --> <!-- --------------- BEGIN CONTENT FILE --------------- --> <!-- -------------------------------------------------- --> <!-- --------------- Link box: begin --------------- --> <table border="0" summary="Simple list" class="simplelist_nottable_last"> <tr> <td> <a href="constructor_examples_mfir.html#copy">Copy an MFIR object</a> </td> </tr> <tr> <td> <a href="constructor_examples_mfir.html#xml_file">Construct a MFIR object by loading the object from a file</a> </td> </tr> <tr> <td> <a href="constructor_examples_mfir.html#ao">Construct a MFIR object from an Analysis Object <tt>(AO)</tt></a> </td> </tr> <tr> <td> <a href="constructor_examples_rational.html#pzmodel">Construct a MFIR object from a pole/zero model <tt>(PZMODEL)</tt></a> </td> </tr> <tr> <td> <a href="constructor_examples_mfir.html#std_type">Construct a MFIR object from a standard type</a> </td> </tr> <tr> <td> <a href="constructor_examples_mfir.html#exist_model">Construct a MFIR object from an existing filter model</a> </td> </tr> <tr> <td> <a href="constructor_examples_mfir.html#equation">Construct a MFIR object from a difference equation</a> </td> </tr> </table> <!-- --------------- Link box: end --------------- --> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="copy"></a>Copy an FIR filter object</h2> <p>The following example creates a copy of an FIR filter object (blue command).</p> <div class="fragment"><pre class="programlisting"> >> fir1 = mfir(plist(<span class="string">'type'</span>, <span class="string">'lowpass'</span>)); <span class="blue">>> fir2 = mfir(fir2)</span> ------ mfir/1 ------- gd: 32.5 version: $Id: mfir.m,v 1.84 2009/02/24 17:02:44 ingo Exp ntaps: 65 fs: 1 infile: a: [0.0007 0.0004 -6.9093e-19 -0.0006 -0.0012 -0.0014 -0.0011 1.4147e-18 ... histout: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ... iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: mfir.hist [1x1 history] name: lowpass --------------------- </pre></div> <br></br> <p>REMARK: The following command copies only the handle of an object and doesn't create a copy of the object (as above). This means that everything that happens to the copy or original happens to the other object.</p> <div class="fragment"><pre class="programlisting"> >> fir1 = mfir() ------ mfir/1 ------- gd: [] version: $Id: mfir.m,v 1.84 2009/02/24 17:02:44 ingo Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: mfir.hist [1x1 history] name: none --------------------- >> fir2 = fir1; >> fir2.setName(<span class="string">'my new name'</span>) ------ mfir/1 ------- gd: [] version: $Id: mfir.m,v 1.84 2009/02/24 17:02:44 ingo Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: mfir.hist [1x1 history] name: <span class="string">my new name</span> --------------------- </pre></div> <br></br> <p>If we display fir1 again then we see that the property 'name' was changed although we only have changed fir2.</p> <div class="fragment"><pre class="programlisting"> >> fir1 ------ mfir/1 ------- gd: [] version: $Id: mfir.m,v 1.84 2009/02/24 17:02:44 ingo Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: mfir.hist [1x1 history] name: <span class="string">my new name</span> ---------------------</pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="xml_file"></a>Construct a MFIR object by loading the object from a file</h2> <p>The following example creates a new mfir object by loading the mfir object from disk.</p> <div class="fragment"><pre class="programlisting"> fir = mfir(<span class="string">'fir.mat'</span>) fir = mfir(<span class="string">'fir.xml'</span>) </pre></div> <p>or in a <tt>PLIST</tt></p> <div class="fragment"><pre class="programlisting"> pl = plist(<span class="string">'filename'</span>, <span class="string">'fir.xml'</span>); fir = mfir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="ao"></a>Construct a MFIR object from an Analysis Object</h2> <p> An FIR filter object can be generated based on the magnitude of the input AO/fsdata object. In the following example an AO/fsdata object is first generated and then passed to the mfir constructor to obtain the equivalent FIR filter.</p> <div class="fragment"><pre class="programlisting"> a1 = ao(plist(<span class="string">'fsfcn'</span>, <span class="string">'1./(50+f)'</span>, <span class="string">'fs'</span>, 1000, <span class="string">'f'</span>, linspace(0, 500, 1000))); fir = mfir(a1); iplot(a1, resp(fir)); </pre></div> <p>or in a PLIST with the relevant parameters:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'method'</p> </td> <td> <p>the design method:<br></br> 'frequency-sampling' - uses fir2()<br></br> 'least-squares' - uses firls()<br></br> 'Parks-McClellan' - uses firpm()<br></br> [default: 'frequency-sampling']</p> </td> </tr> <tr valign="top"> <td> <p>'win'</p> </td> <td> <p>Window function for frequency-sampling method [default: 'Hanning']</p> </td> </tr> <tr valign="top"> <td> <p>'N'</p> </td> <td> <p>Filter order [default: 512]</p> </td> </tr> </tbody> </table> </p> <p>The following example creates a mfir object from an analysis object.</p> <div class="fragment"><pre class="programlisting"> a1 = ao(plist(<span class="string">'fsfcn'</span>, <span class="string">'1./(50+f)'</span>, <span class="string">'fs'</span>, 1000, <span class="string">'f'</span>, linspace(0, 500, 1000))); pl = plist(<span class="string">'ao'</span>, a1); fir = mfir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="pzmodel"></a>Construct an FIR filter object from a pole/zero model</h2> <p>The following example creates a new FIR filter object from a pole/zero model.</p> <div class="fragment"><pre class="programlisting"> >> pzm = pzmodel(1, {1 2 3}, {4 5}, <span class="string">'my pzmodel'</span>) ---- pzmodel 1 ---- name: my pzmodel gain: 1 delay: 0 iunits: [] ounits: [] pole 001: (f=1 Hz,Q=NaN) pole 002: (f=2 Hz,Q=NaN) pole 003: (f=3 Hz,Q=NaN) zero 001: (f=4 Hz,Q=NaN) zero 002: (f=5 Hz,Q=NaN) ------------------- >> fir = mfir(pzm) <span class="comment">% Use the default sample rate fs=8 * frequency of the highest pole or zero in the model</span> >> fir = mfir(pzm, plist(<span class="string">'fs'</span>, 100)) ------ mfir/1 ------- gd: 257 version: $Id: mfir.m,v 1.84 2009/02/24 17:02:44 ingo Exp ntaps: 513 fs: 100 infile: a: [-0 -3.013e-10 -1.2486e-09 -2.8506e-09 -5.1166e-09 -7.8604e-09 -1.1133e-08 ... histout: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ... iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: mfir.hist [1x1 history] name: my pzmodel --------------------- </pre></div> <p>or in a PLIST with the relevant parameters:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'pzmodel'</p> </td> <td> <p>A pzmodel object to construct the filter from [default: empty pzmodel]</p> </td> </tr> <tr valign="top"> <td> <p>'fs'</p> </td> <td> <p>Sample rate [default: 8 * frequency of the highest pole or zero in the model]</p> </td> </tr> </tbody> </table> </p> <div class="fragment"><pre class="programlisting"> >> pzm = pzmodel(1, {1 2 3}, {4 5}, <span class="string">'my pzmodel'</span>) >> pl = plist(<span class="string">'pzmodel'</span>, pzm, <span class="string">'fs'</span>, 100) >> fir = mfir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr></hr> <h2 class="title"><a name="std_type"></a>Construct a MFIR object from a standard type</h2> <p>Construct an FIR filter object from a standard type: 'lowpass', 'highpass', 'bandpass' or 'bandreject'</p> <p>The relevant parameters are:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'type'</p> </td> <td> <p>one of the types: 'highpass', 'lowpass', 'bandpass', 'bandreject'<br></br> [default 'lowpass']</p> </td> </tr> </tbody> </table> </p> <p>You can also specify optional parameters:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'gain'</p> </td> <td> <p>The gain of the filter [default: 1]</p> </td> </tr> <tr valign="top"> <td> <p>'fc'</p> </td> <td> <p>The roll-off frequency [default: 0.1 Hz]</p> </td> </tr> <tr valign="top"> <td> <p>'fs'</p> </td> <td> <p>The sampling frequency to design for [default: 1 Hz]</p> </td> </tr> <tr valign="top"> <td> <p>'order'</p> </td> <td> <p>The filter order [default: 64]</p> </td> </tr> <tr valign="top"> <td> <p>'win'</p> </td> <td> <p>Specify window function used in filter design [default: 'Hamming']</p> </td> </tr> <tr valign="top"> <td> <p>'iunits'</p> </td> <td> <p>the input unit of the filter</p> </td> </tr> <tr valign="top"> <td> <p>'ounits'</p> </td> <td> <p>the output unit of the filter</p> </td> </tr> </tbody> </table> </p> <p>The following example creates an order 64 highpass filter with high frequency gain 2. Filter is designed for 1 Hz sampled data and has a cut-off frequency of 0.2 Hz.</p> <div class="fragment"><pre class="programlisting"> pl = plist(<span class="string">'type'</span>, <span class="string">'highpass'</span>, ... <span class="string">'order'</span>, 64, ... <span class="string">'gain'</span>, 2.0, ... <span class="string">'fs'</span>, 1, ... <span class="string">'fc'</span>, 0.2); f = mfir(pl) </pre></div> <p>Furthermore it is possible to specify a spectral window.</p> <div class="fragment"><pre class="programlisting"> win = specwin(<span class="string">'Kaiser'</span>, 11, 150); pl = plist(<span class="string">'type'</span>, <span class="string">'lowpass'</span>, ... <span class="string">'Win'</span>, win, ... <span class="string">'fs'</span>, 100, ... <span class="string">'fc'</span>, 20, ... <span class="string">'order'</span>, 10); f = mfir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="exist_model"></a>Construct a MFIR object from an existing filter</h2> <p>The mfir constructor also accepts as an input existing filters stored in different formats:</p> <p>LISO files</p> <div class="fragment"><pre class="programlisting"> f = mfir(<span class="string">'foo_fir.fil'</span>) </pre></div> <p>XML files</p> <div class="fragment"><pre class="programlisting"> f = mfir(<span class="string">'foo_fir.xml'</span>) </pre></div> <p>MAT files</p> <div class="fragment"><pre class="programlisting"> f = mfir(<span class="string">'foo_fir.mat'</span>) </pre></div> <p>From an LTPDA repository</p> <p>The relevant parameters for retrieving a FIR filter from a LTPDA repository are:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'hostname'</p> </td> <td> <p>the repository hostname. [default: 'localhost']</p> </td> </tr> <tr valign="top"> <td> <p>'database'</p> </td> <td> <p>The database name [default: 'ltpda']</p> </td> </tr> <tr valign="top"> <td> <p>'id'</p> </td> <td> <p>A vector of object IDs. [default: []]</p> </td> </tr> <tr valign="top"> <td> <p>'cid'</p> </td> <td> <p>Retrieve all rational objects from a particular collection</p> </td> </tr> <tr valign="top"> <td> <p>'binary'</p> </td> <td> <p>Set to 'yes' to retrieve from stored binary representation (not always available). [default: yes]</p> </td> </tr> </tbody> </table> </p> <div class="fragment"><pre class="programlisting"> f = mfir(plist(<span class="string">'hostname'</span>, <span class="string">'localhost'</span>, <span class="string">'database'</span>, <span class="string">'ltpda'</span>, <span class="string">'ID'</span>, [])) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="equation"></a>Construct a MFIR object from a difference equation</h2> <p>The filter can be defined in terms of two vectors specifying the coefficients of the filter and the sampling frequency. The following example creates a FIR filter with sampling frequency 1 Hz and the following recursive equation:</p> <div align="center"> <IMG src="images/sigproc_10.png" width="202" height="28" align="middle" border="0"> </div> <div class="fragment"><pre class="programlisting"> a = [-0.8 10]; fs = 1; f = mfir(a,fs) </pre></div> <p>or in a <tt>PLIST</tt></p> <p>The relevant parameters are:</p> <p> <table cellspacing="0" border="0" cellpadding="2" class="simplelist_nottable_last" width="80%"> <colgroup> <col width="25%"/> <col width="75%"/> </colgroup> <thead> <tr valign="top"> <th class="subcategorylist">Key</th> <th class="subcategorylist">Description</th> </tr> </thead> <tbody> <tr valign="top"> <td> <p>'a'</p> </td> <td> <p>vector of A coefficients. (see note ** below) [default: empty]</p> </td> </tr> <tr valign="top"> <td> <p>'fs'</p> </td> <td> <p>sampling frequency of the filter [default: empty]</p> </td> </tr> <tr valign="top"> <td> <p>'name'</p> </td> <td> <p>name of filter [default: 'None']</p> </td> </tr> </tbody> </table> </p> <div class="fragment"><pre class="programlisting"> a = [-0.8 10]; fs = 1; pl = plist(<span class="string">'a'</span>, a, <span class="string">'fs'</span>, fs); fir = mfir(pl) </pre></div> <br></br> <div class="fragment"> NOTES:<br></br> ** The convention used here for naming the filter coefficients is the opposite to MATLAB's convention. The recursion formula for this convention is<br></br> y(n) = a(1)*x(n) + a(2)*x(n-1) + ... + a(na+1)*x(n-na). </div> <!-- ------------------------------------------------ --> <!-- --------------- END CONTENT FILE --------------- --> <!-- ------------------------------------------------ --> </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="constructor_examples_smodel.html"><img src= "b_prev.gif" border="0" align="bottom" alt= "Constructor examples of the SMODEL class"></a> </td> <td align="left">Constructor examples of the SMODEL class</td> <td> </td> <td align="right">Constructor examples of the MIIR class</td> <td align="right" width="20"><a href= "constructor_examples_miir.html"><img src="b_next.gif" border="0" align= "bottom" alt="Constructor examples of the MIIR class"></a></td> </tr> </table><br> <p class="copy">©LTP Team</p> </body> </html>