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| author | Daniele Nicolodi <nicolodi@science.unitn.it> |
|---|---|
| date | Wed, 07 Dec 2011 17:29:47 +0100 |
| parents | f0afece42f48 |
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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 MIIR 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_mfir.html"><img src="b_prev.gif" border="0" align= "bottom" alt="Constructor examples of the MFIR class"></a> <a href= "constructor_examples_pzmodel.html"><img src="b_next.gif" border="0" align= "bottom" alt="Constructor examples of the PZMODEL class"></a></td> </tr> </table> <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Constructor examples of the MIIR 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_miir.html#empty">Copy a MIIR object</a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#xml_file">Construct a MIIR object by loading the object from a file</a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#parfrac">Construct a MIIR object from a parfrac object <tt>(PARFRAC)</tt></a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#pzmodel">Construct a MIIR object from a pole/zero model <tt>(PZMODEL)</tt></a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#std_type">Construct a MIIR object from a standard type</a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#exist_model">Construct a MIIR object from an existing model</a> </td> </tr> <tr> <td> <a href="constructor_examples_miir.html#equation">Construct a MIIR object from a difference equation</a> </td> </tr> </table> <!-- --------------- Link box: end --------------- --> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="copy"></a>Copy an IIR filter object</h2> <p>The following example creates a copy of an IIR filter object (blue command).</p> <div class="fragment"><pre class="programlisting"> >> iir1 = miir(plist(<span class="string">'type'</span>, <span class="string">'lowpass'</span>)); <span class="blue">>> iir2 = miir(iir2)</span> ------ miir/1 ------- b: [1 -0.509525449494429] histin: 0 version: $Id: miir.m,v 1.98 2009/02/20 15:59:48 nicola Exp ntaps: 2 fs: 1 infile: a: [0.245237275252786 0.245237275252786] histout: 0 iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: miir.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"> >> iir1 = miir() ------ miir/1 ------- b: [] histin: [] version: $Id: miir.m,v 1.98 2009/02/20 15:59:48 nicola Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: miir.hist [1x1 history] name: none --------------------- >> iir2 = iir1; >> iir2.setName(<span class="string">'my new name'</span>) ------ miir/1 ------- b: [] histin: [] version: $Id: miir.m,v 1.98 2009/02/20 15:59:48 nicola Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: miir.hist [1x1 history] name: <span class="string">my new name</span> --------------------- </pre></div> <br></br> <p>If we display iir1 again then we see that the property 'name' was changed although we only have changed iir2.</p> <div class="fragment"><pre class="programlisting"> >> iir1 ------ miir/1 ------- b: [] histin: [] version: $Id: miir.m,v 1.98 2009/02/20 15:59:48 nicola Exp ntaps: 0 fs: [] infile: a: [] histout: [] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: miir.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 MIIR object by loading the object from a file</h2> <p>The following example creates a new miir object by loading the miir object from disk.</p> <div class="fragment"><pre class="programlisting"> f = miir(<span class="string">'f.mat'</span>) f = miir(<span class="string">'f.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">'iir.xml'</span>); iir = miir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="parfrac"></a>Construct a MIIR object from a parfrac object</h2> <p> An IIR filter object can be generated based on a parfrac object. The next example shows how you can convert a parfrac object into a iir filter object.</p> <div class="fragment"><pre class="programlisting"> pf = parfrac([1 2+1i 2-1i], [6 1+3i 1-3i], 3); iir = miir(pf) </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>'parfrac'</p> </td> <td> <p>a parfrac object to construct the filters from [default: empty parfrac]</p> </td> </tr> <tr valign="top"> <td> <p>'fs'</p> </td> <td> <p>sample rate for the filter(s) [default: 8 * upper frequency of the parfrac object]</p> </td> </tr> </tbody> </table> </p> <p>The following example creates a IIR filter object from an parfrac object.</p> <div class="fragment"><pre class="programlisting"> pf = parfrac([1 2+1i 2-1i], [6 1+3i 1-3i], 3); pl = plist(<span class="string">'parfrac'</span>, pf, <span class="string">'fs'</span>, 100); </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="pzmodel"></a>Construct an IIR filter object from a pole/zero model</h2> <p>The following example creates a new IIR 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) ------------------- >> iir = miir(pzm) <span class="comment">% Use the default sample rate fs=8 * frequency of the highest pole or zero in the model</span> >> iir = miir(pzm, plist(<span class="string">'fs'</span>, 100)) ------ miir/1 ------- b: [1 -0.6485 -1.9619 1.3364 0.9644 -0.6854] histin: [0 0 0 0 0] version: $Id: miir.m,v 1.98 2009/02/20 15:59:48 nicola Exp ntaps: 6 fs: 100 infile: a: [0.0102 0.0152 -0.0097 -0.0186 0.0019 0.0057] histout: [0 0 0 0 0] iunits: [] [1x1 unit] ounits: [] [1x1 unit] hist: miir.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) >> iir = miir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr></hr> <h2 class="title"><a name="std_type"></a>Construct a MIIR object from a standard type</h2> <p>Construct an IIR 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 = miir(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 = miir(pl) </pre></div> <!-- --------------- NEXT EXAMPLE --------------- --> <hr> <h2 class="title"><a name="exist_model"></a>Construct a MIIR object from an existing model</h2> <p>The miir constructor also accepts as an input existing models in different formats:</p> <p>LISO files</p> <div class="fragment"><pre class="programlisting"> f = miir(<span class="string">'foo_iir.fil'</span>) </pre></div> <p>XML files</p> <div class="fragment"><pre class="programlisting"> f = miir(<span class="string">'foo_iir.xml'</span>) </pre></div> <p>MAT files</p> <div class="fragment"><pre class="programlisting"> f = miir(<span class="string">'foo_iir.mat'</span>) </pre></div> <p>From repository</p> <p>The relevant parameters for retrieving a IIR 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 = miir(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 MIIR object from a difference equation</h2> <p>Alternatively, 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 IIR filter with sampling frequency 1 Hz and the following recursive equation:</p> <div align="center"> <IMG src="images/sigproc_9.png" width="299" height="28" align="middle" border="0"> </div> <div class="fragment"><pre class="programlisting"> a = [0.5 -0.01]; b = [1 0.1] fs = 1; f = miir(a,b,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>'b'</p> </td> <td> <p>vector of B 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 = [0.5 -0.01]; b = [1 0.1] fs = 1; name = <span class="string">'my IIR'</span>; pl = plist(<span class="string">'a'</span>, a, <span class="string">'fs'</span>, fs, <span class="string">'name'</span>, name); iir = miir(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> b(1)*y(n) = a(1)*x(n) + a(2)*x(n-1) + ... + a(na+1)*x(n-na) - b(2)*y(n-1) - ... - b(nb+1)*y(n-nb) </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_mfir.html"><img src= "b_prev.gif" border="0" align="bottom" alt= "Constructor examples of the MFIR class"></a> </td> <td align="left">Constructor examples of the MFIR class</td> <td> </td> <td align="right">Constructor examples of the PZMODEL class</td> <td align="right" width="20"><a href= "constructor_examples_pzmodel.html"><img src="b_next.gif" border="0" align= "bottom" alt="Constructor examples of the PZMODEL class"></a></td> </tr> </table><br> <p class="copy">©LTP Team</p> </body> </html>