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  <title>Constructor examples of the MFIR class (LTPDA Toolbox)</title>
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  <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Constructor examples of the MFIR class</h1>
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<!-- --------------- 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>
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<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>


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<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>

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<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>


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<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>


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<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>

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<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>


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      <td align="left" width="20"><a href="constructor_examples_smodel.html"><img src=
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      <td align="left">Constructor examples of the SMODEL class</td>

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      <td align="right">Constructor examples of the MIIR class</td>

      <td align="right" width="20"><a href=
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  <p class="copy">&copy;LTP Team</p>
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author	Daniele Nicolodi <nicolodi@science.unitn.it>
date	Mon, 05 Dec 2011 16:20:06 +0100
parents	f0afece42f48
children