<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<title>GNU Radio 3.3.0 C++ API: gr_iir_filter_ffd Class Reference</title>
<link href="tabs.css" rel="stylesheet" type="text/css"/>
<link href="doxygen.css" rel="stylesheet" type="text/css"/>
</head>
<body>
<!-- Generated by Doxygen 1.6.3 -->
<div class="contents">
<h1>gr_iir_filter_ffd Class Reference<br/>
<small>
[<a class="el" href="group__filter__blk.html">Filters</a>]</small>
</h1><!-- doxytag: class="gr_iir_filter_ffd" --><!-- doxytag: inherits="gr_sync_block" -->
<p>IIR filter with float input, float output and double tapsThis filter uses the Direct Form I implementation, where <code>fftaps</code> contains the feed-forward taps, and <code>fbtaps</code> the feedback ones.
<a href="#_details">More...</a></p>
<p><code>#include <<a class="el" href="gr__iir__filter__ffd_8h_source.html">gr_iir_filter_ffd.h</a>></code></p>
<div class="dynheader">
Inheritance diagram for gr_iir_filter_ffd:</div>
<div class="dynsection">
<div class="center"><img src="classgr__iir__filter__ffd__inherit__graph.png" border="0" usemap="#gr__iir__filter__ffd_inherit__map" alt="Inheritance graph"/></div>
<map name="gr__iir__filter__ffd_inherit__map" id="gr__iir__filter__ffd_inherit__map">
<area shape="rect" id="node2" href="classgr__sync__block.html" title="synchronous 1:1 input to output with historyOverride work to provide the signal processing..." alt="" coords="21,315,128,344"/><area shape="rect" id="node4" href="classgr__block.html" title="The abstract base class for all 'terminal' processing blocks.A signal processing..." alt="" coords="40,237,109,267"/><area shape="rect" id="node6" href="classgr__basic__block.html" title="The abstract base class for all signal processing blocks.Basic blocks are the bare..." alt="" coords="20,160,129,189"/><area shape="rect" id="node8" href="classgr__msg__accepter.html" title="Accepts messages and inserts them into a message queue, then notifies subclass gr_basic_block..." alt="" coords="13,83,136,112"/><area shape="rect" id="node10" href="classgruel_1_1msg__accepter.html" title="Virtual base class that accepts messages." alt="" coords="5,5,144,35"/></map>
<center><span class="legend">[<a target="top" href="graph_legend.html">legend</a>]</span></center></div>
<p><a href="classgr__iir__filter__ffd-members.html">List of all members.</a></p>
<table border="0" cellpadding="0" cellspacing="0">
<tr><td colspan="2"><h2>Public Member Functions</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classgr__iir__filter__ffd.html#ac148a24a79ef56d9bc0bd3c29f8a2c63">~gr_iir_filter_ffd</a> ()</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="classgr__iir__filter__ffd.html#a8b05458a7a2acc934bbec2c51d01ce06">set_taps</a> (const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > &fftaps, const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > &fbtaps) throw (std::invalid_argument)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="classgr__iir__filter__ffd.html#a4770f163efdd77381faebffcac5d4d3f">work</a> (int noutput_items, <a class="el" href="classstd_1_1vector.html">gr_vector_const_void_star</a> &input_items, <a class="el" href="classstd_1_1vector.html">gr_vector_void_star</a> &output_items)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">just like <a class="el" href="classgr__block.html#a137b93d87dc83bbdb6369d33f4ea8197" title="compute output items from input items">gr_block::general_work</a>, only this arranges to call consume_each for you <a href="#a4770f163efdd77381faebffcac5d4d3f"></a><br/></td></tr>
<tr><td colspan="2"><h2>Friends</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="classboost_1_1shared__ptr.html">gr_iir_filter_ffd_sptr</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="classgr__iir__filter__ffd.html#ac08a7d833832d96349a35afcf4ba8060">gr_make_iir_filter_ffd</a> (const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > &fftaps, const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > &fbtaps) throw (std::invalid_argument)</td></tr>
</table>
<hr/><a name="_details"></a><h2>Detailed Description</h2>
<p>IIR filter with float input, float output and double taps</p>
<p>This filter uses the Direct Form I implementation, where <code>fftaps</code> contains the feed-forward taps, and <code>fbtaps</code> the feedback ones. </p>
<p>The input and output satisfy a difference equation of the form</p>
<p class="formulaDsp">
<img class="formulaDsp" alt="\[ y[n] - \sum_{k=1}^{M} a_k y[n-k] = \sum_{k=0}^{N} b_k x[n-k] \]" src="form_0.png"/>
</p>
<p>with the corresponding rational system function</p>
<p class="formulaDsp">
<img class="formulaDsp" alt="\[ H(z) = \frac{\sum_{k=0}^{M} b_k z^{-k}}{1 - \sum_{k=1}^{N} a_k z^{-k}} \]" src="form_1.png"/>
</p>
<p>Note that some texts define the system function with a + in the denominator. If you're using that convention, you'll need to negate the feedback taps. </p>
<hr/><h2>Constructor & Destructor Documentation</h2>
<a class="anchor" id="ac148a24a79ef56d9bc0bd3c29f8a2c63"></a><!-- doxytag: member="gr_iir_filter_ffd::~gr_iir_filter_ffd" ref="ac148a24a79ef56d9bc0bd3c29f8a2c63" args="()" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">gr_iir_filter_ffd::~gr_iir_filter_ffd </td>
<td>(</td>
<td class="paramname"></td>
<td> ) </td>
<td></td>
</tr>
</table>
</div>
<div class="memdoc">
</div>
</div>
<hr/><h2>Member Function Documentation</h2>
<a class="anchor" id="a8b05458a7a2acc934bbec2c51d01ce06"></a><!-- doxytag: member="gr_iir_filter_ffd::set_taps" ref="a8b05458a7a2acc934bbec2c51d01ce06" args="(const std::vector< double > &fftaps, const std::vector< double > &fbtaps)" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void gr_iir_filter_ffd::set_taps </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > & </td>
<td class="paramname"> <em>fftaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > & </td>
<td class="paramname"> <em>fbtaps</em></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td> throw (std::invalid_argument)</td>
</tr>
</table>
</div>
<div class="memdoc">
</div>
</div>
<a class="anchor" id="a4770f163efdd77381faebffcac5d4d3f"></a><!-- doxytag: member="gr_iir_filter_ffd::work" ref="a4770f163efdd77381faebffcac5d4d3f" args="(int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">int gr_iir_filter_ffd::work </td>
<td>(</td>
<td class="paramtype">int </td>
<td class="paramname"> <em>noutput_items</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="classstd_1_1vector.html">gr_vector_const_void_star</a> & </td>
<td class="paramname"> <em>input_items</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="classstd_1_1vector.html">gr_vector_void_star</a> & </td>
<td class="paramname"> <em>output_items</em></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td><code> [virtual]</code></td>
</tr>
</table>
</div>
<div class="memdoc">
<p>just like <a class="el" href="classgr__block.html#a137b93d87dc83bbdb6369d33f4ea8197" title="compute output items from input items">gr_block::general_work</a>, only this arranges to call consume_each for you </p>
<p>The user must override work to define the signal processing code </p>
<p>Implements <a class="el" href="classgr__sync__block.html#a0c523f4285a6eb690f677ee6295ab117">gr_sync_block</a>.</p>
</div>
</div>
<hr/><h2>Friends And Related Function Documentation</h2>
<a class="anchor" id="ac08a7d833832d96349a35afcf4ba8060"></a><!-- doxytag: member="gr_iir_filter_ffd::gr_make_iir_filter_ffd" ref="ac08a7d833832d96349a35afcf4ba8060" args="(const std::vector< double > &fftaps, const std::vector< double > &fbtaps)" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname"><a class="el" href="classboost_1_1shared__ptr.html">gr_iir_filter_ffd_sptr</a> gr_make_iir_filter_ffd </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > & </td>
<td class="paramname"> <em>fftaps</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const <a class="el" href="classstd_1_1vector.html">std::vector</a>< double > & </td>
<td class="paramname"> <em>fbtaps</em></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td> throw (std::invalid_argument)<code> [friend]</code></td>
</tr>
</table>
</div>
<div class="memdoc">
</div>
</div>
<hr/>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="gr__iir__filter__ffd_8h_source.html">gr_iir_filter_ffd.h</a></li>
</ul>
</div>
<hr class="footer"/><address style="text-align: right;"><small>Generated on Wed Dec 29 19:52:47 2010 for GNU Radio 3.3.0 C++ API by
<a href="http://www.doxygen.org/index.html">
<img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.6.3 </small></address>
</body>
</html>
