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<a href="digital__lms__dd__equalizer__cc_8h.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/* -*- c++ -*- */</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment">/*</span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment"> * Copyright 2011 Free Software Foundation, Inc.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment"> * This file is part of GNU Radio</span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"> * GNU Radio is free software; you can redistribute it and/or modify</span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment"> * it under the terms of the GNU General Public License as published by</span></div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment"> * the Free Software Foundation; either version 3, or (at your option)</span></div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment"> * any later version.</span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment"> * GNU Radio is distributed in the hope that it will be useful,</span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</span></div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span></div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment"> * GNU General Public License for more details.</span></div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"> * </span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment"> * You should have received a copy of the GNU General Public License</span></div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment"> * along with GNU Radio; see the file COPYING. If not, write to</span></div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="comment"> * the Free Software Foundation, Inc., 51 Franklin Street,</span></div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment"> * Boston, MA 02110-1301, USA.</span></div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span> </div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="preprocessor">#ifndef INCLUDED_DIGITAL_LMS_DD_EQUALIZER_CC_H</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="preprocessor"></span><span class="preprocessor">#define INCLUDED_DIGITAL_LMS_DD_EQUALIZER_CC_H</span></div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="preprocessor">#include <<a class="code" href="digital__api_8h.html">digital_api.h</a>></span></div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="preprocessor">#include <<a class="code" href="gr__adaptive__fir__ccc_8h.html">gr_adaptive_fir_ccc.h</a>></span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="preprocessor">#include <<a class="code" href="digital__constellation_8h.html">digital_constellation.h</a>></span></div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> </div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="keyword">class </span><a class="code" href="classdigital__lms__dd__equalizer__cc.html" title="Least-Mean-Square Decision Directed Equalizer (complex in/out)This block implements an LMS-based deci...">digital_lms_dd_equalizer_cc</a>;</div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="keyword">typedef</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">boost::shared_ptr<digital_lms_dd_equalizer_cc></a> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">digital_lms_dd_equalizer_cc_sptr</a>;</div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span> </div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <a class="code" href="digital__api_8h.html#ae14969f36ec69051c4b2f13a0db7e9ba">DIGITAL_API</a> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">digital_lms_dd_equalizer_cc_sptr</a> <a class="code" href="digital__lms__dd__equalizer__cc_8h.html#a874b0a76a8fb89614d1ffb8086b9f74e">digital_make_lms_dd_equalizer_cc</a> (<span class="keywordtype">int</span> num_taps,</div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span>  <span class="keywordtype">float</span> mu, <span class="keywordtype">int</span> sps,</div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span>  <a class="code" href="classboost_1_1shared__ptr.html">digital_constellation_sptr</a> cnst);</div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span>  <span class="comment"></span></div>
<div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment">/*!</span></div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment"> * \brief Least-Mean-Square Decision Directed Equalizer (complex in/out)</span></div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment"> * \ingroup eq_blk</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment"> * \ingroup digital</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment"> * This block implements an LMS-based decision-directed equalizer.</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment"> * It uses a set of weights, w, to correlate against the inputs, u,</span></div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment"> * and a decisions is then made from this output. The error</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment"> * in the decision is used to update teh weight vector.</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="comment"> * y[n] = conj(w[n]) u[n]</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="comment"> * d[n] = decision(y[n])</span></div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="comment"> * e[n] = d[n] - y[n]</span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="comment"> * w[n+1] = w[n] + mu u[n] conj(e[n])</span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="comment"> * Where mu is a gain value (between 0 and 1 and usualy small,</span></div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="comment"> * around 0.001 - 0.01.</span></div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment"> * This block uses the digital_constellation object for making</span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment"> * the decision from y[n]. Create the constellation object for</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment"> * whatever constellation is to be used and pass in the object.</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment"> * In Python, you can use something like:</span></div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment"> * self.constellation = digital.constellation_qpsk()</span></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment"> * To create a QPSK constellation (see the digital_constellation</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment"> * block for more details as to what constellations are available</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment"> * or how to create your own). You then pass the object to this</span></div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment"> * block as an sptr, or using "self.constellation.base()".</span></div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment"> * The theory for this algorithm can be found in Chapter 9 of:</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment"> * S. Haykin, Adaptive Filter Theory, Upper Saddle River, NJ:</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment"> * Prentice Hall, 1996.</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"><a class="code" href="classdigital__lms__dd__equalizer__cc.html"> 70</a></span> <span class="keyword">class </span><a class="code" href="digital__api_8h.html#ae14969f36ec69051c4b2f13a0db7e9ba">DIGITAL_API</a> <a class="code" href="classdigital__lms__dd__equalizer__cc.html" title="Least-Mean-Square Decision Directed Equalizer (complex in/out)This block implements an LMS-based deci...">digital_lms_dd_equalizer_cc</a> : <span class="keyword">public</span> <a class="code" href="classgr__adaptive__fir__ccc.html" title="Adaptive FIR filter with gr_complex input, gr_complex output and float taps.">gr_adaptive_fir_ccc</a></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span> {</div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="keyword">private</span>:</div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  <span class="keyword">friend</span> <a class="code" href="digital__api_8h.html#ae14969f36ec69051c4b2f13a0db7e9ba">DIGITAL_API</a> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">digital_lms_dd_equalizer_cc_sptr</a> <a class="code" href="digital__lms__dd__equalizer__cc_8h.html#a874b0a76a8fb89614d1ffb8086b9f74e">digital_make_lms_dd_equalizer_cc</a> (<span class="keywordtype">int</span> num_taps,</div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span>  <span class="keywordtype">float</span> mu, <span class="keywordtype">int</span> sps,</div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  <a class="code" href="classboost_1_1shared__ptr.html">digital_constellation_sptr</a> cnst);</div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  </div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  <span class="keywordtype">float</span> d_mu;</div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  std::vector<gr_complex> <a class="code" href="classgr__adaptive__fir__ccc.html#a941d6aec36e0aa1c7def91e1a292d480">d_taps</a>;</div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  <a class="code" href="classboost_1_1shared__ptr.html">digital_constellation_sptr</a> d_cnst;</div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span> </div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  <a class="code" href="classdigital__lms__dd__equalizer__cc.html" title="Least-Mean-Square Decision Directed Equalizer (complex in/out)This block implements an LMS-based deci...">digital_lms_dd_equalizer_cc</a> (<span class="keywordtype">int</span> num_taps,</div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  <span class="keywordtype">float</span> mu, <span class="keywordtype">int</span> sps,</div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  <a class="code" href="classboost_1_1shared__ptr.html">digital_constellation_sptr</a> cnst);</div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span> </div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="keyword">protected</span>:</div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span> </div>
<div class="line"><a name="l00087"></a><span class="lineno"><a class="code" href="classdigital__lms__dd__equalizer__cc.html#aeff7f61076e6c97458fc1655b77aa08f"> 87</a></span>  <span class="keyword">virtual</span> <a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> <a class="code" href="classgr__adaptive__fir__ccc.html#aae045dd303aa7363bdae104600d5bad1">error</a>(<span class="keyword">const</span> <a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> &out) </div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  { </div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  <a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> decision, <a class="code" href="classgr__adaptive__fir__ccc.html#aae045dd303aa7363bdae104600d5bad1">error</a>;</div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span>  d_cnst->map_to_points(d_cnst->decision_maker(&out), &decision);</div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  error = decision - out;</div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  <span class="keywordflow">return</span> <a class="code" href="classgr__adaptive__fir__ccc.html#aae045dd303aa7363bdae104600d5bad1">error</a>;</div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span>  }</div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span> </div>
<div class="line"><a name="l00095"></a><span class="lineno"><a class="code" href="classdigital__lms__dd__equalizer__cc.html#aed00b745b5eb8e2f17bd72aab5641192"> 95</a></span>  <span class="keyword">virtual</span> <span class="keywordtype">void</span> <a class="code" href="classgr__adaptive__fir__ccc.html#ab58ea7d9ff7433232d1d6310c2676b48">update_tap</a>(<a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> &tap, <span class="keyword">const</span> <a class="code" href="gr__complex_8h.html#aec4bfe41433369afae9327f1b0bc9109">gr_complex</a> &in) </div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  {</div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  tap += d_mu*conj(in)*<a class="code" href="classgr__adaptive__fir__ccc.html#a994350541adabaa9718a2eec3aa2809f">d_error</a>;</div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  }</div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span> </div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span> <span class="keyword">public</span>:</div>
<div class="line"><a name="l00101"></a><span class="lineno"><a class="code" href="classdigital__lms__dd__equalizer__cc.html#a40f5a28db71f57497f41d5af4ccab7fc"> 101</a></span>  <span class="keywordtype">float</span> get_gain()</div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  {</div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  <span class="keywordflow">return</span> d_mu;</div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  }</div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  </div>
<div class="line"><a name="l00106"></a><span class="lineno"><a class="code" href="classdigital__lms__dd__equalizer__cc.html#a6b3917e69eedfd9effcae25a6a0d1c06"> 106</a></span>  <span class="keywordtype">void</span> set_gain(<span class="keywordtype">float</span> mu)</div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  {</div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  <span class="keywordflow">if</span>(mu < 0.0f || mu > 1.0f) {</div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  <span class="keywordflow">throw</span> std::out_of_range(<span class="stringliteral">"digital_lms_dd_equalizer::set_mu: Gain value must in [0, 1]"</span>);</div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span>  }</div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="keywordflow">else</span> {</div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  d_mu = mu;</div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  }</div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  }</div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  </div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span> };</div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span> </div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span> <span class="preprocessor">#endif</span></div>
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