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<a href="dc__blocker__ff_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 2011,2012 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_FILTER_DC_BLOCKER_FF_H</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="preprocessor"></span><span class="preprocessor">#define INCLUDED_FILTER_DC_BLOCKER_FF_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="gr-filter_2include_2filter_2api_8h.html">filter/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__sync__block_8h.html">gr_sync_block.h</a>></span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> </div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="keyword">namespace </span>gr {</div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span>  <span class="keyword">namespace </span>filter {</div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span>  </div>
<div class="line"><a name="l00032"></a><span class="lineno"><a class="code" href="classgr_1_1filter_1_1dc__blocker__ff.html"> 32</a></span>  <span class="keyword">class </span><a class="code" href="gr-filter_2include_2filter_2api_8h.html#a7d33c890adb08fbd7c1c524f2c889357">FILTER_API</a> <a class="code" href="classgr_1_1filter_1_1dc__blocker__ff.html">dc_blocker_ff</a> : <span class="keyword">virtual</span> <span class="keyword">public</span> <a class="code" href="classgr__sync__block.html" title="synchronous 1:1 input to output with historyOverride work to provide the signal processing implementa...">gr_sync_block</a></div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span>  {</div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span>  <span class="keyword">public</span>:</div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span> </div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span>  <span class="comment">// gr::filter::dc_blocker_ff::sptr</span></div>
<div class="line"><a name="l00037"></a><span class="lineno"><a class="code" href="classgr_1_1filter_1_1dc__blocker__ff.html#a1f2c8207483c248eec813bb51099fd9f"> 37</a></span>  <span class="keyword">typedef</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">boost::shared_ptr<dc_blocker_ff></a> <a class="code" href="classgr_1_1filter_1_1dc__blocker__ff.html#a1f2c8207483c248eec813bb51099fd9f">sptr</a>;</div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment"></span></div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment"> /*!</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment"> * \class dc_blocker_ff</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment"> * \brief a computationally efficient controllable DC blocker</span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment"> * \ingroup filter_blk</span></div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment"> * This block implements a computationally efficient DC blocker that produces</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="comment"> * a tighter notch filter around DC for a smaller group delay than an</span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="comment"> * equivalent FIR filter or using a single pole IIR filter (though the IIR</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="comment"> * filter is computationally cheaper).</span></div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="comment"> * The block defaults to using a delay line of length 32 and the long form</span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="comment"> * of the filter. Optionally, the delay line length can be changed to alter</span></div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="comment"> * the width of the DC notch (longer lines will decrease the width).</span></div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="comment"> * The long form of the filter produces a nearly flat response outside of</span></div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment"> * the notch but at the cost of a group delay of 2D-2.</span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment"> * The short form of the filter does not have as flat a response in the</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment"> * passband but has a group delay of only D-1 and is cheaper to compute.</span></div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment"> * The theory behind this block can be found in the paper:</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment"> * <B><EM>R. Yates, "DC Blocker Algorithms," IEEE Signal Processing Magazine,</span></div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment"> * Mar. 2008, pp 132-134.</EM></B></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"> * \param D (int) the length of the delay line</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment"> * \param long_form (bool) whether to use long (true, default) or short form</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span>  <span class="keyword">static</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">sptr</a> make(<span class="keywordtype">int</span> D, <span class="keywordtype">bool</span> long_form=<span class="keyword">true</span>);</div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> </div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  <span class="keyword">virtual</span> <span class="keywordtype">int</span> group_delay() = 0;</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> </div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  } <span class="comment">/* namespace filter */</span></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span> } <span class="comment">/* namespace gr */</span></div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span> </div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span> <span class="preprocessor">#endif </span><span class="comment">/* INCLUDED_FILTER_DC_BLOCKER_FF_H */</span><span class="preprocessor"></span></div>
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