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<h1>gr_fll_band_edge_cc.h</h1><a href="gr__fll__band__edge__cc_8h.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* -*- c++ -*- */</span>
<a name="l00002"></a>00002 <span class="comment">/*</span>
<a name="l00003"></a>00003 <span class="comment"> * Copyright 2009 Free Software Foundation, Inc.</span>
<a name="l00004"></a>00004 <span class="comment"> * </span>
<a name="l00005"></a>00005 <span class="comment"> * This file is part of GNU Radio</span>
<a name="l00006"></a>00006 <span class="comment"> * </span>
<a name="l00007"></a>00007 <span class="comment"> * GNU Radio is free software; you can redistribute it and/or modify</span>
<a name="l00008"></a>00008 <span class="comment"> * it under the terms of the GNU General Public License as published by</span>
<a name="l00009"></a>00009 <span class="comment"> * the Free Software Foundation; either version 3, or (at your option)</span>
<a name="l00010"></a>00010 <span class="comment"> * any later version.</span>
<a name="l00011"></a>00011 <span class="comment"> * </span>
<a name="l00012"></a>00012 <span class="comment"> * GNU Radio is distributed in the hope that it will be useful,</span>
<a name="l00013"></a>00013 <span class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<a name="l00014"></a>00014 <span class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span>
<a name="l00015"></a>00015 <span class="comment"> * GNU General Public License for more details.</span>
<a name="l00016"></a>00016 <span class="comment"> * </span>
<a name="l00017"></a>00017 <span class="comment"> * You should have received a copy of the GNU General Public License</span>
<a name="l00018"></a>00018 <span class="comment"> * along with GNU Radio; see the file COPYING. If not, write to</span>
<a name="l00019"></a>00019 <span class="comment"> * the Free Software Foundation, Inc., 51 Franklin Street,</span>
<a name="l00020"></a>00020 <span class="comment"> * Boston, MA 02110-1301, USA.</span>
<a name="l00021"></a>00021 <span class="comment"> */</span>
<a name="l00022"></a>00022
<a name="l00023"></a>00023
<a name="l00024"></a>00024 <span class="preprocessor">#ifndef INCLUDED_GR_FLL_BAND_EDGE_CC_H</span>
<a name="l00025"></a>00025 <span class="preprocessor"></span><span class="preprocessor">#define INCLUDED_GR_FLL_BAND_EDGE_CC_H</span>
<a name="l00026"></a>00026 <span class="preprocessor"></span>
<a name="l00027"></a>00027 <span class="preprocessor">#include <<a class="code" href="gr__sync__block_8h.html">gr_sync_block.h</a>></span>
<a name="l00028"></a>00028
<a name="l00029"></a>00029 <span class="keyword">class </span><a class="code" href="classgr__fll__band__edge__cc.html" title="Frequency Lock Loop using band-edge filters.">gr_fll_band_edge_cc</a>;
<a name="l00030"></a>00030 <span class="keyword">typedef</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">boost::shared_ptr<gr_fll_band_edge_cc></a> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_fll_band_edge_cc_sptr</a>;
<a name="l00031"></a>00031 <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_fll_band_edge_cc_sptr</a> <a class="code" href="gr__fll__band__edge__cc_8h.html#a08ba6b1f1e708e854d1bfd4533819bd9">gr_make_fll_band_edge_cc</a> (<span class="keywordtype">float</span> samps_per_sym, <span class="keywordtype">float</span> rolloff,
<a name="l00032"></a>00032 <span class="keywordtype">int</span> filter_size, <span class="keywordtype">float</span> alpha, <span class="keywordtype">float</span> beta);
<a name="l00033"></a>00033
<a name="l00034"></a>00034 <span class="keyword">class </span><a class="code" href="classgr__fir__ccc.html" title="Abstract class for FIR with gr_complex input, gr_complex output and gr_complex tapsThis...">gr_fir_ccc</a>;
<a name="l00035"></a>00035 <span class="keyword">class </span><a class="code" href="classgri__fft__complex.html" title="FFT: complex in, complex out.">gri_fft_complex</a>;
<a name="l00036"></a>00036 <span class="comment"></span>
<a name="l00037"></a>00037 <span class="comment">/*!</span>
<a name="l00038"></a>00038 <span class="comment"> * \class gr_fll_band_edge_cc</span>
<a name="l00039"></a>00039 <span class="comment"> * \brief Frequency Lock Loop using band-edge filters</span>
<a name="l00040"></a>00040 <span class="comment"> *</span>
<a name="l00041"></a>00041 <span class="comment"> * \ingroup general</span>
<a name="l00042"></a>00042 <span class="comment"> *</span>
<a name="l00043"></a>00043 <span class="comment"> * The frequency lock loop derives a band-edge filter that covers the upper and lower bandwidths</span>
<a name="l00044"></a>00044 <span class="comment"> * of a digitally-modulated signal. The bandwidth range is determined by the excess bandwidth</span>
<a name="l00045"></a>00045 <span class="comment"> * (e.g., rolloff factor) of the modulated signal. The placement in frequency of the band-edges</span>
<a name="l00046"></a>00046 <span class="comment"> * is determined by the oversampling ratio (number of samples per symbol) and the excess bandwidth.</span>
<a name="l00047"></a>00047 <span class="comment"> * The size of the filters should be fairly large so as to average over a number of symbols.</span>
<a name="l00048"></a>00048 <span class="comment"> *</span>
<a name="l00049"></a>00049 <span class="comment"> * The FLL works by filtering the upper and lower band edges into x_u(t) and x_l(t), respectively.</span>
<a name="l00050"></a>00050 <span class="comment"> * These are combined to form cc(t) = x_u(t) + x_l(t) and ss(t) = x_u(t) - x_l(t). Combining</span>
<a name="l00051"></a>00051 <span class="comment"> * these to form the signal e(t) = Re{cc(t) \\times ss(t)^*} (where ^* is the complex conjugate)</span>
<a name="l00052"></a>00052 <span class="comment"> * provides an error signal at the DC term that is directly proportional to the carrier frequency.</span>
<a name="l00053"></a>00053 <span class="comment"> * We then make a second-order loop using the error signal that is the running average of e(t).</span>
<a name="l00054"></a>00054 <span class="comment"> *</span>
<a name="l00055"></a>00055 <span class="comment"> * In theory, the band-edge filter is the derivative of the matched filter in frequency, </span>
<a name="l00056"></a>00056 <span class="comment"> * (H_be(f) = \\frac{H(f)}{df}. In practice, this comes down to a quarter sine wave at the point</span>
<a name="l00057"></a>00057 <span class="comment"> * of the matched filter's rolloff (if it's a raised-cosine, the derivative of a cosine is a sine).</span>
<a name="l00058"></a>00058 <span class="comment"> * Extend this sine by another quarter wave to make a half wave around the band-edges is equivalent</span>
<a name="l00059"></a>00059 <span class="comment"> * in time to the sum of two sinc functions. The baseband filter fot the band edges is therefore</span>
<a name="l00060"></a>00060 <span class="comment"> * derived from this sum of sincs. The band edge filters are then just the baseband signal</span>
<a name="l00061"></a>00061 <span class="comment"> * modulated to the correct place in frequency. All of these calculations are done in the</span>
<a name="l00062"></a>00062 <span class="comment"> * 'design_filter' function.</span>
<a name="l00063"></a>00063 <span class="comment"> *</span>
<a name="l00064"></a>00064 <span class="comment"> * Note: We use FIR filters here because the filters have to have a flat phase response over the</span>
<a name="l00065"></a>00065 <span class="comment"> * entire frequency range to allow their comparisons to be valid.</span>
<a name="l00066"></a>00066 <span class="comment"> */</span>
<a name="l00067"></a>00067
<a name="l00068"></a><a class="code" href="classgr__fll__band__edge__cc.html">00068</a> <span class="keyword">class </span><a class="code" href="classgr__fll__band__edge__cc.html" title="Frequency Lock Loop using band-edge filters.">gr_fll_band_edge_cc</a> : <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...">gr_sync_block</a>
<a name="l00069"></a>00069 {
<a name="l00070"></a>00070 <span class="keyword">private</span>:<span class="comment"></span>
<a name="l00071"></a>00071 <span class="comment"> /*!</span>
<a name="l00072"></a>00072 <span class="comment"> * Build the FLL</span>
<a name="l00073"></a>00073 <span class="comment"> * \param samps_per_sym (float) Number of samples per symbol of signal</span>
<a name="l00074"></a>00074 <span class="comment"> * \param rolloff (float) Rolloff factor of signal</span>
<a name="l00075"></a>00075 <span class="comment"> * \param filter_size (int) Size (in taps) of the filter</span>
<a name="l00076"></a>00076 <span class="comment"> * \param alpha (float) Loop gain 1</span>
<a name="l00077"></a>00077 <span class="comment"> * \param beta (float) Loop gain 2</span>
<a name="l00078"></a>00078 <span class="comment"> */</span>
<a name="l00079"></a>00079 <span class="keyword">friend</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_fll_band_edge_cc_sptr</a> <a class="code" href="classgr__fll__band__edge__cc.html#a08ba6b1f1e708e854d1bfd4533819bd9">gr_make_fll_band_edge_cc</a> (<span class="keywordtype">float</span> samps_per_sym, <span class="keywordtype">float</span> rolloff,
<a name="l00080"></a>00080 <span class="keywordtype">int</span> filter_size, <span class="keywordtype">float</span> alpha, <span class="keywordtype">float</span> beta);
<a name="l00081"></a>00081
<a name="l00082"></a>00082 <span class="keywordtype">float</span> d_alpha;
<a name="l00083"></a>00083 <span class="keywordtype">float</span> d_beta;
<a name="l00084"></a>00084 <span class="keywordtype">float</span> d_max_freq;
<a name="l00085"></a>00085 <span class="keywordtype">float</span> d_min_freq;
<a name="l00086"></a>00086
<a name="l00087"></a>00087 <a class="code" href="classgr__fir__ccc.html" title="Abstract class for FIR with gr_complex input, gr_complex output and gr_complex tapsThis...">gr_fir_ccc</a>* d_filter_upper;
<a name="l00088"></a>00088 <a class="code" href="classgr__fir__ccc.html" title="Abstract class for FIR with gr_complex input, gr_complex output and gr_complex tapsThis...">gr_fir_ccc</a>* d_filter_lower;
<a name="l00089"></a>00089 <span class="keywordtype">bool</span> d_updated;
<a name="l00090"></a>00090 <span class="keywordtype">float</span> d_error;
<a name="l00091"></a>00091 <span class="keywordtype">float</span> d_freq;
<a name="l00092"></a>00092 <span class="keywordtype">float</span> d_phase;
<a name="l00093"></a>00093 <span class="comment"></span>
<a name="l00094"></a>00094 <span class="comment"> /*!</span>
<a name="l00095"></a>00095 <span class="comment"> * Build the FLL</span>
<a name="l00096"></a>00096 <span class="comment"> * \param samps_per_sym (float) number of samples per symbol</span>
<a name="l00097"></a>00097 <span class="comment"> * \param rolloff (float) Rolloff (excess bandwidth) of signal filter</span>
<a name="l00098"></a>00098 <span class="comment"> * \param filter_size (int) number of filter taps to generate</span>
<a name="l00099"></a>00099 <span class="comment"> * \param alpha (float) Alpha gain in the control loop</span>
<a name="l00100"></a>00100 <span class="comment"> * \param beta (float) Beta gain in the control loop</span>
<a name="l00101"></a>00101 <span class="comment"> */</span>
<a name="l00102"></a>00102 <a class="code" href="classgr__fll__band__edge__cc.html" title="Frequency Lock Loop using band-edge filters.">gr_fll_band_edge_cc</a>(<span class="keywordtype">float</span> samps_per_sym, <span class="keywordtype">float</span> rolloff,
<a name="l00103"></a>00103 <span class="keywordtype">int</span> filter_size, <span class="keywordtype">float</span> alpha, <span class="keywordtype">float</span> beta);
<a name="l00104"></a>00104
<a name="l00105"></a>00105 <span class="keyword">public</span>:
<a name="l00106"></a>00106 <a class="code" href="classgr__fll__band__edge__cc.html#a0ee6ad05307c6a5e373d950c0ceb2f4d">~gr_fll_band_edge_cc</a> ();
<a name="l00107"></a>00107 <span class="comment"></span>
<a name="l00108"></a>00108 <span class="comment"> /*!</span>
<a name="l00109"></a>00109 <span class="comment"> * Design the band-edge filter based on the number of samples per symbol,</span>
<a name="l00110"></a>00110 <span class="comment"> * filter rolloff factor, and the filter size</span>
<a name="l00111"></a>00111 <span class="comment"> * \param samps_per_sym (float) Number of samples per symbol of signal</span>
<a name="l00112"></a>00112 <span class="comment"> * \param rolloff (float) Rolloff factor of signal</span>
<a name="l00113"></a>00113 <span class="comment"> * \param filter_size (int) Size (in taps) of the filter</span>
<a name="l00114"></a>00114 <span class="comment"> */</span>
<a name="l00115"></a>00115 <span class="keywordtype">void</span> <a class="code" href="classgr__fll__band__edge__cc.html#a7c2e8ce6b5bf3df42638a25a21ba7d50">design_filter</a>(<span class="keywordtype">float</span> samps_per_sym, <span class="keywordtype">float</span> rolloff, <span class="keywordtype">int</span> filter_size);
<a name="l00116"></a>00116 <span class="comment"></span>
<a name="l00117"></a>00117 <span class="comment"> /*!</span>
<a name="l00118"></a>00118 <span class="comment"> * Set the alpha gainvalue</span>
<a name="l00119"></a>00119 <span class="comment"> * \param alpha (float) new gain value</span>
<a name="l00120"></a>00120 <span class="comment"> */</span>
<a name="l00121"></a>00121 <span class="keywordtype">void</span> <a class="code" href="classgr__fll__band__edge__cc.html#a68924abf51cc8a89c8b1bb607393bad2">set_alpha</a>(<span class="keywordtype">float</span> alpha);
<a name="l00122"></a>00122 <span class="comment"></span>
<a name="l00123"></a>00123 <span class="comment"> /*!</span>
<a name="l00124"></a>00124 <span class="comment"> * Set the beta gain value</span>
<a name="l00125"></a>00125 <span class="comment"> * \param beta (float) new gain value</span>
<a name="l00126"></a>00126 <span class="comment"> */</span>
<a name="l00127"></a><a class="code" href="classgr__fll__band__edge__cc.html#ad72c8be97b8ab0ecdfdd85c9f173ee3d">00127</a> <span class="keywordtype">void</span> <a class="code" href="classgr__fll__band__edge__cc.html#ad72c8be97b8ab0ecdfdd85c9f173ee3d">set_beta</a>(<span class="keywordtype">float</span> beta) { d_beta = beta; }
<a name="l00128"></a>00128 <span class="comment"></span>
<a name="l00129"></a>00129 <span class="comment"> /*!</span>
<a name="l00130"></a>00130 <span class="comment"> * Print the taps to screen.</span>
<a name="l00131"></a>00131 <span class="comment"> */</span>
<a name="l00132"></a>00132 <span class="keywordtype">void</span> <a class="code" href="classgr__fll__band__edge__cc.html#ae6a5e618ea0e85bb3ea15375a24195b7">print_taps</a>();
<a name="l00133"></a>00133
<a name="l00134"></a>00134 <span class="keywordtype">int</span> <a class="code" href="classgr__fll__band__edge__cc.html#ac7757cfebce35e4ff869d0636875760f" title="just like gr_block::general_work, only this arranges to call consume_each for you...">work</a> (<span class="keywordtype">int</span> noutput_items,
<a name="l00135"></a>00135 <a class="code" href="classstd_1_1vector.html">gr_vector_const_void_star</a> &input_items,
<a name="l00136"></a>00136 <a class="code" href="classstd_1_1vector.html">gr_vector_void_star</a> &output_items);
<a name="l00137"></a>00137 };
<a name="l00138"></a>00138
<a name="l00139"></a>00139 <span class="preprocessor">#endif</span>
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