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<h1>gr_pfb_arb_resampler_ccf.h</h1><a href="gr__pfb__arb__resampler__ccf_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 2009,2010 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_PFB_ARB_RESAMPLER_CCF_H</span>
<a name="l00025"></a>00025 <span class="preprocessor"></span><span class="preprocessor">#define INCLUDED_GR_PFB_ARB_RESAMPLER_CCF_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__block_8h.html">gr_block.h</a>></span>
<a name="l00028"></a>00028
<a name="l00029"></a>00029 <span class="keyword">class </span><a class="code" href="classgr__pfb__arb__resampler__ccf.html" title="Polyphase filterbank arbitrary resampler with gr_complex input, gr_complex output...">gr_pfb_arb_resampler_ccf</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_pfb_arb_resampler_ccf></a> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_pfb_arb_resampler_ccf_sptr</a>;
<a name="l00031"></a>00031 <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_pfb_arb_resampler_ccf_sptr</a> <a class="code" href="gr__pfb__arb__resampler__ccf_8h.html#a965bfad7ed076874f98aa553e5156f9d">gr_make_pfb_arb_resampler_ccf</a> (<span class="keywordtype">float</span> rate,
<a name="l00032"></a>00032 <span class="keyword">const</span> <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &<a class="code" href="interpolator__taps_8h.html#a30bf032e13c2a9fc4a98e14e390cd65a">taps</a>,
<a name="l00033"></a>00033 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> filter_size=32);
<a name="l00034"></a>00034
<a name="l00035"></a>00035 <span class="keyword">class </span><a class="code" href="classgr__fir__ccf.html" title="Abstract class for FIR with gr_complex input, gr_complex output and float tapsThis...">gr_fir_ccf</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_pfb_arb_resampler_ccf</span>
<a name="l00039"></a>00039 <span class="comment"> *</span>
<a name="l00040"></a>00040 <span class="comment"> * \brief Polyphase filterbank arbitrary resampler with </span>
<a name="l00041"></a>00041 <span class="comment"> * gr_complex input, gr_complex output and float taps</span>
<a name="l00042"></a>00042 <span class="comment"> *</span>
<a name="l00043"></a>00043 <span class="comment"> * \ingroup filter_blk</span>
<a name="l00044"></a>00044 <span class="comment"> * </span>
<a name="l00045"></a>00045 <span class="comment"> * This block takes in a signal stream and performs arbitrary</span>
<a name="l00046"></a>00046 <span class="comment"> * resampling. The resampling rate can be any real</span>
<a name="l00047"></a>00047 <span class="comment"> * number <EM>r</EM>. The resampling is done by constructing</span>
<a name="l00048"></a>00048 <span class="comment"> * <EM>N</EM> filters where <EM>N</EM> is the interpolation rate. We</span>
<a name="l00049"></a>00049 <span class="comment"> * then calculate <EM>D</EM> where <EM>D = floor(N/r)</EM>.</span>
<a name="l00050"></a>00050 <span class="comment"> *</span>
<a name="l00051"></a>00051 <span class="comment"> * Using <EM>N</EM> and <EM>D</EM>, we can perform rational resampling</span>
<a name="l00052"></a>00052 <span class="comment"> * where <EM>N/D</EM> is a rational number close to the input rate</span>
<a name="l00053"></a>00053 <span class="comment"> * <EM>r</EM> where we have <EM>N</EM> filters and we cycle through</span>
<a name="l00054"></a>00054 <span class="comment"> * them as a polyphase filterbank with a stride of <EM>D</EM> so that</span>
<a name="l00055"></a>00055 <span class="comment"> * <EM>i+1 = (i + D) % N</EM>.</span>
<a name="l00056"></a>00056 <span class="comment"> *</span>
<a name="l00057"></a>00057 <span class="comment"> * To get the arbitrary rate, we want to interpolate between two</span>
<a name="l00058"></a>00058 <span class="comment"> * points. For each value out, we take an output from the current</span>
<a name="l00059"></a>00059 <span class="comment"> * filter, <EM>i</EM>, and the next filter <EM>i+1</EM> and then</span>
<a name="l00060"></a>00060 <span class="comment"> * linearly interpolate between the two based on the real resampling</span>
<a name="l00061"></a>00061 <span class="comment"> * rate we want.</span>
<a name="l00062"></a>00062 <span class="comment"> *</span>
<a name="l00063"></a>00063 <span class="comment"> * The linear interpolation only provides us with an approximation to</span>
<a name="l00064"></a>00064 <span class="comment"> * the real sampling rate specified. The error is a quantization error</span>
<a name="l00065"></a>00065 <span class="comment"> * between the two filters we used as our interpolation points. To</span>
<a name="l00066"></a>00066 <span class="comment"> * this end, the number of filters, <EM>N</EM>, used determines the</span>
<a name="l00067"></a>00067 <span class="comment"> * quantization error; the larger <EM>N</EM>, the smaller the</span>
<a name="l00068"></a>00068 <span class="comment"> * noise. You can design for a specified noise floor by setting the</span>
<a name="l00069"></a>00069 <span class="comment"> * filter size (parameters <EM>filter_size</EM>). The size defaults to</span>
<a name="l00070"></a>00070 <span class="comment"> * 32 filters, which is about as good as most implementations need.</span>
<a name="l00071"></a>00071 <span class="comment"> *</span>
<a name="l00072"></a>00072 <span class="comment"> * The trick with designing this filter is in how to specify the taps</span>
<a name="l00073"></a>00073 <span class="comment"> * of the prototype filter. Like the PFB interpolator, the taps are</span>
<a name="l00074"></a>00074 <span class="comment"> * specified using the interpolated filter rate. In this case, that</span>
<a name="l00075"></a>00075 <span class="comment"> * rate is the input sample rate multiplied by the number of filters</span>
<a name="l00076"></a>00076 <span class="comment"> * in the filterbank, which is also the interpolation rate. All other</span>
<a name="l00077"></a>00077 <span class="comment"> * values should be relative to this rate.</span>
<a name="l00078"></a>00078 <span class="comment"> *</span>
<a name="l00079"></a>00079 <span class="comment"> * For example, for a 32-filter arbitrary resampler and using the</span>
<a name="l00080"></a>00080 <span class="comment"> * GNU Radio's firdes utility to build the filter, we build a low-pass</span>
<a name="l00081"></a>00081 <span class="comment"> * filter with a sampling rate of <EM>fs</EM>, a 3-dB bandwidth of</span>
<a name="l00082"></a>00082 <span class="comment"> * <EM>BW</EM> and a transition bandwidth of <EM>TB</EM>. We can also</span>
<a name="l00083"></a>00083 <span class="comment"> * specify the out-of-band attenuation to use, <EM>ATT</EM>, and the</span>
<a name="l00084"></a>00084 <span class="comment"> * filter window function (a Blackman-harris window in this case). The</span>
<a name="l00085"></a>00085 <span class="comment"> * first input is the gain of the filter, which we specify here as the</span>
<a name="l00086"></a>00086 <span class="comment"> * interpolation rate (<EM>32</EM>).</span>
<a name="l00087"></a>00087 <span class="comment"> *</span>
<a name="l00088"></a>00088 <span class="comment"> * <B><EM>self._taps = gr.firdes.low_pass_2(32, 32*fs, BW, TB, </span>
<a name="l00089"></a>00089 <span class="comment"> * attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)</EM></B></span>
<a name="l00090"></a>00090 <span class="comment"> *</span>
<a name="l00091"></a>00091 <span class="comment"> * The theory behind this block can be found in Chapter 7.5 of </span>
<a name="l00092"></a>00092 <span class="comment"> * the following book.</span>
<a name="l00093"></a>00093 <span class="comment"> *</span>
<a name="l00094"></a>00094 <span class="comment"> * <B><EM>f. harris, "Multirate Signal Processing for Communication </span>
<a name="l00095"></a>00095 <span class="comment"> * Systems", Upper Saddle River, NJ: Prentice Hall, Inc. 2004.</EM></B></span>
<a name="l00096"></a>00096 <span class="comment"> */</span>
<a name="l00097"></a>00097
<a name="l00098"></a><a class="code" href="classgr__pfb__arb__resampler__ccf.html">00098</a> <span class="keyword">class </span><a class="code" href="classgr__pfb__arb__resampler__ccf.html" title="Polyphase filterbank arbitrary resampler with gr_complex input, gr_complex output...">gr_pfb_arb_resampler_ccf</a> : <span class="keyword">public</span> <a class="code" href="classgr__block.html" title="The abstract base class for all &#39;terminal&#39; processing blocks.A signal processing...">gr_block</a>
<a name="l00099"></a>00099 {
<a name="l00100"></a>00100 <span class="keyword">private</span>:<span class="comment"></span>
<a name="l00101"></a>00101 <span class="comment"> /*!</span>
<a name="l00102"></a>00102 <span class="comment"> * Build the polyphase filterbank arbitray resampler.</span>
<a name="l00103"></a>00103 <span class="comment"> * \param rate (float) Specifies the resampling rate to use</span>
<a name="l00104"></a>00104 <span class="comment"> * \param taps (vector/list of floats) The prototype filter to populate the filterbank. The taps</span>
<a name="l00105"></a>00105 <span class="comment"> * should be generated at the filter_size sampling rate.</span>
<a name="l00106"></a>00106 <span class="comment"> * \param filter_size (unsigned int) The number of filters in the filter bank. This is directly</span>
<a name="l00107"></a>00107 <span class="comment"> related to quantization noise introduced during the resampling.</span>
<a name="l00108"></a>00108 <span class="comment"> Defaults to 32 filters.</span>
<a name="l00109"></a>00109 <span class="comment"> */</span>
<a name="l00110"></a>00110 <span class="keyword">friend</span> <a class="code" href="classboost_1_1shared__ptr.html" title="shared_ptr documentation stub">gr_pfb_arb_resampler_ccf_sptr</a> <a class="code" href="classgr__pfb__arb__resampler__ccf.html#a552deca439bb07afc671de47afbbf24e">gr_make_pfb_arb_resampler_ccf</a> (<span class="keywordtype">float</span> rate,
<a name="l00111"></a>00111 <span class="keyword">const</span> <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &<a class="code" href="interpolator__taps_8h.html#a30bf032e13c2a9fc4a98e14e390cd65a">taps</a>,
<a name="l00112"></a>00112 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> filter_size);
<a name="l00113"></a>00113
<a name="l00114"></a>00114 <a class="code" href="classstd_1_1vector.html">std::vector<gr_fir_ccf*></a> d_filters;
<a name="l00115"></a>00115 <a class="code" href="classstd_1_1vector.html">std::vector<gr_fir_ccf*></a> d_diff_filters;
<a name="l00116"></a>00116 <a class="code" href="classstd_1_1vector.html" title="vector documentation stub">std::vector< std::vector<float></a> > d_taps;
<a name="l00117"></a>00117 <a class="code" href="classstd_1_1vector.html" title="vector documentation stub">std::vector< std::vector<float></a> > d_dtaps;
<a name="l00118"></a>00118 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> d_int_rate; <span class="comment">// the number of filters (interpolation rate)</span>
<a name="l00119"></a>00119 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> d_dec_rate; <span class="comment">// the stride through the filters (decimation rate)</span>
<a name="l00120"></a>00120 <span class="keywordtype">float</span> d_flt_rate; <span class="comment">// residual rate for the linear interpolation</span>
<a name="l00121"></a>00121 <span class="keywordtype">float</span> d_acc;
<a name="l00122"></a>00122 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> d_last_filter;
<a name="l00123"></a>00123 <span class="keywordtype">int</span> d_start_index;
<a name="l00124"></a>00124 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> d_taps_per_filter;
<a name="l00125"></a>00125 <span class="keywordtype">bool</span> d_updated;
<a name="l00126"></a>00126 <span class="comment"></span>
<a name="l00127"></a>00127 <span class="comment"> /*!</span>
<a name="l00128"></a>00128 <span class="comment"> * Build the polyphase filterbank arbitray resampler.</span>
<a name="l00129"></a>00129 <span class="comment"> * \param rate (float) Specifies the resampling rate to use</span>
<a name="l00130"></a>00130 <span class="comment"> * \param taps (vector/list of floats) The prototype filter to populate the filterbank. The taps</span>
<a name="l00131"></a>00131 <span class="comment"> * should be generated at the filter_size sampling rate.</span>
<a name="l00132"></a>00132 <span class="comment"> * \param filter_size (unsigned int) The number of filters in the filter bank. This is directly</span>
<a name="l00133"></a>00133 <span class="comment"> related to quantization noise introduced during the resampling.</span>
<a name="l00134"></a>00134 <span class="comment"> Defaults to 32 filters.</span>
<a name="l00135"></a>00135 <span class="comment"> */</span>
<a name="l00136"></a>00136 <a class="code" href="classgr__pfb__arb__resampler__ccf.html" title="Polyphase filterbank arbitrary resampler with gr_complex input, gr_complex output...">gr_pfb_arb_resampler_ccf</a> (<span class="keywordtype">float</span> rate,
<a name="l00137"></a>00137 <span class="keyword">const</span> <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &taps,
<a name="l00138"></a>00138 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> filter_size);
<a name="l00139"></a>00139
<a name="l00140"></a>00140 <span class="keywordtype">void</span> create_diff_taps(<span class="keyword">const</span> <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &newtaps,
<a name="l00141"></a>00141 <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &difftaps);
<a name="l00142"></a>00142 <span class="comment"></span>
<a name="l00143"></a>00143 <span class="comment"> /*!</span>
<a name="l00144"></a>00144 <span class="comment"> * Resets the filterbank's filter taps with the new prototype filter</span>
<a name="l00145"></a>00145 <span class="comment"> * \param newtaps (vector of floats) The prototype filter to populate the filterbank. </span>
<a name="l00146"></a>00146 <span class="comment"> * The taps should be generated at the interpolated sampling rate.</span>
<a name="l00147"></a>00147 <span class="comment"> * \param ourtaps (vector of floats) Reference to our internal member of holding the taps.</span>
<a name="l00148"></a>00148 <span class="comment"> * \param ourfilter (vector of filters) Reference to our internal filter to set the taps for.</span>
<a name="l00149"></a>00149 <span class="comment"> */</span>
<a name="l00150"></a>00150 <span class="keywordtype">void</span> create_taps (<span class="keyword">const</span> <a class="code" href="classstd_1_1vector.html">std::vector<float></a> &newtaps,
<a name="l00151"></a>00151 <a class="code" href="classstd_1_1vector.html" title="vector documentation stub">std::vector</a>< <a class="code" href="classstd_1_1vector.html">std::vector<float></a> > &ourtaps,
<a name="l00152"></a>00152 <a class="code" href="classstd_1_1vector.html">std::vector<gr_fir_ccf*></a> &ourfilter);
<a name="l00153"></a>00153
<a name="l00154"></a>00154
<a name="l00155"></a>00155 <span class="keyword">public</span>:
<a name="l00156"></a>00156 <a class="code" href="classgr__pfb__arb__resampler__ccf.html#a24aef28515295bbbe73f02fe0b3ca432">~gr_pfb_arb_resampler_ccf</a> ();
<a name="l00157"></a>00157
<a name="l00158"></a>00158 <span class="comment">// FIXME: See about a set_taps function during runtime.</span>
<a name="l00159"></a>00159 <span class="comment"></span>
<a name="l00160"></a>00160 <span class="comment"> /*!</span>
<a name="l00161"></a>00161 <span class="comment"> * Print all of the filterbank taps to screen.</span>
<a name="l00162"></a>00162 <span class="comment"> */</span>
<a name="l00163"></a>00163 <span class="keywordtype">void</span> <a class="code" href="classgr__pfb__arb__resampler__ccf.html#a6750f5b1232fe85982e30f20efdf87db">print_taps</a>();
<a name="l00164"></a>00164
<a name="l00165"></a>00165 <span class="keywordtype">int</span> <a class="code" href="classgr__pfb__arb__resampler__ccf.html#ae1758735ee29c79cf3c1b962f17b1b4f" title="compute output items from input items">general_work</a> (<span class="keywordtype">int</span> noutput_items,
<a name="l00166"></a>00166 <a class="code" href="classstd_1_1vector.html">gr_vector_int</a> &ninput_items,
<a name="l00167"></a>00167 <a class="code" href="classstd_1_1vector.html">gr_vector_const_void_star</a> &input_items,
<a name="l00168"></a>00168 <a class="code" href="classstd_1_1vector.html">gr_vector_void_star</a> &output_items);
<a name="l00169"></a>00169 };
<a name="l00170"></a>00170
<a name="l00171"></a>00171 <span class="preprocessor">#endif</span>
</pre></div></div>
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