GNU Radio v3.6.2-149-ga6d285d9 C++ API
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00001 /* -*- c++ -*- */ 00002 /* 00003 * Copyright 2009,2012 Free Software Foundation, Inc. 00004 * 00005 * This file is part of GNU Radio 00006 * 00007 * GNU Radio is free software; you can redistribute it and/or modify 00008 * it under the terms of the GNU General Public License as published by 00009 * the Free Software Foundation; either version 3, or (at your option) 00010 * any later version. 00011 * 00012 * GNU Radio is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 * GNU General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU General Public License 00018 * along with GNU Radio; see the file COPYING. If not, write to 00019 * the Free Software Foundation, Inc., 51 Franklin Street, 00020 * Boston, MA 02110-1301, USA. 00021 */ 00022 00023 00024 #ifndef INCLUDED_PFB_INTERPOLATOR_CCF_H 00025 #define INCLUDED_PFB_INTERPOLATOR_CCF_H 00026 00027 #include <filter/api.h> 00028 #include <gr_sync_interpolator.h> 00029 00030 namespace gr { 00031 namespace filter { 00032 00033 /*! 00034 * \class gr_pfb_interpolator_ccf 00035 * 00036 * \brief Polyphase filterbank interpolator with gr_complex input, 00037 * gr_complex output and float taps 00038 * 00039 * \ingroup filter_blk 00040 * \ingroup pfb_blk 00041 * 00042 * This block takes in a signal stream and performs interger up- 00043 * sampling (interpolation) with a polyphase filterbank. The first 00044 * input is the integer specifying how much to interpolate by. The 00045 * second input is a vector (Python list) of floating-point taps 00046 * of the prototype filter. 00047 * 00048 * The filter's taps should be based on the interpolation rate 00049 * specified. That is, the bandwidth specified is relative to the 00050 * bandwidth after interpolation. 00051 * 00052 * For example, using the GNU Radio's firdes utility to building 00053 * filters, we build a low-pass filter with a sampling rate of 00054 * <EM>fs</EM>, a 3-dB bandwidth of <EM>BW</EM> and a transition 00055 * bandwidth of <EM>TB</EM>. We can also specify the out-of-band 00056 * attenuation to use, ATT, and the filter window function (a 00057 * Blackman-harris window in this case). The first input is the 00058 * gain, which is also specified as the interpolation rate so that 00059 * the output levels are the same as the input (this creates an 00060 * overall increase in power). 00061 * 00062 * <B><EM>self._taps = filter.firdes.low_pass_2(interp, interp*fs, BW, TB, 00063 * attenuation_dB=ATT, window=filter.firdes.WIN_BLACKMAN_hARRIS)</EM></B> 00064 * 00065 * The PFB interpolator code takes the taps generated above and 00066 * builds a set of filters. The set contains <EM>interp</EM> 00067 * number of filters and each filter contains 00068 * ceil(taps.size()/interp) number of taps. Each tap from the 00069 * filter prototype is sequentially inserted into the next 00070 * filter. When all of the input taps are used, the remaining 00071 * filters in the filterbank are filled out with 0's to make sure 00072 * each filter has the same number of taps. 00073 * 00074 * The theory behind this block can be found in Chapter 7.1 of the 00075 * following book. 00076 * 00077 * <B><EM>f. harris, "Multirate Signal Processing for Communication 00078 * Systems</EM>," Upper Saddle River, NJ: Prentice Hall, 00079 * Inc. 2004.</EM></B> 00080 */ 00081 00082 class FILTER_API pfb_interpolator_ccf : virtual public gr_sync_interpolator 00083 { 00084 public: 00085 // gr::filter::pfb_interpolator_ccf::sptr 00086 typedef boost::shared_ptr<pfb_interpolator_ccf> sptr; 00087 00088 /*! 00089 * Build the polyphase filterbank interpolator. 00090 * \param interp (unsigned integer) Specifies the interpolation rate to use 00091 * \param taps (vector/list of floats) The prototype filter to populate the filterbank. The taps 00092 * should be generated at the interpolated sampling rate. 00093 */ 00094 static sptr make(unsigned int interp, 00095 const std::vector<float> &taps); 00096 00097 /*! 00098 * Resets the filterbank's filter taps with the new prototype filter 00099 * \param taps (vector/list of floats) The prototype filter to populate the filterbank. 00100 * The taps should be generated at the interpolated sampling rate. 00101 */ 00102 virtual void set_taps(const std::vector<float> &taps) = 0; 00103 00104 /*! 00105 * Return a vector<vector<>> of the filterbank taps 00106 */ 00107 virtual std::vector<std::vector<float> > taps() const = 0; 00108 00109 /*! 00110 * Print all of the filterbank taps to screen. 00111 */ 00112 virtual void print_taps() = 0; 00113 }; 00114 00115 } /* namespace filter */ 00116 } /* namespace gr */ 00117 00118 #endif /* INCLUDED_FILTER_PFB_INTERPOLATOR_CCF_H */