diff options
Diffstat (limited to 'gr-filter/include/filter')
| -rw-r--r-- | gr-filter/include/filter/CMakeLists.txt | 2 | ||||
| -rw-r--r-- | gr-filter/include/filter/pfb_arb_resampler_ccf.h | 138 | ||||
| -rw-r--r-- | gr-filter/include/filter/pfb_arb_resampler_fff.h | 139 | ||||
| -rw-r--r-- | gr-filter/include/filter/pfb_decimator_ccf.h | 2 |
4 files changed, 280 insertions, 1 deletions
diff --git a/gr-filter/include/filter/CMakeLists.txt b/gr-filter/include/filter/CMakeLists.txt index 3d8e0c932..b0412aaba 100644 --- a/gr-filter/include/filter/CMakeLists.txt +++ b/gr-filter/include/filter/CMakeLists.txt @@ -100,6 +100,8 @@ install(FILES fractional_interpolator_ff.h hilbert_fc.h iir_filter_ffd.h + pfb_arb_resampler_ccf.h + pfb_arb_resampler_fff.h pfb_channelizer_ccf.h pfb_decimator_ccf.h pfb_interpolator_ccf.h diff --git a/gr-filter/include/filter/pfb_arb_resampler_ccf.h b/gr-filter/include/filter/pfb_arb_resampler_ccf.h new file mode 100644 index 000000000..1436674b2 --- /dev/null +++ b/gr-filter/include/filter/pfb_arb_resampler_ccf.h @@ -0,0 +1,138 @@ +/* -*- c++ -*- */ +/* + * Copyright 2009,2010,2012 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, + * Boston, MA 02110-1301, USA. + */ + + +#ifndef INCLUDED_PFB_ARB_RESAMPLER_CCF_H +#define INCLUDED_PFB_ARB_RESAMPLER_CCF_H + +#include <filter/api.h> +#include <gr_block.h> + +namespace gr { + namespace filter { + + /*! + * \class pfb_arb_resampler_ccf + * + * \brief Polyphase filterbank arbitrary resampler with + * gr_complex input, gr_complex output and float taps + * + * \ingroup filter_blk + * \ingroup pfb_blk + * + * This block takes in a signal stream and performs arbitrary + * resampling. The resampling rate can be any real number + * <EM>r</EM>. The resampling is done by constructing <EM>N</EM> + * filters where <EM>N</EM> is the interpolation rate. We then + * calculate <EM>D</EM> where <EM>D = floor(N/r)</EM>. + * + * Using <EM>N</EM> and <EM>D</EM>, we can perform rational + * resampling where <EM>N/D</EM> is a rational number close to the + * input rate <EM>r</EM> where we have <EM>N</EM> filters and we + * cycle through them as a polyphase filterbank with a stride of + * <EM>D</EM> so that <EM>i+1 = (i + D) % N</EM>. + * + * To get the arbitrary rate, we want to interpolate between two + * points. For each value out, we take an output from the current + * filter, <EM>i</EM>, and the next filter <EM>i+1</EM> and then + * linearly interpolate between the two based on the real + * resampling rate we want. + * + * The linear interpolation only provides us with an approximation + * to the real sampling rate specified. The error is a + * quantization error between the two filters we used as our + * interpolation points. To this end, the number of filters, + * <EM>N</EM>, used determines the quantization error; the larger + * <EM>N</EM>, the smaller the noise. You can design for a + * specified noise floor by setting the filter size (parameters + * <EM>filter_size</EM>). The size defaults to 32 filters, which + * is about as good as most implementations need. + * + * The trick with designing this filter is in how to specify the + * taps of the prototype filter. Like the PFB interpolator, the + * taps are specified using the interpolated filter rate. In this + * case, that rate is the input sample rate multiplied by the + * number of filters in the filterbank, which is also the + * interpolation rate. All other values should be relative to this + * rate. + * + * For example, for a 32-filter arbitrary resampler and using the + * GNU Radio's firdes utility to build the filter, we build a + * low-pass filter with a sampling rate of <EM>fs</EM>, a 3-dB + * bandwidth of <EM>BW</EM> and a transition bandwidth of + * <EM>TB</EM>. We can also specify the out-of-band attenuation to + * use, <EM>ATT</EM>, and the filter window function (a + * Blackman-harris window in this case). The first input is the + * gain of the filter, which we specify here as the interpolation + * rate (<EM>32</EM>). + * + * <B><EM>self._taps = gr.firdes.low_pass_2(32, 32*fs, BW, TB, + * attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)</EM></B> + * + * The theory behind this block can be found in Chapter 7.5 of + * the following book. + * + * <B><EM>f. harris, "Multirate Signal Processing for Communication + * Systems", Upper Saddle River, NJ: Prentice Hall, Inc. 2004.</EM></B> + */ + + class FILTER_API pfb_arb_resampler_ccf : virtual public gr_block + { + public: + // gr::filter::pfb_arb_resampler_ccf::sptr + typedef boost::shared_ptr<pfb_arb_resampler_ccf> sptr; + + /*! + * Build the polyphase filterbank arbitray resampler. + * \param rate (float) Specifies the resampling rate to use + * \param taps (vector/list of floats) The prototype filter to populate the filterbank. The taps + * should be generated at the filter_size sampling rate. + * \param filter_size (unsigned int) The number of filters in the filter bank. This is directly + * related to quantization noise introduced during the resampling. + * Defaults to 32 filters. + */ + static FILTER_API sptr make(float rate, + const std::vector<float> &taps, + unsigned int filter_size=32); + /*! + * Resets the filterbank's filter taps with the new prototype filter + * \param taps (vector/list of floats) The prototype filter to populate the filterbank. + */ + virtual void set_taps(const std::vector<float> &taps) = 0; + + /*! + * Return a vector<vector<>> of the filterbank taps + */ + virtual std::vector<std::vector<float> > taps() const = 0; + + /*! + * Print all of the filterbank taps to screen. + */ + virtual void print_taps() = 0; + + virtual void set_rate (float rate) = 0; + }; + + } /* namespace filter */ +} /* namespace gr */ + +#endif /* INCLUDED_PFB_ARB_RESAMPLER_CCF_H */ diff --git a/gr-filter/include/filter/pfb_arb_resampler_fff.h b/gr-filter/include/filter/pfb_arb_resampler_fff.h new file mode 100644 index 000000000..7449ea0cb --- /dev/null +++ b/gr-filter/include/filter/pfb_arb_resampler_fff.h @@ -0,0 +1,139 @@ +/* -*- c++ -*- */ +/* + * Copyright 2009-2012 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, + * Boston, MA 02110-1301, USA. + */ + + +#ifndef INCLUDED_PFB_ARB_RESAMPLER_FFF_H +#define INCLUDED_PFB_ARB_RESAMPLER_FFF_H + +#include <filter/api.h> +#include <gr_block.h> + +namespace gr { + namespace filter { + + /*! + * \class pfb_arb_resampler_fff + * + * \brief Polyphase filterbank arbitrary resampler with + * float input, float output and float taps + * + * \ingroup filter_blk + * \ingroup pfb_blk + * + * This block takes in a signal stream and performs arbitrary + * resampling. The resampling rate can be any real number + * <EM>r</EM>. The resampling is done by constructing <EM>N</EM> + * filters where <EM>N</EM> is the interpolation rate. We then + * calculate <EM>D</EM> where <EM>D = floor(N/r)</EM>. + * + * Using <EM>N</EM> and <EM>D</EM>, we can perform rational + * resampling where <EM>N/D</EM> is a rational number close to the + * input rate <EM>r</EM> where we have <EM>N</EM> filters and we + * cycle through them as a polyphase filterbank with a stride of + * <EM>D</EM> so that <EM>i+1 = (i + D) % N</EM>. + * + * To get the arbitrary rate, we want to interpolate between two + * points. For each value out, we take an output from the current + * filter, <EM>i</EM>, and the next filter <EM>i+1</EM> and then + * linearly interpolate between the two based on the real + * resampling rate we want. + * + * The linear interpolation only provides us with an approximation + * to the real sampling rate specified. The error is a + * quantization error between the two filters we used as our + * interpolation points. To this end, the number of filters, + * <EM>N</EM>, used determines the quantization error; the larger + * <EM>N</EM>, the smaller the noise. You can design for a + * specified noise floor by setting the filter size (parameters + * <EM>filter_size</EM>). The size defaults to 32 filters, which + * is about as good as most implementations need. + * + * The trick with designing this filter is in how to specify the + * taps of the prototype filter. Like the PFB interpolator, the + * taps are specified using the interpolated filter rate. In this + * case, that rate is the input sample rate multiplied by the + * number of filters in the filterbank, which is also the + * interpolation rate. All other values should be relative to this + * rate. + * + * For example, for a 32-filter arbitrary resampler and using the + * GNU Radio's firdes utility to build the filter, we build a + * low-pass filter with a sampling rate of <EM>fs</EM>, a 3-dB + * bandwidth of <EM>BW</EM> and a transition bandwidth of + * <EM>TB</EM>. We can also specify the out-of-band attenuation to + * use, <EM>ATT</EM>, and the filter window function (a + * Blackman-harris window in this case). The first input is the + * gain of the filter, which we specify here as the interpolation + * rate (<EM>32</EM>). + * + * <B><EM>self._taps = gr.firdes.low_pass_2(32, 32*fs, BW, TB, + * attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)</EM></B> + * + * The theory behind this block can be found in Chapter 7.5 of the + * following book. + * + * <B><EM>f. harris, "Multirate Signal Processing for Communication + * Systems", Upper Saddle River, NJ: Prentice Hall, Inc. 2004.</EM></B> + */ + + class FILTER_API pfb_arb_resampler_fff : virtual public gr_block + { + public: + // gr::filter::pfb_arb_resampler_fff::sptr + typedef boost::shared_ptr<pfb_arb_resampler_fff> sptr; + + /*! + * Build the polyphase filterbank arbitray resampler. + * \param rate (float) Specifies the resampling rate to use + * \param taps (vector/list of floats) The prototype filter to populate the filterbank. The taps + * should be generated at the filter_size sampling rate. + * \param filter_size (unsigned int) The number of filters in the filter bank. This is directly + * related to quantization noise introduced during the resampling. + * Defaults to 32 filters. + */ + static FILTER_API sptr make(float rate, + const std::vector<float> &taps, + unsigned int filter_size=32); + + /*! + * Resets the filterbank's filter taps with the new prototype filter + * \param taps (vector/list of floats) The prototype filter to populate the filterbank. + */ + virtual void set_taps(const std::vector<float> &taps) = 0; + + /*! + * Return a vector<vector<>> of the filterbank taps + */ + virtual std::vector<std::vector<float> > taps() const = 0; + + /*! + * Print all of the filterbank taps to screen. + */ + virtual void print_taps() = 0; + + virtual void set_rate (float rate) = 0; + }; + + } /* namespace filter */ +} /* namespace gr */ + +#endif /* INCLUDED_PFB_ARB_RESAMPLER_FFF_H */ diff --git a/gr-filter/include/filter/pfb_decimator_ccf.h b/gr-filter/include/filter/pfb_decimator_ccf.h index e0b8dce15..e41f16cd2 100644 --- a/gr-filter/include/filter/pfb_decimator_ccf.h +++ b/gr-filter/include/filter/pfb_decimator_ccf.h @@ -128,4 +128,4 @@ namespace gr { } /* namespace filter */ } /* namespace gr */ -#endif /* INCLUDED_FILTER_PFB_DECIMATOR_CCF_H */ +#endif /* INCLUDED_PFB_DECIMATOR_CCF_H */ |