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Diffstat (limited to 'gr-digital/lib/digital_fll_band_edge_cc.h')
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diff --git a/gr-digital/lib/digital_fll_band_edge_cc.h b/gr-digital/lib/digital_fll_band_edge_cc.h deleted file mode 100644 index 6ef8376ac..000000000 --- a/gr-digital/lib/digital_fll_band_edge_cc.h +++ /dev/null @@ -1,213 +0,0 @@ -/* -*- c++ -*- */ -/* - * Copyright 2009,2011 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_DIGITAL_FLL_BAND_EDGE_CC_H -#define INCLUDED_DIGITAL_FLL_BAND_EDGE_CC_H - -#include <digital_api.h> -#include <gr_sync_block.h> -#include <gri_control_loop.h> - -class digital_fll_band_edge_cc; -typedef boost::shared_ptr<digital_fll_band_edge_cc> digital_fll_band_edge_cc_sptr; -DIGITAL_API digital_fll_band_edge_cc_sptr digital_make_fll_band_edge_cc (float samps_per_sym, - float rolloff, - int filter_size, - float bandwidth); - -/*! - * \class digital_fll_band_edge_cc - * \brief Frequency Lock Loop using band-edge filters - * - * \ingroup general - * - * The frequency lock loop derives a band-edge filter that covers the - * upper and lower bandwidths of a digitally-modulated signal. The - * bandwidth range is determined by the excess bandwidth (e.g., - * rolloff factor) of the modulated signal. The placement in frequency - * of the band-edges is determined by the oversampling ratio (number - * of samples per symbol) and the excess bandwidth. The size of the - * filters should be fairly large so as to average over a number of - * symbols. - * - * The FLL works by filtering the upper and lower band edges into - * x_u(t) and x_l(t), respectively. These are combined to form cc(t) - * = x_u(t) + x_l(t) and ss(t) = x_u(t) - x_l(t). Combining these to - * form the signal e(t) = Re{cc(t) \\times ss(t)^*} (where ^* is the - * complex conjugate) provides an error signal at the DC term that is - * directly proportional to the carrier frequency. We then make a - * second-order loop using the error signal that is the running - * average of e(t). - * - * In practice, the above equation can be simplified by just comparing - * the absolute value squared of the output of both filters: - * abs(x_l(t))^2 - abs(x_u(t))^2 = norm(x_l(t)) - norm(x_u(t)). - * - * In theory, the band-edge filter is the derivative of the matched - * filter in frequency, (H_be(f) = \\frac{H(f)}{df}. In practice, this - * comes down to a quarter sine wave at the point of the matched - * filter's rolloff (if it's a raised-cosine, the derivative of a - * cosine is a sine). Extend this sine by another quarter wave to - * make a half wave around the band-edges is equivalent in time to the - * sum of two sinc functions. The baseband filter fot the band edges - * is therefore derived from this sum of sincs. The band edge filters - * are then just the baseband signal modulated to the correct place in - * frequency. All of these calculations are done in the - * 'design_filter' function. - * - * Note: We use FIR filters here because the filters have to have a - * flat phase response over the entire frequency range to allow their - * comparisons to be valid. - * - * It is very important that the band edge filters be the derivatives - * of the pulse shaping filter, and that they be linear - * phase. Otherwise, the variance of the error will be very large. - * - */ - -class DIGITAL_API digital_fll_band_edge_cc : public gr_sync_block, public gri_control_loop -{ - private: - /*! - * Build the FLL - * \param samps_per_sym (float) Number of samples per symbol of signal - * \param rolloff (float) Rolloff factor of signal - * \param filter_size (int) Size (in taps) of the filter - * \param bandwidth (float) Loop bandwidth - */ - friend DIGITAL_API digital_fll_band_edge_cc_sptr digital_make_fll_band_edge_cc (float samps_per_sym, - float rolloff, - int filter_size, - float bandwidth); - - float d_sps; - float d_rolloff; - int d_filter_size; - - std::vector<gr_complex> d_taps_lower; - std::vector<gr_complex> d_taps_upper; - bool d_updated; - - /*! - * Build the FLL - * \param samps_per_sym (float) number of samples per symbol - * \param rolloff (float) Rolloff (excess bandwidth) of signal filter - * \param filter_size (int) number of filter taps to generate - * \param bandwidth (float) Loop bandwidth - */ - digital_fll_band_edge_cc(float samps_per_sym, float rolloff, - int filter_size, float bandwidth); - - /*! - * Design the band-edge filter based on the number of samples per symbol, - * filter rolloff factor, and the filter size - * - * \param samps_per_sym (float) Number of samples per symbol of signal - * \param rolloff (float) Rolloff factor of signal - * \param filter_size (int) Size (in taps) of the filter - */ - void design_filter(float samps_per_sym, float rolloff, int filter_size); - -public: - ~digital_fll_band_edge_cc (); - - /******************************************************************* - SET FUNCTIONS - *******************************************************************/ - - /*! - * \brief Set the number of samples per symbol - * - * Set's the number of samples per symbol the system should - * use. This value is uesd to calculate the filter taps and will - * force a recalculation. - * - * \param sps (float) new samples per symbol - * - */ - void set_samples_per_symbol(float sps); - - /*! - * \brief Set the rolloff factor of the shaping filter - * - * This sets the rolloff factor that is used in the pulse shaping - * filter and is used to calculate the filter taps. Changing this - * will force a recalculation of the filter taps. - * - * This should be the same value that is used in the transmitter's - * pulse shaping filter. It must be between 0 and 1 and is usually - * between 0.2 and 0.5 (where 0.22 and 0.35 are commonly used - * values). - * - * \param rolloff (float) new shaping filter rolloff factor [0,1] - * - */ - void set_rolloff(float rolloff); - - /*! - * \brief Set the number of taps in the filter - * - * This sets the number of taps in the band-edge filters. Setting - * this will force a recalculation of the filter taps. - * - * This should be about the same number of taps used in the - * transmitter's shaping filter and also not very large. A large - * number of taps will result in a large delay between input and - * frequency estimation, and so will not be as accurate. Between 30 - * and 70 taps is usual. - * - * \param filter_size (float) number of taps in the filters - * - */ - void set_filter_size(int filter_size); - - /******************************************************************* - GET FUNCTIONS - *******************************************************************/ - - /*! - * \brief Returns the number of sampler per symbol used for the filter - */ - float get_samples_per_symbol() const; - - /*! - * \brief Returns the rolloff factor used for the filter - */ - float get_rolloff() const; - - /*! - * \brief Returns the number of taps of the filter - */ - int get_filter_size() const; - - /*! - * Print the taps to screen. - */ - void print_taps(); - - int work (int noutput_items, - gr_vector_const_void_star &input_items, - gr_vector_void_star &output_items); -}; - -#endif |