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Diffstat (limited to 'gr-digital/lib/digital_fll_band_edge_cc.cc')
| -rw-r--r-- | gr-digital/lib/digital_fll_band_edge_cc.cc | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/gr-digital/lib/digital_fll_band_edge_cc.cc b/gr-digital/lib/digital_fll_band_edge_cc.cc new file mode 100644 index 000000000..05c092622 --- /dev/null +++ b/gr-digital/lib/digital_fll_band_edge_cc.cc @@ -0,0 +1,259 @@ +/* -*- 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. + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include <digital_fll_band_edge_cc.h> +#include <gr_io_signature.h> +#include <gr_expj.h> +#include <cstdio> + +#define M_TWOPI (2*M_PI) + +float sinc(float x) +{ + if(x == 0) + return 1; + else + return sin(M_PI*x)/(M_PI*x); +} + +digital_fll_band_edge_cc_sptr +digital_make_fll_band_edge_cc (float samps_per_sym, float rolloff, + int filter_size, float bandwidth) +{ + return gnuradio::get_initial_sptr(new digital_fll_band_edge_cc (samps_per_sym, rolloff, + filter_size, bandwidth)); +} + + +static int ios[] = {sizeof(gr_complex), sizeof(float), sizeof(float), sizeof(float)}; +static std::vector<int> iosig(ios, ios+sizeof(ios)/sizeof(int)); +digital_fll_band_edge_cc::digital_fll_band_edge_cc (float samps_per_sym, float rolloff, + int filter_size, float bandwidth) + : gr_sync_block ("fll_band_edge_cc", + gr_make_io_signature (1, 1, sizeof(gr_complex)), + gr_make_io_signaturev (1, 4, iosig)), + gri_control_loop(bandwidth, M_TWOPI*(2.0/samps_per_sym), -M_TWOPI*(2.0/samps_per_sym)), + d_updated (false) +{ + // Initialize samples per symbol + if(samps_per_sym <= 0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid number of sps. Must be > 0."); + } + d_sps = samps_per_sym; + + // Initialize rolloff factor + if(rolloff < 0 || rolloff > 1.0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid rolloff factor. Must be in [0,1]."); + } + d_rolloff = rolloff; + + // Initialize filter length + if(filter_size <= 0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid filter size. Must be > 0."); + } + d_filter_size = filter_size; + + // Build the band edge filters + design_filter(d_sps, d_rolloff, d_filter_size); +} + +digital_fll_band_edge_cc::~digital_fll_band_edge_cc () +{ +} + + +/******************************************************************* + SET FUNCTIONS +*******************************************************************/ + +void +digital_fll_band_edge_cc::set_samples_per_symbol(float sps) +{ + if(sps <= 0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid number of sps. Must be > 0."); + } + d_sps = sps; + design_filter(d_sps, d_rolloff, d_filter_size); +} + +void +digital_fll_band_edge_cc::set_rolloff(float rolloff) +{ + if(rolloff < 0 || rolloff > 1.0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid rolloff factor. Must be in [0,1]."); + } + d_rolloff = rolloff; + design_filter(d_sps, d_rolloff, d_filter_size); +} + +void +digital_fll_band_edge_cc::set_filter_size(int filter_size) +{ + if(filter_size <= 0) { + throw std::out_of_range ("digital_fll_band_edge_cc: invalid filter size. Must be > 0."); + } + d_filter_size = filter_size; + design_filter(d_sps, d_rolloff, d_filter_size); +} + +/******************************************************************* + GET FUNCTIONS +*******************************************************************/ + +float +digital_fll_band_edge_cc::get_samples_per_symbol() const +{ + return d_sps; +} + +float +digital_fll_band_edge_cc::get_rolloff() const +{ + return d_rolloff; +} + +int +digital_fll_band_edge_cc:: get_filter_size() const +{ + return d_filter_size; +} + + +/******************************************************************* +*******************************************************************/ + +void +digital_fll_band_edge_cc::design_filter(float samps_per_sym, + float rolloff, int filter_size) +{ + int M = rint(filter_size / samps_per_sym); + float power = 0; + + // Create the baseband filter by adding two sincs together + std::vector<float> bb_taps; + for(int i = 0; i < filter_size; i++) { + float k = -M + i*2.0/samps_per_sym; + float tap = sinc(rolloff*k - 0.5) + sinc(rolloff*k + 0.5); + power += tap; + + bb_taps.push_back(tap); + } + + d_taps_lower.resize(filter_size); + d_taps_upper.resize(filter_size); + + // Create the band edge filters by spinning the baseband + // filter up and down to the right places in frequency. + // Also, normalize the power in the filters + int N = (bb_taps.size() - 1.0)/2.0; + for(int i = 0; i < filter_size; i++) { + float tap = bb_taps[i] / power; + + float k = (-N + (int)i)/(2.0*samps_per_sym); + + gr_complex t1 = tap * gr_expj(-M_TWOPI*(1+rolloff)*k); + gr_complex t2 = tap * gr_expj(M_TWOPI*(1+rolloff)*k); + + d_taps_lower[filter_size-i-1] = t1; + d_taps_upper[filter_size-i-1] = t2; + } + + d_updated = true; + + // Set the history to ensure enough input items for each filter + set_history(filter_size+1); +} + +void +digital_fll_band_edge_cc::print_taps() +{ + unsigned int i; + + printf("Upper Band-edge: ["); + for(i = 0; i < d_taps_upper.size(); i++) { + printf(" %.4e + %.4ej,", d_taps_upper[i].real(), d_taps_upper[i].imag()); + } + printf("]\n\n"); + + printf("Lower Band-edge: ["); + for(i = 0; i < d_taps_lower.size(); i++) { + printf(" %.4e + %.4ej,", d_taps_lower[i].real(), d_taps_lower[i].imag()); + } + printf("]\n\n"); +} + +int +digital_fll_band_edge_cc::work (int noutput_items, + gr_vector_const_void_star &input_items, + gr_vector_void_star &output_items) +{ + const gr_complex *in = (const gr_complex *) input_items[0]; + gr_complex *out = (gr_complex *) output_items[0]; + + float *frq = NULL; + float *phs = NULL; + float *err = NULL; + if(output_items.size() == 4) { + frq = (float *) output_items[1]; + phs = (float *) output_items[2]; + err = (float *) output_items[3]; + } + + if (d_updated) { + d_updated = false; + return 0; // history requirements may have changed. + } + + int i; + float error; + gr_complex nco_out; + gr_complex out_upper, out_lower; + for(i = 0; i < noutput_items; i++) { + nco_out = gr_expj(d_phase); + out[i+d_filter_size-1] = in[i] * nco_out; + + // Perform the dot product of the output with the filters + out_upper = 0; + out_lower = 0; + for(int k = 0; k < d_filter_size; k++) { + out_upper += d_taps_upper[k] * out[i+k]; + out_lower += d_taps_lower[k] * out[i+k]; + } + error = norm(out_lower) - norm(out_upper); + + advance_loop(error); + phase_wrap(); + frequency_limit(); + + if(output_items.size() == 4) { + frq[i] = d_freq; + phs[i] = d_phase; + err[i] = error; + } + } + + return noutput_items; +} |