diff options
Diffstat (limited to 'gr-digital/lib/digital_ofdm_frame_acquisition.cc')
| -rw-r--r-- | gr-digital/lib/digital_ofdm_frame_acquisition.cc | 210 |
1 files changed, 0 insertions, 210 deletions
diff --git a/gr-digital/lib/digital_ofdm_frame_acquisition.cc b/gr-digital/lib/digital_ofdm_frame_acquisition.cc deleted file mode 100644 index 93b58aeca..000000000 --- a/gr-digital/lib/digital_ofdm_frame_acquisition.cc +++ /dev/null @@ -1,210 +0,0 @@ -/* -*- c++ -*- */ -/* - * Copyright 2006-2008,2010,2011 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_ofdm_frame_acquisition.h> -#include <gr_io_signature.h> -#include <gr_expj.h> -#include <gr_math.h> -#include <cstdio> - -#define VERBOSE 0 -#define M_TWOPI (2*M_PI) -#define MAX_NUM_SYMBOLS 1000 - -digital_ofdm_frame_acquisition_sptr -digital_make_ofdm_frame_acquisition (unsigned int occupied_carriers, - unsigned int fft_length, - unsigned int cplen, - const std::vector<gr_complex> &known_symbol, - unsigned int max_fft_shift_len) -{ - return gnuradio::get_initial_sptr(new digital_ofdm_frame_acquisition (occupied_carriers, fft_length, cplen, - known_symbol, max_fft_shift_len)); -} - -digital_ofdm_frame_acquisition::digital_ofdm_frame_acquisition (unsigned occupied_carriers, - unsigned int fft_length, - unsigned int cplen, - const std::vector<gr_complex> &known_symbol, - unsigned int max_fft_shift_len) - : gr_block ("ofdm_frame_acquisition", - gr_make_io_signature2 (2, 2, sizeof(gr_complex)*fft_length, sizeof(char)*fft_length), - gr_make_io_signature2 (2, 2, sizeof(gr_complex)*occupied_carriers, sizeof(char))), - d_occupied_carriers(occupied_carriers), - d_fft_length(fft_length), - d_cplen(cplen), - d_freq_shift_len(max_fft_shift_len), - d_known_symbol(known_symbol), - d_coarse_freq(0), - d_phase_count(0) -{ - d_symbol_phase_diff.resize(d_fft_length); - d_known_phase_diff.resize(d_occupied_carriers); - d_hestimate.resize(d_occupied_carriers); - - unsigned int i = 0, j = 0; - - std::fill(d_known_phase_diff.begin(), d_known_phase_diff.end(), 0); - for(i = 0; i < d_known_symbol.size()-2; i+=2) { - d_known_phase_diff[i] = norm(d_known_symbol[i] - d_known_symbol[i+2]); - } - - d_phase_lut = new gr_complex[(2*d_freq_shift_len+1) * MAX_NUM_SYMBOLS]; - for(i = 0; i <= 2*d_freq_shift_len; i++) { - for(j = 0; j < MAX_NUM_SYMBOLS; j++) { - d_phase_lut[j + i*MAX_NUM_SYMBOLS] = gr_expj(-M_TWOPI*d_cplen/d_fft_length*(i-d_freq_shift_len)*j); - } - } -} - -digital_ofdm_frame_acquisition::~digital_ofdm_frame_acquisition(void) -{ - delete [] d_phase_lut; -} - -void -digital_ofdm_frame_acquisition::forecast (int noutput_items, gr_vector_int &ninput_items_required) -{ - unsigned ninputs = ninput_items_required.size (); - for (unsigned i = 0; i < ninputs; i++) - ninput_items_required[i] = 1; -} - -gr_complex -digital_ofdm_frame_acquisition::coarse_freq_comp(int freq_delta, int symbol_count) -{ - // return gr_complex(cos(-M_TWOPI*freq_delta*d_cplen/d_fft_length*symbol_count), - // sin(-M_TWOPI*freq_delta*d_cplen/d_fft_length*symbol_count)); - - return gr_expj(-M_TWOPI*freq_delta*d_cplen/d_fft_length*symbol_count); - - //return d_phase_lut[MAX_NUM_SYMBOLS * (d_freq_shift_len + freq_delta) + symbol_count]; -} - -void -digital_ofdm_frame_acquisition::correlate(const gr_complex *symbol, int zeros_on_left) -{ - unsigned int i,j; - - std::fill(d_symbol_phase_diff.begin(), d_symbol_phase_diff.end(), 0); - for(i = 0; i < d_fft_length-2; i++) { - d_symbol_phase_diff[i] = norm(symbol[i] - symbol[i+2]); - } - - // sweep through all possible/allowed frequency offsets and select the best - int index = 0; - float max = 0, sum=0; - for(i = zeros_on_left - d_freq_shift_len; i < zeros_on_left + d_freq_shift_len; i++) { - sum = 0; - for(j = 0; j < d_occupied_carriers; j++) { - sum += (d_known_phase_diff[j] * d_symbol_phase_diff[i+j]); - } - if(sum > max) { - max = sum; - index = i; - } - } - - // set the coarse frequency offset relative to the edge of the occupied tones - d_coarse_freq = index - zeros_on_left; -} - -void -digital_ofdm_frame_acquisition::calculate_equalizer(const gr_complex *symbol, int zeros_on_left) -{ - unsigned int i=0; - - // Set first tap of equalizer - d_hestimate[0] = d_known_symbol[0] / - (coarse_freq_comp(d_coarse_freq,1)*symbol[zeros_on_left+d_coarse_freq]); - - // set every even tap based on known symbol - // linearly interpolate between set carriers to set zero-filled carriers - // FIXME: is this the best way to set this? - for(i = 2; i < d_occupied_carriers; i+=2) { - d_hestimate[i] = d_known_symbol[i] / - (coarse_freq_comp(d_coarse_freq,1)*(symbol[i+zeros_on_left+d_coarse_freq])); - d_hestimate[i-1] = (d_hestimate[i] + d_hestimate[i-2]) / gr_complex(2.0, 0.0); - } - - // with even number of carriers; last equalizer tap is wrong - if(!(d_occupied_carriers & 1)) { - d_hestimate[d_occupied_carriers-1] = d_hestimate[d_occupied_carriers-2]; - } - - if(VERBOSE) { - fprintf(stderr, "Equalizer setting:\n"); - for(i = 0; i < d_occupied_carriers; i++) { - gr_complex sym = coarse_freq_comp(d_coarse_freq,1)*symbol[i+zeros_on_left+d_coarse_freq]; - gr_complex output = sym * d_hestimate[i]; - fprintf(stderr, "sym: %+.4f + j%+.4f ks: %+.4f + j%+.4f eq: %+.4f + j%+.4f ==> %+.4f + j%+.4f\n", - sym .real(), sym.imag(), - d_known_symbol[i].real(), d_known_symbol[i].imag(), - d_hestimate[i].real(), d_hestimate[i].imag(), - output.real(), output.imag()); - } - fprintf(stderr, "\n"); - } -} - -int -digital_ofdm_frame_acquisition::general_work(int noutput_items, - gr_vector_int &ninput_items, - gr_vector_const_void_star &input_items, - gr_vector_void_star &output_items) -{ - const gr_complex *symbol = (const gr_complex *)input_items[0]; - const char *signal_in = (const char *)input_items[1]; - - gr_complex *out = (gr_complex *) output_items[0]; - char *signal_out = (char *) output_items[1]; - - int unoccupied_carriers = d_fft_length - d_occupied_carriers; - int zeros_on_left = (int)ceil(unoccupied_carriers/2.0); - - if(signal_in[0]) { - d_phase_count = 1; - correlate(symbol, zeros_on_left); - calculate_equalizer(symbol, zeros_on_left); - signal_out[0] = 1; - } - else { - signal_out[0] = 0; - } - - for(unsigned int i = 0; i < d_occupied_carriers; i++) { - out[i] = d_hestimate[i]*coarse_freq_comp(d_coarse_freq,d_phase_count) - *symbol[i+zeros_on_left+d_coarse_freq]; - } - - d_phase_count++; - if(d_phase_count == MAX_NUM_SYMBOLS) { - d_phase_count = 1; - } - - consume_each(1); - return 1; -} |