Bastian Bloessl
78 lines
2.2 KiB
C++
78 lines
2.2 KiB
C++
/*
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* Copyright (C) 2015 Bastian Bloessl <bloessl@ccs-labs.org>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "comb.h"
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using namespace gr::ieee802_11::equalizer;
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void comb::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, boost::shared_ptr<gr::digital::constellation> mod) {
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gr_complex pilot[4];
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if(n < 2) {
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pilot[0] = in[11];
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pilot[1] = -in[25];
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pilot[2] = in[39];
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pilot[3] = in[53];
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} else {
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gr_complex p = POLARITY[(n - 2) % 127];
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pilot[0] = in[11] * p;
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pilot[1] = in[25] * p;
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pilot[2] = in[39] * p;
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pilot[3] = in[53] * -p;
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}
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gr_complex avg = (pilot[0] + pilot[1] + pilot[2] + pilot[3]) / gr_complex(4, 0);
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for(int i = 0; i < 64; i++) {
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gr_complex H;
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if(i <= 11) {
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H = gr_complex((11-i) / 11.0, 0) * avg + gr_complex( i / 11.0, 0) * pilot[0];
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} else if(i <= 25) {
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H = gr_complex((25-i) / 14.0, 0) * pilot[0] + gr_complex((i-11) / 14.0, 0) * pilot[1];
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} else if(i <= 39) {
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H = gr_complex((39-i) / 14.0, 0) * pilot[1] + gr_complex((i-25) / 14.0, 0) * pilot[2];
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} else if(i <= 53) {
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H = gr_complex((53-i) / 14.0, 0) * pilot[2] + gr_complex((i-39) / 14.0, 0) * pilot[3];
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} else {
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H = gr_complex((64-i) / 11.0, 0) * pilot[3] + gr_complex((i-53) / 11.0, 0) * avg;
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}
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if(n == 0) {
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d_H[i] = H;
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} else {
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d_H[i] = gr_complex(1-alpha, 0) * d_H[i] + gr_complex(alpha, 0) * H;
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}
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}
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int c = 0;
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for(int i = 0; i < 64; i++) {
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if( (i == 11) || (i == 25) || (i == 32) || (i == 39) || (i == 53) || (i < 6) || ( i > 58)) {
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continue;
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} else {
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symbols[c] = in[i] / d_H[i];
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bits[c] = mod->decision_maker(&symbols[c]);
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c++;
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}
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}
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}
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double
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comb::get_snr() {
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return 42;
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}
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