Bastian Bloessl
64 lines
2.2 KiB
C++
64 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 "linear_comb.h"
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using namespace gr::ieee802_11::equalizer;
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void linear_comb::equalize(const gr_complex *in, gr_complex *out, int n) {
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if(n < 2)
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return;
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double avg_mag = (abs(in[11]) + abs(in[25]) + abs(in[39]) + abs(in[53])) / 4;
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gr_complex p = POLARITY[(n - 2) % 127 ];
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double p1 = arg( p * in[11]);
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double p2 = arg( p * in[25] * conj(p * in[11])) + p1;
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double p3 = arg( p * in[39] * conj(p * in[25])) + p2;
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double p4 = arg(-p * in[53] * conj(p * in[39])) + p3;
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double my = (p1 + p2 + p3 + p4) / 4;
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double mx = (11.0 + 25 + 39 + 53) / 4;
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double var = (((11.0 * 11.0) + (25.0 * 25.0) + (39.0 * 39.0) + (53.0 * 53.0)) / 4) - (mx * mx);
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double cov = (( (p1 * 11) + (p2 * 25) + (p3 * 39) + (p4 * 53) ) / 4) - (mx * my);
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double beta = cov / var;
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double alpha = my - beta * mx;
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int c = 0;
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for(int n = 0; n < 64; n++) {
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if( (n == 11) || (n == 25) || (n == 32) || (n == 39) || (n == 53) || (n < 6) || ( n > 58)) {
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continue;
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} else {
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out[c] = in[n] * exp(gr_complex(0, -n * beta - alpha)) * gr_complex(1 / avg_mag, 0);
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c++;
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}
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}
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}
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const gr_complex linear_comb::POLARITY[127] = {
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1, 1, 1, 1,-1,-1,-1, 1,-1,-1,-1,-1, 1, 1,-1, 1,
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-1,-1, 1, 1,-1, 1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,
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1, 1,-1, 1, 1,-1,-1, 1, 1, 1,-1, 1,-1,-1,-1, 1,
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-1, 1,-1,-1, 1,-1,-1, 1, 1, 1, 1, 1,-1,-1, 1, 1,
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-1,-1, 1,-1, 1,-1, 1, 1,-1,-1,-1, 1, 1,-1,-1,-1,
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-1, 1,-1,-1, 1,-1, 1, 1, 1, 1,-1, 1,-1, 1,-1, 1,
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-1,-1,-1,-1,-1, 1,-1, 1, 1,-1, 1,-1, 1, 1, 1,-1,
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-1, 1,-1,-1,-1, 1, 1, 1,-1,-1,-1,-1,-1,-1,-1 };
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