mirror of
https://github.com/f4exb/sdrangel.git
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58 lines
2.4 KiB
C++
58 lines
2.4 KiB
C++
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///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2015 F4EXB //
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// written by Edouard Griffiths //
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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 as version 3 of the License, or //
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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 V3 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 <math.h>
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#include "rdsdemod.h"
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RDSDemod::RDSDemod()
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{
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m_rdsBB = 0.0;
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m_rdsBB_1 = 0.0;
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m_rdsClockPhase = 0.0;
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m_rdsClockOffset = 0.0;
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m_rdsClockLO = 0.0;
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}
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RDSDemod::~RDSDemod()
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{
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}
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void RDSDemod::process(Real rdsSample, Real pilotSample)
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{
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m_rdsBB = filter_lp_2400_iq(rdsSample, 0); // working on real part only
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// 1187.5 Hz clock
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m_rdsClockPhase = (pilotSample / 48.0) + m_rdsClockOffset;
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m_rdsClockLO = (fmod(m_rdsClockPhase, 2 * M_PI) < M_PI ? 1 : -1);
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}
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Real RDSDemod::filter_lp_2400_iq(Real input, int iqIndex)
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{
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/* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
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Command line: /www/usr/fisher/helpers/mkfilter -Bu -Lp -o 10
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-a 4.8000000000e-03 0.0000000000e+00 -l */
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m_xv[iqIndex][0] = m_xv[iqIndex][1]; m_xv[iqIndex][1] = m_xv[iqIndex][2];
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m_xv[iqIndex][2] = input / 4.491730007e+03;
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m_yv[iqIndex][0] = m_yv[iqIndex][1]; m_yv[iqIndex][1] = m_yv[iqIndex][2];
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m_yv[iqIndex][2] = (m_xv[iqIndex][0] + m_xv[iqIndex][2]) + 2 * m_xv[iqIndex][1]
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+ ( -0.9582451124 * m_yv[iqIndex][0]) + ( 1.9573545869 * m_yv[iqIndex][1]);
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return m_yv[iqIndex][2];
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}
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