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BFM demod: added RDS demodulator class

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f4exb 2015-12-10 08:54:57 +01:00
parent 0259868ebe
commit 0705461d8a
2 changed files with 98 additions and 0 deletions
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57
plugins/channel/bfm/rdsdemod.cpp Normal file
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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015 F4EXB //
// written by Edouard Griffiths //
// //
// This program 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 as version 3 of the License, or //
// //
// This program 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 V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <math.h>
#include "rdsdemod.h"
RDSDemod::RDSDemod()
{
m_rdsBB = 0.0;
m_rdsBB_1 = 0.0;
m_rdsClockPhase = 0.0;
m_rdsClockOffset = 0.0;
m_rdsClockLO = 0.0;
}
RDSDemod::~RDSDemod()
{
}
void RDSDemod::process(Real rdsSample, Real pilotSample)
{
m_rdsBB = filter_lp_2400_iq(rdsSample, 0); // working on real part only
// 1187.5 Hz clock
m_rdsClockPhase = (pilotSample / 48.0) + m_rdsClockOffset;
m_rdsClockLO = (fmod(m_rdsClockPhase, 2 * M_PI) < M_PI ? 1 : -1);
}
Real RDSDemod::filter_lp_2400_iq(Real input, int iqIndex)
{
/* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
Command line: /www/usr/fisher/helpers/mkfilter -Bu -Lp -o 10
-a 4.8000000000e-03 0.0000000000e+00 -l */
m_xv[iqIndex][0] = m_xv[iqIndex][1]; m_xv[iqIndex][1] = m_xv[iqIndex][2];
m_xv[iqIndex][2] = input / 4.491730007e+03;
m_yv[iqIndex][0] = m_yv[iqIndex][1]; m_yv[iqIndex][1] = m_yv[iqIndex][2];
m_yv[iqIndex][2] = (m_xv[iqIndex][0] + m_xv[iqIndex][2]) + 2 * m_xv[iqIndex][1]
+ ( -0.9582451124 * m_yv[iqIndex][0]) + ( 1.9573545869 * m_yv[iqIndex][1]);
return m_yv[iqIndex][2];
}

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plugins/channel/bfm/rdsdemod.h Normal file
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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015 F4EXB //
// written by Edouard Griffiths //
// //
// This program 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 as version 3 of the License, or //
// //
// This program 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 V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#ifndef PLUGINS_CHANNEL_BFM_RDSDEMOD_H_
#define PLUGINS_CHANNEL_BFM_RDSDEMOD_H_
class RDSDemod
{
public:
RDSDemod();
~RDSDemod();
void process(Real rdsSample, Real pilotSample);
Real filter_lp_2400_iq(Real in, int iqIndex);
private:
Real m_xv[2][2+1];
Real m_yv[2][2+1];
Real m_rdsBB;
Real m_rdsBB_1;
Real m_rdsClockPhase;
Real m_rdsClockOffset;
Real m_rdsClockLO;
};
#endif /* PLUGINS_CHANNEL_BFM_RDSDEMOD_H_ */