mirror of
https://github.com/DSheirer/sdrtrunk.git
synced 2026-11-12 08:37:25 -05:00
eaf7c7d11e
based on the P25 LSM decoder using a costas loop and a gardner detector. Updates the Demodulator Viewer FX application to add in a symbol chart and a phase error chart. The decoder won't lock on yet ... still a wip.
91 lines
2.2 KiB
Java
91 lines
2.2 KiB
Java
/*******************************************************************************
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* sdr-trunk
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* Copyright (C) 2014-2018 Dennis Sheirer
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*
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* This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 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 along with this program.
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* If not, see <http://www.gnu.org/licenses/>
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*
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******************************************************************************/
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package io.github.dsheirer.dsp.psk;
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import io.github.dsheirer.dsp.symbol.Dibit;
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import io.github.dsheirer.sample.Broadcaster;
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import io.github.dsheirer.sample.Listener;
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import io.github.dsheirer.sample.complex.Complex;
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public class QPSKSymbolDecoder implements Listener<Complex>, IQPSKSymbolDecoder
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{
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private Broadcaster<Dibit> mBroadcaster = new Broadcaster<Dibit>();
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/**
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* Slices a ComplexSample representing a phase shifted symbol according to
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* the following constellation pattern:
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*
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* \ 00 /
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* \ /
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* 01 \/ 10
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* /\
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* / \
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* / 11 \
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*/
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public QPSKSymbolDecoder()
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{
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}
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public void dispose()
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{
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mBroadcaster.dispose();
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mBroadcaster = null;
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}
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public void addListener( Listener<Dibit> listener )
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{
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mBroadcaster.addListener( listener );
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}
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public void removeListener( Listener<Dibit> listener )
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{
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mBroadcaster.removeListener( listener );
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}
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@Override
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public void receive( Complex complex )
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{
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mBroadcaster.broadcast( decode( complex ) );
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}
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public Dibit decode(Complex complex )
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{
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if( Math.abs( complex.inphase() ) > Math.abs( complex.quadrature() ) )
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{
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if( complex.inphase() > 0 )
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{
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return Dibit.D10_MINUS_1;
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}
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else
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{
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return Dibit.D01_PLUS_3;
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}
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}
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else
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{
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if( complex.quadrature() > 0 )
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{
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return Dibit.D00_PLUS_1;
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}
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else
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{
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return Dibit.D11_MINUS_3;
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}
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}
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}
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}
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