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https://github.com/DSheirer/sdrtrunk.git
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9dda1f95a1
Fleetsync II decoder to use it. Adds instrumented version of the decoder and a new Fleetsync2 FX pane to the DemodulatorViewerFX tool. Note: the remaining AFSK-1200 based decoders will all be ported to use this new AFSK1200 decoder (MDC1200, Tait1200, LowJack1200).
123 lines
4.9 KiB
Java
123 lines
4.9 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.afsk;
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import io.github.dsheirer.buffer.FloatAveragingBuffer;
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import io.github.dsheirer.dsp.mixer.IOscillator;
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import io.github.dsheirer.dsp.mixer.Oscillator;
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import io.github.dsheirer.sample.complex.Complex;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.text.DecimalFormat;
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public class AFSKTest
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{
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private final static Logger mLog = LoggerFactory.getLogger(AFSK1200Decoder.class);
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private static final DecimalFormat df = new DecimalFormat("00.000");
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public static String format(double value)
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{
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if(value > 0)
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{
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return " " + df.format(value);
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}
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else
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{
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return df.format(value);
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}
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}
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public static float[] generateAFSK1200(boolean[] symbols, int samplesPerSymbol, float gain)
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{
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float[] samples = new float[symbols.length * samplesPerSymbol];
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Oscillator oscillator = new Oscillator(1200.0, (double)samplesPerSymbol * 1200);
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for(int x = 0; x < symbols.length; x++)
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{
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oscillator.setFrequency(symbols[x] ? 1200.0 : 1800.0);
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for(int y = 0; y < samplesPerSymbol; y++)
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{
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Complex sample = new Complex(oscillator.inphase(), oscillator.quadrature());
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sample.multiply(gain);
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samples[x * samplesPerSymbol + y] = sample.inphase();
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oscillator.rotate();
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}
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}
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return samples;
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}
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public static void main(String[] args)
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{
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int sampleSize = 6;
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FloatAveragingBuffer avg1200 = new FloatAveragingBuffer(sampleSize);
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FloatAveragingBuffer avg1800 = new FloatAveragingBuffer(sampleSize);
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IOscillator oscillator1200 = new Oscillator(1200.0, 7200.0);
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IOscillator oscillator1800 = new Oscillator(1800.0, 7200.0);
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oscillator1200.generateReal(1);
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oscillator1800.generateReal(1);
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float[] reference1200 = oscillator1200.generateReal(sampleSize);
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float[] reference1800 = oscillator1800.generateReal(sampleSize);
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boolean[] symbols = new boolean[]{true,false,true,false,true,false,true,false,true,true,true,false,true,false,
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false,false,true,false,false,false,false,true,false,true,true,true,true,false,true,true,false,true,false,
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true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,
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false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,
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true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,
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false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,
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true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,
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false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,true,false,
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true,false,false,false,false,false,false,false,false,false,false,false,false,false,false,false,false,
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false,false,false,false,false,false,false,false,false,false,false,false,false,false,false,false,false};
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float[] samples = generateAFSK1200(symbols, 6, 0.5f);
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mLog.debug("Length:" + samples.length);
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int offset = 0;
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float correlation1200 = 0.0f;
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float correlation1800 = 0.0f;
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while(offset + sampleSize < samples.length)
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{
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correlation1200 = 0.0f;
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correlation1800 = 0.0f;
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for(int x = 0; x < sampleSize; x++)
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{
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correlation1200 += reference1200[x] * samples[x + offset];
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correlation1800 += reference1800[x] * samples[x + offset];
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}
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correlation1200 = avg1200.get(Math.abs(correlation1200));
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correlation1800 = avg1800.get(Math.abs(correlation1800));
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mLog.debug(offset + " 1200:" + format(correlation1200) + " 1800:" + format(correlation1800) +
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" Decision: " + (correlation1200 > correlation1800 ? "0" : "1"));
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offset++;
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}
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}
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}
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