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#1565 updates LTR, LTRNet and Passport decoders with new slope decoder. Resolves issue with LTR Standard decoder state that was combining individual calls to the same talkgroup and causing excessively long calls. (#1567)

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Co-authored-by: Dennis Sheirer <dsheirer@github.com>
This commit is contained in:
Denny Sheirer
2023-06-05 06:13:12 -04:00
committed by GitHub
parent 5b6377cc11
commit 19f7a5171b
34 changed files with 707 additions and 463 deletions
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114
src/main/java/io/github/dsheirer/module/demodulate/fm/FMDemodulatorModule.java
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@@ -1,6 +1,6 @@
/*
* *****************************************************************************
* Copyright (C) 2014-2022 Dennis Sheirer
* Copyright (C) 2014-2023 Dennis Sheirer
*
* 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
@@ -19,11 +19,14 @@
package io.github.dsheirer.module.demodulate.fm;
import io.github.dsheirer.dsp.filter.FilterFactory;
import io.github.dsheirer.dsp.filter.decimate.DecimationFilterFactory;
import io.github.dsheirer.dsp.filter.decimate.IRealDecimationFilter;
import io.github.dsheirer.dsp.filter.design.FilterDesignException;
import io.github.dsheirer.dsp.filter.fir.FIRFilterSpecification;
import io.github.dsheirer.dsp.filter.fir.real.IRealFilter;
import io.github.dsheirer.dsp.filter.resample.RealResampler;
import io.github.dsheirer.dsp.fm.ScalarFMDemodulator;
import io.github.dsheirer.dsp.fm.FmDemodulatorFactory;
import io.github.dsheirer.dsp.fm.IDemodulator;
import io.github.dsheirer.dsp.squelch.PowerMonitor;
import io.github.dsheirer.dsp.window.WindowType;
import io.github.dsheirer.module.Module;
@@ -46,16 +49,17 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
IComplexSamplesListener, Listener<ComplexSamples>, IRealBufferProvider
{
private final static Logger mLog = LoggerFactory.getLogger(FMDemodulatorModule.class);
private static final double DEMODULATED_AUDIO_SAMPLE_RATE = 8000.0;
private IRealFilter mIBasebandFilter;
private IRealFilter mQBasebandFilter;
private ScalarFMDemodulator mDemodulator = new ScalarFMDemodulator();
private IRealDecimationFilter mIDecimationFilter;
private IRealDecimationFilter mQDecimationFilter;
private IDemodulator mDemodulator = FmDemodulatorFactory.getFmDemodulator();
private PowerMonitor mPowerMonitor = new PowerMonitor();
private RealResampler mResampler;
private SourceEventProcessor mSourceEventProcessor = new SourceEventProcessor();
private Listener<float[]> mResampledBufferListener;
private double mChannelBandwidth;
private double mOutputSampleRate;
/**
* Creates an FM demodulator for the specified channel bandwidth and output sample rate.
@@ -64,10 +68,21 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
* channel bandwidth and the demodulated output will be resampled to the desired output sample rate. The input
* low pass filter is constructed at runtime based on receiving a sample rate notification source event.
*/
public FMDemodulatorModule(double channelBandwidth, double outputSampleRate)
public FMDemodulatorModule(double channelBandwidth)
{
mChannelBandwidth = channelBandwidth;
mOutputSampleRate = outputSampleRate;
}
/**
* Broadcasts the demodulated audio samples to the registered listener.
* @param demodulatedSamples to broadcast
*/
protected void broadcast(float[] demodulatedSamples)
{
if(mResampledBufferListener != null)
{
mResampledBufferListener.receive(demodulatedSamples);
}
}
@Override
@@ -85,25 +100,15 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
@Override
public void dispose()
{
mDemodulator.dispose();
mDemodulator = null;
}
@Override
public void reset()
{
mDemodulator.reset();
}
public void reset() {}
@Override
public void start()
{
}
public void start() {}
@Override
public void stop()
{
}
public void stop() {}
@Override
public void setBufferListener(Listener<float[]> listener)
@@ -120,17 +125,18 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
@Override
public void receive(ComplexSamples samples)
{
if(mIBasebandFilter == null || mQBasebandFilter == null)
if(mIBasebandFilter == null || mIDecimationFilter == null)
{
throw new IllegalStateException("FM demodulator module must receive a sample rate change source " +
"event before it can process complex sample buffers");
}
float[] i = mIBasebandFilter.filter(samples.i());
float[] q = mQBasebandFilter.filter(samples.q());
mPowerMonitor.process(i, q);
float[] demodulated = mDemodulator.demodulate(i, q);
float[] decimatedI = mIDecimationFilter.decimateReal(samples.i());
float[] decimatedQ = mQDecimationFilter.decimateReal(samples.q());
float[] filteredI = mIBasebandFilter.filter(decimatedI);
float[] filteredQ = mQBasebandFilter.filter(decimatedQ);
float[] demodulated = mDemodulator.demodulate(filteredI, filteredQ);
mPowerMonitor.process(filteredI, filteredQ);
if(mResampler != null)
{
@@ -162,23 +168,41 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
{
double sampleRate = sourceEvent.getValue().doubleValue();
if((sampleRate < (2.0 * mChannelBandwidth)))
int decimationRate = 0;
double decimatedSampleRate = sampleRate;
if(sampleRate / 2 >= (mChannelBandwidth * 2))
{
throw new IllegalStateException("FM Demodulator with channel bandwidth [" + mChannelBandwidth +
"] requires a channel sample rate of [" + (2.0 * mChannelBandwidth + "] - sample rate of [" +
sampleRate + "] is not supported"));
decimationRate = 2;
while(sampleRate / decimationRate / 2 >= (mChannelBandwidth * 2))
{
decimationRate *= 2;
}
}
mPowerMonitor.setSampleRate((int)sampleRate);
if(decimationRate > 0)
{
decimatedSampleRate /= decimationRate;
}
double cutoff = sampleRate / 4.0;
int passBandStop = (int)cutoff - 500;
int stopBandStart = (int)cutoff + 500;
mIDecimationFilter = DecimationFilterFactory.getRealDecimationFilter(decimationRate);
mQDecimationFilter = DecimationFilterFactory.getRealDecimationFilter(decimationRate);
if((decimatedSampleRate < (2.0 * mChannelBandwidth)))
{
throw new IllegalStateException("FM demodulator with channel bandwidth [" +
mChannelBandwidth + "] requires a channel sample rate of [" + (2.0 * mChannelBandwidth +
"] - sample rate of [" + decimatedSampleRate + "] is not supported"));
}
int passBandStop = (int) (mChannelBandwidth * .8);
int stopBandStart = (int) mChannelBandwidth;
float[] coefficients = null;
FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
.sampleRate(sampleRate)
.sampleRate(decimatedSampleRate * 2)
.gridDensity(16)
.oddLength(true)
.passBandCutoff(passBandStop)
@@ -186,7 +210,7 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
.passBandRipple(0.01)
.stopBandStart(stopBandStart)
.stopBandAmplitude(0.0)
.stopBandRipple(0.028) //Approximately 60 dB attenuation
.stopBandRipple(0.005) //Approximately 90 dB attenuation
.build();
try
@@ -195,27 +219,25 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
}
catch(FilterDesignException fde)
{
mLog.error("Couldn't design FM demodulator remez filter for sample rate [" + sampleRate +
mLog.error("Couldn't design demodulator remez filter for sample rate [" + sampleRate +
"] pass frequency [" + passBandStop + "] and stop frequency [" + stopBandStart +
"] - using sinc filter");
"] - will proceed using sinc (low-pass) filter");
}
if(coefficients == null)
{
coefficients = FilterFactory.getLowPass(sampleRate, passBandStop, stopBandStart, 60,
mLog.info("Unable to use remez filter designer for sample rate [" + decimatedSampleRate +
"] pass band stop [" + passBandStop +
"] and stop band start [" + stopBandStart + "] - will proceed using simple low pass filter design");
coefficients = FilterFactory.getLowPass(decimatedSampleRate, passBandStop, stopBandStart, 60,
WindowType.HAMMING, true);
}
mIBasebandFilter = FilterFactory.getRealFilter(coefficients);
mQBasebandFilter = FilterFactory.getRealFilter(coefficients);
mResampler = new RealResampler(sampleRate, mOutputSampleRate, 8192, 512);
mResampler.setListener(resampledBuffer -> {
if(mResampledBufferListener != null)
{
mResampledBufferListener.receive(resampledBuffer);
}
});
mResampler = new RealResampler(decimatedSampleRate, DEMODULATED_AUDIO_SAMPLE_RATE, 4192, 512);
mResampler.setListener(resampled -> broadcast(resampled));
}
}
}