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#36 NBFM squelch control. Updates NBFM decoder to incorporate squelch control. Squelch is a configuration item and also available to adjust at runtime with new 'Channel' tab in Now Playing window. All decoders were updated to produce continuous channel power (dB) measurements that are displayed in the Channel tab's new Power Meter. (#1100)

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Co-authored-by: Dennis Sheirer <dsheirer@github.com>
This commit is contained in:
Denny Sheirer
2021-11-14 06:59:58 -05:00
committed by GitHub
parent 7303e06943
commit 4b806ecfde
40 changed files with 2348 additions and 98 deletions
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67
src/main/java/io/github/dsheirer/module/demodulate/fm/FMDemodulatorModule.java
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@@ -22,6 +22,7 @@ import io.github.dsheirer.dsp.filter.fir.FIRFilterSpecification;
import io.github.dsheirer.dsp.filter.fir.complex.ComplexFIRFilter2;
import io.github.dsheirer.dsp.filter.resample.RealResampler;
import io.github.dsheirer.dsp.fm.FMDemodulator;
import io.github.dsheirer.dsp.squelch.PowerMonitor;
import io.github.dsheirer.module.Module;
import io.github.dsheirer.sample.Listener;
import io.github.dsheirer.sample.buffer.IReusableBufferProvider;
@@ -29,6 +30,7 @@ import io.github.dsheirer.sample.buffer.IReusableComplexBufferListener;
import io.github.dsheirer.sample.buffer.ReusableComplexBuffer;
import io.github.dsheirer.sample.buffer.ReusableFloatBuffer;
import io.github.dsheirer.source.ISourceEventListener;
import io.github.dsheirer.source.ISourceEventProvider;
import io.github.dsheirer.source.SourceEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@@ -38,13 +40,14 @@ import org.slf4j.LoggerFactory;
*
* Note: no filtering is applied to the demodulated audio.
*/
public class FMDemodulatorModule extends Module implements ISourceEventListener, IReusableComplexBufferListener,
Listener<ReusableComplexBuffer>, IReusableBufferProvider
public class FMDemodulatorModule extends Module implements ISourceEventListener, ISourceEventProvider,
IReusableComplexBufferListener, Listener<ReusableComplexBuffer>, IReusableBufferProvider
{
private final static Logger mLog = LoggerFactory.getLogger(FMDemodulatorModule.class);
private ComplexFIRFilter2 mIQFilter;
private FMDemodulator mDemodulator = new FMDemodulator();
private PowerMonitor mPowerMonitor = new PowerMonitor();
private RealResampler mResampler;
private SourceEventProcessor mSourceEventProcessor = new SourceEventProcessor();
private Listener<ReusableFloatBuffer> mResampledReusableBufferListener;
@@ -76,6 +79,19 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
return mSourceEventProcessor;
}
@Override
public void dispose()
{
if(mIQFilter != null)
{
mIQFilter.dispose();
mIQFilter = null;
}
mDemodulator.dispose();
mDemodulator = null;
}
@Override
public void reset()
{
@@ -111,10 +127,11 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
{
reusableComplexBuffer.decrementUserCount();
throw new IllegalStateException("FM demodulator module must receive a sample rate change source " +
"event before it can process complex sample buffers");
"event before it can process complex sample buffers");
}
ReusableComplexBuffer basebandFilteredBuffer = mIQFilter.filter(reusableComplexBuffer);
mPowerMonitor.process(basebandFilteredBuffer);
ReusableFloatBuffer demodulatedBuffer = mDemodulator.demodulate(basebandFilteredBuffer);
if(mResampler != null)
@@ -127,6 +144,18 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
}
}
@Override
public void setSourceEventListener(Listener<SourceEvent> listener)
{
mPowerMonitor.setSourceEventListener(listener);
}
@Override
public void removeSourceEventListener()
{
mPowerMonitor.setSourceEventListener(null);
}
/**
* Monitors sample rate change source event(s) to setup the initial I/Q filter
*/
@@ -148,10 +177,12 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
if((sampleRate < (2.0 * mChannelBandwidth)))
{
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"));
"] requires a channel sample rate of [" + (2.0 * mChannelBandwidth + "] - sample rate of [" +
sampleRate + "] is not supported"));
}
mPowerMonitor.setSampleRate((int)sampleRate);
double cutoff = sampleRate / 4.0;
int passBandStop = (int)cutoff - 500;
int stopBandStart = (int)cutoff + 500;
@@ -159,16 +190,16 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
float[] filterTaps = null;
FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
.sampleRate(sampleRate)
.gridDensity(16)
.oddLength(true)
.passBandCutoff(passBandStop)
.passBandAmplitude(1.0)
.passBandRipple(0.01)
.stopBandStart(stopBandStart)
.stopBandAmplitude(0.0)
.stopBandRipple(0.028) //Approximately 60 dB attenuation
.build();
.sampleRate(sampleRate)
.gridDensity(16)
.oddLength(true)
.passBandCutoff(passBandStop)
.passBandAmplitude(1.0)
.passBandRipple(0.01)
.stopBandStart(stopBandStart)
.stopBandAmplitude(0.0)
.stopBandRipple(0.028) //Approximately 60 dB attenuation
.build();
try
{
@@ -177,14 +208,14 @@ public class FMDemodulatorModule extends Module implements ISourceEventListener,
catch(FilterDesignException fde)
{
mLog.error("Couldn't design FM demodulator remez filter for sample rate [" + sampleRate +
"] pass frequency [" + passBandStop + "] and stop frequency [" + stopBandStart +
"] - using sinc filter");
"] pass frequency [" + passBandStop + "] and stop frequency [" + stopBandStart +
"] - using sinc filter");
}
if(filterTaps == null)
{
filterTaps = FilterFactory.getLowPass(sampleRate, passBandStop, stopBandStart, 60,
Window.WindowType.HAMMING, true);
Window.WindowType.HAMMING, true);
}
mIQFilter = new ComplexFIRFilter2(filterTaps);