mirror of
https://github.com/DSheirer/sdrtrunk.git
synced 2026-11-13 00:57:31 -05:00
[WIP] Updates the AM decoder module.
Removes a number of unused classes in an effort to remove RealBuffer usage across the codebase (has been replaced by ReusableBuffers).
This commit is contained in:
Denny
@@ -15,68 +15,144 @@
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******************************************************************************/
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package io.github.dsheirer.module.demodulate.am;
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import io.github.dsheirer.dsp.am.AMDemodulator_CB;
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import io.github.dsheirer.dsp.am.AMDemodulator;
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import io.github.dsheirer.dsp.filter.FilterFactory;
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import io.github.dsheirer.dsp.filter.Window;
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import io.github.dsheirer.dsp.filter.Window.WindowType;
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import io.github.dsheirer.dsp.filter.fir.complex.ComplexFIRFilter_CB_CB;
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import io.github.dsheirer.dsp.filter.fir.real.RealFIRFilter_RB_RB;
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import io.github.dsheirer.dsp.gain.AutomaticGainControl_RB;
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import io.github.dsheirer.dsp.filter.design.FilterDesignException;
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import io.github.dsheirer.dsp.filter.fir.FIRFilterSpecification;
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import io.github.dsheirer.dsp.filter.fir.complex.ComplexFIRFilter2;
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import io.github.dsheirer.dsp.filter.fir.real.RealFIRFilter2;
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import io.github.dsheirer.dsp.filter.resample.RealResampler;
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import io.github.dsheirer.dsp.gain.AutomaticGainControl;
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import io.github.dsheirer.module.Module;
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import io.github.dsheirer.sample.Listener;
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import io.github.dsheirer.sample.buffer.IReusableBufferProvider;
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import io.github.dsheirer.sample.buffer.IReusableComplexBufferListener;
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import io.github.dsheirer.sample.buffer.ReusableBuffer;
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import io.github.dsheirer.sample.buffer.ReusableComplexBuffer;
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import io.github.dsheirer.sample.complex.ComplexBuffer;
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import io.github.dsheirer.sample.real.IFilteredRealBufferProvider;
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import io.github.dsheirer.sample.real.RealBuffer;
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import io.github.dsheirer.source.ISourceEventListener;
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import io.github.dsheirer.source.SourceEvent;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class AMDemodulatorModule extends Module implements IReusableComplexBufferListener, IFilteredRealBufferProvider
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/**
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* AM Demodulator Module for demodulating complex baseband channel sample buffers and producing demodulated audio
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* at a specified output sample rate, normally 8 kHz.
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*
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* This module requires a sample rate SourceEvent prior to processing baseband sample buffers in order to configure
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* internal filters and the resampler.
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*/
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public class AMDemodulatorModule extends Module implements ISourceEventListener, IReusableComplexBufferListener,
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IReusableBufferProvider, Listener<ReusableComplexBuffer>
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{
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private static final int SAMPLE_RATE = 48000;
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private ComplexFIRFilter_CB_CB mIQFilter;
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private AMDemodulator_CB mDemodulator;
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private RealFIRFilter_RB_RB mLowPassFilter;
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private AutomaticGainControl_RB mAGC;
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private ReusableBufferListener mReusableBufferListener = new ReusableBufferListener();
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private final static Logger mLog = LoggerFactory.getLogger(AMDemodulatorModule.class);
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private static float[] mLowPassFilterTaps;
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private ComplexFIRFilter2 mIQFilter;
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private AMDemodulator mDemodulator;
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private RealFIRFilter2 mLowPassFilter;
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private AutomaticGainControl mAGC = new AutomaticGainControl();
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private double mChannelBandwidth;
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private double mOutputSampleRate;
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private RealResampler mResampler;
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private Listener<ReusableBuffer> mResampledReusableBufferListener;
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private SourceEventProcessor mSourceEventProcessor = new SourceEventProcessor();
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/**
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* AM Demodulator Module
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* Constructs an AM demodulator module
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*
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* @param channelBandwidth to use in filtering the baseband input buffers
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* @param outputSampleRate specifies the resampled output sample rate for demodulated audio
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*/
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public AMDemodulatorModule()
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public AMDemodulatorModule(double channelBandwidth, double outputSampleRate)
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{
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mIQFilter = new ComplexFIRFilter_CB_CB(FilterFactory.getLowPass(
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SAMPLE_RATE, 5000, 73, WindowType.HAMMING), 1.0f);
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mChannelBandwidth = channelBandwidth;
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mOutputSampleRate = outputSampleRate;
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mDemodulator = new AMDemodulator_CB(500.0f);
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mIQFilter.setListener(mDemodulator);
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mDemodulator = new AMDemodulator(500.0f);
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mLowPassFilter = new RealFIRFilter_RB_RB(
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FilterFactory.getLowPass(48000, 3000, 31, WindowType.COSINE), 1.0f);
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mDemodulator.setListener(mLowPassFilter);
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if(mLowPassFilterTaps == null)
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{
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FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
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.sampleRate(mOutputSampleRate)
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.gridDensity(16)
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.oddLength(true)
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.passBandCutoff(3000)
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.passBandAmplitude(1.0)
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.passBandRipple(0.01)
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.stopBandStart(3500)
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.stopBandAmplitude(0.0)
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.stopBandRipple(0.028)
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.build();
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mAGC = new AutomaticGainControl_RB();
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mLowPassFilter.setListener(mAGC);
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try
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{
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mLowPassFilterTaps = FilterFactory.getTaps(specification);
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}
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catch(FilterDesignException fde)
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{
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mLog.error("Couldn't design AM demodulator remez filter for sample rate [" + mOutputSampleRate +
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"] pass frequency [3000] and stop frequency [3500] - using sinc filter");
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}
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if(mLowPassFilterTaps == null)
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{
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mLowPassFilterTaps = FilterFactory.getLowPass(mOutputSampleRate, 3000, 3500,
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60, WindowType.HAMMING, true);
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}
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}
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mLowPassFilter = new RealFIRFilter2(mLowPassFilterTaps);
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}
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@Override
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public void receive(ReusableComplexBuffer basebandBuffer)
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{
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ReusableComplexBuffer filteredBuffer = mIQFilter.filter(basebandBuffer);
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ReusableBuffer demodulated = mDemodulator.demodulate(filteredBuffer);
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mResampler.resample(demodulated);
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}
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/**
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* Processes resampled audio buffers produced by the resampler.
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* @param resampledAudio buffer to process.
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*/
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private void processResampledAudio(ReusableBuffer resampledAudio)
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{
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if(mResampledReusableBufferListener != null)
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{
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ReusableBuffer filteredAudio = mLowPassFilter.filter(resampledAudio);
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ReusableBuffer gainApplied = mAGC.process(filteredAudio);
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mResampledReusableBufferListener.receive(gainApplied);
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}
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else
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{
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resampledAudio.decrementUserCount();
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}
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}
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@Override
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public Listener<ReusableComplexBuffer> getReusableComplexBufferListener()
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{
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return mReusableBufferListener;
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return this;
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}
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@Override
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public void dispose()
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{
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mIQFilter.dispose();
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mIQFilter = null;
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if(mIQFilter != null)
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{
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mIQFilter.dispose();
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mIQFilter = null;
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}
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if(mLowPassFilter != null)
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{
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mLowPassFilter.dispose();
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mLowPassFilter = null;
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}
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mDemodulator.dispose();
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mDemodulator = null;
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mLowPassFilter.dispose();
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mLowPassFilter = null;
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mAGC.dispose();
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mAGC = null;
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}
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@@ -85,18 +161,6 @@ public class AMDemodulatorModule extends Module implements IReusableComplexBuffe
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{
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}
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@Override
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public void setFilteredRealBufferListener(Listener<RealBuffer> listener)
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{
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mAGC.setListener(listener);
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}
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@Override
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public void removeFilteredRealBufferListener()
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{
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mAGC.removeListener();
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}
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@Override
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public void start()
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{
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@@ -107,18 +171,97 @@ public class AMDemodulatorModule extends Module implements IReusableComplexBuffe
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{
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}
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@Override
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public void setBufferListener(Listener<ReusableBuffer> listener)
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{
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mResampledReusableBufferListener = listener;
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}
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public class ReusableBufferListener implements Listener<ReusableComplexBuffer>
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@Override
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public void removeBufferListener()
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{
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mResampledReusableBufferListener = null;
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}
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@Override
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public Listener<SourceEvent> getSourceEventListener()
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{
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return mSourceEventProcessor;
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}
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/**
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* Monitors sample rate change source event(s) to setup the initial I/Q filter and resampler
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*/
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public class SourceEventProcessor implements Listener<SourceEvent>
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{
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@Override
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public void receive(ReusableComplexBuffer reusableComplexBuffer)
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public void receive(SourceEvent sourceEvent)
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{
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float[] samples = reusableComplexBuffer.getSamplesCopy();
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if(sourceEvent.getEvent() == SourceEvent.Event.NOTIFICATION_SAMPLE_RATE_CHANGE)
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{
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if(mIQFilter != null)
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{
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mIQFilter.dispose();
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mIQFilter = null;
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}
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//TODO: redesign the filter chain so that we can simply pass a float array ...
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double sampleRate = sourceEvent.getValue().doubleValue();
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mIQFilter.receive(new ComplexBuffer(samples));
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reusableComplexBuffer.decrementUserCount();
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if((sampleRate < (2.0 * mChannelBandwidth)))
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{
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throw new IllegalStateException("AM Demodulator with channel bandwidth [" + mChannelBandwidth +
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"] requires a channel sample rate of [" + (2.0 * mChannelBandwidth + "] - sample rate of [" +
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sampleRate + "] is not supported"));
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}
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double cutoff = sampleRate / 4.0;
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int passBandStop = (int)cutoff - 500;
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int stopBandStart = (int)cutoff + 500;
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float[] filterTaps = null;
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FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
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.sampleRate(sampleRate)
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.gridDensity(16)
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.oddLength(true)
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.passBandCutoff(passBandStop)
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.passBandAmplitude(1.0)
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.passBandRipple(0.01)
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.stopBandStart(stopBandStart)
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.stopBandAmplitude(0.0)
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.stopBandRipple(0.028) //Approximately 60 dB attenuation
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.build();
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try
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{
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filterTaps = FilterFactory.getTaps(specification);
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}
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catch(FilterDesignException fde)
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{
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mLog.error("Couldn't design FM demodulator remez filter for sample rate [" + sampleRate +
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"] pass frequency [" + passBandStop + "] and stop frequency [" + stopBandStart +
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"] - using sinc filter");
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}
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if(filterTaps == null)
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{
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filterTaps = FilterFactory.getLowPass(sampleRate, passBandStop, stopBandStart, 60,
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Window.WindowType.HAMMING, true);
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}
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mIQFilter = new ComplexFIRFilter2(filterTaps);
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mResampler = new RealResampler(sampleRate, mOutputSampleRate, 2000, 1000);
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mResampler.setListener(new Listener<ReusableBuffer>()
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{
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@Override
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public void receive(ReusableBuffer resampledAudioBuffer)
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{
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processResampledAudio(resampledAudioBuffer);
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}
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});
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}
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}
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}
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}
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