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#2516 DMR Decoder enhancements. Architecture now shares common C4FM framework like P25P1 and NXDN. Adds soft decoding and enhanced/corrected error detection and correction. (#2517)

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Co-authored-by: denny <dennis.sheirer@gmail.com>
This commit is contained in:
Denny Sheirer
2026-10-26 06:34:57 -04:00
committed by GitHub
parent 5635341d12
commit f2c98cdb40
32 changed files with 4044 additions and 1282 deletions
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21
src/main/java/io/github/dsheirer/dsp/c4fm/C4FMEqualizer.java
View File

@@ -179,6 +179,27 @@ public class C4FMEqualizer
mSymbolsUntilTraining = mDelaySymbolCount;
}
/**
* Notifies the equalizer that a sync pattern is detected and updates the sync pattern used for training. This
* supports protocols (ie DMR) that employ multiple sync patterns of the same length.
* @param syncSymbols for the detected sync pattern, which must be the same length as the constructor sync pattern.
*/
public void syncDetected(float[] syncSymbols)
{
if(syncSymbols.length != mReversedSyncSymbols.length)
{
throw new IllegalArgumentException("Sync symbols length [" + syncSymbols.length +
"] must match the equalizer sync pattern length [" + mReversedSyncSymbols.length + "]");
}
for(int x = 0; x < syncSymbols.length; x++)
{
mReversedSyncSymbols[syncSymbols.length - x - 1] = syncSymbols[x];
}
syncDetected();
}
/**
* Indicates that the sync patter is lost and the equalizer should reset.
*/

20
src/main/java/io/github/dsheirer/dsp/c4fm/C4FMMessageFramer.java
View File

@@ -7,6 +7,26 @@ import io.github.dsheirer.dsp.symbol.Dibit;
*/
public abstract class C4FMMessageFramer
{
private static final float SOFT_SYMBOL_SCALE = (float)(4.0 / Math.PI); //Radians to symbol units (+/-1, +/-3)
/**
* Converts the soft symbol into a pair of soft bit values using max-log likelihood ratios for the Gray mapped
* 4-level symbol (D01=+3, D00=+1, D10=-1, D11=-3), where a positive soft bit value favors a 1 bit.
* @param softSymbol in radians
* @param softBits array to receive the two soft bit values
* @param index for the first bit (sign bit), followed by the second (magnitude) bit
*/
protected static void setSoftBits(float softSymbol, float[] softBits, int index)
{
float u = softSymbol * SOFT_SYMBOL_SCALE;
float magnitude = Math.abs(u);
//First bit is 1 for negative symbols
float favorZero = magnitude <= 2.0f ? 4.0f * u : 8.0f * u - 8.0f * Math.signum(u);
softBits[index] = -favorZero;
//Second bit is 1 for the outer (+/-3) symbols
softBits[index + 1] = 4.0f * (magnitude - 2.0f);
}
/**
* Process the symbol
* @param symbol in radians

446
src/main/java/io/github/dsheirer/dsp/c4fm/C4FMSymbolProcessor.java
View File

@@ -22,10 +22,14 @@ package io.github.dsheirer.dsp.c4fm;
import io.github.dsheirer.dsp.filter.interpolator.LinearInterpolator;
import io.github.dsheirer.dsp.symbol.Dibit;
import io.github.dsheirer.dsp.symbol.DibitToByteBufferAssembler;
import io.github.dsheirer.gui.viewer.sync.FMSyncResultsViewer;
import io.github.dsheirer.gui.viewer.sync.ISyncResultsListener;
import io.github.dsheirer.module.decode.FeedbackDecoder;
import io.github.dsheirer.sample.Listener;
import java.nio.ByteBuffer;
import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.concurrent.CountDownLatch;
import org.apache.commons.math3.stat.descriptive.moment.Mean;
import org.apache.commons.math3.stat.descriptive.moment.StandardDeviation;
@@ -59,6 +63,9 @@ public abstract class C4FMSymbolProcessor
private final FeedbackDecoder mFeedbackDecoder;
private final C4FMMessageFramer mMessageFramer;
private final ISoftC4FMSyncDetector mSyncDetectorLagging;
//Detector (primary or lagging) that triggered the current sync detection. For multi-pattern sync detectors, this
//detector's most recently detected sync pattern is used for optimization, validation and equalizer training.
private ISoftC4FMSyncDetector mActiveSyncDetector;
private final C4FMEqualizer mSymbolEqualizer;
private static final double SYMBOL_TIMING_GAIN = 0.25;
//Clip applied to the Gardner timing error (radians squared) to limit the impact of FM discriminator clicks
@@ -68,7 +75,6 @@ public abstract class C4FMSymbolProcessor
private static final double IDEAL_OUTER_SYMBOL_PHASE = 3.0 * Math.PI / 4.0;
//Allowable gain deviation from the nominal gain, as a fraction of the nominal gain.
private static final double SAMPLE_GAIN_TOLERANCE = 0.1;
private ReferenceSyncWaveform mReferenceSyncWaveform;
private double mNoiseStandardDeviationThreshold;
private double mSamplePoint;
protected double mSamplesPerSymbol;
@@ -85,13 +91,13 @@ public abstract class C4FMSymbolProcessor
protected boolean mSynchronized = false;
private boolean mDelayedSyncNotificationPending = false;
// private final boolean mDebugVisualizeSync = true;
// private final boolean mDebugVisualizeSymbols = true;
// private final boolean mDebugLogDetectionScores = false;
// private final int mDebugSymbolStart = 0;
// private ISyncResultsListener mDebugSyncResultsViewer;
// private int mDebugSymbolCounter = 0;
// private int mDebugSampleCounter = 0;
private final boolean mDebugVisualizeSync = false;
private final boolean mDebugVisualizeSymbols = false;
private final boolean mDebugLogDetectionScores = false;
private final int mDebugSymbolStart = 0;
private ISyncResultsListener mDebugSyncResultsViewer;
private int mDebugSymbolCounter = 0;
private int mDebugSampleCounter = 0;
/**
* Constructs an instance
@@ -104,6 +110,7 @@ public abstract class C4FMSymbolProcessor
mFeedbackDecoder = feedbackDecoder;
mSyncDetector = primary;
mSyncDetectorLagging = lagging;
mActiveSyncDetector = primary;
mSymbolEqualizer = new C4FMEqualizer(mSyncDetector.getPatternSymbols(), getEqualizerSymbolLength(),
getEqualizerTrainingPeriodDurationSymbolCount(), getEqualizerSkipTrainingFrameCount());
mSampleEqualizer = new SampleEqualizer(isDynamicBalanceTrackingRequired());
@@ -209,6 +216,37 @@ public abstract class C4FMSymbolProcessor
*/
public abstract float getSyncThresholdEqualized();
/**
* Notification that a sync detection was validated and the correction applied. Subclasses can override this to
* capture protocol specific details (ie the detected sync pattern) from the sync detector that triggered the
* detection. The message framer is notified of the sync detection once the final sync symbol emerges from the
* equalizer delay line, which can be after this method is invoked.
* @param syncDetector that triggered the sync detection.
*/
protected void syncDetected(ISoftC4FMSyncDetector syncDetector)
{
//No-op default implementation
}
/**
* Indicates if a sync detection is allowed at the current symbol. Protocols with fixed length framing (ie DMR)
* can override this to only allow sync detections at the expected frame boundaries once synchronized, to prevent
* false sync detections from the frame payload. Default implementation always allows sync detection.
* @param symbolsSinceLastSync count of symbols since the final symbol of the previous sync detection.
* @return true if a sync detection is allowed.
*/
protected boolean isSyncDetectionAllowed(int symbolsSinceLastSync)
{
return true;
}
/**
* Number of consecutive sync periods (capped at 3) where a sync was detected within the max message length.
*/
protected int getConsecutiveSyncPeriods()
{
return mConsecutiveSyncPeriods;
}
/**
* Finalize and prepare for shutdown.
@@ -290,16 +328,16 @@ public abstract class C4FMSymbolProcessor
bufferPointer++;
samplePoint--;
// mDebugSampleCounter++;
mDebugSampleCounter++;
if(samplePoint < 1)
{
// mDebugSymbolCounter++;
//
// if(mDebugSymbolCounter % mSyncDetector.getDibitLength() == 0)
// {
// visualizeSymbols(bufferPointer, samplePoint, symbolsSinceLastSync);
// }
mDebugSymbolCounter++;
if(mDebugSymbolCounter % mSyncDetector.getDibitLength() == 0)
{
visualizeSymbols(bufferPointer, samplePoint, symbolsSinceLastSync);
}
symbolsSinceLastSync++;
@@ -337,21 +375,26 @@ public abstract class C4FMSymbolProcessor
float scoreLag = mSyncDetectorLagging.process(softSymbolLag);
scorePrimary = mSyncDetector.process(softSymbol);
// if(mDebugLogDetectionScores)
// {
// boolean exceeds = scorePrimary > 45 || scoreLag > 45;
// System.out.println("DETECT - Primary [" + DEBUG_DF.format(scorePrimary) + "] Lag [" + DEBUG_DF.format(scoreLag) + "] at [" + mDebugSymbolCounter + "]" + (exceeds ? " <<<<<<<<<<<<<<<<<<<<<<<<<<" : ""));
// }
if(mDebugLogDetectionScores)
{
boolean exceeds = scorePrimary > 45 || scoreLag > 45;
System.out.println("DETECT - Primary [" + DEBUG_DF.format(scorePrimary) + "] Lag [" + DEBUG_DF.format(scoreLag) + "] at [" + mDebugSymbolCounter + "]" + (exceeds ? " <<<<<<<<<<<<<<<<<<<<<<<<<<" : ""));
}
correctionCandidate = INVALID_SYNC_DETECTION;
if(scorePrimary > getSyncThresholdDetected() && scorePrimary > scoreLag)
if(isSyncDetectionAllowed(symbolsSinceLastSync))
{
correctionCandidate = optimize(0, scorePrimary, (bufferPointer + samplePoint));
}
else if(scoreLag > getSyncThresholdDetected() && symbolsSinceLastSync > 1)
{
correctionCandidate = optimize(-mLaggingSyncOffset, scoreLag, (bufferPointer + samplePoint));
if(scorePrimary > getSyncThresholdDetected() && scorePrimary > scoreLag)
{
mActiveSyncDetector = mSyncDetector;
correctionCandidate = optimize(0, scorePrimary, (bufferPointer + samplePoint));
}
else if(scoreLag > getSyncThresholdDetected() && symbolsSinceLastSync > 1)
{
mActiveSyncDetector = mSyncDetectorLagging;
correctionCandidate = optimize(-mLaggingSyncOffset, scoreLag, (bufferPointer + samplePoint));
}
}
//Equalizer processes current soft symbol and returns a delayed soft symbol that is equalized
@@ -361,10 +404,10 @@ public abstract class C4FMSymbolProcessor
Dibit symbol = Dibit.fromSample(softSymbol);
mFeedbackDecoder.broadcast(softSymbol);
// if(mDebugVisualizeSync)
// {
// getDebugSyncResultsViewer().symbol(softSymbol);
// }
if(mDebugVisualizeSync)
{
getDebugSyncResultsViewer().symbol(softSymbol);
}
//When the message framer emits at least one valid message (ie CRC check passes) and we have at least
// 2 consecutive sync detections, send the current sample equalizer's balance value as a pseudo-PLL
@@ -388,12 +431,13 @@ public abstract class C4FMSymbolProcessor
{
mConsecutiveSyncPeriods = Math.min(3, mConsecutiveSyncPeriods + 1);
// if(mDebugLogDetectionScores)
// {
// System.out.println("DETECT - Primary [" + DEBUG_DF.format(scorePrimary) + "] Lag [" + DEBUG_DF.format(scoreLag) + "] Optimized [" + correctionCandidate.mOptimizationScore + "] at samples [" + mDebugSampleCounter + "] symbols [" + mDebugSymbolCounter + "]");
// }
if(mDebugLogDetectionScores)
{
System.out.println("DETECT - Primary [" + DEBUG_DF.format(scorePrimary) + "] Lag [" + DEBUG_DF.format(scoreLag) + "] Optimized [" + correctionCandidate.mOptimizationScore + "] at samples [" + mDebugSampleCounter + "] symbols [" + mDebugSymbolCounter + "]");
}
mSampleEqualizer.apply(correctionCandidate);
syncDetected(mActiveSyncDetector);
if(mSynchronized)
{
@@ -424,7 +468,7 @@ public abstract class C4FMSymbolProcessor
// need to prime that buffer with aligned samples prior to sync detection training.
if(!mSymbolEqualizer.isEnabled())
{
int symbols = mSyncDetector.getPatternSymbols().length + mSymbolEqualizer.getLength() - mSymbolEqualizer.getDelaySymbolCount();
int symbols = mSyncDetector.getDibitLength() + mSymbolEqualizer.getLength() - mSymbolEqualizer.getDelaySymbolCount();
double offset = bufferPointer + samplePoint - ((symbols - 1) * samplesPerSymbol) - mLaggingSyncOffset;
float mid, sym;
@@ -440,9 +484,9 @@ public abstract class C4FMSymbolProcessor
}
}
mSymbolEqualizer.syncDetected();
mSymbolEqualizer.syncDetected(mActiveSyncDetector.getPatternSymbols());
mSymbolEqualizer.enable();
// visualizeSyncDetect(scorePrimary, true, "DETECT - POST", bufferPointer, samplePoint);
visualizeSyncDetect(scorePrimary, true, "DETECT - POST", bufferPointer, samplePoint);
}
else if(mDelayedSyncNotificationPending)
{
@@ -485,26 +529,27 @@ public abstract class C4FMSymbolProcessor
*/
private Correction validateSyncWaveform(Correction candidate, int bufferPointer, double samplePoint)
{
ReferenceSyncWaveform referenceSyncWaveform = mActiveSyncDetector.getReferenceWaveform(mSamplesPerSymbol);
float gain = mSampleEqualizer.mGain + candidate.getGainAdjustment();
float balance = mSampleEqualizer.mBalance + candidate.getBalanceAdjustment();
double offset = bufferPointer + samplePoint + candidate.getTimingCorrection() - mReferenceSyncWaveform.samples().length;
double offset = bufferPointer + samplePoint + candidate.getTimingCorrection() - referenceSyncWaveform.samples().length;
int integral = (int)Math.ceil(offset);
double mu = integral - offset;
double accumulator = 0.0;
int index;
//Evaluate the reference waveform in reverse order since the final symbol is aligned to the final sample
for(int x = mReferenceSyncWaveform.samples().length - 1; x >= 0; x--)
for(int x = referenceSyncWaveform.samples().length - 1; x >= 0; x--)
{
index = integral + x;
float sample = LinearInterpolator.calculate(mBuffer[index], mBuffer[index + 1], mu);
sample *= gain;
sample += balance;
sample = Math.clamp(sample, -mReferenceSyncWaveform.maxSample(), mReferenceSyncWaveform.maxSample());
accumulator += mReferenceSyncWaveform.samples()[x] * sample;
sample = Math.clamp(sample, -referenceSyncWaveform.maxSample(), referenceSyncWaveform.maxSample());
accumulator += referenceSyncWaveform.samples()[x] * sample;
}
double threshold = mReferenceSyncWaveform.idealCorrelationScore() * 0.85; //85% of the ideal correlation score
double threshold = referenceSyncWaveform.idealCorrelationScore() * 0.85; //85% of the ideal correlation score
//Return the correction as valid if the correlation score exceeds the threshold, otherwise return the static
// invalid sync detection to nullify the correction.
@@ -548,156 +593,157 @@ public abstract class C4FMSymbolProcessor
mSyncWorkspaceLength = (int)Math.ceil((mSyncDetector.getDibitLength() + 1) * samplesPerSymbol);
mBufferReloadLength = (int)Math.ceil(samplesPerSymbol);
mSampleEqualizer.configure(samplesPerSymbol);
mReferenceSyncWaveform = mSyncDetector.getReferenceWaveform(samplesPerSymbol);
//Pre-generate the reference sync waveform for the primary sync pattern
mSyncDetector.getReferenceWaveform(samplesPerSymbol);
// System.out.println("Samples Per Symbol: " + samplesPerSymbol);
}
// /**
// * Debug viewer UI for visualizing sync detections in the sample stream/waveform.
// */
// private ISyncResultsListener getDebugSyncResultsViewer()
// {
// if(mDebugSyncResultsViewer == null)
// {
// mDebugSyncResultsViewer = new FMSyncResultsViewer();
// }
//
// return mDebugSyncResultsViewer;
// }
//
// /**
// * Debug method to visualize the contents of the sync detection for the samples and symbols and symbol timing.
// * @param score from the sync detector
// * @param primary sync detector (true) or secondary (false)
// */
// public void visualizeSyncDetect(float score, boolean primary, String tag, int bufferPointer, double samplePoint)
// {
// if(!mDebugVisualizeSync || mDebugSymbolCounter < mDebugSymbolStart)
// {
// return;
// }
//
// int integral = (int)Math.floor(samplePoint);
// samplePoint -= integral;
// bufferPointer += integral;
//
// int offset = 3;
// int length = (int)Math.ceil(mSamplesPerSymbol * (mSyncDetector.getDibitLength() - 1)) + (2 * offset);
// int end = bufferPointer + offset;
// int start = end - length;
// float[] symbols = new float[mSyncDetector.getDibitLength()];
// float[] samples = Arrays.copyOfRange(mBuffer, start, end);
// for(int i = 0; i < samples.length; i++)
// {
// samples[i] = mSampleEqualizer.equalize(samples[i]);
// }
//
// double symbolPointer = bufferPointer + samplePoint - (mSamplesPerSymbol * (mSyncDetector.getDibitLength() - 1));
// int symbolIntegral = (int)Math.floor(symbolPointer);
// double mu = symbolPointer - symbolIntegral;
//
// for(int x = 0; x < mSyncDetector.getDibitLength(); x++)
// {
// symbols[x] = mSampleEqualizer.getEqualizedSymbol(mBuffer[symbolIntegral], mBuffer[symbolIntegral + 1], mu);
// symbolPointer += mSamplesPerSymbol;
// symbolIntegral = (int)Math.floor(symbolPointer);
// mu = symbolPointer - symbolIntegral;
// }
//
// float[] syncIntervals = new float[mSyncDetector.getDibitLength()];
// int adjust = bufferPointer - length + offset;
// double pointer = bufferPointer + samplePoint - adjust;
//
// for(int x = (mSyncDetector.getDibitLength() - 1); x >= 0; x--)
// {
// syncIntervals[x] = (float)pointer;
// pointer -= mSamplesPerSymbol;
// }
//
// CountDownLatch countDownLatch = new CountDownLatch(1);
// getDebugSyncResultsViewer().receive(symbols, mSyncDetector.getPatternSymbols(), samples, syncIntervals, mSampleEqualizer.mBalance, mSampleEqualizer.mGain,
// tag + " Score: " + score + (primary ? " PRIMARY " : " SECONDARY ") + (mSynchronized ? "FINE " : "COARSE ") +
// " EQ-BO:" + DEBUG_DF.format(mSampleEqualizer.mBalanceOptimized) +
// " EQ-B:" + DEBUG_DF.format(mSampleEqualizer.mBalance) +
// " EQ-G:" + DEBUG_DF.format(mSampleEqualizer.mGain) + " " +
// " SAM:" + mDebugSampleCounter +
// " SYM:" + mDebugSymbolCounter +
// " DUR:" + DEBUG_DF.format(mDebugSymbolCounter / 2400.0),
// countDownLatch);
//
// try
// {
// countDownLatch.await();
// }
// catch(InterruptedException e)
// {
// throw new RuntimeException(e);
// }
// }
//
// /**
// * Debug method to visualize the symbol decisions
// */
// public void visualizeSymbols(int bufferPointer, double samplePoint, int symbolsSinceLastSync)
// {
// if(!mDebugVisualizeSymbols || mDebugSymbolCounter < mDebugSymbolStart)
// {
// return;
// }
//
// int syncLength = mSyncDetector.getDibitLength();
//
// int offset = 3;
// int length = (int)Math.ceil(mSamplesPerSymbol * (syncLength - 1)) + (2 * offset);
// int end = bufferPointer + offset;
// int start = end - length;
// float[] symbols = new float[syncLength];
// float[] decisions = new float[syncLength];
// float[] samples = Arrays.copyOfRange(mBuffer, start, end);
// for(int i = 0; i < samples.length; i++)
// {
// samples[i] = mSampleEqualizer.equalize(samples[i]);
// }
//
// double symbolPointer = bufferPointer + samplePoint - (mSamplesPerSymbol * (syncLength - 1));
// int symbolIntegral = (int)Math.floor(symbolPointer);
// double mu = symbolPointer - symbolIntegral;
//
// for(int x = 0; x < syncLength; x++)
// {
// symbols[x] = mSampleEqualizer.getEqualizedSymbol(mBuffer[symbolIntegral], mBuffer[symbolIntegral + 1], mu);
// decisions[x] = Dibit.fromSample(symbols[x]).getIdealPhase();
// symbolPointer += mSamplesPerSymbol;
// symbolIntegral = (int)Math.floor(symbolPointer);
// mu = symbolPointer - symbolIntegral;
// }
//
// float[] syncIntervals = new float[syncLength];
// int adjust = bufferPointer - length + offset;
// double pointer = bufferPointer + samplePoint - adjust;
//
// for(int x = syncLength - 1; x >= 0; x--)
// {
// syncIntervals[x] = (float)pointer;
// pointer -= mSamplesPerSymbol;
// }
//
// CountDownLatch countDownLatch = new CountDownLatch(1);
// getDebugSyncResultsViewer().receive(symbols, decisions, samples, syncIntervals, mSampleEqualizer.mBalance, mSampleEqualizer.mGain,
// "Balance:" + mSampleEqualizer.mBalance + " Gain:" + mSampleEqualizer.mGain +
// " SAM:" + mDebugSampleCounter + " SYM:" + mDebugSymbolCounter +
// " DUR:" + DEBUG_DF.format(mDebugSymbolCounter / 2400.0) +
// " ELAPSED:" + symbolsSinceLastSync, countDownLatch);
//
// try
// {
// countDownLatch.await();
// }
// catch(InterruptedException e)
// {
// throw new RuntimeException(e);
// }
// }
/**
* Debug viewer UI for visualizing sync detections in the sample stream/waveform.
*/
private ISyncResultsListener getDebugSyncResultsViewer()
{
if(mDebugSyncResultsViewer == null)
{
mDebugSyncResultsViewer = new FMSyncResultsViewer();
}
return mDebugSyncResultsViewer;
}
/**
* Debug method to visualize the contents of the sync detection for the samples and symbols and symbol timing.
* @param score from the sync detector
* @param primary sync detector (true) or secondary (false)
*/
public void visualizeSyncDetect(float score, boolean primary, String tag, int bufferPointer, double samplePoint)
{
if(!mDebugVisualizeSync || mDebugSymbolCounter < mDebugSymbolStart)
{
return;
}
int integral = (int)Math.floor(samplePoint);
samplePoint -= integral;
bufferPointer += integral;
int offset = 3;
int length = (int)Math.ceil(mSamplesPerSymbol * (mSyncDetector.getDibitLength() - 1)) + (2 * offset);
int end = bufferPointer + offset;
int start = end - length;
float[] symbols = new float[mSyncDetector.getDibitLength()];
float[] samples = Arrays.copyOfRange(mBuffer, start, end);
for(int i = 0; i < samples.length; i++)
{
samples[i] = mSampleEqualizer.equalize(samples[i]);
}
double symbolPointer = bufferPointer + samplePoint - (mSamplesPerSymbol * (mSyncDetector.getDibitLength() - 1));
int symbolIntegral = (int)Math.floor(symbolPointer);
double mu = symbolPointer - symbolIntegral;
for(int x = 0; x < mSyncDetector.getDibitLength(); x++)
{
symbols[x] = mSampleEqualizer.getEqualizedSymbol(mBuffer[symbolIntegral], mBuffer[symbolIntegral + 1], mu);
symbolPointer += mSamplesPerSymbol;
symbolIntegral = (int)Math.floor(symbolPointer);
mu = symbolPointer - symbolIntegral;
}
float[] syncIntervals = new float[mSyncDetector.getDibitLength()];
int adjust = bufferPointer - length + offset;
double pointer = bufferPointer + samplePoint - adjust;
for(int x = (mSyncDetector.getDibitLength() - 1); x >= 0; x--)
{
syncIntervals[x] = (float)pointer;
pointer -= mSamplesPerSymbol;
}
CountDownLatch countDownLatch = new CountDownLatch(1);
getDebugSyncResultsViewer().receive(symbols, mSyncDetector.getPatternSymbols(), samples, syncIntervals, mSampleEqualizer.mBalance, mSampleEqualizer.mGain,
tag + " Score: " + score + (primary ? " PRIMARY " : " SECONDARY ") + (mSynchronized ? "FINE " : "COARSE ") +
" EQ-BO:" + DEBUG_DF.format(mSampleEqualizer.mBalanceOptimized) +
" EQ-B:" + DEBUG_DF.format(mSampleEqualizer.mBalance) +
" EQ-G:" + DEBUG_DF.format(mSampleEqualizer.mGain) + " " +
" SAM:" + mDebugSampleCounter +
" SYM:" + mDebugSymbolCounter +
" DUR:" + DEBUG_DF.format(mDebugSymbolCounter / 2400.0),
countDownLatch);
try
{
countDownLatch.await();
}
catch(InterruptedException e)
{
throw new RuntimeException(e);
}
}
/**
* Debug method to visualize the symbol decisions
*/
public void visualizeSymbols(int bufferPointer, double samplePoint, int symbolsSinceLastSync)
{
if(!mDebugVisualizeSymbols || mDebugSymbolCounter < mDebugSymbolStart)
{
return;
}
int syncLength = mSyncDetector.getDibitLength();
int offset = 3;
int length = (int)Math.ceil(mSamplesPerSymbol * (syncLength - 1)) + (2 * offset);
int end = bufferPointer + offset;
int start = end - length;
float[] symbols = new float[syncLength];
float[] decisions = new float[syncLength];
float[] samples = Arrays.copyOfRange(mBuffer, start, end);
for(int i = 0; i < samples.length; i++)
{
samples[i] = mSampleEqualizer.equalize(samples[i]);
}
double symbolPointer = bufferPointer + samplePoint - (mSamplesPerSymbol * (syncLength - 1));
int symbolIntegral = (int)Math.floor(symbolPointer);
double mu = symbolPointer - symbolIntegral;
for(int x = 0; x < syncLength; x++)
{
symbols[x] = mSampleEqualizer.getEqualizedSymbol(mBuffer[symbolIntegral], mBuffer[symbolIntegral + 1], mu);
decisions[x] = Dibit.fromSample(symbols[x]).getIdealPhase();
symbolPointer += mSamplesPerSymbol;
symbolIntegral = (int)Math.floor(symbolPointer);
mu = symbolPointer - symbolIntegral;
}
float[] syncIntervals = new float[syncLength];
int adjust = bufferPointer - length + offset;
double pointer = bufferPointer + samplePoint - adjust;
for(int x = syncLength - 1; x >= 0; x--)
{
syncIntervals[x] = (float)pointer;
pointer -= mSamplesPerSymbol;
}
CountDownLatch countDownLatch = new CountDownLatch(1);
getDebugSyncResultsViewer().receive(symbols, decisions, samples, syncIntervals, mSampleEqualizer.mBalance, mSampleEqualizer.mGain,
"Balance:" + mSampleEqualizer.mBalance + " Gain:" + mSampleEqualizer.mGain +
" SAM:" + mDebugSampleCounter + " SYM:" + mDebugSymbolCounter +
" DUR:" + DEBUG_DF.format(mDebugSymbolCounter / 2400.0) +
" ELAPSED:" + symbolsSinceLastSync, countDownLatch);
try
{
countDownLatch.await();
}
catch(InterruptedException e)
{
throw new RuntimeException(e);
}
}
/**
* Calculates the standard deviation of the samples at the specified offset that aligns with a sync detection.
@@ -965,7 +1011,10 @@ public abstract class C4FMSymbolProcessor
/**
* Applies decision directed correction to the constellation balance when dynamic balance tracking is enabled
* and the processor is synchronized following a valid sync detection.
* and the processor is synchronized following a valid sync detection. In periods of high noise or when the
* signal has stopped but we haven't yet detected it, we apply a correction that gradually restores the balance
* back towards the optimized balance decided at the last valid sync detection. This ensures that when the
* signal returns, the balance can be reestablished quickly.
* @param symbol sliced at the correct timing
*/
public float correct(float symbol)
@@ -1153,8 +1202,9 @@ public abstract class C4FMSymbolProcessor
{
int maxPointer = mBuffer.length - 1;
float softSymbol;
float[] patternSymbols = mActiveSyncDetector.getPatternSymbols();
double pointer = offset - (samplesPerSymbol * (mSyncDetector.getDibitLength() - 1));
double pointer = offset - (samplesPerSymbol * (patternSymbols.length - 1));
int bufferPointer = (int)Math.floor(pointer);
double fractional = pointer - bufferPointer;
@@ -1162,7 +1212,7 @@ public abstract class C4FMSymbolProcessor
float sample1, sample2;
float idealSymbol;
for(int x = 0; x < mSyncDetector.getDibitLength(); x++)
for(int x = 0; x < patternSymbols.length; x++)
{
if(bufferPointer < maxPointer)
{
@@ -1175,7 +1225,7 @@ public abstract class C4FMSymbolProcessor
softSymbol = 0.0f;
}
idealSymbol = mSyncDetector.getPatternSymbols()[x];
idealSymbol = patternSymbols[x];
//Constrain the contribution of the soft symbol to +/- the ideal symbol value.
if(idealSymbol > 0)
@@ -1246,22 +1296,24 @@ public abstract class C4FMSymbolProcessor
public Correction getCorrection(double additionalOffset, double timingCorrection,
float detectionScore, float optimizationScore, double offset, float measuredBalance)
{
double resampleStart = offset + additionalOffset + timingCorrection - (mSamplesPerSymbol * (mSyncDetector.getDibitLength() - 1));
float[] patternSymbols = mActiveSyncDetector.getPatternSymbols();
Dibit[] patternDibits = mActiveSyncDetector.getPatternDibits();
double resampleStart = offset + additionalOffset + timingCorrection - (mSamplesPerSymbol * (patternSymbols.length - 1));
int resampleStartIntegral = (int)Math.floor(resampleStart);
float symbol, gainAccumulator = 0, idealMagnitudeAccumulator = 0, resampledSoftSymbol;
Dibit resampledDibit;
int bitErrorCount = 0;
for(int x = 0; x < mSyncDetector.getDibitLength(); x++)
for(int x = 0; x < patternSymbols.length; x++)
{
if(resampleStartIntegral >= 0)
{
symbol = mSyncDetector.getPatternSymbols()[x];
symbol = patternSymbols[x];
resampledSoftSymbol = LinearInterpolator.calculate(mBuffer[resampleStartIntegral],
mBuffer[resampleStartIntegral + 1], resampleStart - resampleStartIntegral);
resampledSoftSymbol = resampledSoftSymbol * mSampleEqualizer.mGain + measuredBalance;
resampledDibit = Dibit.fromSample(resampledSoftSymbol);
bitErrorCount += mSyncDetector.getPatternDibits()[x].getBitErrorFrom(resampledDibit);
bitErrorCount += patternDibits[x].getBitErrorFrom(resampledDibit);
gainAccumulator += Math.abs(symbol) - Math.abs(resampledSoftSymbol);
idealMagnitudeAccumulator += Math.abs(symbol);
}

8
src/main/java/io/github/dsheirer/dsp/c4fm/ISoftC4FMSyncDetector.java
View File

@@ -15,13 +15,14 @@ public interface ISoftC4FMSyncDetector
float process(float softSymbol);
/**
* Soft symbols that represent the sync pattern
* Soft symbols that represent the sync pattern. For detectors that monitor multiple sync patterns (ie DMR), this
* is the sync pattern that produced the score from the most recent call to process().
* @return soft symbols array
*/
float[] getPatternSymbols();
/**
* Array of dibits for the sync pattern
* Array of dibits for the sync pattern (or most recently detected sync pattern for multi-pattern detectors).
* @return sync pattern dibit array
*/
Dibit[] getPatternDibits();
@@ -32,7 +33,8 @@ public interface ISoftC4FMSyncDetector
int getDibitLength();
/**
* Provides a reference waveform that represents the sync pattern for sync detection validation
* Provides a reference waveform that represents the sync pattern (or most recently detected sync pattern for
* multi-pattern detectors) for sync detection validation
* @param samplesPerSymbol for each symbol
* @return reference waveform
*/