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39 - WIP - incorporates the latest P25 C4FM decoder from master and

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updates the LSM decoder to follow the same design pattern.  Adds LSM
decoder support to the demodulator viewer application.  The current
symbol timing gain for LSM is set too high -- is using the C4FM gain
and causes too much fluctuation in the timing error.
This commit is contained in:
Denny
2018-03-24 06:59:41 -04:00
parent c3b405a752
commit bfaacb309d
40 changed files with 1817 additions and 1291 deletions
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53
src/main/java/io/github/dsheirer/dsp/psk/InterpolatingSampleBuffer.java
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@@ -24,6 +24,7 @@ public class InterpolatingSampleBuffer
private Complex mPrecedingSample = new Complex(0,0);
private Complex mCurrentSample = new Complex(0,0);
private Complex mMiddleSample = new Complex(0,0);
private float[] mDelayLineInphase;
private float[] mDelayLineQuadrature;
@@ -42,8 +43,9 @@ public class InterpolatingSampleBuffer
/**
* Buffer to store complex sample data and produce interpolated samples.
* @param samplesPerSymbol
* @param symbolTimingGain for the symbol timing error adjustments
*/
public InterpolatingSampleBuffer(float samplesPerSymbol)
public InterpolatingSampleBuffer(float samplesPerSymbol, float symbolTimingGain)
{
mSamplingPoint = samplesPerSymbol;
mDetectedSamplesPerSymbol = samplesPerSymbol;
@@ -52,6 +54,7 @@ public class InterpolatingSampleBuffer
mTwiceSamplesPerSymbol = (int)Math.floor(2.0 * samplesPerSymbol);
mDelayLineInphase = new float[2 * mTwiceSamplesPerSymbol];
mDelayLineQuadrature = new float[2 * mTwiceSamplesPerSymbol];
mDetectedSamplesPerSymbolGain = symbolTimingGain * mSampleCounterGain * mSampleCounterGain;
}
/**
@@ -125,18 +128,21 @@ public class InterpolatingSampleBuffer
}
/**
* Un-interpolated sample that precedes the current interpolated sampling point. The current sampling point falls
* somewhere between sample index 3 and index 4, therefore the preceding sample is located at index 3.
* Un-interpolated sample that precedes the current interpolated sampling point. The current interpolated sampling
* point falls somewhere between sample index 3 and index 4 and the sample is interpolated from sample
* indexes 0 - 7, therefore the uninterpolated sample that immediately precedes the current sample is
* located at index 3.
*/
public Complex getPrecedingSample()
{
mPrecedingSample.setValues(mDelayLineInphase[mDelayLinePointer + 4], mDelayLineQuadrature[mDelayLinePointer + 3]);
mPrecedingSample.setValues(mDelayLineInphase[mDelayLinePointer + 3], mDelayLineQuadrature[mDelayLinePointer + 3]);
return mPrecedingSample;
}
/**
* Interpolated middle sample for the symbol. Note: this method should only be invoked after testing for a
* complete symbol with the hasSymbol() method.
* Interpolated current sample for the symbol.
*
* Note: this method should only be invoked after testing for a complete symbol with the hasSymbol() method.
*/
public Complex getCurrentSample()
{
@@ -145,6 +151,21 @@ public class InterpolatingSampleBuffer
return mCurrentSample;
}
/**
* Interpolated sample that is 1/2 symbol away from (after) the current sample.
*
* Note: this method should only be invoked after testing for a complete symbol with the hasSymbol() method.
*/
public Complex getMiddleSample()
{
float halfDetectedSamplesPerSymbol = mDetectedSamplesPerSymbol / 2.0f;
//Interpolated sample that is half a symbol away from (occurred before) the current sample.
mMiddleSample.setValues(getInphase(halfDetectedSamplesPerSymbol),
getQuadrature(halfDetectedSamplesPerSymbol));
return mMiddleSample;
}
/**
* Returns the interpolated inphase value for the specified offset
* @param interpolation into the buffer to calculate the interpolated sample
@@ -152,7 +173,15 @@ public class InterpolatingSampleBuffer
*/
public float getInphase(float interpolation)
{
return mInterpolator.filter(mDelayLineInphase, mDelayLinePointer + 1, interpolation);
if(interpolation < 1.0f)
{
return mInterpolator.filter(mDelayLineInphase, mDelayLinePointer, interpolation);
}
else
{
int offset = (int)Math.floor(interpolation);
return mInterpolator.filter(mDelayLineInphase, mDelayLinePointer + offset, interpolation - offset);
}
}
/**
@@ -162,6 +191,14 @@ public class InterpolatingSampleBuffer
*/
public float getQuadrature(float interpolation)
{
return mInterpolator.filter(mDelayLineQuadrature, mDelayLinePointer + 1, interpolation);
if(interpolation < 1.0f)
{
return mInterpolator.filter(mDelayLineQuadrature, mDelayLinePointer, interpolation);
}
else
{
int offset = (int)Math.floor(interpolation);
return mInterpolator.filter(mDelayLineQuadrature, mDelayLinePointer + offset, interpolation - offset);
}
}
}