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Changes audio module decimation filter from lowpass to bandpass so that we can remove 0-250 Hz and any LTR signalling from the audio output.

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This commit is contained in:
Denny
2016-08-21 07:21:38 -04:00
parent 3af4b953f4
commit d466ec9f5e
5 changed files with 745 additions and 735 deletions
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50
src/dsp/filter/design/FilterViewer.java
View File

@@ -40,37 +40,35 @@ public class FilterViewer extends Application
*/
private float[] getFilter()
{
FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
.sampleRate( 48000 )
.gridDensity( 16 )
.passBandCutoff( 3000 )
// FIRFilterSpecification specification = FIRFilterSpecification.lowPassBuilder()
// .sampleRate( 48000 )
// .gridDensity( 16 )
// .passBandCutoff( 3000 )
// .passBandAmplitude( 1.0 )
// .passBandRipple( 0.01 )
// .stopBandStart( 4000 )
// .stopBandAmplitude( 0.0 )
// .stopBandRipple( 0.027 )
// .build();
FIRFilterSpecification specification = FIRFilterSpecification.highPassBuilder()
.sampleRate( 8000 )
.stopBandCutoff( 250 )
.stopBandAmplitude( 0.0 )
.stopBandRipple( 0.01 )
.passBandStart( 300 )
.passBandAmplitude( 1.0 )
.passBandRipple( 0.01 )
.stopBandStart( 4000 )
.stopBandAmplitude( 0.0 )
.stopBandRipple( 0.027 )
.build();
// FIRFilterSpecification specification = FIRFilterSpecification.highPassBuilder()
// .sampleRate( 8000 )
// .gridDensity( 16 )
// .stopBandCutoff( 2000 )
// .stopBandAmplitude( 0.0 )
// .stopBandRipple( 0.003 )
// .passBandStart( 3000 )
// .passBandAmplitude( 1.0 )
// .passBandRipple( 0.001 )
// .build();
// FIRFilterSpecification specification = FIRFilterSpecification.bandPassBuilder()
// .sampleRate( 8000 )
// .order( 164 )
// .stopFrequency1( 1100 )
// .passFrequencyBegin( 1200 )
// .passFrequencyEnd( 2400 )
// .stopFrequency2( 2500 )
// .stopRipple( 0.01 )
// .passRipple( 0.01 )
// .sampleRate( 48000 )
// .stopFrequency1( 150 )
// .passFrequencyBegin( 200 )
// .passFrequencyEnd( 3950 )
// .stopFrequency2( 4000 )
// .stopRipple( 0.0005 )
// .passRipple( 0.003)
// .build();
float[] taps = null;

10
src/dsp/filter/polyphase/PolyphaseFIRDecimatingFilter_RB.java
View File

@@ -43,6 +43,7 @@ public class PolyphaseFIRDecimatingFilter_RB extends FIRFilter implements Listen
private RealToRealBufferAssembler mAssembler;
private int mDecimationRatio;
private float mAccumulator = 0.0f;
private float mGain = 1.0f;
/**
* Polyphase filter stage for decimating real-valued sample buffers by the decimation ratio. Creates a number of
@@ -55,10 +56,13 @@ public class PolyphaseFIRDecimatingFilter_RB extends FIRFilter implements Listen
* to the nyquist frequency for an output sample rate equal to the input sample rate divided by the decimation ratio.
*
* @param decimationRatio to decimate the input sample rate by.
* @param gain to apply to the filtered output. Use a value of 1.0 to apply no gain.
*/
public PolyphaseFIRDecimatingFilter_RB(float[] coefficients, int decimationRatio)
public PolyphaseFIRDecimatingFilter_RB(float[] coefficients, int decimationRatio, float gain)
{
mDecimationRatio = decimationRatio;
mGain = gain;
createFilterStages(coefficients, mDecimationRatio);
mFilterStagePointer = mFilterStages.size() - 1;
}
@@ -127,7 +131,7 @@ public class PolyphaseFIRDecimatingFilter_RB extends FIRFilter implements Listen
if(mFilterStagePointer < 0)
{
mAssembler.receive(mAccumulator);
mAssembler.receive(mAccumulator * mGain);
mAccumulator = 0.0f;
mFilterStagePointer = mFilterStages.size() - 1;
@@ -177,7 +181,7 @@ public class PolyphaseFIRDecimatingFilter_RB extends FIRFilter implements Listen
}
float[] coefficients = designer.getImpulseResponse();
PolyphaseFIRDecimatingFilter_RB filter = new PolyphaseFIRDecimatingFilter_RB(coefficients, 6);
PolyphaseFIRDecimatingFilter_RB filter = new PolyphaseFIRDecimatingFilter_RB(coefficients, 6, 1.0f);
filter.setListener(new Listener<RealBuffer>()
{
@Override