/*******************************************************************************
* sdrtrunk
* Copyright (C) 2014-2017 Dennis Sheirer
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
******************************************************************************/
package dsp.filter.cic;
import dsp.filter.FilterFactory;
import dsp.filter.Filters;
import dsp.filter.Window.WindowType;
import dsp.filter.fir.complex.ComplexFIRFilter_CB_CB;
import dsp.filter.halfband.complex.HalfBandFilter_CB_CB;
import org.apache.commons.lang3.Validate;
import sample.Listener;
import sample.complex.ComplexBuffer;
import sample.complex.ComplexSampleListener;
import sample.complex.ComplexToComplexBufferAssembler;
import sample.decimator.ComplexDecimator;
import java.util.ArrayList;
import java.util.List;
public class ComplexPrimeCICDecimate implements Listener<ComplexBuffer>
{
public static int[] PRIMES = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53,
59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151,
157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251,
257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359,
367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463,
467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593,
599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691};
private ArrayList<DecimatingStage> mDecimatingStages =
new ArrayList<DecimatingStage>();
private DecimatingStage mFirstDecimatingStage;
private Output mOutput;
/**
* Non-Recursive Prime-Factor CIC Filter with float sample array inputs and
* decimated, single paired i/q float sample output.
*
* Implements the CIC filter described in Understanding Digital Signal
* Processing, 3e, Lyons, on page 769. This filter is comprised of multiple
* decimating stages each with a prime factor decimation rate. Multiple
* stages are cascaded to achieve the overall decimation rate.
*
* This filter supports a maximum decimation rate of 700. This filter can
* be adapted to higher decimation rates by adding additional prime factors
* to the PRIMES array.
*
* @param decimation - overall decimation rate
* @param order - filter order
*/
public ComplexPrimeCICDecimate(int decimation, int order,
int passFrequency, int attenuation, WindowType windowType)
{
Validate.isTrue(decimation <= 700);
List<Integer> stageSizes = getPrimeFactors(decimation);
for(int x = 0; x < stageSizes.size(); x++)
{
DecimatingStage stage = new DecimatingStage(stageSizes.get(x), order);
mDecimatingStages.add(stage);
if(x == 0)
{
/* Reference to first stage -- will receive all samples */
mFirstDecimatingStage = stage;
}
else
{
/* Wire the current stage to the previous stage */
mDecimatingStages.get(x - 1).setListener(stage);
}
}
mOutput = new Output(48000, passFrequency, attenuation, windowType);
mDecimatingStages.get(mDecimatingStages.size() - 1)
.setListener(mOutput);
}
public void dispose()
{
for(DecimatingStage stage : mDecimatingStages)
{
stage.dispose();
}
mDecimatingStages.clear();
mDecimatingStages = null;
mFirstDecimatingStage = null;
mOutput.dispose();
mOutput = null;
}
/**
* Adds a listener to receive the output of this CIC decimation filter
*/
public void setListener(Listener<ComplexBuffer> listener)
{
mOutput.setListener(listener);
}
/**
* Removes listener from output of this CIC decimation filter
*/
public void removeListener()
{
mOutput.removeListener();
}
/**
* Calculates the prime factors of the decimation rate up to a maximum
* decimation rate of 700. If you wish to have decimation rates higher
* than 700, then add additional prime factors to the PRIMES array.
*
* @param decimation - integral decimation rate
* @return - ordered list (smallest to largest) of prime factors
*/
public static List<Integer> getPrimeFactors(int decimation)
{
ArrayList<Integer> stages = new ArrayList<Integer>();
int pointer = 0;
while(decimation > 0 && pointer < PRIMES.length)
{
int prime = PRIMES[pointer];
if(decimation % prime == 0)
{
stages.add(prime);
decimation /= prime;
}
else
{
pointer++;
}
}
return stages;
}
/**
* Primary input method for receiving sample arrays composed as I,Q,I,Q, etc.
*/
@Override
public void receive(ComplexBuffer buffer)
{
if(mFirstDecimatingStage != null)
{
float[] samples = buffer.getSamples();
for(int x = 0; x < samples.length; x += 2)
{
mFirstDecimatingStage.receive(samples[x], samples[x + 1]);
}
}
}
/**
* Decimating stage combines multiple CIC stages with a decimator. The
* number of stages is indicated by the order value and the size indicates
* the decimation rate of this stage.
*/
public class DecimatingStage implements ComplexSampleListener
{
private ArrayList<Stage> mStages = new ArrayList<Stage>();
private Stage mFirstStage;
private ComplexDecimator mDecimator;
public DecimatingStage(int size, int order)
{
for(int x = 0; x < order; x++)
{
Stage stage;
if(size == 2)
{
stage = new TwoStage();
}
else
{
stage = new Stage(size);
}
mStages.add(stage);
if(x == 0)
{
mFirstStage = stage;
}
else
{
mStages.get(x - 1).setListener(stage);
}
}
mDecimator = new ComplexDecimator(size);
mStages.get(mStages.size() - 1).setListener(mDecimator);
}
public void dispose()
{
for(Stage stage : mStages)
{
stage.dispose();
}
mStages.clear();
mDecimator.dispose();
mDecimator = null;
mFirstStage = null;
mStages = null;
}
@Override
public void receive(float i, float q)
{
mFirstStage.receive(i, q);
}
public void setListener(ComplexSampleListener listener)
{
mDecimator.setListener(listener);
}
}
/**
* Single non-decimating CIC stage component. Uses a circular buffer and a
* running average internally to implement the stage so that stage size has
* essentially no impact on the computational requirements of the stage
*/
public class Stage implements ComplexSampleListener
{
protected ComplexSampleListener mListener;
private float[] mISamples;
private float[] mQSamples;
protected float mISum;
protected float mQSum;
private int mSamplePointer = 0;
private int mSize;
protected float mGain;
public Stage()
{
}
public Stage(int size)
{
mSize = size - 1;
mISamples = new float[mSize];
mQSamples = new float[mSize];
mGain = 1.0f / (float)size;
}
public void dispose()
{
mListener = null;
}
public void receive(float i, float q)
{
/* Subtract the oldest sample and add back in the newest */
mISum = mISum - mISamples[mSamplePointer] + i;
mQSum = mQSum - mQSamples[mSamplePointer] + q;
/* Overwrite the oldest sample with the newest */
mISamples[mSamplePointer] = i;
mQSamples[mSamplePointer] = q;
mSamplePointer++;
if(mSamplePointer >= mSize)
{
mSamplePointer = 0;
}
if(mListener != null)
{
mListener.receive((mISum * mGain), (mQSum * mGain));
}
}
public void setListener(ComplexSampleListener listener)
{
mListener = listener;
}
}
/**
* Size 2 stage that removes the unnecessary circular buffer management for
* a two-stage.
*/
public class TwoStage extends Stage
{
public TwoStage()
{
super();
mGain = 0.5f;
}
public void receive(float i, float q)
{
float iSum = mISum + i;
float qSum = mQSum + q;
mISum = i;
mQSum = q;
if(mListener != null)
{
mListener.receive((iSum * mGain), (qSum * mGain));
}
}
}
/**
* Output adapter - applies gain correction and cleanup filter and broadcast
* to registered listener.
*/
public class Output implements ComplexSampleListener
{
/* Decimated output buffers will contain 1024 samples */
private ComplexToComplexBufferAssembler mAssembler =
new ComplexToComplexBufferAssembler(2048);
private ComplexFIRFilter_CB_CB mCleanupFilter;
private HalfBandFilter_CB_CB mHalfBandFilter = new HalfBandFilter_CB_CB(
Filters.FIR_HALF_BAND_31T_ONE_EIGHTH_FCO.getCoefficients(), 0.4f, false);
public Output(int outputSampleRate, int passFrequency, int attenuation,
WindowType windowType)
{
mCleanupFilter = new ComplexFIRFilter_CB_CB(FilterFactory
.getCICCleanupFilter(outputSampleRate,
passFrequency,
attenuation,
windowType), 0.4f);
//Bypassing the CIC cleanup filter for now
mAssembler.setListener(mHalfBandFilter);
// mAssembler.setListener( mCleanupFilter );
// mCleanupFilter.setListener( mHalfBandFilter );
}
public void dispose()
{
mAssembler.dispose();
mCleanupFilter.dispose();
mHalfBandFilter.dispose();
}
/**
* Receiver method for the output adapter to receive a filtered,
* decimated sample, apply gain correction, apply cleanup filtering
* and output the sample values as a complex sample.
*/
@Override
public void receive(float inphase, float quadrature)
{
mAssembler.receive(inphase, quadrature);
}
/**
* Adds a listener to receive output samples
*/
public void setListener(Listener<ComplexBuffer> listener)
{
mHalfBandFilter.setListener(listener);
}
/**
* Removes the listener from receiving output samples
*/
public void removeListener()
{
mHalfBandFilter.removeListener();
}
}
}