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https://github.com/DSheirer/sdrtrunk.git
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39f6d6c831
* Misc minor performance improvements * Use more concise loop syntax * Use more concise Collection sort syntax * Use StringUtils pad methods * Optimize some loops and double-map-lookups * Optimize array instantiation There are two styles to convert a collection to an array: either using a pre-sized array (like c.toArray(new String[c.size()])) or using an empty array (like c.toArray(new String[0]). In older Java versions using pre-sized array was recommended, as the reflection call which is necessary to create an array of proper size was quite slow. However since late updates of OpenJDK 6 this call was intrinsified, making the performance of the empty array version the same and sometimes even better, compared to the pre-sized version. Also passing pre-sized array is dangerous for a concurrent or synchronized collection as a data race is possible between the size and toArray call which may result in extra nulls at the end of the array, if the collection was concurrently shrunk during the operation. * Cleanup string concatenation * Use EnumMap where possible * Use FastMath instead of Math * Initialize complex things only once * Reduce method size to aloow more JIT inlining * remove map of short->float * Move field to local variable * Cleanup Map lookup Co-authored-by: Rob Ekl <xwq876@zebra.com>
116 lines
3.4 KiB
Java
116 lines
3.4 KiB
Java
/*
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*
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* * ******************************************************************************
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* * Copyright (C) 2014-2019 Dennis Sheirer
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* *
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* * This program is free software: you can redistribute it and/or modify
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* * it under the terms of the GNU General Public License as published by
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* * the Free Software Foundation, either version 3 of the License, or
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* * (at your option) any later version.
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* *
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* * This program is distributed in the hope that it will be useful,
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* * but WITHOUT ANY WARRANTY; without even the implied warranty of
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* * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* * GNU General Public License for more details.
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* *
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* * You should have received a copy of the GNU General Public License
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* * along with this program. If not, see <http://www.gnu.org/licenses/>
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* * *****************************************************************************
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*
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*
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*/
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package io.github.dsheirer.dsp.psk;
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import io.github.dsheirer.buffer.ComplexCircularBuffer;
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import io.github.dsheirer.sample.complex.Complex;
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import org.apache.commons.math3.util.FastMath;
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public class SymbolDecisionData
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{
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//45 degrees rotation to orient the symbol to a polar axis to make error calculation easy/efficient
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public static final Complex DIFFERENTIAL_OFFSET = Complex.fromAngle(FastMath.PI / 4.0d);
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private ComplexCircularBuffer mBuffer;
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private float mSamplingPoint;
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private float mSamplesPerSymbol;
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/**
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* Circular buffer for capturing two symbols worth of sample data for use in instrumentation.
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* @param samplesPerSymbol to size the buffer
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*/
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public SymbolDecisionData(float samplesPerSymbol)
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{
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mSamplesPerSymbol = samplesPerSymbol;
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mBuffer = new ComplexCircularBuffer(8);
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}
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/**
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* Stores the complex sample in the buffer
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*/
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public void receive(float inphase, float quadrature)
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{
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mBuffer.put(new Complex(inphase, quadrature));
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}
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/**
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* Stores the complex sample in the buffer
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*/
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public void receive(Complex complex)
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{
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mBuffer.put(complex.copy());
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}
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/**
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* Sets the fractional sampling point for the current symbol to use in interpolating the current symbol.
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*/
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public void setSamplingPoint(float samplingPoint)
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{
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mSamplingPoint = samplingPoint;
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}
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/**
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* Fractional sampling point
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*/
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public float getSamplingPoint()
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{
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return mSamplingPoint;
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}
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/**
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* Raw samples
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*/
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public Complex[] getSamples()
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{
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return mBuffer.getAll();
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}
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public Complex[] getSamples(int length)
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{
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return mBuffer.get(length);
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}
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/**
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* Array of (FM) demodulated samples representing the current symbol where each current sample is demodulated against
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* the previous symbol's sample to produce the differential demodulated sample. Samples are in time order.
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*
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* Note: differential decoding is on an integral samples-per-symbol basis and does not use fractional interpolation.
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*/
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public Complex[] getDemodulated()
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{
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Complex[] samples = mBuffer.getAll();
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int length = samples.length / 2;
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Complex[] demodulated = new Complex[length];
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for(int x = 0; x < samples.length / 2; x++)
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{
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Complex copy = samples[length + x].copy();
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copy.multiply(samples[x].conjugate());
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demodulated[x] = copy;
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}
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return demodulated;
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}
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}
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