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123 lines
4.2 KiB
C++
123 lines
4.2 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright 2006-2021 Free Software Foundation, Inc. //
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// Copyright (C) 2018 Edouard Griffiths, F4EXB //
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// Copyright (C) 2021 Jon Beniston, M7RCE //
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// //
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// Based on the Costas Loop from GNU Radio //
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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 as 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 V3 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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#ifndef SDRBASE_DSP_COSTASLOOP_H_
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#define SDRBASE_DSP_COSTASLOOP_H_
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#include <QDebug>
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#include "dsp/dsptypes.h"
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#include "export.h"
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/** Costas Loop for phase and frequency tracking. */
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class SDRBASE_API CostasLoop
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{
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public:
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CostasLoop(float loopBW, unsigned int pskOrder);
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~CostasLoop();
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void computeCoefficients(float loopBW);
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void setPskOrder(unsigned int pskOrder) { m_pskOrder = pskOrder; }
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void reset();
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void setSampleRate(unsigned int sampleRate);
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void feed(float re, float im);
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const std::complex<float>& getComplex() const { return m_y; }
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float getReal() const { return m_y.real(); }
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float getImag() const { return m_y.imag(); }
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float getFreq() const { return m_freq; }
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float getPhiHat() const { return m_phase; }
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private:
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std::complex<float> m_y;
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float m_phase;
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float m_freq;
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float m_error;
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float m_maxFreq;
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float m_minFreq;
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float m_alpha;
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float m_beta;
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unsigned int m_pskOrder;
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void advanceLoop(float error)
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{
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m_freq = m_freq + m_beta * error;
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m_phase = m_phase + m_freq + m_alpha * error;
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}
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void phaseWrap()
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{
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const float two_pi = (float)(2.0 * M_PI);
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while (m_phase > two_pi)
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m_phase -= two_pi;
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while (m_phase < -two_pi)
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m_phase += two_pi;
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}
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void frequencyLimit()
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{
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if (m_freq > m_maxFreq)
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m_freq = m_maxFreq;
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else if (m_freq < m_minFreq)
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m_freq = m_minFreq;
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}
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void setMaxFreq(float freq)
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{
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m_maxFreq = freq;
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}
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void setMinFreq(float freq)
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{
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m_minFreq = freq;
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}
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float phaseDetector2(std::complex<float> sample) const // for BPSK
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{
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return (sample.real() * sample.imag());
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}
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float phaseDetector4(std::complex<float> sample) const // for QPSK
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{
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return ((sample.real() > 0.0f ? 1.0f : -1.0f) * sample.imag() -
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(sample.imag() > 0.0f ? 1.0f : -1.0f) * sample.real());
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};
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float phaseDetector8(std::complex<float> sample) const // for 8PSK
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{
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const float K = (sqrtf(2.0) - 1);
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if (fabsf(sample.real()) >= fabsf(sample.imag()))
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{
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return ((sample.real() > 0.0f ? 1.0f : -1.0f) * sample.imag() -
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(sample.imag() > 0.0f ? 1.0f : -1.0f) * sample.real() * K);
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}
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else
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{
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return ((sample.real() > 0.0f ? 1.0f : -1.0f) * sample.imag() * K -
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(sample.imag() > 0.0f ? 1.0f : -1.0f) * sample.real());
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}
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};
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};
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#endif /* SDRBASE_DSP_COSTASLOOP_H_ */
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