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94 lines
3.1 KiB
C++
94 lines
3.1 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2018 F4EXB //
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// written by Edouard Griffiths //
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// //
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// See: http://liquidsdr.org/blog/pll-howto/ //
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// Fixed filter registers saturation //
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// Added order for PSK locking. This brilliant idea actually comes from this //
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// post: https://www.dsprelated.com/showthread/comp.dsp/36356-1.php //
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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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#include "freqlockcomplex.h"
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#include <cmath>
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FreqLockComplex::FreqLockComplex() :
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m_a0(0.998),
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m_a1(0.002),
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m_y(1.0, 0.0),
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m_yRe(1.0),
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m_yIm(0.0),
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m_freq(0.0),
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m_phi(0.0),
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m_phiX0(0.0),
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m_phiX1(0.0),
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m_y1(0.0f)
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{
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}
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FreqLockComplex::~FreqLockComplex()
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{
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}
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void FreqLockComplex::reset()
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{
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m_y.real(1.0);
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m_y.imag(0.0);
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m_yRe = 1.0f;
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m_yIm = 0.0f;
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m_freq = 0.0f;
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m_phi = 0.0f;
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m_phiX0 = 0.0f;
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m_phiX1 = 0.0f;
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m_y1 = 0.0f;
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}
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void FreqLockComplex::setSampleRate(unsigned int sampleRate)
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{
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m_a1 = 10.0f / sampleRate; // 1 - alpha
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m_a0 = 1.0f - m_a1; // alpha
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reset();
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}
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void FreqLockComplex::feed(float re, float im)
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{
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m_yRe = cos(m_phi);
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m_yIm = sin(m_phi);
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m_y.real(m_yRe);
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m_y.imag(m_yIm);
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std::complex<float> x(re, im);
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m_phiX0 = std::arg(x);
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float eF = normalizeAngle(m_phiX0 - m_phiX1);
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float fHat = m_a1*eF + m_a0*m_y1;
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m_y1 = fHat;
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m_freq = fHat; // correct instantaneous frequency
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m_phi += fHat; // advance phase with instantaneous frequency
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m_phiX1 = m_phiX0;
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}
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float FreqLockComplex::normalizeAngle(float angle)
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{
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while (angle <= -M_PI) {
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angle += 2.0*M_PI;
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}
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while (angle > M_PI) {
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angle -= 2.0*M_PI;
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}
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return angle;
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}
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