mirror of https://github.com/g4klx/MMDVM.git
Add Goertzel
This commit is contained in:
Geoffrey Merck
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/*
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* Copyright (C) 2020 by Jonathan Naylor G4KLX / Geoffrey Merck F4FXL - KC3FRA
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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 2 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, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "Goertzel.h"
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CGoertzel::CGoertzel(const TGoertzelParameters& f1, const TGoertzelParameters& f2, const TGoertzelParameters& f3, const int* window, int windowCorr, uint16_t n) :
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m_min(0),
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m_max(0),
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m_processedSamplesCount(0),
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m_n(n),
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m_window(window),//Window should not be deleted by someone else
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m_windowCorr(windowCorr)
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{
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m_freqs[0] = f1;
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m_freqs[1] = f2;
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m_freqs[2] = f3;
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reset();
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}
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void CGoertzel::reset()
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{
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::memset(m_q1s, 0, sizeof(m_q1s));
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::memset(m_q2s, 0, sizeof(m_q2s));
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m_processedSamplesCount = 0U;
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m_max = 0U;
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m_min = 0U;
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}
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GOERTZEL_RESULT CGoertzel::samples(const q15_t *samples, uint8_t length, unsigned int * f1MagSquared, unsigned int * f2MagSquared, unsigned int* f3MagSquared)
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{
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int scalingFactor = (length / 2) * m_windowCorr;
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unsigned int * magnitudes[3] = {f1MagSquared, f2MagSquared, f3MagSquared};
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GOERTZEL_RESULT magnitudesComputed = GR_NOT_READY;
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for(uint8_t sampleIdx = 0; sampleIdx < length; sampleIdx++) {
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if(samples[sampleIdx] < m_min) m_min = samples[sampleIdx];
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if(samples[sampleIdx] > m_max) m_max = samples[sampleIdx];
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for(uint8_t i = 0; i < 3; i++) {
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int q0 = m_freqs[i].coeff * m_q1s[i] - m_q2s[i] + (samples[sampleIdx] * m_window[m_processedSamplesCount]);
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m_q2s[i] = m_q1s[i];
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m_q1s[i] = q0;
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}
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m_processedSamplesCount++;
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//we have collected enough samples, evaluate now,
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if(m_processedSamplesCount == m_n) {
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if(magnitudesComputed == GR_NOT_READY) {
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//however if we already had collected enough samples only keep the magnitudes we computed the first time
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int span = m_max - m_min;
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for(uint8_t i = 0; i < 3; i++) {
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int real = ((m_q1s[i] * m_freqs[i].cos - m_q2s[i]) / scalingFactor)/span;//we divide by max-min so that we are normalized in the range [0, 1], this way we are input signal levels agnostic
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int imag = ((m_q1s[i] * m_freqs[i].sin) / scalingFactor)/span;
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*(magnitudes[i]) = real * real + imag * imag;
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}
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magnitudesComputed = GR_READY;
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}
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reset();
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}
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}
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return magnitudesComputed;
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}
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@ -0,0 +1,66 @@
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/*
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* Copyright (C) 2020 by Jonathan Naylor G4KLX / Geoffrey Merck F4FXL - KC3FRA
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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 2 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, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#if !defined(GOERTZEL_H)
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#define GOERTZEL_H
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#include "Globals.h"
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typedef struct
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{
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int sin, cos, coeff;
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} TGoertzelParameters;
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enum GOERTZEL_RESULT : uint8_t
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{
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GR_NOT_READY = 0,
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GR_READY = 1
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};
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class CGoertzel {
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public:
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//f1,f2,f3 are natural frequencies
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CGoertzel(const TGoertzelParameters& f1, const TGoertzelParameters& f2, const TGoertzelParameters& f3, const int* window, int windowCorr, uint16_t n);
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void reset();
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GOERTZEL_RESULT samples(const q15_t *samples, uint8_t length, unsigned int * f1MagSquared, unsigned int * f2MagSquared, unsigned int* f3MagSquared);
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private:
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TGoertzelParameters m_freqs[3];
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q15_t m_min;
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q15_t m_max;
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q15_t m_omegas[3];
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int m_sines[3];
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int m_cosines[3];
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int m_coeffs[3];
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int m_q1s[3];
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int m_q2s[3];
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uint16_t m_processedSamplesCount;
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uint16_t m_n;
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const int* m_window;
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int m_windowCorr;
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};
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#endif
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