| 1 | // Copyright (C) 2024 The Qt Company Ltd. |
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| 2 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only |
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| 3 | |
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| 4 | #ifndef QSINEWAVEVALIDATOR_H |
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| 5 | #define QSINEWAVEVALIDATOR_H |
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| 6 | |
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| 7 | // |
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| 8 | // W A R N I N G |
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| 9 | // ------------- |
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| 10 | // |
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| 11 | // This file is not part of the Qt API. It exists purely as an |
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| 12 | // implementation detail. This header file may change from version to |
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| 13 | // version without notice, or even be removed. |
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| 14 | // |
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| 15 | // We mean it. |
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| 16 | // |
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| 17 | |
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| 18 | #include <array> |
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| 19 | |
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| 20 | // sine wave validator: accumulating peak value and result of passing the signal through a notch |
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| 21 | // filter. A sine wave of that frequency should not pass the notch filter, so if the peak exceeds a |
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| 22 | // small threshold, it we can detect discontinuities for example. |
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| 23 | struct QSineWaveValidator |
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| 24 | { |
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| 25 | QSineWaveValidator(const QSineWaveValidator &) = delete; |
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| 26 | QSineWaveValidator(QSineWaveValidator &&) = delete; |
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| 27 | QSineWaveValidator &operator=(const QSineWaveValidator &) = delete; |
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| 28 | QSineWaveValidator &operator=(QSineWaveValidator &&) = delete; |
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| 29 | |
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| 30 | QSineWaveValidator(float notchFrequency, float sampleRate); |
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| 31 | |
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| 32 | void feedSample(float sample); |
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| 33 | |
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| 34 | float peak() const { return accumPeak; } |
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| 35 | float notchPeak() const; |
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| 36 | |
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| 37 | private: |
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| 38 | float a0, a1, a2; |
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| 39 | float b0, b1, b2; |
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| 40 | |
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| 41 | std::array<float, 3> x{}, y{}; |
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| 42 | int framesBeforeAnalysis = 128; // unscientific estimate, larger than the transient response |
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| 43 | // time for the IIR filter |
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| 44 | int pendingFramesBeforeAnalysis = framesBeforeAnalysis; |
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| 45 | |
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| 46 | float accumPeak{}; |
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| 47 | float accumNotchPeak{}; |
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| 48 | }; |
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| 49 | |
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| 50 | #endif // QSINEWAVEVALIDATOR_H |
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| 51 | |
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