kopia lustrzana https://github.com/mobilinkd/NucleoTNC
88 wiersze
1.4 KiB
C++
88 wiersze
1.4 KiB
C++
// Copyright 2020-2022 Mobilinkd LLC <rob@mobilinkd.com>
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// All rights reserved.
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#pragma once
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#include "main.h"
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#include <arm_math.h>
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#include <cstdint>
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namespace mobilinkd {
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/**
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* Compute a running standard deviation.
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*
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* Based on https://dsp.stackexchange.com/a/1187/36581
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*/
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struct StandardDeviation
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{
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float mean{0.0};
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float S{0.0};
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uint32_t samples{0};
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void reset()
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{
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mean = 0.0;
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S = 0.0;
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samples = 0;
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}
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void capture(float sample)
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{
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auto prev = mean;
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samples += 1;
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mean = mean + (sample - mean) / samples;
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S = S + (sample - mean) * (sample - prev);
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}
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float variance() const
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{
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return samples == 0 ? -1.0 : S / samples;
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}
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float stdev() const
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{
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float result = -1.0;
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arm_sqrt_f32(variance(), &result);
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return result;
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}
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// SNR in dB
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float SNR() const
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{
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return 10.0 * log10(mean / stdev());
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}
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};
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template <typename FloatType, size_t N>
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struct RunningStandardDeviation
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{
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FloatType S{1.0};
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FloatType alpha{1.0 / N};
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void reset()
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{
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S = 0.0;
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}
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void capture(float sample)
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{
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S -= S * alpha;
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S += (sample * sample) * alpha;
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}
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FloatType variance() const
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{
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return S;
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}
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FloatType stdev() const
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{
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return std::sqrt(variance());
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}
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};
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} // mobilinkd
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