#include <stddef.h>
#include <stdint.h>

Include dependency graph for feature_extract.h:

Macros
#define	ADCSAMPLESIZE 125

#define	SAMPLING_FREQ 25

#define	PADDING_SIZE_LEFT 4

#define	PADDING_SIZE_RIGHT 3

#define	PADDED_INPUT_SIZE (ADCSAMPLESIZE + PADDING_SIZE_LEFT + PADDING_SIZE_RIGHT)

#define	WINDOW_SIZE 32

#define	WINDOW_STRIDE_SIZE 4

#define	NUM_WINDOWS 25

#define	FFT_SIZE 64

#define	NUM_BINS (FFT_SIZE / 2)

#define	POOLED_BINS (NUM_BINS / 2)

#define	TOP_N_FREQ 2

#define	KURTOSIS_CHUNK_SIZE 8

#define	KURTOSIS_STRIDE_SIZE 8

#define	NUM_FEAT_FFT 16

#define	NUM_FEAT_TOPFREQ TOP_N_FREQ

#define	NUM_FEAT_KURTOSIS 4

#define	NUM_FEAT_ZCR 1

#define	NUM_FEAT_SLOPE 1

#define	NUM_FEAT_PW_SPEC 1

#define	NUM_TOTAL_FEATURES 25

Enumerations
enum	fe_status_t { FE_OK = 0x00, FE_ERR_NULLPTR = 0x01, FE_ERR_BAD_PARAM = 0x02, FE_ERR_DSP = 0x03 }
	Specifies the FE status codes. More...

Functions
fe_status_t	FE_applyWindow (const uint8_t *data_stream, uint8_t output_windows[25][32])
	Builds padded/sliding windows from an input stream considering a stride size. More...

fe_status_t	FE_zeroCrossingRate (const uint8_t input_window, float zcr_out)
	Measures of how often a signal crosses the zero axis, indicating the frequency or noisiness of a signal. More...

fe_status_t	FE_slopeChanges (const uint8_t input_window, float slope_changes)
	Counts the sign changes of signal differences. More...

fe_status_t	FE_fftPool (const uint8_t input_window, float fft_output_pool_mag)
	calculate FFT magnitudes and pooling (averaging) to produce NUM_FEAT_FFT features. More...

fe_status_t	FE_topFrequencies (const uint8_t input_window, float top_freqs)
	Extract the index of the dominant frequencies (Hz) per window. More...

fe_status_t	FE_spectralEntropy (const uint8_t input_window, float entropy_out)
	Calculates the Shannon spectral entropy. The Spectral Entropy acts as an indicator of how spread out the power is. More...

fe_status_t	FE_kurtosis (const uint8_t input_window, float kurtosis_output)
	Calculates the fisher or excess kurtosis without bias for each segment of a given series. Kurtosis describes the "peakedness" of a probability distribution. More...

fe_status_t	FE_concatenateFeatures (const float fft_output_pool_mag, uint32_t window_index, const float kurtosis_output, const float zcr, const float slope_changes, const float top_dominant_freq, const float power_spectrum, float *concatenated_features)
	Concatenate many feature arrays into a big feature vector. The offsets are determined by NUM_FEAT_X and NUM_WINDOWS macros. More...

Variables
uint32_t	samplingfreq

Macro Definition Documentation

§ ADCSAMPLESIZE

#define ADCSAMPLESIZE 125

§ SAMPLING_FREQ

#define SAMPLING_FREQ 25

§ PADDING_SIZE_LEFT

#define PADDING_SIZE_LEFT 4

§ PADDING_SIZE_RIGHT

#define PADDING_SIZE_RIGHT 3

§ PADDED_INPUT_SIZE

#define PADDED_INPUT_SIZE (ADCSAMPLESIZE + PADDING_SIZE_LEFT + PADDING_SIZE_RIGHT)

§ WINDOW_SIZE

#define WINDOW_SIZE 32

§ WINDOW_STRIDE_SIZE

#define WINDOW_STRIDE_SIZE 4

§ NUM_WINDOWS

#define NUM_WINDOWS 25

§ FFT_SIZE

#define FFT_SIZE 64

§ NUM_BINS

#define NUM_BINS (FFT_SIZE / 2)

§ POOLED_BINS

#define POOLED_BINS (NUM_BINS / 2)

§ TOP_N_FREQ

#define TOP_N_FREQ 2

§ KURTOSIS_CHUNK_SIZE

#define KURTOSIS_CHUNK_SIZE 8

§ KURTOSIS_STRIDE_SIZE

#define KURTOSIS_STRIDE_SIZE 8

§ NUM_FEAT_FFT

#define NUM_FEAT_FFT 16

§ NUM_FEAT_TOPFREQ

#define NUM_FEAT_TOPFREQ TOP_N_FREQ

§ NUM_FEAT_KURTOSIS

#define NUM_FEAT_KURTOSIS 4

§ NUM_FEAT_ZCR

#define NUM_FEAT_ZCR 1

§ NUM_FEAT_SLOPE

#define NUM_FEAT_SLOPE 1

§ NUM_FEAT_PW_SPEC

#define NUM_FEAT_PW_SPEC 1

§ NUM_TOTAL_FEATURES

#define NUM_TOTAL_FEATURES 25

Enumeration Type Documentation

§ fe_status_t

enum fe_status_t

Specifies the FE status codes.

This enum defines the return states of the FE functions.

Enumerator
FE_OK	Process ended successfully. The pointer to one of the function arguments has a NULL value.
FE_ERR_NULLPTR	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_BAD_PARAM	DSP operation has failed.
FE_ERR_DSP

Function Documentation

§ FE_applyWindow()

fe_status_t FE_applyWindow	(	const uint8_t *	data_stream,
		uint8_t	output_windows[25][32]
	)

Builds padded/sliding windows from an input stream considering a stride size.

Parameters

[in]	data_stream	pointer to input data stream [ADCSAMPLESIZE] for time series.
[out]	output_windows	preallocated 2D-array [NUM_WINDOWS][WINDOW_SIZE].

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_zeroCrossingRate()

fe_status_t FE_zeroCrossingRate	(	const uint8_t *	input_window,
		float *	zcr_out
	)

Measures of how often a signal crosses the zero axis, indicating the frequency or noisiness of a signal.

Parameters

[in]	input_window	input window uint8.
[out]	zcr_out	pointer to result float32.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_slopeChanges()

fe_status_t FE_slopeChanges	(	const uint8_t *	input_window,
		float *	slope_changes
	)

Counts the sign changes of signal differences.

Parameters

[in]	input_window	input window uint8.
[out]	slope_changes	pointer to result float32.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_fftPool()

fe_status_t FE_fftPool	(	const uint8_t *	input_window,
		float *	fft_output_pool_mag
	)

calculate FFT magnitudes and pooling (averaging) to produce NUM_FEAT_FFT features.

Parameters

[in]	input_window	input window uint8.
[out]	fft_output_pool_mag	preallocated array of NUM_FEAT_FFT float32.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_topFrequencies()

fe_status_t FE_topFrequencies	(	const uint8_t *	input_window,
		float *	top_freqs
	)

Extract the index of the dominant frequencies (Hz) per window.

Parameters

[in]	input_window	input window uint8.
[out]	top_freqs	preallocated array of length TOP_N_FREQ.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_spectralEntropy()

fe_status_t FE_spectralEntropy	(	const uint8_t *	input_window,
		float *	entropy_out
	)

Calculates the Shannon spectral entropy. The Spectral Entropy acts as an indicator of how spread out the power is.

Parameters

[in]	input_window	input window uint8.
[out]	entropy_out	pointer to float32 result.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_kurtosis()

fe_status_t FE_kurtosis	(	const uint8_t *	input_window,
		float *	kurtosis_output
	)

Calculates the fisher or excess kurtosis without bias for each segment of a given series. Kurtosis describes the "peakedness" of a probability distribution.

Parameters

[in]	input_window	input window uint8.
[out]	kurtosis_output	preallocated array of NUM_FEAT_KURTOSIS float32.

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

§ FE_concatenateFeatures()

fe_status_t FE_concatenateFeatures	(	const float *	fft_output_pool_mag,
		uint32_t	window_index,
		const float *	kurtosis_output,
		const float *	zcr,
		const float *	slope_changes,
		const float *	top_dominant_freq,
		const float *	power_spectrum,
		float *	concatenated_features
	)

Concatenate many feature arrays into a big feature vector. The offsets are determined by NUM_FEAT_X and NUM_WINDOWS macros.

Parameters

[in]	fft_output_pool_mag	pointer to FFT features (NUM_FEAT_FFT)
[in]	window_index	which window this belongs to (0 .. NUM_WINDOWS-1)
[in]	kurtosis_output	pointer to NUM_FEAT_KURTOSIS values
[in]	zcr	pointer to zcr value (scalar)
[in]	slope_changes	pointer to slope_changes value (scalar)
[in]	top_dominant_freq	pointer to TOP_N_FREQ values
[in]	power_spectrum	pointer to spectral entropy (scalar)
[out]	concatenated_features	preallocated feature vector of size NUM_TOTAL_FEATURES * NUM_WINDOWS

Return values

FE_OK	Process ended successfully.
FE_ERR_NULLPTR	The pointer to one of the function arguments has a NULL value.
FE_ERR_BAD_PARAM	One of the Feature Extraction configuration parameters is incorrect or not supported.
FE_ERR_DSP	DSP operation has failed.

Variable Documentation

§ samplingfreq

uint32_t samplingfreq

Macros

Enumerations

Functions

Variables

Macro Definition Documentation

§ ADCSAMPLESIZE

§ SAMPLING_FREQ

§ PADDING_SIZE_LEFT

§ PADDING_SIZE_RIGHT

§ PADDED_INPUT_SIZE

§ WINDOW_SIZE

§ WINDOW_STRIDE_SIZE

§ NUM_WINDOWS

§ FFT_SIZE

§ NUM_BINS

§ POOLED_BINS

§ TOP_N_FREQ

§ KURTOSIS_CHUNK_SIZE

§ KURTOSIS_STRIDE_SIZE

§ NUM_FEAT_FFT

§ NUM_FEAT_TOPFREQ

§ NUM_FEAT_KURTOSIS

§ NUM_FEAT_ZCR

§ NUM_FEAT_SLOPE

§ NUM_FEAT_PW_SPEC

§ NUM_TOTAL_FEATURES

Enumeration Type Documentation

§ fe_status_t

Function Documentation

§ FE_applyWindow()

§ FE_zeroCrossingRate()

§ FE_slopeChanges()

§ FE_fftPool()

§ FE_topFrequencies()

§ FE_spectralEntropy()

§ FE_kurtosis()

§ FE_concatenateFeatures()

Variable Documentation

§ samplingfreq