File syn_signal.h¶

FileList > dsp > syn_signal.h

Signal statistics — sliding window min/max/mean/variance/RMS. More...

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

Classes¶

Type	Name
struct	SYN_Signal Signal statistics — sliding window with incremental min/max/mean.

Public Functions¶

Type	Name
int32_t	syn_signal_at (const SYN_Signal * sig, size_t index) Get sample at index (0 = oldest, count-1 = newest).
void	syn_signal_clear (SYN_Signal * sig) Clear all samples.
int32_t	syn_signal_crest_factor_q16 (SYN_Signal * sig) Signal Crest Factor in Q16.16: Peak / RMS.
int32_t	syn_signal_delta (const SYN_Signal * sig) Rate of change: latest - previous.
void	syn_signal_init (SYN_Signal * sig, int32_t * buf, size_t capacity) Initialize with a caller-provided sample buffer.
int32_t	syn_signal_latest (const SYN_Signal * sig) Get the most recent sample.
int32_t	syn_signal_max (SYN_Signal * sig) Maximum value in the window.
int32_t	syn_signal_min (SYN_Signal * sig) Minimum value in the window.
int32_t	syn_signal_power_q16 (const SYN_Signal * sig) Mean signal power in Q16.16: Σ(x²) / N.
void	syn_signal_push (SYN_Signal * sig, int32_t sample) Push a new sample.
int32_t	syn_signal_rms_q16 (const SYN_Signal * sig) Root-Mean-Square in Q16.16: sqrt(Σ(x²) / N).
int32_t	syn_signal_std_dev_q16 (const SYN_Signal * sig) Standard deviation in Q16.16: sqrt(variance).
int32_t	syn_signal_variance_q16 (const SYN_Signal * sig) Variance in Q16.16 format.

Public Static Functions¶

Type	Name
size_t	syn_signal_count (const SYN_Signal * sig) Number of samples in the window.
bool	syn_signal_full (const SYN_Signal * sig) True if the window is full.
int32_t	syn_signal_mean (const SYN_Signal * sig) Integer mean (truncated).
int32_t	syn_signal_peak_to_peak (SYN_Signal * sig) Peak-to-peak = max - min.
int64_t	syn_signal_sum (const SYN_Signal * sig) Sum of all samples in window.

Detailed Description¶

Maintains a circular buffer of samples and computes statistics incrementally. Designed for sensor data conditioning.

All math is integer-only. Mean and variance use Q16.16 for fractional precision without floating point.

** **

int32_t samples[32];
SYN_Signal sig;
syn_signal_init(&sig, samples, 32);

// Feed samples:
syn_signal_push(&sig, adc_read());

// Query stats:
int32_t min = syn_signal_min(&sig);
int32_t max = syn_signal_max(&sig);
int32_t avg = syn_signal_mean(&sig);       // integer mean
int32_t pp  = syn_signal_peak_to_peak(&sig);
int32_t var = syn_signal_variance_q16(&sig); // Q16.16

Public Functions Documentation¶

function syn_signal_at¶

Get sample at index (0 = oldest, count-1 = newest).

int32_t syn_signal_at (
    const SYN_Signal * sig,
    size_t index
)

Parameters:

sig Signal instance.
index Sample index.

Returns:

Sample value.

function syn_signal_clear¶

Clear all samples.

void syn_signal_clear (
    SYN_Signal * sig
)

Parameters:

sig Signal instance.

function syn_signal_crest_factor_q16¶

Signal Crest Factor in Q16.16: Peak / RMS.

int32_t syn_signal_crest_factor_q16 (
    SYN_Signal * sig
)

Measures signal peakiness (e.g. 1.414 for sine wave). Returns 0 if RMS is 0 or window is empty.

Parameters:

sig Signal instance.

Returns:

Crest Factor in Q16.16 format.

function syn_signal_delta¶

Rate of change: latest - previous.

int32_t syn_signal_delta (
    const SYN_Signal * sig
)

Returns 0 if fewer than 2 samples.

Parameters:

sig Signal instance.

Returns:

Delta between last two samples.

function syn_signal_init¶

Initialize with a caller-provided sample buffer.

void syn_signal_init (
    SYN_Signal * sig,
    int32_t * buf,
    size_t capacity
)

Parameters:

sig Signal instance.
buf Sample buffer (caller-owned).
capacity Buffer capacity (number of samples).

function syn_signal_latest¶

Get the most recent sample.

int32_t syn_signal_latest (
    const SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Latest sample, or 0 if empty.

function syn_signal_max¶

Maximum value in the window.

int32_t syn_signal_max (
    SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Max, or 0 if empty.

function syn_signal_min¶

Minimum value in the window.

int32_t syn_signal_min (
    SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Min, or 0 if empty.

function syn_signal_power_q16¶

Mean signal power in Q16.16: Σ(x²) / N.

int32_t syn_signal_power_q16 (
    const SYN_Signal * sig
)

Returns 0 if the window is empty.

Parameters:

sig Signal instance.

Returns:

Mean power in Q16.16 format.

function syn_signal_push¶

Push a new sample.

void syn_signal_push (
    SYN_Signal * sig,
    int32_t sample
)

If the window is full, the oldest sample is evicted.

Parameters:

sig Signal instance.
sample New sample value.

function syn_signal_rms_q16¶

Root-Mean-Square in Q16.16: sqrt(Σ(x²) / N).

int32_t syn_signal_rms_q16 (
    const SYN_Signal * sig
)

Returns 0 if the window is empty.

Parameters:

sig Signal instance.

Returns:

RMS value in Q16.16.

function syn_signal_std_dev_q16¶

Standard deviation in Q16.16: sqrt(variance).

int32_t syn_signal_std_dev_q16 (
    const SYN_Signal * sig
)

Returns 0 if fewer than 2 samples.

Parameters:

sig Signal instance.

Returns:

Standard deviation in Q16.16.

function syn_signal_variance_q16¶

Variance in Q16.16 format.

int32_t syn_signal_variance_q16 (
    const SYN_Signal * sig
)

Population variance: Σ(x - mean)² / N, returned as Q16.16. Returns 0 if fewer than 2 samples.

Parameters:

sig Signal instance.

Returns:

Variance in Q16.16.

Public Static Functions Documentation¶

function syn_signal_count¶

Number of samples in the window.

static inline size_t syn_signal_count (
    const SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Sample count.

function syn_signal_full¶

True if the window is full.

static inline bool syn_signal_full (
    const SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

true if count == capacity.

function syn_signal_mean¶

Integer mean (truncated).

static inline int32_t syn_signal_mean (
    const SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Truncated mean, or 0 if empty.

function syn_signal_peak_to_peak¶

Peak-to-peak = max - min.

static inline int32_t syn_signal_peak_to_peak (
    SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Peak-to-peak value, or 0 if empty.

function syn_signal_sum¶

Sum of all samples in window.

static inline int64_t syn_signal_sum (
    const SYN_Signal * sig
)

Parameters:

sig Signal instance.

Returns:

Running sum.

The documentation for this class was generated from the following file src/syntropic/dsp/syn_signal.h