ZeroCrossDetector

ZeroCrossDetector

A class to detect zero-crossings in a signal after applying a low-pass filter.

This detector processes input data to identify points where the signal crosses a specified threshold (both positive and negative), accounting for the phase delay introduced by the filter.

Attributes:

Name	Type	Description
f_cutoff	float	Cutoff frequency of the low-pass filter in Hz.
threshold	float	Threshold for detecting zero-crossings.
samplerate	float	Sampling rate of the signal in Hz.
_filter_coeff	tuple	Coefficients of the low-pass filter.
_filter_zi	ndarray	Initial conditions for the filter.
_last_filtered_sample	float	Last sample of the filtered data.
_first_run	bool	Flag to indicate the first processing cycle.
_last_zc_p	int or None	Last positive zero-crossing index from the previous block.
_last_zc_n	int or None	Last negative zero-crossing index from the previous block.
_filter_delay_samples	float	Filter delay in samples due to phase shift.
_filtered_data	list	Temporary storage for filtered data during processing.

__init__(f_cutoff, threshold, samplerate)

Initializes the ZeroCrossDetector with the specified parameters.

Parameters:

Name	Type	Description	Default
f_cutoff	float	Cutoff frequency of the low-pass filter in Hz.	required
threshold	float	Threshold for detecting zero-crossings.	required
samplerate	float	Sampling rate of the signal in Hz.	required

process(data)

Processes a block of input data and detect zero-crossings.

Parameters:

Name	Type	Description	Default
data	ndarray	Input data block to be processed.	required

Returns:

Name	Type	Description
list	list	A list of zero-crossing points (in sample indices).