Overview

Zero crossing detector

Discussion

Multichannel zero-crossing detector, running at the sampling rate. The module outputs a 1.0 whenever a zero crossing is detected and 0.0 otherwise. The detectorType parameter controls the behavior of the detector.

If detectorType == 0, then all zero crossing are detected. If detectorType > 0, then only positive transitions (negative->positive) are detected. If detectorType < 0, then only negative transitions (positive->negative) are detected.

Type Definition

typedef struct _ModuleZeroCrossingDetectorFract32
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 detectorType;                           // Determines which zero crossings are detected. 0=all, >0 negative->positive, <0 positive->negative
    INT32* lastSign;                              // Holds the sign of the last input value. This is an array so that multiple channels can be supported.
} ModuleZeroCrossingDetectorFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
detectorType	int	parameter	0	0	-1:1
lastSign	int*	state	1	[1 x 1]	Unrestricted

Pins

Input Pins

Name: in

Description: audio input

Data type: fract32

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: fract32

MATLAB Usage

File Name: zero_cross_detector_fract32_module.m

 M=zero_cross_detector_fract32_module(NAME)
 Creates a zero crossing detector module for use in the Audio Weaver.
 The module has a single multichannel input pin and a single output
 pin of the same size as the input pin.  The module outputs a 1.0
 whenever a zero crossing is detected and 0.0 otherwise.
 Arguments:
    NAME - name of the module.
 The .detectorType field of the instance structure controls the
 behavior of the detector.
 If detectorType == 0, then all zero crossing are detected.
 If detectorType > 0, then only positive transitions (negative->positive) are detected.
 If detectorType < 0, then only negative transitions (positive->negative) are detected.