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dsp.ZeroCrossingDetector System object

Package: dsp

Zero crossing detector

Description

The ZeroCrossingDetector object counts the number of times the signal crosses zero, or changes sign. The zero crossing detector supports both floating-point and fixed-point data types.

To count the number of times a signal crosses zero or changes sign:

  1. Define and set up your zero crossing detector. See Construction.

  2. Call step to count the number of times according to the properties of dsp.ZeroCrossingDetector. The behavior of step is specific to each object in the toolbox.

    Note:   Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Construction

zcd = dsp.ZeroCrossingDetector returns a zero crossing detector object, zcd, that counts the number of zero crossings in the real-valued,, floating-point, or fixed-point frame-based vector or matrix.

Methods

stepCount zero crossings in input
Common to All System Objects
clone

Create System object with same property values

getNumInputs

Expected number of inputs to a System object

getNumOutputs

Expected number of outputs of a System object

isLocked

Check locked states of a System object (logical)

release

Allow System object property value changes

Examples

expand all

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

Find number of zero crossings in electrocardiogram data.

EcgData = ecg(500)';
zcd = dsp.ZeroCrossingDetector;
numZeroCross = zcd(EcgData);  % Equal to 4
plot(1:500,EcgData,'b',[0 500],[0 0],'r','linewidth',2);

Algorithms

This object implements the algorithm, inputs, and outputs described on the Zero Crossing block reference page. The object properties correspond to the block parameters.

Extended Capabilities

Introduced in R2012a

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