Zero Crossing

Count number of times signal crosses zero in single time step

• 

Libraries:
DSP System Toolbox / Signal Operations

Description

The Zero Crossing block concludes that a signal in a given channel has passed through zero if it meets any of the following criteria, where x_i is the current value of the signal, x_i−1 is the previous value, and so on:

• x_i < 0 and x_i−1 > 0

• x_i > 0 and x_i−1 < 0

• For a positive integer L, x_i < 0, x_i−1 = 0, and x_i−L−1 > 0, where $$0\le l\le L$$.

• For a positive integer L, x_i > 0, x_i−1 = 0, and x_i−L−1 < 0, where $$0\le l\le L$$.

For the first value of the input signal, x_i−1 and x_i−2 are zero. The block outputs the number of times the signal crosses zero in a single time step at the Cnt port.

Examples

Detect Number of Zero Crossings in Signal

Detect number of zero crossings using Zero Crossing block.

• Open Model

Ports

Input

Port_1 — Data input

vector | matrix

The input signal specified as a real-valued vector or matrix.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | fixed point

Output

Cnt — Number of zero crossings

scalar | row vector

The block outputs the number of zero crossings in the data input as one of these:

• Scalar –– When the data input is a column vector, the block outputs a scalar value representing the number of zero crossings in the data input.

• Row vector –– When the data input is a matrix, the block outputs a row vector with each element in the row vector representing the number of zero crossings in the corresponding column of the data input.

Data Types: uint32

Parameters

Input processing — Method to process input signals

Columns as channels (frame based) (default) | Elements as channels (sample based)

Specify how the block should process the input.

• Columns as channels (frame based) — When you select this option, the block treats each column of the input as a separate channel.

• Elements as channels (sample based) — When you select this option, the block treats each element of the input as a separate channel.

Block Characteristics

Data Types	double | fixed point | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a