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Discrete Filter

Implement IIR and FIR filters.

Library

Discrete

Description

The Discrete Filter block implements Infinite Impulse Response (IIR) and Finite Impulse Response (FIR) filters. You specify the coefficients of the numerator and denominator polynomials in ascending powers of z-1 as vectors using the Numerator and Denominator parameters. The order of the denominator must be greater than or equal to the order of the numerator. See Discrete Transfer Fcn for more information about coefficients.

The Discrete Filter block represents the method often used by signal processing engineers, who describe digital filters using polynomials in z-1 (the delay operator). The Discrete Transfer Fcn block represents the method often used by control engineers, who represent a discrete system as polynomials in z. The methods are identical when the numerator and denominator are the same length. A vector of n elements describes a polynomial of degree n-1.

The block icon displays the numerator and denominator according to how they are specified. For a discussion of how Simulink displays the icon, see Transfer Fcn.

Data Type Support

A Discrete Filter block accepts and outputs a real signal of type double.

Parameters and Dialog Box

Numerator
The vector of numerator coefficients. The default is [1].
Denominator
The vector of denominator coefficients. The default is [1 2].
Sample time
The time interval between samples.

Characteristics

Direct Feedthrough
 Only if the lengths of the Numerator and Denominator parameters are equal
Sample Time
 Discrete
Scalar Expansion
 No
States
 Length of Denominator parameter -1
Vectorized
 No
Zero Crossing
 No


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