Main Content

Discrete Varying Lowpass

Discrete Butterworth filter with varying coefficients

expand all in page
  • Discrete Varying Lowpass block

Libraries:
Control System Toolbox / Linear Parameter Varying

Description

The block implements the Tustin discretization of a continuous-time Nth-order Butterworth filter. The result is a digital filter with unit DC gain and varying cutoff frequency.

Use this block and the other blocks in the Linear Parameter Varying library to implement common control elements with variable parameters or coefficients. For more information, seeModel Gain-Scheduled Control Systems in Simulink.

Ports

Input

expand all

Lowpass filter input signal.

Continuous-time value of the cutoff frequency, specified in rad/s.

Output

expand all

Lowpass filter output signal.

Parameters

expand all

Lowpass filter order, specified as a positive integer.

Pre-warping frequency, specified as a positive scalar. Discretization of the continuous-time Butterworth filter can shift the cutoff frequency when it is close to the Nyquist frequency. To ensure that the analog and digital filters have matching frequency response near a particular frequencyw0, set this parameter tow0. The default valuew0 = 0corresponds to the bilinear (Tustin) transformation without pre-warp:

s = 2 T s ( z − 1 z + 1 ) ,

whereTsis the block sample time, specified with theSample time Tsparameter.

Block sample time, specified as a positive scalar. This block does not support inherited sample time, because it requires a specified sample time to compute the discretization of the Butterworth filter.

Extended Capabilities

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

PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.

版本历史

Introduced in R2017b

See Also

Topics