DSP Blockset

Digital Filter Design

Design and implement a variety of digital FIR and IIR filters

Library

Filtering / Filter Designs

Description

Note    Use this block to design, analyze, and then efficiently implement floating-point filters. The following blocks also implement digital filters, but serve slightly different purposes: Digital Filter -- Use to efficiently implement floating-point filters that you have already designed. This block provides the same exact filter implementation as the Digital Filter Design block. Filter Realization Wizard -- Use to implement floating-point or fixed-point filters built from Sum, Gain, and Unit Delay blocks. (You can either design the filter within the block, or import the coefficients of a filter that you designed elsewhere.)

The Digital Filter Design block implements a digital FIR or IIR filter that you design using the Filter Design and Analysis Tool (FDATool) GUI. This block provides the same exact filter implementation as the Digital Filter block.

The block applies the specified filter to each channel of a discrete-time input signal, and outputs the result. The outputs of the block numerically match the outputs of the Digital Filter block, the filter function in the Signal Processing Toolbox, and the filter function in the Filter Design Toolbox.

The sampling frequency, Fs, you specify in the FDATool GUI should be identical to the sampling frequency of the Digital Filter Design block's input block. If the sampling frequencies of these blocks do not match, the Digital Filter Design block returns a warning message and inherits the sampling frequency of the input block.

Sections of This Reference Page

• Valid Inputs and Corresponding Outputs
• Designing the Filter
• Tuning the Filter During Simulation
• Examples
• Dialog Box
• Supported Data Types
• See Also

Valid Inputs and Corresponding Outputs

The block accepts inputs that are sample-based or frame-based vectors and matrices. The block filters each input channel independently over time, where

• Each column of a frame-based vector or matrix is an independent channel.
• Each element of a sample-based vector or matrix is an independent channel.

The output has the same dimensions and frame status as the input.

Designing the Filter

Double-click the Digital Filter Design block to open FDATool. Use FDATool to design or import a digital FIR or IIR filter. To learn how to design filters with this block and FDATool, see the following topics:

• Digital Filter Design Block
• Topic on the Filter Design and Analysis Tool (FDATool) in the Signal Processing Toolbox documentation.

Tuning the Filter During Simulation

You can tune the filter specifications in FDATool during simulations as long as your changes do not modify the filter length or filter order. The block's filter updates as soon as you apply any filter changes in FDATool.

Examples

You can open the following model by clicking here in the MATLAB Help browser (not in a Web browser). To build the model yourself, follow the step-by-step instructions in Digital Filter Design Block, which also provides a full explanation of the model.

Model Using the Digital Filter Block to Implement Filters

Vector Scope Display After Running the Model

Dialog Box


The FDATool GUI Opened from the Digital Filter Design Block

To get the Transform Filter button , install the Filter Design Toolbox. To get the Targets menu, install the Embedded Target for the TI TMS320C6000^TM DSP Platform.

To learn how to use the FDATool GUI, see Designing the Filter.

Supported Data Types

• Double-precision floating point
• Single-precision floating point

To learn how to convert your data types to the above data types in MATLAB and Simulink, see Supported Data Types and How to Convert to Them.

See Also

Analog Filter Design	DSP Blockset
Window Function	DSP Blockset
fdatool	Signal Processing Toolbox
filter	Signal Processing Toolbox
fvtool	Signal Processing Toolbox
sptool	Signal Processing Toolbox
filter	Filter Design Toolbox

To learn how to use this block and FDATool, see the following topics:

• Filters -- Examples of when and how to use DSP Blockset filtering blocks
• Digital Filter Design Block
• Topic on the Filter Design and Analysis Tool (FDATool) in the Signal Processing Toolbox documentation.

Digital Filter

Discrete Impulse