Signal Processing Blockset™

Digital Filter Design - Design and implement digital FIR and IIR filters

Library

Filtering / Filter Designs

dsparch4

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 or fixed-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 this 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 MATLAB^® filter function, and the Filter Design Toolbox™ filter function.

The sampling frequency, Fs, that you specify in the FDATool GUI should be identical to the sampling frequency of the Digital Filter Design block's input block. When 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.

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

• fdatool reference page 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.

Dialog Box

The FDATool GUI Opened from the Digital Filter Design Block

To get the Transform Filter button , install the Filter Design Toolbox product. To get the Targets menu, install the Target Support Package™ TC6 product.

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

Supported Data Types

• Double-precision floating point

• Single-precision floating point

See Also

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

• Filters

• Digital Filter Design Block

• fdatool reference page in the Signal Processing Toolbox documentation

Digital Filter

Digital FIR Filter Design