Filter Realization Wizard

(To be removed) Construct filter realizations using digital filter blocks or Sum, Gain, and Delay blocks

The Filter Realization Wizard block will be removed in a future release. Currently, there is no replacement.

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Libraries:
DSP System Toolbox / Filtering / Filter Designs

Description

Note

Use this block to implement fixed-point or floating-point digital filters using Sum, Gain, and Delay blocks or digital filter blocks from the DSP System Toolbox™ library. You can either design a filter by using the block parameters, or import the coefficients of a filter you have designed elsewhere.

These blocks also implement digital filters, but serve slightly different purposes:

• Discrete FIR Filter (Simulink) and Biquad Filter— Use these blocks to implement floating-point or fixed-point filters that you have already designed

• Digital Filter Design — Use this block to design, analyze, and then implement floating-point filters.

The Filter Realization Wizard is a tool for automatically implementing a digital filter. You must specify a filter, its structure, and the data types for the inputs, outputs, and computations. The filter can support double-precision, single-precision, or fixed-point data types.

The Filter Realization Wizard can implement a digital filter in one of two ways. It can use digital filter blocks from the DSP System Toolbox library, or it can create a subsystem block that implements the specified filter using Sum (Simulink), Gain (Simulink), and Delay blocks. If the Filter Realization Wizard creates a block, double-click the block to open the dialog box. If it creates a subsystem, double-click the subsystem block to see the filter implementation as shown in this figure.

For more information about filter implementation, see Specify the Filter Implementation.

The parameters of the Filter Realization Wizard are a part of a larger app, the Filter Designer (filterDesigner). You can use filter designer to design and analyze your filter and then use the Filter Realization Wizard parameters to implement the filter in your models.

The Filter Realization Wizard supports single-precision, double-precision, and fixed-point (signed and unsigned). The block supports single-precision and fixed-point data types only when you install Fixed-Point Designer™.

Parameters

Note

These parameters for the Filter Realization Wizard are in the Realize Model pane of the filter designer app. To open different panels of filter designer, click the different buttons at the lower-left corner. For more information about relevant panels, see Specify the Filter and Data Types.

Block Name — Name of new filter block

Filter (default) | character vector | string scalar

Enter the name of the new filter block.

Destination — Destination of new filter block

Current (default) | New | User-defined

Specify the model in which the Filter Realization Wizard creates the new filter block. The wizard can create the block in a new model or in the current (most recently selected) model.

User Defined — Target subsystem

Untitled | character vector

Specify the name of the target subsystem in which the Filter Realization Wizard creates the new filter block.

Dependencies

To enable this parameter, set Destination to User-defined.

Overwrite generated 'Filter' block — Overwrite generated Filter block

off (default) | on

When you select this check box, the block overwrites any filter block in the current model with the name you specify in the Block Name parameter.

Dependencies

To enable this parameter, set the Destination parameter to Current.

Build model using basic elements — Build model using basic elements

off (default) | on

Select this check box to implement your filter using Sum, Gain, and Delay blocks. Clear this check box to implement your filter using digital filter blocks from the DSP System Toolbox library.

Dependencies

This parameter is available only when your filter can be modeled using a digital filter block available in the DSP System Toolbox library.

Optimize for zero gains — Optimize for zero gains

on (default) | off

Select this check box to remove zero-gain paths from the filter structure. For an example, see Optimize the Filter Structure.

Dependencies

To enable this parameter, select the Build model using basic elements check box.

Optimize for unity gains — Optimize for unity gains

on (default) | off

Select this check box to substitute gains equal to 1 with a wire (short circuit). For an example, see Optimize the Filter Structure.

Dependencies

To enable this parameter, select the Build model using basic elements check box.

Optimize for negative gains — Optimize for negative gains

on (default) | off

Select this check box to substitute gains equal to −1 with a wire (short circuit), and change the corresponding sums to subtractions. For an example, see Optimize the Filter Structure.

Dependencies

To enable this parameter, select the Build model using basic elements check box.

Optimize delay chains — Optimize delay chains

on (default) | off

Select this check box to substitute any delay chains made up of n unit delays with a single delay by n. For an example, see Optimize the Filter Structure.

Dependencies

To enable this parameter, select the Build model using basic elements check box.

Optimize for unity scale values — Optimize for unity scale values

on (default) | off

Select this check box to remove all scale value multiplications by 1 from the filter structure.

Input processing — Input processing

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

Specify how the generated filter block or subsystem block processes the input. Depending on the type of filter you are designing, one or both of these options can be available:

• 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.

For more information about sample- and frame-based processing, see Sample- and Frame-Based Concepts.

Rate options — Method of processing input

Enforce single-rate processing (default) | Allow multirate processing

For multirate filters, specify how the block should process the input. You can set this parameter to one of these options:

• Enforce single-rate processing — When you select this option, the block maintains the input sample rate.

• Allow multirate processing — When you select this option, the block adjusts the rate at the output to accommodate an increased or reduced number of samples.

Realize Model — Create a filter block

button

Click this button to create a filter block according to the settings you have specified. When you select the Build model using basic elements check box, the filter is implemented as a subsystem block consisting of Sum, Gain, and Delay blocks. To see the filter implementation, double-click the subsystem block in your model.

Note

For more information about relevant parameters in other panels of filter designer, see Specify the Filter and Data Types.

Block Characteristics

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

More About

Specify the Filter and Data Types

To specify a purely double-precision filter, you can either design a filter using the Design Filter panel, or import a filter using the Import Filter panel. In the Import Filter panel, you can specify the coefficients directly or specify the workspace variables which store the coefficients.

You can also specify a fixed-point filter or a single-precision filter by using the Set Quantization Parameters panel.

Note

Running a model containing implementations of fixed-point filters requires the Fixed-Point Designer product, but you can still edit models containing such filter implementations without it. See the Fixed-Point Designer documentation for more information.

See these topics to learn how to use the panels to specify your filter:

• For more information on the Design Filter panel, see filterDesigner.

• For more information on the Import Filter panel, see Importing a Filter Design.

• For more information on the Set Quantization Parameters panel, see Access the Quantization Features of Filter Designer.

To open a panel, click the appropriate button in the lower-left corner of filter designer.

Supported Data Types

• Double-precision floating point

• Single-precision floating point — Supported only when you install Fixed-Point Designer

• Fixed point (signed and unsigned) — Supported only when you install Fixed-Point Designer

Supported Filter Structures

The Filter Realization Wizard supports the following structures:

• Direct form I

• Direct form I, second-order sections

• Direct form I transposed

• Direct form I transposed, second-order sections

• Direct form II

• Direct form II, second-order sections

• Direct form II transposed

• Direct form II transposed, second-order sections

• Direct form FIR

• Direct form FIR transposed

• Direct form symmetric FIR

• Direct form antisymmetric FIR

• Lattice all-pass

• Lattice AR

• Lattice ARMA

• Lattice MA for maximum phase

• Lattice MA for minimum phase

• Cascade

• Parallel

Specify the Filter Implementation

You can determine how the Filter Realization Wizard models the specified filter. In the Realize Model panel, select the Build model using basic elements check box. When you select this check box and click on the Realize Model button, the Filter Realization Wizard creates a subsystem block that implements your filter using Sum (Simulink), Gain (Simulink), and Delay blocks. When you clear this check box, the Filter Realization Wizard uses a digital filter block to implement your filter. The Build model using basic elements check box is available only when your filter can be implemented using a digital filter block available in the DSP System Toolbox library.

The Filter Realization Wizard can generate a subsystem that represents either a double-precision or fixed-point filter. You must install the Fixed-Point Designer product to simulate a fixed-point filter. You can still edit the blocks used to implement the filter without installing the Fixed-Point Designer product.

Implementations of Double-Precision and Fixed-Point Filters

Command Line Alternative to Realize Model Button

You can enter realizemdl(sysobj) in the MATLAB^® command prompt to generate an architectural model of the filter System object™, sysobj, in a Simulink^® subsystem block using individual sum, gain, and delay blocks, according to user-defined specifications. For more information, see realizemdl.

References

[1] Oppenheim, A. V. and R. W. Schafer. Discrete-Time Signal Processing. Englewood Cliffs, NJ: Prentice Hall, 1989.

[2] Proakis, J. and D. Manolakis. Digital Signal Processing. 3rd ed. Englewood Cliffs, NJ: Prentice-Hall, 1996.

Extended Capabilities

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

Version History

Introduced before R2006a

R2024b: Filter Realization Wizard will be removed

The Filter Realization Wizard block will be removed in a future release. Currently, there is no replacement.