Filter Design Toolbox Release Notes

New Transformations Pane Added to FDATool

A new Transformations pane in FDATool provides access to the new transformation functions. All filter transformations work from the command line as well. In addition, Version 2.2 modifies the existing filter transformations in FDATool--they use the same input and output arguments but with modified transformation techniques.

Replaces the Transformations menu option in earlier toolbox versions and expands the capability to transform filters.

nlm Filter Analysis Method in FDATool

The new release of Filter Design Toolbox adds the noise loading method (nlm) to FDATool. While this analytical method was in the toolbox as a command line function, nlm is now available in the GUI.

To run the noise loading method in FDATool:

1. Design or import a filter into FDATool.
2. Quantize the filter, remembering to set the quantization parameters as required.
3. To use the noise loading method to estimate the frequency response of your quantized filter, select Analysis -> Noise Loading Method on the FDATool menu bar.

1. FDATool runs the noise loading method Monte Carlo trials on the filter and displays the result in the Analysis area. For more information about nlm and using FDATool to perform the analysis, refer to Analyzing Filters with the Noise Loading Method in the Filter Design Toolbox online help.

New Functions for Calculating Quantizer Noise Statistics

Three new functions for determining the noise statistics of a quantizer now appear in the toolbox:

• errmean--return the mean of the quantization error resulting from quantizing a signal
• errpdf--calculate the probability density function (pdf) of the quantization error
• errvar--return the variance of the quantization error resulting from quantizing a signal

Enhanced Quantizer Optimization

For this release, a new Optimization... option replaces the scaling functions on the quantization panel. Optimization enables you to specify a larger range of optimization options for your quantized filters. When you click Optimization... on the quantizer panel, you see the following Quantized Optimizations dialog, shown with the default settings:

For more information about using the new optimization features, refer to Optimizing the Quantization Process For Your Filter in the online help.

Enable and Disable Quantizers in a Filter

In the revised Quantized Filter pane in FDATool, you find a new option--six check boxes that enable or disable the quantizers in a filter. By clearing or selecting a check box, you determine whether to apply the associated quantizer to the filter during the quantization process. For example, you can elect not to apply the Input quantizer by clearing the check box Convert input to. During quantization, the inputs will be passed on without modification or changes to their values.

Quantizer Status Functions Added

To help you determine various characteristics of quantizers, the toolbox includes three new functions:

• isfixed--test and return whether a quantizer is fixed point
• isfloat--test and return whether a quantizer is floating point
• isnone--determine and return whether a quantizer has quantization mode equal to none

New Frequency Transformation Functions Added

Enhanced Quantized Filter Structures