| Filter Design Toolbox Release Notes | |
New Features
This section introduces the new features and enhancements added in the Filter Design Toolbox 2.1 since Filter Design Toolbox 2.0 (Release 12).
For information about Filter Design Toolbox features that are incorporated from recent releases, see New Features in the Filter Design Toolbox 2.0 Release Notes.
New Adaptive Filtering Functions
The Filter Design Toolbox 2.1 includes these new filter design functions:
adaptkalman -- Use a Kalman filtering algorithm in an adaptive filter role
adaptlms - Use an LMS-based adaptive algorithm in an adaptive filter role
adaptnlms - Use a normalized LMS-based adaptive algorithm in an adaptive filter role
adaptrls - Use an RLS-based adaptive algorithm in an adaptive filter role
adaptsd - Use the sign-data variant of the LMS-based adaptive algorithm in an adaptive filter role
adaptse - Use the sign-error variant of the LMS-based adaptive algorithm in an adaptive filter role
adaptss -- Use the sign-sign variant of the LMS-based adaptive algorithm in an adaptive filter role
To support you when you use these new functions, the Toolbox includes corresponding functions for initializing the associated adaptive filter algorithm.
initkalman -- Initialize the input argument s for the Kalman-based algorithm adaptive filter function
initlms -- Initialize the input argument s for the LMS-based adaptive filter function
initnlms -- Initialize the input argument s for the normalized LMS-based adaptive filter function
initrls -- Initialize the input argument s for the RLS-based adaptive filter function
initsd -- Initialize the input argument s for the sign-data variant of the LMS-based adaptive filter function
initse -- Prepare the input arguments for the sign-error variant of the LMS-based adaptive filter function
initss -- Prepare the input arguments for the sign-sign variant of the LMS-based adaptive filter function
New FIR Filter Design Functions
In addition to the new adaptive filtering capabilities, this version of the toolbox has four new filter design functions.
firhalfband -- Design Lth-band filters where L=2. About half of the filter coefficients are zero so the filters are very efficient to calculate
firminphase -- Calculate the minimum-phase FIR spectral factor of a linear-phase FIR filter
firnyquist -- Design lowpass filters with certain specified coefficients in the transfer functions set to zero by design
ifir -- Design an interpolated FIR filter
FDATool includes Halfband and Nyquist entries under Filter Type so you can design and analyze these kinds of filters within FDATool.
New Filter Transformation Functions
The Filter Design Toolbox 2.1 includes several new filter transformation functions. Each transformation maintains the ripple characteristics and passband/stopband shapes of the source filter while transforming to the new specification.
firlp2lp -- Transforms lowpass FIR filters to lowpass FIR filters with different passband width or cutoff specifications
firlp2hp -- Transforms lowpass FIR filters to highpass FIR filters
iirlp2bp -- Transforms lowpass IIR filters to bandpass IIR filters
iirlp2bs -- Transforms lowpass IIR filters to bandstop IIR filters
iirlp2hp -- Transforms lowpass IIR filters to highpass IIR filters
iirlp2lp -- Transforms lowpass IIR filters to lowpass IIR filters
The new Transformations option (refer to the next entry in this section) in FDATool provides access to these transformations from the GUI.
Transformations Option in FDATool
When you use Filter Design and Analysis Tool (FDATool) with Filter Design Toolbox 2.1, the Toolbox adds a new menu to the FDATool menu bar. Named Transformations, the new selection provides direct access to the new FIR and IIR filter transformation functions added to the Toolbox in this release (refer to New Filter Transformation Functions). Transformations appears as shown in this figure only when you have installed the Filter Design Toolbox.
With this new option, FIR and IIR filters whose characteristics are particularly valuable become the sources for other FIR and IIR filters that share the same desirable features in a different passband configuration. Transforming a filter saves you from repeating the filter design process. For more information, refer to Transforming Filters in your Filter Design Toolbox User's Guide.
In the figure, the Targets option is available only when you have the Developer's Kit for Texas Instruments DSP installed.
New Analysis Method
Filter Design Toolbox 2.1 includes one new analysis method -- zerophase -- that returns the zero-phase response of a linear-phase FIR filter.
[hr,w] = zerophase(b), and the other available syntax options for zerophase, returns the zero-phase response hr and the frequency vector w (in rad/sample) at which hr is computed, given a linear-phase FIR filter b. The zero-phase response is evaluated at 512 equally spaced points on the upper half of the unit circle.
Note that the zero-phase response is always real, but it is not equivalent to the magnitude response. In particular, the zero-phase response can be negative; the magnitude response is always positive.
New Context-Sensitive Help for Quantization
FDATool Quantization mode now includes context sensitive or What's This? help. For each option on the Set Quantization Parameters page, right-click to use the What's This? option to open a brief text description of the option.
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