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Overview

FDATool

The Filter Design and Analysis Tool (FDATool) is a user interface for designing and analyzing filters quickly. FDATool enables you to design digital FIR or IIR filters by setting filter specifications, by importing filters from your MATLAB® workspace, or by adding, moving or deleting poles and zeros. FDATool also provides tools for analyzing filters, such as magnitude and phase response and pole-zero plots.

Filter Design Methods

FDATool gives you access to the following Signal Processing Toolbox™ filter design methods.

Design Method

Function

Butterworth

butter

Chebyshev Type I

cheby1

Chebyshev Type II

cheby2

Elliptic

ellip

Maximally Flat

maxflat

Equiripple

firpm

Least-squares

firls

Constrained least-squares

fircls

Complex equiripple

cfirpm

Window

fir1

When using the window method in FDATool, all Signal Processing Toolbox window functions are available, and you can specify a user-defined window by entering its function name and input parameter.

Advanced Filter Design Methods

The following advanced filter design methods are available if you have DSP System Toolbox™ software.

Design Method

Function

Constrained equiripple FIR

firceqrip

Constrained-band equiripple FIR

fircband

Generalized remez FIR

firgr

Equripple halfband FIR

firhalfband

Least P-norm optimal FIR

firlpnorm

Equiripple Nyquist FIR

firnyquist

Interpolated FIR

ifir

IIR comb notching or peaking

iircomb

Allpass filter (given group delay)

iirgrpdelay

Least P-norm optimal IIR

iirlpnorm

Constrained least P-norm IIR

iirlpnormc

Second-order IIR notch

iirnotch

Second-order IIR peaking (resonator)

iirpeak

Using the Filter Design and Analysis Tool

There are different ways that you can design filters using the Filter Design and Analysis Tool. For example:

  • You can first choose a response type, such as bandpass, and then choose from the available FIR or IIR filter design methods.

  • You can specify the filter by its type alone, along with certain frequency- or time-domain specifications such as passband frequencies and stopband frequencies. The filter you design is then computed using the default filter design method and filter order.

Analyzing Filter Responses

Once you have designed your filter, you can display the filter coefficients and detailed filter information, export the coefficients to the MATLAB workspace, and create a C header file containing the coefficients, and analyze different filter responses in FDATool or in a separate Filter Visualization Tool (fvtool). The following filter responses are available:

Filter Design and Analysis Tool Panels

The Filter Design and Analysis Tool has sidebar buttons that display particular panels in the lower half of the tool. The panels are

  • Design Filter. See Choosing a Filter Design Method for more information. You use this panel to

    • Design filters from scratch.

    • Modify existing filters designed in FDATool.

    • Analyze filters.

  • Import filter. You use this panel to

    • Import previously saved filters or filter coefficients that you have stored in the MATLAB workspace.

    • Analyze imported filters.

  • Pole/Zero Editor. See Editing the Filter Using the Pole/Zero Editor. You use this panel to add, delete, and move poles and zeros in your filter design.

If you also have DSP System Toolbox product installed, additional panels are available:

  • Set quantization parameters — Use this panel to quantize double-precision filters that you design in FDATool, quantize double-precision filters that you import into FDATool, and analyze quantized filters.

  • Transform filter — Use this panel to change a filter from one response type to another.

  • Multirate filter design — Use this panel to create a multirate filter from your existing FIR design, create CIC filters, and linear and hold interpolators.

If you have Simulink® installed, this panel is available:

  • Realize Model — Use this panel to create a Simulink block containing the filter structure.

Getting Help

At any time, you can right-click or click the What's this? button, , to get information on the different parts of the tool. You can also use the Help menu to see complete Help information.

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