Signal Processing Toolbox

Options Region

This region allows you to specify the filter design method options. FIR Equiripple, FIR Window, and some Filter Design Toolbox design methods have settable options.

FIR Equiripple and Complex Equiripple Option

The FIR Equiripple and FIR Complex Equirpple design methods, which uses the firpm and cfirpm functions, respectively, have a Density Factor option. This option controls the density of the frequency grid. Increasing the value creates a filter which more closely approximates an ideal equiripple filter, but the time required for computation increases.

FIR Window Options

The FIR Window design method has four options:

• Scale Passband--normalizes the filter so its magnitude response at the center frequency of the passband is 0 dB.
• Window--specifies the window type.
• Function Name--only active for User defined window
• Parameter--Beta, Alpha, Sidelobe atten., or Parameter

The following windows and settable parameters are available.

Window	Corresponding Function	Parameter
Bartlett	bartlett	none
Bartlett-Hanning	barthannwin	none
Blackman	blackman	none
Blackman-Harris	blackmanharris	none
Bohman	bohmanwin	none
Chebyshev	chebwin	Sidelobe atten.--amount of dB sidelobe is below mainlobe
Flat Top	flattopwin	none
Gaussian	gausswin	Alpha--affects the width of the window. Larger alpha produces a more narrow window.
Hamming	hamming	none
Hann	hann	none
Kaiser	kaiser	Beta--affects sidelobe attenuation. Higher beta widens the mainlobe and decreases the sidelobe amplitude.
Nuttall	nuttallwin	none
Rectangular	rectwin	none
Tukey (cosine-tapered)	tukeywin	Alpha--specifies the ratio of taper to constant sections, affecting the window shape. Alpha is between 0 and 1.
Triangular	triang	none
User defined	user defined function name	user-defined parameter

View Button

The View button launches the Window Visualization Tool (wvtool) where you can view and compare windows.

Filter Order Region

Frequency Specifications Region

© 1994-2005 The MathWorks, Inc.