Signal Processing Toolbox    

Filter Type Region

Choose a filter type from the five mutually exclusive radio buttons.

The filter type you choose is reflected in the Display, Options, Frequency Specifications, and Magnitude Specifications regions.

Lowpass Filters

When you select this option, a lowpass filter is displayed in the Display region, and the Frequency Specifications and Magnitude Specifications regions are updated with the appropriate parameters.

See butter, cheby1, cheby2, ellip, remez, firls, or fir1 for more information.

Highpass Filters

When you select this option, a highpass filter is displayed in the Display region, and the Frequency Specifications and Magnitude Specifications regions are updated with the appropriate parameters.

See butter, cheby1, cheby2, ellip, remez, firls, or fir1 for more information.

Bandpass Filters

When you select this option, a bandpass filter is displayed in the Display region, and the Frequency Specifications and Magnitude Specifications regions are updated with the appropriate parameters.

See butter, cheby1, cheby2, ellip, remez, firls, or fir1 for more information.

Bandstop Filters

You can specify the frequencies that determine the pass band and the stopband. When you select this option, a bandstop filter is displayed in the Display region, and the Frequency Specifications and Magnitude Specifications regions are updated with the appropriate parameters.

See butter, cheby1, cheby2, ellip, remez, firls, or fir1 for more information.

Other Filter Types

Differentiator Filters.   A differentiator filter generates the derivative of the input signal. See Multiband FIR Filter Design with Transition Bands and remez for more information.

Hilbert Transformer Filters.   A Hilbert transformer is a filter that generates an approximation of the discrete Hilbert transform of the input signal. See Multiband FIR Filter Design with Transition Bands and remez for more information.

Multiband Filters.   A multiband filter has multiple passbands interleaved with multiple stopbands. See Multiband FIR Filter Design with Transition Bands and remez for more information.

Arbitrary Magnitude Filters.   An arbitrary magnitude filter can be designed to have any desired magnitude response shape. See Multiband FIR Filter Design with Transition Bands and remez for more information.

Arbitrary Group Delay Filters.   An arbitrary group delay filter is an allpass IIR filter which provides the best approximation to the specified relative group-delay response in the least-pth sense. This filter type is available only when the Filter Design Toolbox is installed. See iirgrpdelay in the Filter Design Toolbox documentation for more information.

Halfband.   Halfband filters are Lth-band filters where L=2. About half of the filter coefficients are zero, creating a design that is very efficient to calculate. See firhalfband in the Filter Design Toolbox documentation for more information.

Nyquist.   Nyquist filters are lowpass filters whose transfer function contains certain coefficient equal to zero by design. Specifying the zero- valued coefficients makes the resulting filter more efficient to compute than other lowpass filters of the same order. Also called Lth-band filters. See firnyquist in the Filter Design Toolbox documentation for more information.

Raised Cosine.   Raised Cosine (RC) filters are linear-phase, lowpass filters with raised cosine transition bands. At low frequencies the passband is flat. The transition band rolls off in a cosine shape towards the stopband. Digital communications systems often use RC filters to reduce intersymbol interference. See firrcos for more information.


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