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FIR Filter Design page (Digital Filter Design wizard) |
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Use this page to specify the characteristics of the finite impulse response (FIR) filter you want to design.
Filter Options
Specifies the method that will be used to create the filter. Select one of the following options:
Sinc Function
Select this option to create a filter using the sinc function.
Remez Exchange
Select this option to create an optimal filter using the Remez Exchange Algorithm.
 | This method may opt between a minimum attenuation under a given length or a minimum length under a given attenuation as described by Ichige, Iwaki, and Ishii (2000). |
Frequency Custom
Select this option to create a custom filter in the frequency domain.
| This filter is designed in the frequency domain in normalized form (in accordance with the number of points specified for the smallest transition bandwidth) by interactively specifying a series of frequency sections as pass, stop and transition, arbitrarily. After this, the inverse Fourier Transform of the design yields the desired filter coefficients, which are then pruned to the desired filter length. The resulting filter coefficients can also be smoothed with a window function. |
Refer to Using Flexible Graphs for additional information on this subject.
| The Sinc and Custom methods allow for windowing. The Sinc and Remez methods require Filter Type specification [low, high, bandpass or bandstop] along with parameters for determining the cutoff frequency, stop band attenuation, etc. The Custom method requires filter specification in the frequency domain. The Sinc and Custom methods require Filter Length specification. The Remez method may opt between a minimum attenuation under a given length or a minimum length under a given attenuation. |
Specifies the length of the resulting filter impulse response. Type in this box a length for the filter you want to design.
| This length may not be honored under some circumstances in the Remez Exchange method (see notes on Remez). |
If you chose Sinc Function or Remez Exchange in Design Method, select one of the following options for the type of filter you want to design:
Lowpass
Select this option if you want to design a lowpass filter.
Highpass
Select this option if you want to design a highpass filter.
Bandpass
Select this option if you want to design a bandpass filter.
Bandstop
Select this option if you want to design a bandstop filter.
Specifies a window function to be applied to the filter coefficients. If you do not want to apply a window function, set this option to None.
Refer to the Apply Window Function dialog box for additional information on this subject.
When you select the Dolph-Chebyshev or the Kaiser Window Type, you must specify an additional argument to the window function.
Refer to the Apply Window Function dialog box for additional information on this subject.
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