Design a Filter Using filterbuilder

Filterbuilder presents the option of designing a filter using a GUI dialog box as opposed to the command line instructions. You can use Filterbuilder to design the same bandpass filter designed in the previous section, Basic Filter Design Process

Design a Simple Filter in Filterbuilder

To design the filter using the Filterbuilder GUI:

1. Type the following at the MATLAB prompt:

   filterbuilder

   The dialog box using the DSP System Toolbox software appears as follows:

   

   The dialog box using only the Signal Processing Toolbox software appears as follows:

   

2. Select Bandpass filter response from the list in the dialog box, and hit the OK button. The following dialog box opens:

   

3. Enter the correct frequencies for Fpass2 and Fstop2, as shown in the preceding figure, then click OK. Here the specification uses normalized frequency, so that the passband and stopband edges are expressed as a fraction of the Nyquist frequency (in this case, 48/2 kHz). The following message appears at the MATLAB prompt:

   The variable 'Hbp' has been exported to the command window.

   If you display the Workspace tab, as shown in the following figure, you see the object Hbp has been placed on your workspace.

   

4. To check your work, plot the filter magnitude response using the Filter Visualization tool. Verify that all the design parameters are met:

   fvtool(Hbp) %plot the filter magnitude response

   

   Note that the dashed red lines on the preceding figure will only appear if you are using the DSP System Toolbox software.

Basic Filter Design Process

Filter Design with the FDATool GUI

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