Modifying the Plot

In FVTool, you can interactively change view settings, set analysis parameters, and specify sampling frequency for the displayed analysis. In the toolstrip, select an option from the View or Analysis sections. You can also access the analysis parameters and sampling frequency menus by right-clicking on the plot.

To change the properties of a plot, first click the Send to Figure button in the toolstrip to open a new figure window and then use any of the buttons in the plot editing toolbar.

Analysis Parameters contains parameter settings applicable to the displayed analysis. If more than one analysis is displayed, FVTool shows only the parameters specific to the current plot. You can modify any of these parameter settings.

• Normalized Frequency — Check the box to normalize the frequency between 0 and 1. If not checked, the frequency is in hertz.

• Frequency Scale — Set the frequency scale of the y-axis scale to Linear or Log.

• Frequency Range — Set the range of the frequency axis or select Specify freq. vector to specify a frequency vector.

• Number of Points — Specify the number of samples to use to compute the response.

• Frequency Vector — Specify the frequency vector to use for plotting, if Specify freq. vector is selected in Frequency Range.

• Magnitude Display — Set they-axis units for magnitude to Magnitude, Magnitude (dB), Magnitude squared, or Zero-Phase.

• Phase Units — Set the y-axis units for phase to Degrees or Radians.

• Phase Display — Specify the type of phase plot as Phase or Continuous Phase.

• Group Delay Units — Set they-axis units for group delay to Samples or Time.

• Specify Length — Specify the length of the impulse or step response as Default or Specified.

• Length — Specify the number of points to use for the impulse or step response.

Note

Not all of these analysis fields are available for all types of plots.

In addition to these analysis parameters, you can

• change the plot type for the Impulse Response and Step Response plots by right-clicking and selecting Line with Marker, Stem or Line from the context menu.

• change the x-axis units by right-clicking the x-axis label and selecting Samples or Time.

• save the displayed parameters as the default values to use when Filter Designer or FVTool is opened by clicking Save as Default. To restore the default values, click Restore Original Defaults.

• display information about a particular point in the plot. For more information on data tips, see Interactively Explore Plotted Data.

• zoom to the passband region. To use passband zoom, your filter must have been designed using fdesign or Filter Designer. Passband zoom is not provided for cascaded integrator-comb (CIC) filters because CICs do not have conventional passbands.

Note

If you have the DSP System Toolbox™ software, FVTool displays a specification mask along with your designed filter on a magnitude plot.