主要内容

How to Filter Data Using the App

Filtering Time-Domain Data in the App

The System Identification app lets you filter time-domain data using a fifth-order Butterworth filter by enhancing or selecting specific passbands.

To create a filtered data set:

  1. 导入的时间-domain data into the System Identification app, as described inRepresent Data.

  2. Drag the data set you want to filter to theWorking Dataarea.

  3. Select<--Preprocess>Filter. By default, this selection shows a periodogram of the input and output spectra (see theetfereference page).

    Note

    To display smoothed spectral estimates instead of the periodogram, selectOptions>Spectral analysis. This spectral estimate is computed using水疗中心and your previous settings in the Spectral Model dialog box. To change these settings, select<--Estimate>Spectral modelin the System Identification app, and specify new model settings.

  4. If your data contains multiple input/output channels, in the通道menu, select the channel pair you want to view. Although you view only one channel pair at a time, the filter applies to all input/output channels in this data set.

  5. Select the data of interest using one of the following ways:

    • Graphically — Draw a rectangle with the mouse on either the input-signal or the output-signal plot to select the desired frequency interval. Your selection is displayed on both plots regardless of the plot on which you draw the rectangle. TheRangefield is updated to match the selected region. If you need to clear your selection, right-click the plot.

    • Specify theRange— Edit the beginning and the end frequency values.

      For example:

      8.5 20.0(rad/s).

      Tip

      To change the frequency units fromrad/stoHz中,选择Style>Frequency (Hz). To change the frequency units fromHztorad/s中,选择Style>Frequency (rad/s).

  6. 在Range islist, select one of the following:

    • Pass band— Allows data in the selected frequency range.

    • Stop band— Excludes data in the selected frequency range.

  7. ClickFilterto preview the filtered results. If you are satisfied, go to step 8. Otherwise, return to step 5.

  8. 在Data namefield, enter the name of the data set containing the selected data.

  9. Click插入to save the selection as a new data set and add it to the Data Board.

  10. To select another range, repeat steps 5 to 9.

Filtering Frequency-Domain or Frequency-Response Data in the App

For frequency-domain and frequency-response data,filteringis equivalent to selecting specific data ranges.

To select a range of data in frequency-domain or frequency-response data:

  1. Import data into the System Identification app, as described inRepresent Data.

  2. Drag the data set you want you want to filter to theWorking Dataarea.

  3. Select<--Preprocess>Select range. This selection displays one of the following plots:

    • Frequency-domain data — Plot shows the absolute of the squares of the input and output spectra.

    • Frequency-response data — Top axes show the frequency response magnitude equivalent to the ratio of the output to the input, and the bottom axes show the ratio of the input signal to itself, which has the value of1at all frequencies.

  4. If your data contains multiple input/output channels, in the通道menu, select the channel pair you want to view. Although you view only one channel pair at a time, the filter applies to all input/output channels in this data set.

  5. Select the data of interest using one of the following ways:

    • Graphically — Draw a rectangle with the mouse on either the input-signal or the output-signal plot to select the desired frequency interval. Your selection is displayed on both plots regardless of the plot on which you draw the rectangle. TheRangefield is updated to match the selected region.

      If you need to clear your selection, right-click the plot.

    • Specify theRange— Edit the beginning and the end frequency values.

      For example:

      8.5 20.0(rad/s).

      Tip

      If you need to change the frequency units fromrad/stoHz中,选择Style>Frequency (Hz). To change the frequency units fromHztorad/s中,选择Style>Frequency (rad/s).

  6. 在Range islist, select one of the following:

    • Pass band— Allows data in the selected frequency range.

    • Stop band— Excludes data in the selected frequency range.

  7. 在Data namefield, enter the name of the data set containing the selected data.

  8. Click插入. This action saves the selection as a new data set and adds it to the Data Board.

  9. To select another range, repeat steps 5 to 8.

Related Examples

More About