The Filter dialog is opened by chosing the corresponding item in the pop-up menu Preprocessing in the ident window. The Filter dialog also opens when you select the Filter option under Focus in the Parametric Models Dialog

The plot shows the input and output spectra for the chosen input-output channel of the Working Data set.

1. Select a frequency range by either:
a) Typing its lower and upper frequencies in the Range edit box,
b) Clicking-and-dragging a rectangle in either plot.

2. Using the pop-up menu, specify whether the marked frequency range is a pass band or a stop band.

3. When you are satisfied with the frequency range, press Filter to compute the filtered data. Its spectra will be shown in the same plot to check that the filtering was successful. If you have multivariable data, you can at this point change channels in the plot window to check the filtering effect on the whole data set. The filter used is a 5th order Butterworth filter.

4a. In the Preprocessing case: When you are satisfied with the filtered data, enter any string in the Data name: edit box and press Insert to insert it into the Data board.

4b. In the Focus: Filter case: You cannot insert the data into the data board. The chosen filter will be used for internal filtering in the estimation algorithm.

Press Revert to delete all the filtered plots.

A 5:th order Butterworth filter is used for the filtering.

Help topics.

(file idfilt.htm)