User`s guide

1 Data Processing
To get a reliable noise model, avoid prefiltering the data. Instead, set
the
Focus property of the estimation algorithm to Simulation.Formore
information about the
Focus property, see the Algorithm Prop erties
reference page.
Note When you prefilter during model estimation, the filtered da ta is use d to
only model th e in put-to-output dynamics. However, the disturbance model is
calculated from the unfiltered data.
How to Filter Data Using the GUI
• “Filtering Time-Domain Data in the GUI” on page 1-108
• “Filtering Frequency-Domain or Frequency-Response Data in the GUI” on
page 1-110
Filtering Time-Domain Data in the GUI
The System Identification Tool GUI lets you filter time-domain data using a
fifth-order Butterw orth filter by enhancing or selecting specifi c passbands.
To create a filtered data set:
1 Import time-domain data into the System Identification Tool GUI, as
described i n “R epresenting Da ta in the GUI” o n page 1-13.
2 Drag the data set you want you want to filter to the Working Data are a.
3 Select <–Preprocess > Filter. By default, this selection shows a
periodogram of the input and output spectra (see the
etfe reference page).
Note To display smoothed spectral estimates instead of the periodogram,
select Options > Spectral analysis. This spectral estimate is computed
using
spa and your p revious settings in the Spectral Mo de l dialog box. To
change these settings, select <–Estimate > Spectral model in the System
Identification Tool GUI, and specify new model settings.
1-108