User`s guide

Identifying F requency-Response Models
Data Suppor ted b
y Frequency-Response Models
You can estimate
spectral analysis models from data with the following
characteristic
s:
• Complex or real d
ata.
• Time- or frequen
cy-domain
iddata or idfrd data object. To learn more
about estimatin
g time-series models, see Chapter 6, “Time Series Model
Identification
”.
• Single- or m ult
iple-output data.
How to Estimate
Frequency-Response Models in the
GUI
You must have al
ready imported your data into the GUI and performed any
necessary pre
processing operations. For more information, see Chapter
1, “Data Proce
ssing”.
To estimate fr
equency-response models in the System Identification Tool GUI:
1 In the S ystem I
dentification Tool GUI, select Estimate > Spectral
models to open
the Spectral Model dialog box.
2 In the Method list, select the spectral analysis method you w ant to use.
For information about each me tho d, see “Options for Computing Spectral
Models” on page 3-5.
3 Specify the frequencies at which to compute the spectral model in one of
the following ways:
• In the Frequencies field, enter eithe r a vector of values, a MATLAB
expression that evaluates to a vector, or a variable name of a vector in
the M ATLA B workspace . For example,
logspace(-1,2,500).
• Use the combination of Frequency Spacing and Frequencies to
construct the frequency vector of values:
– In the Frequency Spacing list, select
Linear or Logarithmic
frequency spacing.
3-3