User`s guide

Identifying F requency-Response Models
How to Estimate F
requency-Response Models a t the
Command Line
You can use the et
fe
, spa,andspafdr commands to estimate spectral
models. The foll
owing table provides a brief description of each command
and usage examp
les.
The resulting m
odels are stored as
idfrd model objects. F or detailed
information ab
out the commands and their arguments, see the corresponding
reference pag
e.
Commands for F
requency Response
Command
Description
Usage
etfe
Estimates an e
mpirical
transfer func
tion using
Fourier anal
ysis.
To estimate a model
m, use the following syntax:
m=etfe(data)
spa
Estimates a f
requency
response wit
hafixed
frequency r
esolution
using spect
ral analysis.
To estimate a
model
m, use the following syntax:
m=spa(data)
spafdr
Estimates a
frequency
response wi
th a v ariable
frequency
resolution
using spec
tral ana lys is.
To estimate
a model
m, use the following syntax:
m=spafdr(data,R,w)
where R is th
e res olution vector and
w is the frequency
vector.
After estimating the model, see Chapter 8, “Model Analysis” to validate the
model.
Options for Computing Spectral Models
This section d escribes how to select the m ethod for computing spectral models
in the estimation procedures “How to Estimate Frequency-Response Models
intheGUI”onpage3-3and“HowtoEstimateFrequency-ResponseModels
at the Command Line” on page 3-5.
3-5