
2 LTI Models
2-18
Here is the input frequency of each sinusoid, i = 1 ... n,andG(w)=
. The steady state output response of this system satisfies
A frequency response data (FRD) object is a model form you can use to store
frequency response data (complex frequency response, a long with a
corresponding vector of frequency points) that you obtain either through
simulationsor experimentally. In this example, the frequency response data is
obtained from the set of response pairs: .
Once you sto re y our dat a in a n FRD model, yo u can tre at it as an LTI model,
and manipulate an F RD mod el in m os t of the sa me wa ys you manipulate TF ,
SS, and ZPK model s.
The basic s yntax for creating a S ISO F RD model i s
sys = frd(response,frequencies,units)
where
•
frequencies is a real vector of length Nf.
•
response is a vector of length Nf of complex frequency response values for
these frequencies.
•
units is an optional string for the units of frequency: either 'rad/s' (default)
or '
Hz'
i
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i
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i
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;
…
==
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(,){}
,
…
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