User`s guide

3 Linear Model Identification

Note You cannot concatenate the single-output idproc and idpo ly model

objects.

The following syntax creates a ne w model object m that contains the vertical

concatenation of

m1,m2,...,mN:

m = [m1;m2;... ;mN]

takes the same inputs in the original models to a ll of the output o f

m1,m2,...,mN. The following diagram is a graphical representation of vertical

concatenation of frequency-response data.

Model 1 Model 2

Vertical Concatenation

of Model 1 and Model 2

Combined

Outputs

Same

Inputs

Concatenating Noise Spectral Data of idfrd Objects

When the idfrd objects contain the f requency-response data you measured

or constructed manually, the concatenation operation combines only the

ResponseData prope rties. Be cause no ise spectral data does not exist (unless

you also entered it manually),

SpectralData is empty in both the individual

idfrd objects and the concatenated idfr d object.

However, when the

idfrd objects are spectral models that you estimated, the

SpectralData property is not empty and contains the power spectra and

cross spectra of the output noise in the system. For each output channel, this

toolbox es timates one nois e channel toexplainthedifferencebetweenthe

output of the model and the measured output.

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