User`s guide

1 Data Processing
• Output data
- For single-in p ut/single-output (SI S O ) data, the output mus t be a column
vector.
- For a data set with N
y
outputs a nd N
f
frequencies, the output is an
N
f
-by-N
y
matrix.
• Frequency values
Must be a c olumn vector.
For more information about importing data into the M ATL AB workspace, see
the MATLAB documentation.
After you import data, y ou can impo rt i t into the System Identification
Tool GUI or create a data object for working at the command line. F or
more information about importing data into the GUI, see “Importing
Frequency-DomainDataintotheGUI”onpage1-18. Tolearnmoreabout
creating a data object, see “Representing Time- and Frequency-Domain Data
Using iddata Objects” on page 1-47.
Importing Frequency-Response D ata into MATLAB
• “What Is Frequency-Response Data?” on page 1-10
• “How to Import Frequency-Response Data into the Software” on page 1-11
What Is Frequency-Response Data?
Frequency-response data, also called frequency-function data, consists of
complex frequency-response values for a linear system characterized by
its transfer function G. You can measure frequency-response data values
directly using a spectrum analyzer, for example, which provides a compact
representation of the input and the output (compared to storing input and
output independently).
The transfer function G is an operator that takes the input u of a linear
system to the output y:
yGu=
1-10