How do I obtain the transfer function of a system from my frequency data using the System Identification Toolbox?

How do I obtain the transfer function of a system from my frequency data using the System Identification Toolbox?

How do I obtain the transfer function (zeros and poles) of a system from the frequency data? If I have magnitude and phase data as a function of frequency, how do I model the transfer function which fits my data? How do I obtain the transfer function, if I have the time-series data of my system?

Answer 1

[MathWorks Support Team]

You have a few choices for obtaining the transfer function of a system:

1.) The System Identification Toolbox 6.0 (R13SP1+) offers an interactive environment for building models of complex systems from both time-series and frequency response data.

For further information on this product, see the following URL:

https://www.mathworks.com/products/sysid.html

To see the list of functinality it supports and some examples on how to use this tool, please see the product documentation page here:

https://www.mathworks.com/help/ident/index.html

2.) The Signal Processing Toolbox 6.1 (R13SP1) offers the functions INVFREQS and INVFREQZ. These functions take the frequency response as an input and return the coefficients of the transfer function which fit this data as an output. More information on these functions is available in the MATLAB documentation or at the following URLs:

invfreqs (Signal Processing Toolbox)

https://www.mathworks.com/help/signal/ref/invfreqs.html

invfreqz (Signal Processing Toolbox)

https://www.mathworks.com/help/signal/ref/invfreqz.html