Transfer function from a frequency response graph
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Arkadiy Turevskiy on 22 Aug 2012
Edited: Arkadiy Turevskiy on 19 Dec 2018
System Identification Toolbox is an add-on to MATLAB for estimating transfer functions as well as other model types from time or frequency domain data.
You can estimate a transfer function from frequency domain data using the function tfest from this toolbox.
Here is a demo that might be helpful. The demo is using ssest for estimating state-space models, but you can definitely use tfest instead for estimating a transfer function.
Azzi Abdelmalek on 14 Aug 2012
- from your frequency response, calculate a temporel pulse response h(t) (it's the inverse Fourier transform of your frequency response
- choose a white band signal x(t), and calculate y(t)=x(t)*h(t) (* is convolution).
- from x and y identify your transfer function (you must know the order of your system which is given by your frequency response)