I would like to use the "Simulink Extras -> Additional Sinks -> Spectrum Analyzer" block to compute the frequency response of my Simulink model so that I can compute an equivalent linear system.
However, I see a difference between the phase response computed by the Spectrum Analyzer and the actual phase response of the system. I have connected a "Simulink -> Sources -> Band-Limited White Noise" block to the input of a "Simulink -> Continuous -> Transfer Function" block which is configured to be a first-order lag, and then the phase lag shown by the spectrum analyzer is rolling off to minus infinity instead of approaching 90 degrees as expected.
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