Ignoring Transient Data in Frequency Response

I am looking to store steady state amplitudes output from the frequency response of a First-Order system. In order to achieve this I have created a 'for' loop incrementing the frequency from 10rad/s to 10000rad/s and placing this into a Simulink model (Sine Wave block). However, performing a loglog plot produces some rather... anomalous... results. I can only think this is due to the use of max(simout) giving me the amplitude when the system is in a transient state.

Any ideas on how get the amplitude when the system is in a steady state please??

Thanks for reading

Answer 1

[Jack]

From further analysis it would seem that it is in fact just that certain anomalous results appear in the simulation. Any way to just get the overall amplitude of the sine wave, ignoring any strange pieces of data?

[Doug Eastman]

Have you tried calculating the FFT of the result and looking at the magnitude of the response at the input frequency?

If you happen to have Simulink Control Design there is a function that carries out this analysis for you. See http://www.mathworks.com/products/simcontrol/demos.html?file=/products/demos/shipping/slcontrol/scdenginepad.html