peteroznewman
Subscriber

Xiaofu,


You seem to have forgotten the lesson on how many samples are needed to create a good sine wave. The answer is a minimum of 20 samples per period. You created a sine sweep from 80 to 230 Hz over 25 seconds, but you only sampled it at 600 Hz.  600/230 = 2.6 samples per period at 230 Hz. You should have sampled it at 4600 Hz or 20 samples per period.  The sampling frequency is not even adequate at 80 Hz where you have 600/80 = 7.5 samples per period.


Look at the quality of the input you are giving to your model...



The third plot is what your model needs. I know that these large time histories take a long time to load into the model, but you won't get a high quality result if you don't have a high quality input. You may have heard the term "garbage in, garbage out"?


Regards,
Peter