The amplitude is the easier of the two to get. If you have the displacement, you can just measure the minimum and the maximum values to get an estimate of the amplitude.
For frequency, you can take that displacement signal and take an FFT of it. You can either
- Export the data to MATLAB and use the fft function on it.
- Use a Spectrum Analyzer block (requires DSP System Toolbox)
In both cases, you'll need to make sure the displacement data is sampled at a constant rate which is small enough to capture all the right dynamics of the system.
Oh, I guess you could also try linearizing the system and getting a Bode plot directly. This one requires Simulink Control Design.
- Sebastian
