Advanced Design System_spectral_density

hello,

can any one show me how can i find the spectral density of an unknow signal.

thank you a lot

By doing FFT if you know the period of the signal.
Look at "fs()" function

thank you a lot, but the signal is not known for me

i found the solution : i used the Harmonic Balance and OscPort then activate the OscPort in the dialog box of the Harmonic Balance this is it

thank you a lot