Obtaining fundamental frequency wave from a PWM signal

Hi, Is there a way to get harmonic waves extracted from a signal. Say if I have a square wave I want to extract and plot 3 sin waves.

Similarly if a a PWM signal (ie a square wave), is it possible to plot the 1st fundamental sine wave.

Please refer to the subplot #5 of the attached screen shot http://imgur.com/CSdqRyV

Thank you

Answer 1

[laurie]

it seems you want to do a Fourier transform of your signal. See http://www.mathworks.fr/fr/help/matlab/ref/fft.html

once you get the Fourier transform results, you can delete all frequencies except for the fundamental one, do a reverse Fourier transform and plot the result.