1. x y Response of an LTI system to a periodic input.

2. H(s) Multiply magnitudes, add phases. n 0123-2-3 n 0123-2-3 Attenuate higher frequencies: “lowpass filter”.

3. Back to rectifier example AC y=|x| DC + Idea: add a lowpass filter in cascade to attenuate the AC components, and get a “purer” DC source.

4. y=|x| + H(s) + Rectifier plus filter

6. What does z(t) look like?

7. Mean square approximation

8. Extension to Fourier

11. Example: Square Wave

13. Convergence in mean square

14. Mean square convergence for the square wave