# Lecture 4 Blog, ECE438 Fall 2014, Prof. Boutin

Wednesday September 3, 2013 (Week 2) - See Course Outline.

Jump to Lecture 1, 2, 3 ,4 ,5 ,6 ,7 ,8 ,9 ,10 ,11 ,12 ,13 ,14 ,15 ,16 ,17 ,18 ,19 ,20 ,21 ,22 ,23 ,24 ,25 ,26 ,27 ,28 ,29 ,30 ,31 ,32 ,33 ,34 ,35 ,36 ,37 ,38 ,39 ,40 ,41 ,42 ,43 ,44

In the fourth lecture, we finished computing the Fourier transform of a rep, and we computed the Fourier transform of a comb. We then began the second topic: "Spectral representation of DT signals". After giving the formulas for the DTFT and the inverse DTFT, we observed the periodicity property of the DTFT and observed that one can thus write any DTFT transform as a "rep" function. We also obtained the DTFT of a complex exponential. We observed that it is not wise to attempt to Fourier transform a complex exponential using the definition, but we found a way around that problem by using the inverse Fourier transform formula to guess the answer.

Action items:

• Finish the first homework. It is due Friday (in class).