# Lecture 4 Blog, ECE438 Fall 2011, Prof. Boutin

Monday August 29, 2011 (Week 2) - See Course Outline.

In the fourth lecture, we computed the CTFT of signal that would "sound" like a middle C and the CTFT of a signal that would "sound" like the next higher C. We also obtained the DTFT of a sampling of each of these signals (using the same sampling frequency). It was observed that, while the sampling of middle C yields a DT signal that also sounds like a middle C, the sampling of the higher C does not at all sound like a C.

In the last few minutes of the lecture, we introduced the z-transform formula and observed its similarity to the DTFT formula. More precisely, we noticed that the DTFT is a restriction of the z-transform to the unit circle.

Relevant links:

Action items:

- Solve the following practice problem
- Keep working on the first homework. It is due next Wednesday (in class).

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