# Lecture 7 Blog, ECE438 Fall 2013, Prof. Boutin

Wednesday September 4, 2013 (Week 3) - See Course Outline.

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Today 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. We then computed a couple of z-transforms as examples. It was observed that there may be values of z for which the z-transform does not exist. Even though we did not see the formula for the inverse z-transform, we were able to invert a z-transform simply by comparing the expression for the given z-transform to the formula for the z-transform. As we will see later, this trick will be very handy for inverting z-transforms in general.

## Action Items

• Solve the following practice problems and share your answer to get feedback. It will help you get full credit on the second homework and on the test.

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## Alumni Liaison

Sees the importance of signal filtering in medical imaging

Dhruv Lamba, BSEE2010