# Lecture 22 Blog, ECE438 Fall 2010, Prof. Boutin

Friday October 15, 2010.

Hello "Makers"!

Given the disappointing results on the first midterm, I have decided to give you more opportunities to practice solving problems. So before the lecture begins, I will post the following practice question. Please feel free to write your solution/questions below the question, and I will look at it and reply this weekend. Note that the practice question is related to the next homework.

Today in class, we continued looking at a specific low-pass filter (filter A) and a specific band-pass filter (filter B). We noticed the two different ways of writing the transfer function (as a function of z, and as a function of 1/z) and noted that it is just as easy to find the poles/zeros with either representation (using a change of variable when the function is in terms of 1/z). We then began talking about systems defined by difference equations with constant coefficients. Our focus is going to be on "causal" systems, so the general form of equations we are interested in is

$ \sum_{l=1}^N a_l y[n-l]= \sum_{k=1}^M b_k x[n-k]. $

Comments:

Also, if possible I was hoping to work though some of the exam problems in a little more detail. In class, Prof. Boutin suggested that a lunch help session might be useful in answering these question and asked that we try to find a time for such a meeting. Would some time around 12:30 Monday, Wednesday, or Friday work for anyone else who is interested? -Clayton

- 12:30 is NanoElectronics for me. MWF. And Lab/ECE400 T/TH.
- 11:30 and 1:30 are suitable all days but Tuesday. ~Ajfunche
- 11:30-1:30 anytime between then MWF or TH before 12:30 ~Whaywood
- Monday and Wednesday at 1230pm works for me, but not Friday. ~ksoong

Would Monday 12:00-1:00 suit everybody? In particular, Clayton, would this time work for you? -pm

12-1 on Monday would work for me. Thank you Professor. -Clayton

- Ok, let's begin next week then. We will meet in MSEE383. (By the way I saw you in the newspaper. Nice work!) -pm

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