EE 329: Class Exercise
March 31, 1997
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A neat Matlab program called pez
has been written by a student at Georgia Tech
This program allows you to change the locations of poles and
zeros in the z-plane and see the effects on the impulse response
and the frequency response.
Please try to perform steps 3 and 4 before class on
Monday, March 31.
The pez program is useful
to experiment with various pole-zero combinations
and build your insight about poles and zeros.
Create a directory pez in your account.
Download the files from the directory
pez to your pez directory.
Help for running the program pez is available at
Run pez by starting Matlab and then typing
pez at the Matlab prompt.
Experiment with a variety of pole-zero combinations.
Try poles with negative real parts, poles outside the
unit circle, multiple poles and zeros, etc.
Can you make a low-pass filter?
What about high-pass, band-pass, and band-reject (or notch) filters?
Is there any problem with zeros outside the unit circle?
It is useful to have insight about how pole and zero locations
influence the frequency response.
However, in order to design digital filters that satisfy
certain specifications (such as cutoff frequency, stopband
attenuation, etc.), more formal mathematical approaches are
In fact, many approaches to digital filter design
No digital filter is "perfect", and different approaches are
used to achieve different objectives.
We will discuss some of these approaches to digital filter
Chapters 5, 6, and 7 of the text.