Rich Kozick
Spring, 1997

EE 329: Class Exercise
March 31, 1997

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  1. A neat Matlab program called pez has been written by a student at Georgia Tech ( Craig Ulmer). 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.

  2. 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.

  3. Create a directory pez in your account.

  4. Download the files from the directory pez to your pez directory.

  5. Help for running the program pez is available at

  6. 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?

  7. 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 required. In fact, many approaches to digital filter design are available. No digital filter is "perfect", and different approaches are used to achieve different objectives. We will discuss some of these approaches to digital filter design in Chapters 5, 6, and 7 of the text.
Thank you.