Rich Kozick
Spring, 1997
EE 329: Homework 8
Date Assigned: Wednesday, April 2, 1997
Date Due: Friday, April 4, 1997
Please work on the following digital filter problems.

Please begin reading Chapter 6 on FIR filters, sections 6.16.5.
We will design digital filters using the "window method" in
lab on Friday.

Use Matlab to design different types of IIR
lowpass filters to meet the
following specifications:
Sampling rate = 10,000 samples/second
Passband: 0 to 2,000 Hz
Stopband: 2,500 to 5,000 Hz
Passband ripple: less than 1 dB
Stopband attenuation: 40 dB or more
A procedure that you might follow is:
 Use filtdemo to get an idea how the four types
of IIR filters (butter, cheby1, cheby2, ellip) perform for
these specifications.
Note that filtdemo does not return the digital
filter coefficients.
 Design each filter in Matlab using the functions:
butter and buttord,
cheby1 and cheb1ord,
cheby2 and cheb2ord,
ellip and ellipord
 For each filter, check the frequency response with
freqz, and plot the pole and zero locations with
pzmap.

What to submit:
Submit a Matlab script containing the commands that you
used for the filter design.
Which type of filter achieves the specifications with the
smallest order?
Also, please comment on the pole and zero locations for each
filter type, and briefly explain how the pole/zero locations
correspond with the observed frequency response of
each filter.
You do not have to submit the frequency response plots.

Try processing some
sound data with a digital filter.
You can load a sound file with the
Matlab command:
f = auread('/home/pleiades/ACM/snd/spacemusic.au');
Then you can design a digital filter and process the sound with
the filter command.
The sound command can be used to play the sound.
Thank you.