MATLAB Support Tools - Digital Signal Processing and Applications with the C6713 and C6416 DSK - page 469

FIGURE D.6. Frequency response of the FIR bandpass filter design obtained with
MATLAB.

and 1250 Hz represent passband frequencies with normalized frequencies of 0.15
and 0.25, respectively, and associated magnitudes of 1. The frequencies 500 and
1500 Hz represent stopband frequencies with normalized frequencies of 0.1 and 0.3,
respectively, and associated magnitudes of 0. The last normalized frequency value
of 1 corresponds to the Nyquist frequency of 5000 Hz and has a magnitude of zero.
The program generates a set of 33 coefficients saved in the file matbp33.cof
in ASCII format.

Example D.4: Multiband FIR Filter Design Using MATLAB

This example extends the preceding three-band example to a five-band design in
order to obtain two passbands. The program mat63.m (Figure D.7) is similar to
the preceding MATLAB program, mat33.m . This filter with two passbands is rep-
resented by a total of five bands: the first band (stopband) has normalized fre-
quencies between 0 and 0.1 (0 to 500 Hz), with corresponding magnitude of 0; the
second band (passband) has normalized frequencies between 0.12 and 0.18 (600 to
900 Hz), with a corresponding magnitude of 1, and so on. This is summarized as
follows:

Band Frequency (Hz) Normalized f / F N Magnitude

1 0-500 0-0.1 0

2 600-900 0.12-0.18 1

3 1000-1500 0.2-0.3 0

4 1600-1900 0.32-0.38 1

5 2000-5000 0.4-1 0