MATLAB Support Tools - Digital Signal Processing and Applications with the C6713 and C6416 DSK - page 477

FIGURE D.11. Plot of the magnitude response of a fourth-order IIR bandpass filter using
AMPLIT.CCP .

From the plot of the magnitude response of H ( z ), the normalized center frequency
is shown at v

0.4.
Run this program again to plot the magnitude response associated with the
fourth-order IIR bandpass filter in Exercise D.4. Verify the plot shown in Figure
D.11. The normalized center frequency is shown at v

= f / F N = 1000/2500 =

0.25.
A utility program MAGPHSE.BAS (on the CD), written in BASIC, can be used to
tabulate the magnitude and phase responses.

= 1250/5000 =

D.6 FFT AND IFFT

MATLAB can be used to find both the fast Fourier transform FFT of a sequence
of numbers and the inverse Fourier transform IFFT.

Exercise D.8: Eight-Point FFT and IFFT Using MATLAB

The eight-point FFT in Exercise 6.1 can readily be verified with MATLAB, with the
following commands:

>>x = [1 1 1 1 0 0 0 0];
>>y = fft(x)
>>magy = abs(y)
>>plot (magy)

The resulting output magnitude transform is also plotted.