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164 Chapter 5 THE DISCRETE FOURIER TRANSFORM
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signal x(n), 0 subplot(2,1,1); stem(n,x);
>> title(’signal x(n), 0 X = dft(x,100); magX = abs(X(1:1:51));
>> k = 0:1:50; w = 2*pi/100*k;
>> subplot(2,1,2); plot(w/pi,magX); title(’DTFT Magnitude’);
>> xlabel(’frequency in pi units’)
Now the discrete-time Fourier transform plot in Figure 5.11 clearly shows two
frequencies, which are very close to each other. This is the high-resolution spectrum
of x(n). Note that padding more zeros to the 100-point sequence will result
in a smoother rendition of the spectrum in Figure 5.11 but will not reveal any
new information. Readers are encouraged to verify this.
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