of Microprocessors

SOURCE-SIGNAL ANALYSIS 561
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Fig. 16--11. Equivalent half-bandpass filter shapes of common windows. (A)
Rectangular window. (B) Triangular window.
Of course, an FFT of the window shape will only evaluate the equivalent
BPF at certain discrete frequencies. To get an accurate plot of the curve
shape, a very large FFT must be performed with the window occupying a
small portion at the beginning and zeroes occupying the remainder. For
example, to check the response at eight different frequencies between each
null point, an FFT eight times the window length will have to be computed.
In our example, this means a 4,096-poinr FFT. On the other hand, most all