Windowed-Sinc Filters

Windowed-sinc filters are used to separate one band of frequencies from another. They are very
stable, produce few surprises, and can be pushed to incredible performance levels. These
exceptional frequency domain characteristics are obtained at the expense of poor performance in
the time domain, including excessive ripple and overshoot in the step response. When carried out
by standard convolution, windowed-sinc filters are easy to program, but slow to execute. Chapter
18 shows how the FFT can be used to dramatically improve the computational speed of these
filters.
CHAPTER
Windowed-Sinc Filters
16

Windowed-sinc filters are used to separate one band of frequencies from another. They are very
stable, produce few surprises, and can be pushed to incredible performance levels. These
exceptional frequency domain characteristics are obtained at the expense of poor performance in
the time domain, including excessive ripple and overshoot in the step response. When carried out
by standard convolution, windowed-sinc filters are easy to program, but slow to execute. Chapter
18 shows how the FFT can be used to dramatically improve the computational speed of these
filters.




Strategy of the Windowed-Sinc
Figure 16-1 illustrates the idea behind the windowed-sinc filter. In (a), the
f