A Bessel filter has a fairly constant
transit time (delay) over the pass
band, but its amplitude characteristic
starts to fall off rather earlier than in
a Butterworth filter. Moreover, the
skirts of the amplitude characteristic
are not as steep as those of a Butterworth
filter. For instance, the -0.1 dB
point in a Bessel filter occurs at
184 Hz, and the -1 dB point at
581 Hz; the same points in a Butterworth
filter occur at 827 Hz and
934 Hz respectively.
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