Band Stop Equiripple FIR Filter.
Cuthbert Nyack
In this applet a band pass equiripple filter for small number of
extrema can be derived. In this case Fp1(56), Fp2(57) are the edges of the lower and
upper pass bands of the filter. Ft(58) is the width of the
transition region, Te(59) is the total number of extrema, P1e(60) is the number of the extrema in the lower pass band, Se(61) is the number of extrema in the stop band and the number of extrema in the upper pass
band is Te(59) - P1e(60) - Se(61). In this applet changes should be
made slowly.
One possibility with 83 taps, a transition width of 0.03 and a
stop band attenuation of 62dB is shown by the gif image below:-
The image below shows the filter obtained with the applet's starting parameters, 49 taps, a transition width of 0.05
and a stop band attenuation of 62dB.
Below shows a case where the transition band is 0.03, the number of taps is 89 and the stop band attenuation is 64dB.
Below shows a case where the transition band is 0.035, the number of taps is 101 and the stop band attenuation is 77dB.
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COPYRIGHT © 2008 Cuthbert Nyack.