One zero, LP/HP

  • Author or source: Bram
  • Created: 2002-08-29 23:18:43
notes
LP is only 'valid' for cutoffs > samplerate/4
HP is only 'valid' for cutoffs < samplerate/4
code
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theta = cutoff*2*pi / samplerate

LP:
H(z) = (1+p*z^(-1)) / (1+p)
out[i] = 1/(1+p) * in[i] + p/(1+p) * in[i-1];
p = (1-2*cos(theta)) - sqrt((1-2*cos(theta))^2 - 1)
Pi/2 < theta < Pi

HP:
H(z) = (1-p*z^(-1)) / (1+p)
out[i] = 1/(1+p) * in[i] - p/(1+p) * in[i-1];
p = (1+2*cos(theta)) - sqrt((1+2*cos(theta))^2 - 1)
0 < theta < Pi/2