This is an old revision of the document!
Octave Filter Design Example
pkg list pkg update
Filter design
pkg load signal % Simple but has a large transition band and only about 50 to 60 db attenuation freqz(fir1(63,0.125))
The parks McClellan algorithm incorporates both the Remez exchange algorithm and the Chebyshev approximation theorem to achieve an optimal fit between your desired and actual filter response.
% --- Parks-McClellan lowpass Filter n = 64 f = [0.0 0.3 0.4 1.0 ]; a = [1.0 1.0 0.0 0.0]; w = [1.0 0.1]; b = remez(n, f, a, w); [h,w] = freqz(b,1,512); plot(f,a,w/pi,abs(h)) legend('Ideal','remez Design') xlabel 'Radian Frequency (\omega/\pi)', ylabel 'Magnitude'