www.gusucode.com > signal 案例源码程序 matlab代码 > signal/LowpassEllipticFilterOrderExample.m
%% Lowpass Elliptic Filter Order % For 1000 Hz data, design a lowpass filter with less than 3 dB of ripple % in the passband, defined from 0 to 40 Hz, and at least 60 dB of ripple in % the stopband, defined from 150 Hz to the Nyquist frequency, 500 Hz. Find % the filter order and cutoff frequency. % Copyright 2015 The MathWorks, Inc. %% Wp = 40/500; Ws = 150/500; Rp = 3; Rs = 60; [n,Wp] = ellipord(Wp,Ws,Rp,Rs) %% % Specify the filter in terms of second-order sections and plot the % frequency response. [z,p,k] = ellip(n,Rp,Rs,Wp); sos = zp2sos(z,p,k); freqz(sos,512,1000) title(sprintf('n = %d Elliptic Lowpass Filter',n))