www.gusucode.com > dsp 案例源码程序 matlab代码 > dsp/FrequencyResponseOfSOSFilterExample.m

    %% Frequency Response of SOS Filter
% This example plots the relative responses of the sections of a 
% sixth-order filter  with three sections. Each curve adds 
% one more section to form the filter response.
hs = fdesign.lowpass('n,fc',6,.4); hd = butter(hs); 
h = cumsec(hd); hfvt = fvtool(h); 
legend(hfvt,'First Section','First Two Sections','Overall  Filter');