designlowerfilter.m

DTMF编解码在MATLAB中的仿真（gui设计）

%DesignLowerFilter.m
function B=DesignLowerFilter(W0)
fs=8000;
N=399;
k=2*pi/fs;
Bandwidth=70;
wc1=(W0-Bandwidth/2)*k;
wc2=(W0+Bandwidth/2)*k;
B=fir2(N,[0,wc1/pi,wc2/pi,1],[0 ,1, 1, 0]);