dtmf.m

双音多频编解码系统

function hn=DTMF(num,a,b)
phone='123A456B789C*0#D';
fl=[697 770 852 941];
fh=[1209 1336 1447 1633];
fs=8000;
N=80;
for i=1:4
    for j=1:4
        d=(i-1)*4+j;
        if phone(d)==num
            nl=i;
            nh=j;
        end
    end
end
wl=2*pi*fl(nl)/fs;
wh=2*pi*fh(nh)/fs;
hnn =DTMFn(a,b,wl,wh,N);
hn=[zeros(1,360) hnn zeros(1,360)];