fft1.m

用matlab实现的DTMF解码3种算法

% DIF-FFT

x1=yn;
x=[x1 zeros(1,N-length(x1))];


NV2=N/2;
NM1=N-1;
I=0;
J=0;
while I<NM1
if I<J
T=x(J+1);
x(J+1)=x(I+1);
x(I+1)=T;
end
K=NV2;

while K<=J
J=J-K;
K=K/2;
end
J=J+K;
I=I+1;
end
x;

L=1;
M=log2(N);
while L<=M
LE=2^L;
LE1=LE/2;
U=1;
W=exp(-j*2*pi/LE);
J=0;
while J<=LE1-1;
I=J;
while I<=N-1
IP=I+LE1;
T=x(IP+1)*U;
x(IP+1)=x(I+1)-T;
x(I+1)=x(I+1)+T;
I=I+LE;
end
U=U*W;
J=J+1;
end
L=L+1;
end
x;

q=n*2*pi/N;
axes(handles.fig4);
stem(n,x,'.') 
title('FFT translation');grid;
xlabel('k');ylabel('Amplitude');