t0=1.15;
ts=0.001;
Fc=250;
Fs=1/ts;
df=0.3;
t=[0:ts:t0];
m=[ones(1,t0/(3*ts)),-2*ones(1,t0/(3*ts)),zeros(1,t0/(3*ts)+1)];
c=cos(2*pi*Fc*t);
b=sin(2*pi*Fc.*t);
ussb=m.*c-imag(hilbert(m)).*b;
lssb=m.*c+imag(hilbert(m)).*b;
[M,m,df1]=fft_seq(m,ts,df);
M=M/Fs;
[U,ussb,df1]=fft_seq(ussb,ts,df);
U=U/Fs;
[L,lssb,df1]=fft_seq(lssb,ts,df);
f=[0:df1:df1*(length(m)-1)]-Fs/2;
clf
subplot(2,2,1);plot(t,ussb(1:length(t)));
title('上邊帶調制信號');
subplot(2,2,2);plot(t,ussb(1:length(t)));
title('下邊帶調制信號');
subplot(2,2,3);plot(t,ussb(1:length(U)));
title('上邊帶調制信號頻譜');
subplot(2,2,4);plot(t,ussb(1:length(L)));
title('下邊帶調制信號頻譜');