双边带抑制载波模拟调制.m

以余弦波信号为例

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%模拟载波双边带调制
fs=100;
ts=1/fs;
t=[0:ts:2]
N=length(t)-1;
df=fs/N;
x=cos(10*2*pi*t);
y=cos(2*pi*t);
for i=1:N+1
    z(i)=x(i)*y(i);
end
subplot(4,1,1)
plot(t,y)
title('我的方法')
subplot(4,1,2)
plot(t,x)
subplot(4,1,3)
plot(t,z)
%求频谱
[M,m,df1]=fftseq(z,ts,df);
f=[0:df1:df1*(length(m)-1)]-fs/2;
subplot(4,1,4)
%stem(f,fftshift(abs(M)))%散点图
plot(f,fftshift(abs(M)))
figure
%%%%%%%%%%%%%%%%%%%%5%%%%%%%%%%%%%%%%%%%%%%%书本上的方法
t=[0:2*fs+1]/fs;
fc=10;
x=cos(2*pi*t);
ydouble=amod(x,fc,fs,'amdsb-sc');
ysingle=amod(x,fc,fs,'amssb');
%做出频谱图
zdouble=fft(ydouble);
zdouble=abs(zdouble(1:length(zdouble)/2+1));
frqdouble=[0:length(zdouble)-1]*fs/length(zdouble)/2;
subplot(4,1,1)
plot(t,x)
title('书本上的方法')
subplot(4,1,2)
plot(t,cos(fc*2*pi*t))
subplot(4,1,3)
plot(t,ydouble)
subplot(4,1,4)
plot(frqdouble,zdouble);