ssb.m

SSB调制 完整的调制和信号功率谱与眼图

Fs=100000;
t=[0:1/Fs:0.01];
y=cos(300*2*pi*t);%调制信号
yw=fft(y);
yw=abs(yw(1:length(yw)/2+1));
frqyw=[0:length(yw)-1]*Fs/length(yw)/2;

Fc=30000;
c=cos(Fc*2*pi*t);
b=sin(2*pi*Fc.*t);
lssb=y.*c+imag(hilbert(y)).*b;
y1=awgn(lssb,30); %调制信号加噪声
wsingle=fft(lssb);
wsingle=abs(wsingle(1:length(wsingle)/2+1));
frqsingle=[0:length(wsingle)-1]*Fs/length(wsingle)/2;
asingle=ademod(y1,Fc,Fs,'amssb'); %ssb解调
aa=fft(asingle);
aa=abs(aa(1:length(aa)/2+1));
frqaa=[0:length(aa)-1]*Fs/length(aa)/2; %解调信号频谱
figure(1)
subplot(1,2,1);
plot(t,y);grid on;
title('调制信号时域波形')
subplot(1,2,2);
plot(frqyw,yw); grid on;%调制信号频谱
title('调制信号频谱')
axis([0 1000 0 max(yw)]);
figure(2)
plot(t,lssb)
subplot(2,2,1)
plot(t,lssb);grid on;
title('下边带信号波形')
subplot(2,2,2);
plot(frqsingle,wsingle);  %调制后频谱图
grid on;
title('下边带信号频谱')
subplot(2,2,3);
plot(t,asingle);
grid on;
title('解调后信号波形')
subplot(2,2,4);
plot(frqaa,aa);
grid on;
title('解调后信号频谱')
axis([0 3000 0 max(aa)]);