ssb.m

AM、SSB调制与解调电路的MATLAB实现及调制性能分析

close all;
clear all;
dt=0.001;
fm=1;
fc=10;
T=5;
t=0:dt:T;
mt=sqrt(2)*cos(2*pi*fm*t);
%N0=0.01;

%ssb modulation
A=2;
s_ssb=real(hilbert(mt).*exp(j*2*pi*fc*t));
B=fm;
%noise=noise_nb(fc,B,N0,t);
%s_ssb=s_ssb+noise;

figure(1)
subplot(311)
plot(t,s_ssb);hold on;
plot(t,mt,'r--');
title('ssb调制信号');
xlabel('t');

%SSB demodulation
rt=s_ssb.*cos(2*pi*fc*t);
rt=rt-mean(rt);
[f,rf]=T2F(t,rt);
[t,rt]=lpf(f,rf,2*fm);

subplot(312)
plot(t,rt);hold on;
plot(t,mt/2,'r--');
title('相干解调后的信号波形与输入信号的比较');
xlabel('t')

subplot(313)
[f,sf]=T2F(t,s_ssb);
psf=(abs(sf).^2)/T;
plot(f,psf);
axis([-2*fc 2*fc 0 max(psf)]);
title('SSB信号功率谱');
xlabel('f');