ssb调制 matlab代码.docx

>> clearA=1;fc=10;t0=5;snr=15;dt=0.001;fs=1/dt;df=0.2;t=0:dt:t0;Lt=length(t);snr_lin=10(snr/10);R=A*cos(2.*pi.*t);subplot(3,1,1);plot(t,R)xlabel(t);ylabel(余弦信源);S=1/2*A.*cos(2.*pi.*t).*cos(2.*pi.*fc.*t)-1/2*A.*sin(2.*pi.*t).*sin(2.*pi.*fc.*t);subplot(3,1,2)plot(t,S);xlabel(t);ylabel(调制信号);f,sf=T2F(t,S);subplot(3,1,3);plot(f,abs(sf);axis(-100 100 0 2);xlabel(t);ylabel(频谱);Bw_eq=signalband(sf,df,t0);signal_power=power_x(S);noise_power=(signal_power.*fs)/(snr_lin.*4.*20);noise_std=sqrt(noise_power);noise=noise_std*rand(1,Lt);figure(2)sam=S(1:Lt)+noise(1:Lt);subplot(3,1,1);plot(t,sam)xlabel(t);ylabel(信道中信号);f1,sf1=T2F(t,sam);subplot(3,1,2);plot(f1,abs(sf1);axis(-100 100 0 2);xlabel(f);ylabel(信道中信号频谱);f_start=488;f_cutoff=492;H,f=bp_f(length(sam),f_start,f_cutoff,df,fs,1);subplot(3,1,3)plot(f,H)axis(-100 100 0 2);DEM=H.*sf1;t3,dem=F2T(fs,DEM);figure(3)subplot(2,1,1);plot(t3,dem);xlabel(t);ylabel(BPF输出信号);subplot(2,1,2);f3,demf=T2F(t3,dem);plot(f3,abs(demf);axis(-10 10 0 2);xlabel(f);ylabel(BPF输出信号频谱);der=dem(1:Lt).*cos(2.*pi.*fc.*t);f3,derf=T2F(t,der);figure(4)LPF,f=lp_f(length(der),2,df,fs,2);subplot(2,1,1);plot(f,LPF)DM=LPF.*derf;t2,dm=F2T(fs,DM);subplot(2,1,2);plot(t,dm);xlabel(t);ylabel(解调信号);