ssb.m

你也matlab实现抑制载波单边带调幅的仿真

    %显示模拟调制的波形及解调方法SSB
    %信源
    close all;
    
    clear all;
    
    dt=0.001;       %采样时间间隔
    
    fm=1;           %信源最高频率
    
    fc=10;          %载波中心频率
    
    T=5;            %信号时长
    
    t=0:dt:T;
    
%%%%%%%%% 画画调制信号波形 %%%%%%%%%%%%%%
    
    mt=sqrt(2)*cos(2*pi*fm*t);     %信源
    
    figure(1);
    
    plot(t,mt);         %画调制信号波形
    
    axis([0,5,-2,2]);
    
    xlabel('时间  t');
    
    ylabel('幅度 V');
    
    title('调制信号');
    
%%%%%%%%% 画画调制信号频谱 %%%%%%%%%%%%%%

    [f,sf]=T2F(t,mt);
    
    figure(2);
    
    plot(f,sf);         %画调制信号频谱
    
    axis([-2*fm,2*fm,0,4]);
    
    xlabel('f');
    
    
    title('调制信号频谱');
    

    
%%%%%%%%% 画载波信号波形 %%%%%%%%%%%%%%
    
    mtt=sqrt(2)*cos(2*pi*fc*t);     %信源
    
    figure(3);
    
    plot(t,mtt);                    %画载波信号波形
    
    axis([0,1,-2,2]);
    
    xlabel('时间  t');
    
    title('载波信号');
    
%%%%%%%%% 画出SSB信号波形 %%%%%%%%%%%%%%    
    
    %N0=0.01;                       %白噪声单边功率谱密度
    %SSB modulation
    %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;
    
    s_ssb=0.5*sqrt(2)*cos(2*pi*(fc-fm)*t);
    
    figure(4);
    
    plot(t,s_ssb);                  %画出SSB信号波形
    
    title('SSB调制信号');
    
    xlabel('t');
    
    axis([0,1,-1,1]);
    
    
    %%%%%%%%% 画画SSB信号频谱 %%%%%%%%%%%%%%

    [f,sff]=T2F(t,s_ssb);
    
    figure(5);
    
    plot(f,sff);         %画SSB信号频谱
    
    axis([-10,10,0,2]);
    
    xlabel('f');
    
    
    title('SSB信号频谱');
  
    
    %%%%%%%%% 画单边带信号功率谱 %%%%%%%%%%%%%% 
    
    [f,sf]=T2F(t,s_ssb);                %单边带信号频谱
    
    psf=(abs(sf).^2)/T;                 %单边带信号功率谱
    
    figure(6);
    
    plot(f,psf);
    
    axis([-10,10,0,0.7]);
    
    title('单边带信号功率谱');
    
    xlabel('f');
    
    
 %%%%%%%%% 画出解调波形 %%%%%%%%%%%%%%     
    %SSB  demodulation
    rt=4*s_ssb.*cos(2*pi*fc*t);
    
    rt=rt+mean(rt);
        
    [f,rf]=T2F(t,rt);
    
    [t,rt]=lpf(f,rf,fm);
    
    figure(7);
    
    plot(t,rt);
    
    title('相干解调后的波形'); 
    
    xlabel('t');