SSB(滤波法法)调制解调Matlab.m文件源码

%[H,f] = bp_f(length(sam),f_start,f_cutoff,df1,fs,1);

subplot(323);

plot(f_low,fftshift(abs(H_low))); %画出带通滤波器

xlabel('f');title('下边带带通滤波器');

axis([-f_cutoff_low-1,f_cutoff_low+1,-0.05,1.05]);

subplot(324);

plot(f_high,fftshift(abs(H_high))); %画出带通滤波器 xlabel('f');title('上边带带通滤波器');

axis([-f_cutoff_high-1,f_cutoff_high+1,-0.05,1.05]);

subplot(325);

plot(f_low,fftshift(abs(H_low)));hold on; %画出带通滤波器

plot(f,fftshift(abs(U))); %画出已调信号频谱 axis([-fc-5,fc+5,-0.05,1.05]);

xlabel('f');title('下边带信号');

subplot(326);

plot(f_high,fftshift(abs(H_high)));hold on; %画出带通滤波器

plot(f,fftshift(abs(U))); %画出已调信号频谱 axis([-fc-5,fc+5,-0.05,1.05]);

xlabel('f');title('上边带信号');

%%

%----------------经过带通滤波器，产生单边带信号（以上边带信号为例）

samuf = H_high.*U; %滤波器输出信号的频谱

[samu] = F2T_new(samuf,fs); %滤波器输出信号的波形

figure(3);

subplot(321);

plot(t,samu(1:Lt));

axis([0,t0,-max(samu)-0.3,max(samu)+0.3]);

xlabel('t');title('上边带信号');

%%

[samuf,samu,df1,f] = T2F_new(samu(1:Lt),dt,df,fs);%上边带信号频谱

subplot(322);

plot(f,fftshift(abs(samuf))); %画出经过理想带通滤波器后信号频谱 xlabel('f');title('上边带信号频谱');

axis([-fc-5*f0,fc+5*f0,0,max(samuf)+0.1]);

set(gca,'XTick', -10:10:10);

set(gca,'XGrid','on');