调制方式的matlab仿真实现

function y=QAM_16(snr_in) snr=10^(snr_in/10); x=rand(200,1); h=length(x); fc=10000;fs=100000; ts=10/fc;t=0:1/fs:ts*h-1/fs;l=length(t)/h; t=reshape(t',l,h);t=t'; y=zeros(h/4,l); for i=1:h, if x(i)>=0.5 x(i)=1; else x(i)=0; end end j=1; for i=1:2:h, z(j)=2*x(i)+x(i+1); j=j+1; end for i=1:h/4, I(i)=z(2*i-1); Q(i)=z(2*i); end for i=1:h/4, if I(i)==0&Q(i)==0 y(i,:)=-3*cos(2*pi*fc.*t(i,:))+3*sin(2*pi*fc.*t(i,:));end if I(i)==1&Q(i)==0 y(i,:)=-1*cos(2*pi*fc.*t(i,:))+3*sin(2*pi*fc.*t(i,:));end if I(i)==2&Q(i)==0 y(i,:)=1*cos(2*pi*fc.*t(i,:))+3*sin(2*pi*fc.*t(i,:)); end if I(i)==3&Q(i)==0 y(i,:)=3*cos(2*pi*fc.*t(i,:))+3*sin(2*pi*fc.*t(i,:));end if I(i)==0&Q(i)==1 y(i,:)=-3*cos(2*pi*fc.*t(i,:))+1*sin(2*pi*fc.*t(i,:));end if I(i)==1&Q(i)==1 y(i,:)=-1*cos(2*pi*fc.*t(i,:))+1*sin(2*pi*fc.*t(i,:));end if I(i)==2&Q(i)==1 y(i,:)=1*cos(2*pi*fc.*t(i,:))+1*sin(2*pi*fc.*t(i,:));end if I(i)==3&Q(i)==1 y(i,:)=3*cos(2*pi*fc.*t(i,:))+1*sin(2*pi*fc.*t(i,:));end if I(i)==0&Q(i)==2 y(i,:)=-1*cos(2*pi*fc.*t(i,:))-1*sin(2*pi*fc.*t(i,:));end if I(i)==1&Q(i)==2 y(i,:)=-1*cos(2*pi*fc.*t(i,:))-1*sin(2*pi*fc.*t(i,:));end if I(i)==2&Q(i)==2 y(i,:)=1*cos(2*pi*fc.*t(i,:))-1*sin(2*pi*fc.*t(i,:));end if I(i)==3&Q(i)==2 y(i,:)=3*cos(2*pi*fc.*t(i,:))-1*sin(2*pi*fc.*t(i,:));end if I(i)==0&Q(i)==3 y(i,:)=-3*cos(2*pi*fc.*t(i,:))-3*sin(2*pi*fc.*t(i,:));end if I(i)==1&Q(i)==3 y(i,:)=-1*cos(2*pi*fc.*t(i,:))-3*sin(2*pi*fc.*t(i,:));end if I(i)==2&Q(i)==3 %#ok<AND2> y(i,:)=1*cos(2*pi*fc.*t(i,:))-3*sin(2*pi*fc.*t(i,:));end if I(i)==3&Q(i)==3 y(i,:)=3*cos(2*pi*fc.*t(i,:))-3*sin(2*pi*fc.*t(i,:));end end y0=reshape(y',l*h/4,1); power=y0'*y0; powerzao=power/snr;%以下是产生高斯白噪声序列 a=sqrt(powerzao/(l*h/4)); zao=a*randn(l*h/4,1); powerzao2=zao'*zao; y=y0+zao;%加噪以后的信号 t=0:1/fs:ts*h/4-1/fs; t=reshape(t',l*h/4,1); subplot(311);plot(t,y); grid on title('16QAM信号的时域图形')