【数字信号调制】基于matlab多进制数字振幅调制与解调（4ASK）【含Matlab源码 997期】.zip

M=4; d=1; t=0:0.001:0.999; a=randint(1,20,2); i=1000; for n=0:9 sym(n+1)=a(2*n+1)*2+a(2*n+2); end s=sym(ceil(10*t+0.01)).*cos(2*pi*100*t); subplot(4,1,1); plot(t,a(ceil((100*t+0.1)/5))); title('二进制信号'); axis([0,1,-0.2,1.2]); subplot(4,1,2); plot(t,sym(ceil(10*t+0.01))); title('四进制信号'); subplot(4,1,3); plot(t,s) title('4ASK信号'); %相干解调 at=s.*cos(2*pi*100*t); at=at-mean(at); [f,af]= T2F(t,at);%通过低通滤波器 [t,at]= lpf(f,af,80); % 抽样判决 for m=0:9; if at(1,m*100+50)>0.5; for j=m*100+1:(m+1)*100; at(1,j)=3; end else if at(1,m*100+50)>0; for j=m*100+1:(m+1)*100; at(1,j)=1; end else if at(1,m*100+50)>-0.5; for j=m*100+1:(m+1)*100; at(1,j)=-1; end else for j=m*100+1:(m+1)*100; at(1,j)=-3; end end end end end subplot(4,1,4); plot(t,at); axis([0,1,-3.2,3.2]); title('相干解调后波形');