qam.txt

此代码是有关QAM的MATLAB的仿真

标  题: 用matlab画QAM 
发信站: 荔园晨风BBS站 (Sun Aug 18 13:31:09 2002), 站内信件 

figure(1) 
close 
h=figure('position',[90 341 394 369],'color',[1,1,0]); 
h=axes('position',[100,331,404,379],'color',[0,1,0]); 
clf 

%initialise vectors 

P4qamsym=[]; 
P16qamsym=[]; 
P64qamsym=[]; 
xaxis1=[]; 
xaxis2=[]; 
xaxis3=[]; 


%Calculate BER curves 

M=4; 
for j = 1:100  
i=j/5; 
EbNo=10^(i/10); 
qamsym= (erfc(sqrt(EbNo)))*(1-0.25*(erfc(sqrt(EbNo)))); 
if qamsym < 1e-6, ,break, end 
P4qamsym(j)=qamsym; 
xaxis1(j)=i; 
end 

M=16; 
k=4; 
for j = 1:100  
i=j/5; 
EbNo=10^(i/10); 
qam=(2*(1-1/sqrt(M))*erfc(sqrt(3*k*EbNo/(2*(M-1)))))*(1-0.5*(1-1/sqrt(M))*erfc(sqrt(3*k*EbNo/(2*(M-1))))); 
if qam < 1e-6, ,break, end 
P16qamsym(j)=qam; 
xaxis2(j)=i; 
end 

M=64; 
k=6; 
for j = 1:100  
i=j/5; 
EbNo=10^(i/10); 
qam=(2*(1-1/sqrt(M))*erfc(sqrt(3*k*EbNo/(2*(M-1)))))*(1-0.5*(1-1/sqrt(M))*erfc(sqrt(3*k*EbNo/(2*(M-1))))); 
if qam < 1e-6, ,break, end 
P64qamsym(j)=qam; 
xaxis3(j)=i; 
end 


figure(1) 
semilogy(xaxis1,P4qamsym,'-g','linewidth',2); 
hold on 
semilogy(xaxis2,P16qamsym,'-b','linewidth',2); 
hold on 
semilogy(xaxis3,P64qamsym,'-r','linewidth',2); 
hold on 
title('BER curves for M-ary QAM')