clear;
%用來仿真QAM的誤bit率
snr=1:1:11;
%先來計算理論誤bit率
error_theory=(1-(1-(2*(1-1/sqrt(16))*1/2*erfc(1/sqrt(2)*sqrt(3*4*10.^(snr/10)/(16-1))))).^2)/4;
%用理論的誤bit率來決定需要仿真的點數
N=floor(1./error_theory)*100+100;
N(find(N<5000))=5000;
%開始仿真
global p;
for i=1:length(N);
    %首先產生隨機二進制序列
    source=randsrc(1,N(i),[1,0;p,1-p]);
    %對產生的二進制序列進行QAM調制
    [source1,source2]=Qam_modulation(source); 
    %插值
    sig_insert1=insert_value(source1,8);
    sig_insert2=insert_value(source2,8);
    [source1,source2]=rise_cos(sig_insert1,sig_insert2,0.25,2);
    %====將濾波后的信號加入高斯白噪聲
    [x1,x2]=generate_noise(source1',source2',snr(i));    
    sig_noise1=x1';
    sig_noise2=x2';
    [sig_noise1,sig_noise2]=rise_cos(sig_noise1,sig_noise2,0.25,2);
    [x1,x2]=pick_sig(sig_noise1,sig_noise2,8);
    sig_noise1=x1;
    sig_noise2=x2;
    %解調
    signal=demodulate_sig(sig_noise1,sig_noise2);
    %計算誤bit率
    error_bit(i)=length(find(signal-source)~=0)/N(i);
end;
%畫出圖形
semilogy(snr,error_bit,'-b');
hold on
semilogy(snr,error_theory,'-r')