BPSK調制解調及誤碼率的計算.doc

1、%隨機產生碼元clcclear allnum=10;%碼元個數ek=round(rand(1,num,1);%產生載波t=0:2*pi/999:2*pi;%周期num1=1000;%個數 len=length(t);c=-sin(t);%調制ektemp=;ctemp=;for n=1:numif ek(n)=0 ctemp=ctemp,-c; a=zeros(1,len); ektemp=ektemp,a; elseif ek(n)=1ctemp=ctemp,c; a=ones(1,len); ektemp=ektemp,a; endendsubplot(2,1,1); %分別畫出原信號、已

2、調信號示意plot(ektemp,linewidth,1.5);title(原碼元);grid on;axis(0 num1*num -2.5 2.5);subplot(2,1,2);plot(ctemp,linewidth,1.5);title(已調信號);grid on;axis(0, num1*num, -2.5, 2.5);%相干解調%本地載波loca=;for n=1:num loca=loca,c;%此處c的正負決定解調后是否倒piend locb=loca;%相乘locc=2*ctemp.*locb;%低通濾波器b,a = butter(3,2*pi*0.0003,low); %

3、信號頻率為0.001locd=filter(b,a,locc);%低通濾波后的信號figure;subplot(2,1,1); %相乘后的波形plot(locc,linewidth,1.5);title(相乘后的信號);grid on;axis(0 num1*num -2.5 2.5 );dd=locd+randn(1,10000);%低通濾波后的信號波形圖subplot(2,1,2);plot(dd,linewidth,1.5);title(低通濾波后的信號);grid on;axis(0 num1*num -2.5 2.5 );%抽樣判決for i=1:num1*num if(locd(i

4、)0) %判決，得到解調結果 locd(i)=1; else locd(i)=-1; endendfigure;subplot(2,1,1); %分別畫出原信號、解調后信號示意plot(ektemp,linewidth,1.5);title(原碼元)grid on;axis(0 num1*num -2.5 2.5);subplot(2,1,2);plot(locd,linewidth,1.5);title(解調后的信號);grid on;axis(0 num1*num -2.5 2.5 );p=symerr(ektemp,locd)/10 %誤碼率%誤碼率曲線figure(4)r=0:2:10;rr=10.(r/10);pe1=1/2*exp(-rr);%相干解調的誤碼率曲線hold onplot(r,pe1,r);grid on;pe2=(1-1/2*erfc(sqrt(rr).*erfc(sqrt(rr);%差分相