gpsmain1.m

AWGN信道下高斯噪声干扰下GPS编码译码系统性能仿真

%主函数：输入为信噪比snr_in_dB，产生p1,p2
function p2=GPSmain1(snr_in_DB)

E=1;
G=[1 1 1 1 0 0 1;1 0 1 1 0 1 1];

% snr_in_DB=-4:0.5:10;
snr=10^(snr_in_DB/10);
sgma=sqrt((E/snr)/2);%噪声方差
N=300;%桢个数

input2=round(rand(1,N*30));%信息序列
 

%GPS L2信道编码

%卷积码编码
u2=viterbi_encoder(G,input2);

%GPS L5
u2=2*u2-1;
u2=sign(u2+sgma*randn(size(u2))+eps);
u2=(u2+1)/2;


%信道译码
 %卷积码译码
[receive2, bestmetric] = VitDec(G, u2, 1);
receive2 = receive2';

p2=(length(find(input2~=receive2)))/length(input2);%GPS L5经过信道编译码的误码率