c_a_code_2.m

gps c/a码程序以及模拟卫星定位的源代码、地球模型

clc;clear;
svnum=input('enter the satellite number=');
g2s=[5;6;7;8;17;18;139;140;141;251;252;254;255;256;257;258;;469;470;471;472;473;474;509;512;513;514;515;516;859;860;961;862];
g2shift=g2s(svnum,1);

reg=-1*ones(1,10);
for i=1:1023;
    g1(i)=reg(10);
    slave1=reg(3)*reg(10);       %第三位寄存器和第十位寄存器模2加,并反馈给1号寄存器%
    reg(1,2:10)=reg(1:1:9);
    reg(1)=slave1;
end

reg=-1*ones(1,10);
for i=1:1023;
    g2(i)=reg(10);
    save2=reg(2)*reg(3)*reg(6)*reg(8)*reg(9)*reg(10);
    reg(1,2:10)=reg(1:1:9);
    reg(1)=save2;
end
g2tmp(1,1:g2shift)=g2(1,1023-g2shift+1:1023);
g2tmp(1,g2shift+1:1023)=g2(1,1:1023-g2shift);
g2=g2tmp;
ss_ca=g1.*g2;
ca=ss_ca;

ind1=find(ca==-1);
ind2=find(ca==1);
ca(ind1)=ones(1,length(ind1));
ca(ind2)=zeros(1,length(ind2));
temp=ca(1:1023);
x(1)=0;
show(1)=temp(1);
p=2;
for i=2:length(temp)
    if ((temp(i)~=temp(i-1)))
        x(p)=i;
        show(p)=temp(i-1);
        x(p+1)=i+0.01;
        show(p+1)=temp(i);
        p=p+2;
    else
        show(p)=temp(i);
        x(p)=i;
        p=p+1;
    end
end
plot(x,show);
axis([0 length(x)+5 -1 1.5]);
grid;