GPS C/A Code Signal Structure - Fundamentals of Global Positioning System Receivers: A Software Approach - page 103

%p52.m generate one of the 32 C/A codes written by D.Akos
modified by J.Tsui

svnum=input('enter the satellite number = '); % the

Satellite's ID number

% ca : a vector containing the desired output sequence

% the g2s vector holds the appropriate shift of the g2 code
to generate
% the C/A code (ex. for SV#19 - use a G2 shift of
g2s(19)=471)

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;861;862];

g2shift=g2s(svnum,1);

% Generate G1 code
% load shift register

reg = -1*ones(1,10);

%
for i = 1:1023,
g1(i) = reg(10);
slave1 = reg(3)*reg(10);
reg(1,2:10) = reg(1:1:9);
reg(1) = save1;

end,

%
% Generate G2 code
%

% load shift register

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,
%
% Shift G2 code

%
g2tmp(1,1:g2shift)=g2(1,1023-g2shift+1:1023);
g2tmp(1,g2shift+1:1023)=g2(1,1:1023-g2shift);
%
g2 = g2tmp;

%