digitizg.m

很好的GPS信号的捕获和跟踪程序

% digitizg.m 本程序用来产生C/A码并对它进行量化
function code2 = digitizg(n,fs,offset,svnum);
%code-goldcode
%n-numberofsamples
%fs-samplefrequencyinHz;
%off set-delay time in second must be less than 1/fs can notshiftleft
%svnum-satellitenumber;
gold_rate=1.023e6;%gold code clockrate in Hz.
ts=1/fs;
tc=1/gold_rate;
cmd1=codegen(svnum);%产生C/A码函数
code_in=cmd1;

%*******creating16C/Acodefordigitizing*******
code_a=[code_in code_in code_in code_in];

code_a=[code_a code_a];

code_a=[code_a code_a];

%*******digitizing*******
b=[1:n];
c=ceil((ts*b+offset)/tc);
code=code_a(c);

%*******adjusting first data point*******
if offset>=0;
    code2=[code(1)  code(1:n-1)];
else
    code2=[code(n)  code(1:n-1)];
end