codegen.m

几个BOC 信号的分析例程

%codegen.m generates one of the 32 C/A codes 
function [ca_used]=codegen(svnum)

%ca_used: a vector containing CA code sequence bit stream
%the g2s vector holds the appropriate shift of the G2 code 
%generate the C/A code (ex. for SV#19-use G2 shift of G2S(19)=471)
%svnum: 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;861;862];
g2shift = g2s(svnum,1);

%*******generate G1 code***************

  reg = -1*ones(1,10);
  for i=1:1023
     g1(i)=reg(10);
     save1=reg(3)*reg(10);
     reg(1,2:10)=reg(1:1:9);
     reg(1)=save1;
  end
%********generate G2 code**************

  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;
  
%generate C/A code sample by multipying G1 and G2
  
 ca_used=g1.*g2;