acquiresignal.m

GPS的CA码捕获跟踪源代码

function [fd_ac,f_ac_code] = acquiresignal()

global time_unit; % 数据跳变时间单位
global time; % 数据发送时间
global time_cyc;% 一个完整扩频码周期
global fs; % 采样率
global nn; % 一个完整扩频周期采样点数
global kk; % 数据总采样点
global F_if;   % 载波中频
global CA_freq; % PN码速率 
global tc; 
global CA ; % 扩频码基玛
global F_Carrier; % L1波段载波频率


%%%%%%%%%%%%%%%%%%%%%%%%参数设置%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
svnum=10;
time = 100*(10^(-3));
time_unit = 20*(10^(-3));
time_cyc = 1*(10^(-3));

fs = 5*(10^6);
nn = time_cyc*fs;
kk = (time/time_cyc)*nn;

F_if = 1.25*(10^6);
F_Carrier = 1575.42*(10^6);
CA_freq = 1.023*(10^6);


%%%%%%%%%%%生成C/A以供使用%%%%%%%%%%
PN = codegen(svnum);
CA = [];
k = 5;
for n = 1:length(PN)
CA((1+k*(n-1)):k*n) = PN(n)*ones(1,k);
end

tc = 1/(k*CA_freq); 
loop_time = time/time_cyc;


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%捕获%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[fd_ac,f_ac_code] = acqu1;