createsource.m

GPS的CA码捕获跟踪源代码

function [Signal_Source,Phase_signal,buffer_bit_data]=CreateSource(phcode,fd,ph,snr)

global time_unit;
global time;
global time_cyc;
global fs;
global nn;
global kk;
global F_if 
global CA_Freq;


buffer_bit_data = [];
Tr_data = [];
data = [];
AWGNflag = 1;
SNR = snr;
MBuffer=[];

data_change = time/time_unit;
for n = 1:data_change
    bit_data = (ceil(rand-0.5)*(-2)+1);
    buffer_bit_data = [buffer_bit_data bit_data];
    Tr_data = [Tr_data bit_data*ones(1,time_unit/time_cyc)];  % ceil向上取整
end
data = Tr_data;

for i = 1:1:length(data)
    Md_f = data(i);
    Md_m = Modulate(Md_f,phcode,fd,i);
    MBuffer = [MBuffer Md_m];
end 
MBuffer;
% Phase_signal = 0;


t = [0:kk-1]/fs;
Phase_signal = 2*pi*(F_if+fd)*t+ph;
Carr = cos(Phase_signal);
S_Code=MBuffer.*Carr;
% S_Code = MBuffer;

 
if AWGNflag == 1
   RxSignal = AWGN(S_Code,SNR);   %噪声标志为1时加入高斯白噪声
else
   RxSignal =S_Code;   %噪声标志为0时,不加入噪声
end    
 Signal_Source=RxSignal;