initial commit

.gitignore

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+*.dat

DataReader.m

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+function signal = DataReader(fileIn, duration)
+
+%%% fileIN is the path to access the file that contains the data.
+%%% Duration is the number of samples to read.
+
+% Opening the file
+fidIn = fopen(fileIn,'rb');
+
+% Identifier file = -1 -> cant read the file
+if (fidIn == -1) 
+    error(sprintf('Erreur ouverture %s',fileIn));
+end
+
+[signal,nB] = fread(fidIn,duration,'bit2');
+
+% if (nB ~= duration)
+%     error(sprintf('Erreur lecture %s',fileIn));
+% end
+
+% Closing the file
+fclose(fidIn);

ca_code.m

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+function code = ca_code(prn)
+% function code = ca_code(prn)
+% This function returns the C/A code sequence (1023 bytes long,
+% represented as 1023x1 vector of integers with values of +/- 1
+
+% Error messages
+
+if nargin~=1
+   error('insufficient number of input argumnets')
+end
+if prn<0 | prn > 37
+   error('invalid prn: must be between 1 and 37')
+end
+
+g2shift_vector=[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 ...
+   863 950 947 948 950];
+
+g2shift=g2shift_vector(prn);
+
+
+%
+% Generate G1 code
+%
+
+% load shift regeister
+
+for i=1:10,
+   reg(i) = -1;
+end
+
+% Generate code
+
+for i=1:1023,
+   g1(i) = reg(10);
+   save1 = reg(3)*reg(10);
+   for j=9:-1:1,
+      reg(j+1)=reg(j);
+   end
+   reg(1)=save1;
+end
+
+%
+% Generate G2 code
+%
+
+% load shift regeister
+
+for i=1:10,
+   reg(i) = -1;
+end
+
+% Generate code
+
+for i=1:1023,
+   g2(i) = reg(10);
+   save2 = reg(2)*reg(3)*reg(6)*reg(8)*reg(9)*reg(10);
+   for j=9:-1:1,
+      reg(j+1)=reg(j);
+   end
+   reg(1)=save2;
+end
+
+% Shift the G2 code
+
+for i=1:1023,
+   k = i+g2shift;
+   if k > 1023,
+     k = k-1023;
+   end
+   g2tmp(k) = g2(i);
+end
+
+g2 = g2tmp;
+
+% Form the C/A code by multiplying G1 and G2
+
+code = g1.*g2;

create_code_samples.m

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+function code_samples = create_code_samples(code_sequence, time_vec)
+%%% This function calculates the sampled version of the chosen ca_code_sequence 
+%%% code_sequence is the C/A PRN code sequence to be sampled
+%%% time_vec is the time vector to be                      time vector for which to be sampled
+%                       starting time of the sampling
+%                       code doppler
+%
+%   Output Parameters:  Sampled Array
+%
+%   Error           : Error message generated if the number of inouts incorrect
+%   Date            :    22 May, 2003
+%   Author          : Sameet Deshpande
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+if nargin~=2
+   error('insufficient number of input arguments')
+end
+
+code_index = mod( ceil(time_vec), length(code_sequence) );
+
+% Correct for 1023 mod 1023 which returns 0 but should be 1023
+code_index( find(code_index == 0) ) = length(code_sequence);
+code_samples = code_sequence(code_index);

main.m

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+clear; close all; clc;
+
+filepath = 'test_real_long.dat';
+
+signal = DataReader(filepath, Inf);
+
+load('subsignal.mat');
+
+N = 2^20;
+fIF = 4.348e6; %Hz
+fs = 23.104e6; %Hz
+
+s = signal5000(1:4096);
+
+omega = linspace(-2*pi, 2*pi, 2*N);
+
+figure
+plot(s, 'o-');
+
+figure;
+histogram(s);
+title('Quantized signal in time domain');
+xlabel('k');
+
+S = fft(s);
+
+w = linspace(-2*pi,2*pi,length(s));
+figure
+plot(w, fftshift(abs(S)));
+title('Quantized signal in frequency domain');
+xlabel('w');
+
+Rs = xcorr(s, 'biased');
+Ss = fft(Rs, 2*N);
+
+figure;
+plot(fftshift(abs(Ss)));
+title("Spectral density from autocorrelation");
+xlabel('w');
+
+[Ss, f] = periodogram(s, rectwin(length(s)), fs);
+figure
+plot(f, Ss);
+title("Spectral density from autocorrelation");
+xlabel('f (Hz)');
+
+[Swelch, fwelch] = pwelch(s, [], [], [], fs);
+figure
+plot([-flip(fwelch) fwelch], [flip(Swelch) Swelch]);
+xlabel('f (Hz)'); ylabel('PSD (dB/Hz)');
+title('Welch periodogram');
+
+
+
+
+
+

main.m~

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+clear; close all; clc;
+
+filepath = 'test_real_long.dat';
+
+signal = DataReader(filepath, );