I had not enough time to adjust the code or develop it well. It was my homework and I needed to get it ready quickly before the deadline in spite of the lack of knowledge/experiences of signal applications :)
Here are a few notes for the script;
- PRN codes are verified
- The frequencies of NAV signal and PRN codes are downgraded by 10e3 coefficient to make the signal processing faster and make the signals on graphs more visible/analyzable.
- In BPSK Modulation function, the carrier signal has not the real frequency because of the reason above.
- I have a lot of lack of knowledge of signal analyses/applications for now, so I use a PSD function written by Daniel Pascual. It seems a general plotting, not special for my C/A codes.
- PRN generator functions are just for Space Vehicle 1 and 2, these functions and other functions can be generalized for all vehicles.
- For correlation graphs, the y axes limit of cross correlation plot should be set as [0 1] to get the same y axes with auto correlation plots, so the difference between auto-corr and cross-cor can be seen well.
- I plot the NAV+C/A graph during one period of NAV signal to show the signal behavior while NAV data is 1 and 0. Most probably, you need to zoom in to analyse the signals, because vertical lines are so close each other.
After I study on GPS/GNSS signals and general signal analysis topics well and feel ready to re-code this script or code a new script from the scratch, I will update this repo.
To-Do for Me;
- Draw the FFT graph of PRN correlations(raw and modulated)