GPS Decoding

Some of my blog posts about GPS:

• GPS Visualization
• The GPS PRN
• GSP Spreading

Finding the C/A Code

Using the tiny library in this repo to generate copies of the C/A codes (see above blog posts) run over all the likely phase and doppler combinations to look for the code hidden in the raw signal.

IPython Notebook graphing the results:

https://nbviewer.jupyter.org/github/natronics/gps/blob/master/notebooks/cross-correlation.ipynb

The Raw Data

We've been using a sample data set recorded by amateur radio enthusiasts. The dataset I'm writing this decoder against is from the GNSS-SDR project

• 2013_04_04_GNSS_SIGNAL_at_CTTC_SPAIN.tar.gz (warning! 1.5 GB file)

Run This Yourself

Make sure you have dependencies:

$ pip install -r requirements.txt

To run the program, pipe the datafile into gps.py:

$ ./gps.py < PATH/TO/DATA.dat