https://github.com/codyd51/gypsum

GPS receiver from a raw antenna 🛰️
https://github.com/codyd51/gypsum

gps-tracker python3 sdr

Last synced: 8 days ago
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GPS receiver from a raw antenna 🛰️

• Host: GitHub
• URL: https://github.com/codyd51/gypsum
• Owner: codyd51
• Created: 2023-11-19T14:23:57.000Z (11 months ago)
• Default Branch: release
• Last Pushed: 2024-04-15T17:30:55.000Z (6 months ago)
• Last Synced: 2024-04-18T02:13:12.933Z (6 months ago)
• Topics: gps-tracker, python3, sdr
• Language: Python
• Homepage: https://axleos.com/building-a-gps-receiver-part-1-hearing-whispers/
• Size: 2.74 MB
• Stars: 115
• Watchers: 5
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        


  



gypsum is a homebrew GPS receiver written in Python. gypsum can carry out a position fix in less than 60 seconds of antenna readings from a cold start. 

gypsum implements a GPS signal processing stack with no dependencies aside from `numpy`. 



  



gypsum turns any commodity SDR into a GPS receiver. I primarily use an [RTL-SDR](https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/), and have had success with a [HackRF](https://greatscottgadgets.com/hackrf/one/) as well. Either of these can be paired with any patch antenna sensitive to 1.57542GHz.

[This project comes with a 4-part writeup](https://axleos.com/building-a-gps-receiver-part-1-hearing-whispers/) on implementing a GPS receiver from scratch.

https://github.com/codyd51/gypsum/assets/4972184/e72151fe-994e-4e5a-95b4-19e5c91d2b20

gypsum ships with a web-based dashboard that allows the user to monitor signal quality, track progress, position fix history, and satellite tracking pipeline state.

## Using gypsum

The most convenient way to try out gypsum is to use a file containing saved antenna samples. This allows off-the-air development and signal replays.

I've uploaded a sample antenna recording to the [Releases section](https://github.com/codyd51/gypsum/releases) of the repo. Download [this file](https://github.com/codyd51/gypsum/releases/download/1.0/nov_3_time_18_48_st_ives.zip) and place it in `./gypsum/vendored_signals/`. gypsum needs information on what these files contain, so currently their info is hard-coded [here](https://github.com/codyd51/gypsum/blob/release/gypsum/radio_input.py#L101-L111). In the future, we could introduce a bespoke file format that includes the recording parameters and the antenna samples in-band.

```bash

# Install gypsum's dependencies

$ pip install -r requirements.txt

# If you want to use the web-based tracking dashboard

$ pip install -r requirements-webapp.txt

# Run gypsum against the cached antenna samples

# (And limit the satellite search scope for speed) 

$ python3 gypsum-cli.py --file_name nov_3_time_18_48_st_ives --only_acquire_satellite_ids 25 28 31 32 --present_web_ui

# (In another shell)

# Launch the webserver to observe gypsum

$ gunicorn -b :8080 --timeout 0 web_dashboard:application

```

The receiver has various behaviors that can be tweaked by modifying [config.py](https://github.com/codyd51/gypsum/blob/release/gypsum/config.py).

## License

MIT