FoxGrid is an open-source tool for radio amateurs who locate an interferer on VHF/UHF together (any frequency, for example 2 m, 70 cm or 23 cm, typically on a repeater). Participants record bearings with a position, azimuth, uncertainty and field strength. The backend fuses them live into the most likely transmitter location, with an error ellipse, and pushes the result to everyone.
- Live bearing fusion with error ellipses and 50/80/95 % probability contours; outliers are tolerated
- Homing with S-meter and attenuator for the last metres; fixed omnidirectional stations for a coarse area
- Team chat and tasks, push on transmission start, GPX/KML/JSON/PDF export
- Offline-first app (Android, iOS, web control room) with a sync queue
- Invite-link access with approval, device binding, trust levels and a security log
- Optional automatic stations and a repeater hook over MQTT
Bearings are never deleted, azimuths are always stored as true north, and every bearing carries its uncertainty.
Prerequisites: Docker, uv, Flutter (stable).
cp .env.example .env # set passwords and the JWT secret
docker compose up -d --build # API on port 8000, PostGIS, Redis; migrations run automatically
curl localhost:8000/healthz
cd app && flutter run -d chrome # web control room; server URL http://localhost:8000Create a mission in the app, share the invite from the person icon, and watch a simulated hunt with
uv run tools/simulator/run.py. Details: development setup.
| Directory | Content |
|---|---|
engine/ |
foxgrid_engine, the direction-finding maths (numpy, pyproj; no web/DB dependencies) |
backend/ |
FastAPI, SQLAlchemy/GeoAlchemy2, Alembic, WebSocket + Redis |
app/ |
Flutter app (Android, iOS, web) |
tools/ |
simulator, MQTT sensor client, relay hook, branding and store asset generators |
deploy/ |
Caddy and Mosquitto configuration |
docs/ |
documentation, see docs/README.md |
Start at the documentation index: user guide, concepts (domain rules, engine, architecture), API and configuration reference, operations (deployment, releases, push), development notes and decision records. Running a server: deployment guide. Known limits: limitations.
Contributions are welcome, in English or German: see CONTRIBUTING.md and the code of conduct. Report vulnerabilities as described in SECURITY.md. The privacy policy is in docs/privacy.