Open-source electronic conspicuity for general aviation: ADS-L 4 SRD-860 for aircraft (skyBlip) and ground stations (skyPost).
docs/BEHAVIOR.md lists every claim the firmware makes about itself, straight from the host test suite that checks them. It is generated, so it cannot describe a behavior that stopped being true.
docs/TUNING.md is the other half: every number that behavior is tuned by, with the line of source that justifies it. Also generated, from the constants themselves.
| Directory | What lives there |
|---|---|
firmware/ |
the C++ tree: core/, ui/, ports/, the Zephyr platform, the host test suite, and the simulator's world |
simulator/ |
the development harness page that drives the WASM build of the firmware, and device.css, the case both it and the site draw the panel in |
website/ |
skyblip.eu, a Rails app that Parklife renders to static files |
docs/, schemas/, scripts/, skyship/ |
the generated behavior and tuning indexes, the wire schemas, the build and release tooling, the artwork |
The firmware and the site share a tree so that a change in behavior and the page documenting it can land in one commit. They do not share a build: each has its own workflow, gated on the paths it owns.
The host test suite and the simulator need nothing but a C++ compiler: make -C firmware test, make -C firmware simulator.
The device image is built locally for now, off the committed tip of main, into builds/:
scripts/build_local.sh # skyblip_go, the only product today
SKYBLIP_REF=HEAD scripts/build_local.sh
The first run needs cmake ninja dtc gperf, then bootstraps a Zephyr workspace under ~/.cache/skyblip/west and installs the SDK. CI runs the tests and the linter but no longer builds the image: the product-image job in firmware.yml is commented out until it comes back.
skyBlip stands on a decade of open work by the free-flight community. Thanks to the authors of the projects we learned from while building it:
- Paweł Jałocha: the ADS-L reference implementation and nrf52-ogn-tracker
- Linar Yusupov: SoftRF
- Moshe Braner: the SoftRF fork
The repository is MIT: see LICENSE. The one exception is firmware/, which is GPL-3.0-only under firmware/LICENSE, and that license reaches everything below it: core/, ui/, ports/, hardware/, runtime/, products/, boards/, test/ and the simulated world in firmware/simulator/.
So the schemas, the build and release scripts, the simulator page and the website may be copied into a closed product; a tracker built from this firmware owes its sources.
The simulator page is MIT, but what simulator/ builds is not: make -C simulator build copies the firmware's WASM into simulator/build/, and that binary stays GPL-3.0-only wherever it is served.
"skyBlip" and "skyPost", the wordmark and the airship mark in skyship/ are trademarks of François Catuhe. The licenses above grant copyright permissions, not trademark ones: a fork may say it is compatible with skyBlip or derived from it, and may not use the names or the marks to name its own product or to suggest endorsement.
Copyright (C) 2026 François Catuhe