If you’re into airplanes, you’ve probably had the experience of hearing an unusual aircraft and rushing outside to try and catch a glimpse of it, all while fumbling with a smartphone to open a flight-tracking app. If your home was equipped with [cpaczek]’s Skylight project, which combines ADS-B data with a short throw projector, that little dance would have been totally unnecessary.

ADS-B or the “Automatic Dependent Surveillance-Broadcast”, is the standard by which aircraft broadcast their position and other flight information from onboard transponders. In most of the world, every commercial aircraft has an ADS-B transmitter, and they’re slowly creeping into general aviation as well. The signals aren’t hard to pick up with software-defined radio — like perhaps this RP2040 based unit we featured — or the RTL-SDR v4 this project calls for.

Using data from ADS-B, the Skylight software runs on Raspberry Pi 5 and renders icons of the aircraft exactly where they would appear above you, if that pesky ceiling wasn’t in the way. You get the flight’s code, destination and flightplan with a nice icon representing what type of airplane it is. Thanks to specifying a Pi 5, the projection is a smooth 60 FPS at 1080p. Airplanes aren’t the only things plotted, though — this is also a planetarium, giving you a full view of the stars and any satellites passing overhead. That’s obviously via an API, not SDR, and if you like you can configure it to track aircraft that way to — allowing you to set your Skylight for anywhere in the world, if you aren’t near an interesting airport.

ADS-B isn’t just for pilots and plane nerds — if you’re flying drones, you probably should keep an eye on it, too. In that case, though, you probably won’t be looking at your ceiling.

Thanks to [Thinkerer] for the tip!

如果你对飞机感兴趣，你可能有过这样的经历：听到一架不寻常的飞机，匆忙冲到外面试图一睹其风采，同时手忙脚乱地掏出智能手机打开航班追踪应用。如果你的家中配备了 [cpaczek] 的 Skylight 项目（它将 ADS-B 数据与短焦投影仪相结合），那么那段小小的慌乱就完全没必要了。

ADS-B，全称“广播式自动相关监视（Automatic Dependent Surveillance-Broadcast）”，是飞机通过机载应答器广播其位置及其他飞行信息所采用的标准。在世界上大部分地区，每架商用飞机都配有 ADS-B 发射器，并且它们正逐渐渗透到通用航空领域。使用软件定义无线电（SDR）——比如我们曾介绍的这款基于 RP2040 的装置，或者本项目所需的 RTL-SDR v4——就能轻松接收到这些信号。

Skylight 软件利用 ADS-B 数据在 Raspberry Pi 5 上运行，并精确绘制出飞机在你头顶上方实际位置的图标——如果没有那讨厌的天花板遮挡的话。你会看到航班代码、目的地和飞行计划，以及代表飞机类型的精美图标。得益于 Pi 5 的配置，投影画面能以 1080p 分辨率、60 FPS 的流畅帧率呈现。不过，被绘制的不仅仅是飞机——它还是一个天文馆，让你能完整看到星空以及任何掠过天空的卫星。这显然是通过 API（而非 SDR）实现的，如果你愿意，也可以将其配置为以同样方式追踪飞机——这样即使你附近没有有趣的机场，也能将你的 Skylight 设置成观察世界任何角落。

ADS-B 不只是飞行员和飞机爱好者的专属——如果你在飞无人机，你可能也应该留意一下它。不过，在这种情况下，你大概不会盯着天花板看。

感谢 [Thinkerer] 提供线索！