Build a Ground Tracking Station for the May 2025 RWK Balloon Launch

By Chip Coker KD4C

After the success of last fall’s RWK High Altitude Balloon Launch, we’re planning to do it again this May 2025! Of high priority is tracking the balloon while it is in flight. Those that participated last fall know that the “horus” system developed by the high altitude balloon community (yes, there is one!) offers superior tracking to the antiquated APRS beacons of the past. We will again be using that system for tracking and receiving telemetry (and high-definition video!) from the balloon.

We will need multiple tracking stations – both home-based stations with good outside antennas and mobile stations that can assist with tracking and chasing – and the stations are fairly simple to build, so you can build your own! The RWK Github page has full instructions for how to build a Ground Station:

https://github.com/k5rwk/balloonatics/blob/main/ground_station/README.md

You will need an inexpensive RTL-SDR type receiver (around $30) and a Raspberry Pi 4 or 5 ($40-60), as well as a decent 70cm receive antenna (either omnidirectional or yagi). The hard work is already done for you as everything you need is preconfigured in a Docker Compose download. If you’ve had some experience with Raspberry Pi (and specifically the command line) and can follow instructions, you should have no trouble.

The ground station will do the following:

• Receive and track one or more Horus telemetry transmitters that provide real-time position information (lat/long/altitude) of the balloon. The Horus telemetry is uploaded to amateur.sondehub.com if your ground station is connected to the internet.
• Receive and upload High-Resolution still-frame image packets (wenet). Packets are uploaded and reassembled at wenet.sondehub.com, where you can view the image history of the launch in real time.
• Receive 70cm SSTV images (downscaled wenet images)
• Host an instance of ChaseMapper which you can use to display the balloon position on a map and chase if you are so inclined)

Once you have your ground station built (or if you need help), join our “Balloons and Tea” group (meets every other Sunday) and we can help you out. We have functional sources for telemetry and cameras so you can see if your station works.

So get started on those tracking stations, start working on your ground stations, and stay tuned!

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