GPS tracker at the 2023 Meteor festival

2023 Meteor festival #

The Meteor festival is a rocketry event, that happens once a year at the Błędowska desert in Poland. It is named after the old Meteor rocket program, intended for atmosphere sounding.

The trackers #

I managed to distribute all of the trackers before the event, so people had the time to install them in their rockets. Some of them were small and used low-mid power motors, and the trackers served more as insurance than a necessary piece of avionics. However, there was a number of flights where either the rockets literally disappeared, or landed in the forest. In those cases the tracker greatly helped with recovery, shortened the search time to mere minutes, and did so in style!

Ground station #

The system was designed to use a TTGO board with an OLED display. We launch our rocket, and monitor the telemetry. Once the rocket is near the end of its descent, we lose signal because the rocket touches the ground and might get obstructed. This is not a problem, all we do is go to the last valid coordinates, and at that point we’ll be able to receive the current position of the landed rocket.

Things were a bit different at FM2023. One of the project members, set up a website and database for storing packets. He then deployed an internet connected ground station at the desert, enabling everyone to monitor the status of every tracker-equipped rocket at the festival. This eliminated the need for carrying receivers, all that was needed was a smartphone. People could look up their flight number, and see telemetry, location and even view the flight on google earth.

Performance #

The ground station used a standard whip antenna with a metal ground plane. There wasn’t a time when the receiver couldn’t hear the trackers, even though most of them were running at the default TX power of 10mW. At one point, a rocket flew over the entire desert and crashed when its parachute failed to deploy. The electronics survived, and the signal was still decoded and displayed live on the website. A quick hike across the range, and the rocket was found within minutes. Without the GPS, the rocket would have never been found.

Another case was a premature parachute ejection. Instead of deploying low to limit wind drift, it opened at apogee. The rocket slowly drifted out of site with the wind, and landing in the forest almost a kilometer away. The receiver still managed to decode everything, despite 100% forest in the way. Again, without such tracker the rocket would have been lost.

As planned, all trackers were operating one one frequency (central receiving station was listening on one frequency). This worked perfectly, and the channel activity detection performed flawlessly and reliably. The retransmission mode never had to be switched on, for that I might need to wait for a more hardcore launch, such as LRE.