OH3HAB #4 high-altitude balloon launch at club OH3AA

Amateur radio club OH3AA in Hämeenlinna, Finland launched a high-altitude balloon on September 10th 2022. The payload was a reprogrammed Vaisala RS41 radiosonde transmitting location information using Horus 4FSK and APRS modes on the 70cm amateur radio band.
The goal of the launch was to use a slow ascent rate of around 1.0-1.5 m/s, which we reached successfully. While there was practically no wind on the ground (a requirement for a slow ascent!), the balloon started to move south-east over the treetops, which is why we had to speed up the ascent using "party balloons". This way we could avoid the cord and the sonde getting caught in the trees nearby.
We tracked the balloon in amateur.sondeh... where both the Horus 4FSK and APRS location packets can be tracked.
We used a DJI Mavic Mini drone to record the launch footage. The drone movement on the video looks a bit uncontrolled at times because remote control was not working properly, possibly due to amateur radio repeater transmissions at the club interfering the remote control connection.
The custom radiosonde firmware RS41ng is available here:
github.com/mik...
Horus GUI application used for receiving the Horus 4FSK packets:
github.com/pro...
Club OH3AA website (mostly in Finnish):oh3aa.fi/
Launch team: Jari OH3UW, Sami OH3EYZ and Mikael OH3BHX.
Thanks to Martti OH1ON for recording additional video of the launch.

[@bullyinspace]

Where’s the balloon footage

[@oh2aue]

koleeta :)