• picoAPRS-Lite: 144.8MHz, callsign YO4ESC-11, rate 1/min
  • reprogrammed RS41 radio sonde (as described by OM3BC):
    • APRS 432.500MHz, callsign YO4ESA-11, rate 1/min
    • RTTY 434.500MHz (baudrate 50, shift 540MHz, 7 data bits, parity none, 2 stop bits).  FL-Digi can be configured as presented here.
  • custom APRS tracker (Arduino with LibAPRS + 1W DRA818v), 144.8MHz, callsign YO3MJF-1, rate 1/min
  • Venus GPS + data logger
  • PocketGeiger + data logger

Launch: Stalpu near Buzau, Romania, local time 09:45, 22/Sept/2019.

Thanks to YO3ICT for tutorials.


  • Venus GPS NMEA data.
  • Custom APRS tracker data logs. Unfortunately, radio transmission stopped working after a few minutes, due to a software bug. However, the received APRS messages were logged locally.
  • PocketGeiger data logs.
  • picoAPRS data recorded on

picoAPRS-Lite localization data provided by the on-board GPS was erroneous, making the recovery of the balloon very difficult. A search campaign was conducted based on the barometric data and the GPS position, but was unsuccessful. The balloon was found by locals near Călțuna, Buzău, which then contacted us.