Since July 2020, I’ve used Project Horus’s Radiosonde_auto_rx software running on a dedicated Raspberry Pi with a RTL-SDR to track weather balloons launched daily from the NOAA station in San Diego, CA, US and the US Army’s Yuma Proving Ground (Yuma, AZ, US). Tracks are posted in real-time to APRS.FI and HabHub. Radiosondes typically transmit in the 400-403Mhz range. More information about weather balloons and radiosondes can be found at: