The ReSonde Tracker is the base of the ReSonde System. It is the PCB that has all the tech required to get the data from the ReSonde Sensorboom, process it and then actually transmit it to the ground station.
It uses an STM32WL series microcontroller which conveniently has a LoRa radio built into the same silicon. This allows for the small size and a rather simple rf-design. Furthermore, this allows the Tracker to use LoRa modulation which is extremely efficient compared to other modulation types like FSK and GFSK which are used for most other radiosondes.
To supply the ReSonde with energy, a special AAA battery is used that can withstand even very low temperatures. This has enough energy to power the ReSonde for well over 5 hours.
As of now, I’m still stuck with the MAX31865 IC to read the Pt1000 sensor on the Sensorboom. While I do plan to change it, it is plenty good for now and very easy to use.