Electrical engineering magazine IEEE Spectrum has recently shared a story about how RTL-SDRs can be used for chasing weather balloons. With an RTL-SDR, antenna and appropriate decoding software, it is possible to decode the telemetry signal from weather balloons radiosondes, and track their live GPS location.
The author, Dave Schneider explains how chasing and hunting weather balloons can be a fun sport. To help with his hunt Dave uses an RTL-SDR, a directional antenna and the Sondehub Tracker website.
First Dave logged onto Sondehub Tracker which aggregates multiple weather balloon signals received by volunteer ground stations. One feature of Sondehub is that it can predict an approximate landing position of a balloon. It however cannot track a balloon right to its final landing spot as usually the ground station will loose signal when the balloon gets too low.
Knowing the approximate landing position, Dave drove out to the indicated location and then took out his RTL-SDR and directional antenna and was able to track and find the radiosonde by decoding the telemetry signal with Sonde Monitor.