How does Radiosonde Telemetry work?


Playlists: 'gpn21' videos starting here / audio

In a world filled with cellular communications and spread-spectrum modulation schemes such as LoRa, a simple one-way Narrow-Band FSK transmission seems a bit outdated, doesn't it?

Have you ever wondered what exactly makes up the strange sounds coming from a radiosonde and what is necessary to cram enough data into the transmission? Or are you looking for some inspiration for your next Sub-GHz transmission scheme? Anyways, this will be the right talk for you.

For a radiosonde primer, check out the talks by Mark Jessop and Michaela Wheeler (in english) or myself (in german). In this talk, we will be purely focusing on the telemetry side of things.

After establishing the basics of radiosonde communication, we will be looking at the RS-41 and DFM radiosonde families in particular. Starting from a demodulated baseband stream, we will look at all the steps which need to be undertaken to acquire a single data set. Afterwards, will take a closer look on how software decoders are performing these steps automatically and how to tell apart a good decoder from a bad one.