Hunting Weather Ballon Radiosondes With Open Source

Weather balloons payloads are called radiosondes. These radiosondes transmit their data to national meteorological service ground stations via radio signal, which is typically at around 400 – 406 MHz in most countries.  People around the world are dedicated to picking up radiosondes once they have completed their work, either for fun or to reuse their components (GPS module, sensors, antennas, radiomodem, microcontroller).

Image result for radiosonde

One of the problems is that there are multiple models of radiosondes from different manufacturers, even within a country different models can be launched. This involves an extra job of collecting different launch schedules, frequencies and software for each case. Or at least that’s how it was until the radiosonde_auto_rx project arrived that we can leave running with an cheap $25 RTL-SDR dongle receiver and will do all the work for us automatically.

Image result for radiosonde_auto_rx

Mark Jessop from project Horus developed software based on previous Zilog80’s RS decoders to automatically scan for, decode, and upload radiosonde telemetry, using cheap rtl_sdr dongle available here:

The aim of this project is to make it as easy as possible to track and recover meteorological radiosondes. Recently Michael Wheeler and Mark Jessop  gave a conference talk at, discussing this project, and radiosondes in general.


This software performs the following steps:

Use rtl_power to scan across a user-defined frequency range, and detect peaks in the spectrum.

For each detected peak frequency, run the rs_detect utility, which determines if a radiosonde signal is present, and what type it is.

If a radiosonde signal is found, start demodulating it, and upload data to various internet services.

If no peaks are found, or if no packets are heard from the radiosonde in a given amount of time (2 minutes by default), go back to step 1.

Currently radiosonde_auto_rx support the following radiosonde types:

Vaisala RS92SGP
Vaisala RS41SGP
Graw DFM06/DFM09

There’s a lot of work to be done on the radiosonde_auto_rx project. A few of the major tasks to be done so take a look at the radiosonde_auto_rx issues page and see if there’s anything you can help Mark