Tagged: Radiosonde

RS41 and M20 Android Decoder: A Standalone Radiosonde Decoder Android App for RTL-SDR

Back in June 2025, we posted about a radiosonde decoder and tracker program for Windows written by Mario Ančić (9A4AM). Mario has now written in again to share a new radiosonde decoder for Android, which works with an RTL-SDR dongle connected via a USB OTG adapter. As far as Mario is aware, it is the first standalone Android app dedicated to radiosonde decoding, as other solutions only offer it as an add-on within a larger SDR program.

The app decodes the common RS1729 radiosonde protocol and supports Vaisala RS41 and Meteomodem M20 sondes, with the type detected automatically, so you only need to enter the frequency and start decoding. As it is designed for radiosonde hunters, it skips PTU (pressure, temperature and humidity) data and focuses on position, altitude, speed, climb rate and heading. A 'Geo App' button passes the sonde's coordinates to your map app as a marker.

The decoder runs via the 'SDR driver' app by Signalware and was tested with our RTL-SDR Blog V3 and V4. The code is open source under the GPL-3.0 licence and available on GitHub, with the APK in the Releases section. Since the app runs as a background service, Android's battery optimization settings may need adjusting for it.

RS41 and M20 Android Decoder Screenshot
RS41 and M20 Android Decoder Screenshot

AI Disclaimer: The project README notes that parts of the code were written with the help of an AI assistant and reviewed by the author.

RF-Traffic-Monitor: Track Aircraft, Ships, Drones and Radiosondes in One Program

Thank you to Stefanos (Steeod) for sharing a new program he created, "RF-traffic-monitor." Stefanos created this program because he initially wanted to install adsb.im (an ADS-B feeder image that also tracks ships, radiosondes, and ACARS/VDL2/HFDL) on Windows 10, but was unsuccessful in doing so, as adsb.im is written for Linux machines.

So, to get around this, Stefanos decided to fire up ChatGPT to write his own similar Windows program. The end result was RF-traffic-monitor, which is capable of tracking aircraft, ships, and radiosondes using an RTL-SDR or HackRF. It can also use the SDR to decode ACARS, VDL2, and HFDL. With a compatible WiFi adatper the software is also capable of tracking drones via Wi-Fi Remote ID.

RF-Traffic-Monitor Screenshot
RF-Traffic-Monitor Screenshot

AI Disclaimer: The author notes that this program was written by ChatGPT.

OpenWXSDR Updates: Decoder Improvements and Sondehub.org Uploads

Back in May, we posted about the release of OpenWXSDR, an open-source Python framework that turns one or more RTL-SDR or Airspy SDRs into a fully automated radiosonde ground station running on a Raspberry Pi 4/5 or Linux x86 machine.

Recently, OpenWXSDR creator Mike (DL2MF) wrote in to share that V1.0.62 has been released, bringing improvements to decoder quality and stability. The update also improves the software's setup and configuration stages and adds a radiosonde statistics page.

Another development is that the sondehub.org aggregation site has verified the OpenWXSDR telemetry data and now allows the upload of DFM06, DFM09, DFM17, M10, M20, RS41, and RS92 radiosonde data to its network via OpenWXSDR.

OpenWXSDR Screenshot
OpenWXSDR Screenshot

IC-SDR: A New Multimode SDR Software for Windows Written in Go

Thank you to Luis Lopez Martinez for writing in and sharing the release of his open-source software, IC-SDR, a new multi-mode SDR application for Windows written in Gowith a focus on performance and efficiency. Luis writes:

IC-SDR supports AM, NFM, WFM, LSB and USB demodulation, along with several integrated digital decoders:

  • AIS
  • ADS-B (1090 MHz and UAT 978 MHz)
  • Radiosondes
  • APRS
  • RTL_433
  • DMR
  • SSTV
  • TETRA

It also includes a memory bank, real-time spectrum and waterfall displays, an audio recorder with automatic silence removal, and a frequency-segment scanner with instant triggering.

The Windows release can be found on the project's GitHub Releases page.

OpenWXSDR: A Streamlined Automated Multi-Sonde Decoder for Raspberry Pi with RTL-SDR or Airspy

Thank you to Mike (DL2MF) for writing in about the release of OpenWXSDR, a new open-source Python framework that turns one or more RTL-SDR dongles or Airspy SDRs into a fully automated radiosonde ground station running on a Raspberry Pi 4/5 or Linux x86 machine.

If you are unaware, a radiosonde is a lightweight instrument package typically carried by a weather balloon to collect atmospheric data, including temperature, humidity, pressure, and GPS position. It transmits this data back to the ground via radio signals. Using an RTL-SDR or another software-defined radio (SDR) along with appropriate decoding software, hobbyists or researchers can receive, decode, and visualize these signals. Radiosondes are typically launched by local meteorological agencies in many cities worldwide at least twice per day.

OpenWXSDR continuously scans the 400-406 MHz meteorological band, automatically identifies balloon transmissions using DFT correlation analysis, and spawns dedicated rs1729 decoder subprocesses. Supported sonde types include RS41, RS92, DFM06/09/17, M10, M20, iMet-54, LMS6, and MRZ.

The software also supports multi-sonde and multi-SDR. While one dongle scans for new signals, others simultaneously handle active decoding sessions. Decoded telemetry can be submitted in parallel to SondeHub v2 and to OpenWX.de via MQTT (with optional TLS), and as Horus-compatible UDP JSON datagrams for local tools like SondeMonitor. A built-in Flask and Leaflet web interface shows live positions, flight tracks up to 20,000 points, PTU sensor readings, and signal metrics, with most settings editable from the WebUI during operation.

OpenWXSDR Web Interface
OpenWXSDR Web Interface

A New Radiosonde Decoder and Tracker Program for Windows and RTL-SDR

Thank you to Mario Ančić for informing us about his recently released software, "Radiosonde-decoder-and-tracker-for-Windows". As the name implies, this is Windows only software that can decode and track radiosondes.

A radiosonde is a lightweight instrument package typically carried by a weather balloon to collect atmospheric data such as temperature, humidity, pressure, and GPS position. It transmits this data back to the ground via radio signals. Using an RTL-SDR or another software-defined radio (SDR) along with appropriate decoding software, hobbyists or researchers can receive, decode, and visualize these signals.

Mario has shared the following information about his software:

The program supports four types of sondes: RS-41, M10, M20, and DFM (PS-15, DFM09, DFM17 tested).

The program is designed to run without any additional installations or software, except for the ZADIG driver for RTL-SDR (RTL2832). It uses RTL-FM for SDR reception and the popular open-source RS1729 for decoding. Decoding is also possible via the audio input (using Virtual Audio Cable and SDR# or SDR++ or any other SDR software).

The received data can be sent to servers such as Radiosondy, Wettersonde, or other APRS-based weather radiosonde servers. Optionally, the data can be sent to two servers simultaneously.

Further information and the downloadable program are available in the Release section on the page:
recently released software, "Radiosonde-decoder-and-tracker-for-Windows"

The program is intended for 64-bit Windows OS (Windows 7 or newer) and is Freeware.

We note that the software is freeware; however, it does not appear open source, as no code has been shared.

Radiosonde Decoder and Tracker Screenshot
Radiosonde Decoder and Tracker Screenshot

SDRangel Now Available on Android: Mobile ADS-B, AIS, APT, Digital Voice, POCSAG, APRS, RS41 Radiosonde Decoders

SDRangel is a free open source software defined radio program that is compatible with many SDRs, including RTL-SDRs. SDRAngel is set apart from other programs because of it's huge swath of built in demodulators and decoders.

Thank you to reader Jon for writing in and noting that SDRangel has recently been released for Android as a free Google Play download. This is an amazing development that could open up many doors into portable decoding setups as the Android version supports almost every decoder implemented on the desktop version. Jon writes:

It includes most of the functionality of the desktop version of SDRangel, including:

  • AM, FM, SSB, Broadcast FM and DAB, AIS, ADS-B, Digital Voice (DMR, dPMR, D-Star, FreeDV), Video (DVB-S, DVB-S2, NTSC, PAL), VOR, LoRa, M17, Packet (AX.25), Pager (POCSAG), Radiosonde (RS41), Time signal (MSF, DCF77, TDF and WWVB) modems.
  • RTL SDR, Airspy, Airspy HF, LimeSDR, HackRF and SDRplay support via USB OTG as well as networked SDRs
  • 2D and 3D signal analysis in both time and frequency domain with statistical measurements of SNR, THD, THD+N, SINAD, SFDR and channel power
  • Satellite tracker, star tracker, maps and rotator controller

It should work on Android 6 and up. It’s a straight port of the desktop application, so although it will run on a phone, probably best used on a large tablet with a stylus or mouse.

SDRangel on Android
SDRangel on Android
SDRangel

Tech Minds: Testing a Radiosonde Decoder Plugin for SDR++

In one of his latest YouTube videos, Matt who runs the Tech Minds YouTube channels has posted a demonstration of the Radiosonde decoder plugin for SDR++ called sdrpp_radionsonde.

SDR++ is a software defined radio receiver program that is compatible with almost every SDR, including the RTL-SDR. Like other SDR programs, is has plugin capability, allowing third parties to develop additional features like decoders.

In the video Matt first shows how to install the plugin, demonstrates it being used with an example RS-41 radiosonde, and then shows how to use the log file outputs like the GPX track file on a free GPX map plotting website.

Radiosonde Decoder Plugin for SDR++

A radiosonde is a small sensor and radio package normally attached to a weather balloon. Meteorological agencies around the world typically launch two balloons a day from several locations to gather data for weather prediction. With an RTL-SDR, appropriate antenna and decoding software it is possible to decode the telemetry signal and gather the weather data yourself. You can also use the GPS data to chase and collect the fallen radiosonde package. We have an alternative tutorial on setting up a basic radiosonde decoder in Windows here.