Javions

Javions is an open-source ADS-B messages demodulator. It was coded as a first-year project in computer science at EPFL. The instruction set along with the main course resources is available here. After the conclusion of the 2022-2023 academic year, it will instead be available here. The instruction set provided by our instructor, Michel Schinz, was grounded on the book The 1090 Megahertz Riddle authored by Junzi Sun.

Figure 1: Final graphic interface of Javions

Main contributors

• @franklintra
• @chukla

Getting started

This project is designed to function with JavaFX version 20.0.1 and Java 17, ensuring that the preview feature is enabled. (--enable-preview)

If you don't have Java 17 installed on your computer, please visit Adoptium, and download the installer corresponding to your operating system (macOS, Linux ou Windows). For further help installing JavaFX, please follow this guide.

Usage Guidelines

Viewing Pre-Demodulated and Stored Messages in GUI

If the main class is executed with a single additional argument - the file path for the saved messages, the program will activate the GUI, decoding the saved messages in real time in accordance with the timeStampNs. Example:

java --enable-preview -cp out/production/Javions/ --module-path ${JFX_PATH?} --add-modules javafx.controls ch.epfl.javions.gui.Main resources/messages_20230318_0915.bin

Real-Time Radio Message Decoding

By running the main class without any additional arguments, the GUI (Graphic User Interface) will launch, enabling real-time decoding of radio messages that are received via the System.In input port.

To retrieve messages from the radio, you will first need to install and configure the driver. On MacOS, for example, you could use the brew install airspy command.

Once you've completed this step, simply connect your radio. To start the program and begin decoding incoming messages, run the following command:

airspy_rx -r - -f 1090 -t 5 -g 17 | cat samples_20230304_1442.bin | java --enable-preview -cp out/production/Javions/ --module-path ${JFX_PATH?} --add-modules javafx.controls ch.epfl.javions.gui.Main

This command will initiate the program and demodulate the messages as they are received.

Test Procedures

The project was thoroughly tested throughout its development using JUnit5. All tests can be executed using Maven with the following command:

mvn clean test

This command will run all configured tests (should take about 2 to 3 seconds depending on your hardware). The tests are most thorough for the first part of the project (week 1 to 6 aka messages demodulation).

Additional informations

We will try to create and support two images of this app. A native image for all major platforms and a jar containing all necessary libraries. This is a work in progress and you will be notified as soon as it is available.

Contribution

You are very welcome to contribute to the project. If you wish to do so, please fork the project, make your changes, and then make a pull request which will be examined by @franklintra as soon as possible. Welcome changes are any useful changes which can make the user experience nicer and / or bug fixes.

Licence

This project is distributed under the MIT licence.

Main class

Logic

The logic diagram for the main class of the program.

For better performance, and non-blocking demodulation, the demodulation of the messages is not done on the main JavaFX thread. Instead it is done on a separate thread and the decoded messages are given to a queue which is then polled by the JavaFX thread.

• Further improvements: Make the TileManager asynchronous by returning empty Images as long as the tile hasn't been loaded from either the memory, drive or server. This could be implemented as a bonus for week 12 of the project.