The Open Source Project, IQEngine, Lets You Share and Analyze RF Recordings

Software-defined radios (SDRs) have been gaining popularity in the recent years. This is mostly due to RF ICs that have been released that have enabled the technology to become more practical, but also due to the release of various platforms such as RTL-SDR and HackRF One. These inexpensive devices allow users to immediately get started in capturing and analyzing RF signals. In the case of HackRF One, users can experiment with transmitting their own signals as well. Although this is probably best left to more experienced users since there is rules and regulations on where and what you can transmit wirelessly. Nevertheless, the devices open a door to the rich subjects of RF and DSP to a wide audience.

SDRs work by capturing wireless spectrum over the air using an antenna. These wireless signals then route through the radio circuitry which amplifies, filters, and translates the input spectrum to lower frequencies such that they can be converted from the analog domain into the digital domain using an analog to digital converter (ADC). What you get at the output is what is known as IQ data, which is sampled data of the captured spectrum. With IQ data a user can begin to perform a wide array of signal processing functions. For example, the data can be plotted against time to view the time domain wave form, the data can be filtered with digital filter techniques, FFTs can be performed on the data to view the frequency content of the spectrum, and radio signals can even be de-modulated.

This is where IQEngine comes in. IQEngine is an open source web based project that allows users to upload, share, and analyze RF recordings. One of the goals of the project is to build up a large database over time which can help with identifying signals, testing algorithms, and training machine learning systems. Through the web based interface users can look at spectrograms, time domain waveforms, frequency spectrum, and IQ data. In addition, users can test algorithms, apply their own DSP transforms, and test out digital filters for educational purposes or to better understand a specific signal.

The idea for the project was inspired while trying to install SDR software for a university course. Through combining all the functionality needed for working with SDRs into a single online tool SDR and DSP education will be more accessible. Furthermore, the project integrates signal metadata format (SigMF). SigMF is a way to describe information about a set of IQ data through a JSON format. As a result, information about the captured signal can be saved that can allow the data to be organized more easily and overall be more useful. The tool is still in the early development phase and is looking for participants to help contribute to the project. A canonical version of the software can be found at IQengine.org that is hosted by GNU Radio and connected to the SigMF repository. For users interested in the project, a monthly news letter is available to stay up to date with the latest features. They are also actively looking for anyone interested in contributing to the project. Anyone looking to get involved can check out the discord.