The Thought Emporium's XJ-9 Is a 3D-Printable "Wi-Fi Camera" Based on Radio Telescope Technology
Powered by a HackRF software-defined radio, this gadget scans for radio signals and captures them pixel-by-pixel as a Wi-Fi photograph.
Research and education collective The Thought Emporium has released a 3D-printable kit to turn a software-defined radio (SDR) dongle into a camera that captures otherwise-invisible Wi-Fi radio signals — rather than visible light.
"Can humans see Wi-Fi? No, definitely not, otherwise your evening browsing habits would have blinded half the neighborhood," the group jokes in the introduction to its latest video. "Now, Wi-Fi is the name that we gave the tech priest magic that allows us to download cat videos literally through the air — but what is really? The short answer is 'light,' or more accurately a type of electromagnetic radiation called microwaves."
The human eye is pretty good at seeing the frequencies of radiation we call "visible light," but not so good at seeing frequencies above and below this — and in the case of Wi-Fi signals, they're quite some distance away from anything you can perceive with the naked eye. Cameras, likewise, are designed to capture more or less the same light frequencies as the human eye — unless you design them otherwise.
The Thought Emporium's project turns a HackRF SDR into a "camera" that captures a view of the Wi-Fi portion of the electromagnetic spectrum, rather than visible light — effectively acting as a short-range radio telescope for nearby radio sources.
"It's got proper geared stepper motors, belt drive, nice 3D-pritned parts," the group explains of its second-generation attempt at a Wi-Fi camera, dubbed the XJ-9. "What [it does] is move the antenna around and, at each location, record the intensity of the radio waves we receive. Just like radio astronomy, by plotting each intensity as a pixel for each location we can build up an image as we scan the area."
The build is detailed in full in the video embedded above and on The Thought Emporium YouTube channel; 3D-print files have been published to GitHub under an unspecified license.