Engineer Al Alkadi Offers a Look at the Raspberry Pi Radar HAT in Action — and Cat Spotting

Engineer Al Alkadi has revealed more details of a project to create a radar HAT add-on for the Raspberry Pi and compatible single-board computers — part of a project to offer "computer vision without a camera," he says.

Alkadi announced the project publicly a week ago, offering a first look at a Hardware Attached on Top (HAT) accessory for the Raspberry Pi built around a 7.9GHz radar module.

"Our motive behind building it is mostly privacy-related," Alkadi wrote at the time. "We wanted to avoid using cameras. The radar unit can be used to detect respiration, sleeping and movement patterns and we are working on few other scenarios."

Now, Alkadi has released a short video which shows the camera in action. "In this video I demo real-time activity monitoring using radar on the Raspberry Pi," he writes. "The data is then sent to our web server for display (this produces a bit of lag as the web server is en Europe so keep that in mind).

"Firstly, I show that the radar can reflect upon simple activities such as hand waving. It is capable of detecting tiny changes in the environment so it's great as an accurate occupancy detection device! In the last few seconds of the video, I demo a higher activity spike by performing some jumping around (poor neighbors) and finally I demo our live histogram feature by walking across the detection area of the sensor."

Alkadi has also offered a look at the development roadmap, saying that a range of features - including compatibility with Raspberry Pi 3 and Raspberry Pi 4 boards, data parsing, a real-time data feed, subscription event functions for a range of activities, a web client, and a Bluetooth Low Energy (BLE) low-level interface — are already fully-functional.

"What needs more work," Alkadi admits: "SDK analytics; sleep analysis functions; fall detection event subscription; [an] enclosure and other physical related work; [and] a lot more — will be covered in future updates!"

More information on the project is available on Alkadi's latest Reddit thread. Finished hardware may go up for sale, he has suggested, but at an as-yet unconfirmed price point.