A presently anonymous pair of researchers are working on building a radar HAT for the Raspberry Pi family of single-board computers (SBCs) and compatibles — as part of a smart home project.
"My colleague and I are building a little Raspberry Pi HAT with a radar sensor on it," one-half of the team, identified only by the username "Darkangel-86," explains. "We are going to use it for a smart home project, but we see many other applications for it. Our motive behind building it is mostly privacy-related; 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."
Using a 7.9GHz radar module at -42dBm, the prototype HAT — a standard for add-on boards that interface with a Raspberry Pi or compatible via the 40-pin general-purpose input/output (GPIO) header — offers a 10m (around 33 feet) range, and is designed for installation so it's on a ceiling or wall across from the subject to be monitored.
Thus far, Darkangel-86 has not published any source code or design files - nor indicated whether the prototype design is likely to make it to production as a purchasable product. More information can be found on the project's Reddit thread.