mmWave presence sensing
Smart-home sensing is getting smarter — a new German-language roundup highlights the Shelly mmWave device as proof that presence sensing (millimeter-wave radar) is arriving in consumer gear, not just niche hobby projects. mmWave can detect whether someone is sitting still or walking, which fixes the classic motion‑sensor problem of lights or HVAC turning off when you’re just quiet — that means more reliable automations. If you hate lights that go dark mid‑movie, this is the kind of sensor you should start watching closely. (youtube.com)
A regular motion sensor is like a security guard who only notices you when you wave. If you sit still on a couch for 20 minutes, a passive infrared sensor often decides the room is empty because it is watching for changes in heat, not for a person who stays put. (docs.homeseer.com) Millimeter-wave radar fixes that by sending out radio waves and measuring the reflections that come back. Research teams use frequency-modulated continuous-wave radar at 24 gigahertz and 60 gigahertz to detect and localize even stationary people indoors without a camera. (ieeexplore.ieee.org, wiki.seeedstudio.com) That is why smart-home hobbyists have spent the last few years wiring in radar boards from companies like Seeed Studio and DFRobot. Those modules were sold more like parts for tinkerers than like finished consumer sensors, with setup aimed at Arduino, Raspberry Pi, and Home Assistant users. (wiki.seeedstudio.com, wiki.dfrobot.com) Now that hardware is showing up as an ordinary retail product from Shelly. Shelly’s new Presence Gen4 is described by the company as a millimeter-wave radar presence sensor that can detect people even when they are sitting still. (shelly.com, kb.shelly.cloud) Shelly is not pitching it as a lab gadget. The product page says it is built for room automation, and outside coverage says it supports up to 10 configurable detection zones across spaces up to 42 square meters, which is roughly 452 square feet. (kb.shelly.cloud, homekitnews.com) Those zones are the part to watch. A zone turns one room into a small map, so a sensor can treat a desk, a sofa, and a doorway as different places instead of treating the whole room like one big on-off switch. (homekitnews.com, kb.shelly.cloud) Shelly is also tying this sensor to newer smart-home standards instead of trapping it inside one app. Recent coverage says Presence Gen4 is part of Shelly’s Gen4 line with Matter support, which is the common language backed by Apple, Google, Amazon, and Samsung for cross-platform smart-home devices. (homekitnews.com, shelly.com) This does not mean old motion sensors disappear overnight. Passive infrared sensors are still cheaper, simpler, and good at catching someone who walks through a hallway, while radar is better at the “person reading quietly in a chair” problem that motion sensors keep getting wrong. (docs.homeseer.com, shelly.com) The change is that presence sensing is no longer stuck in niche forums and do-it-yourself builds. When a mainstream smart-home brand starts selling millimeter-wave radar as a finished room sensor, the annoying “lights off during the movie” bug starts looking less like a smart-home quirk and more like an old sensor problem that is finally getting replaced. (shelly.com, verdrahtet.info)
