How radar fall detection works, in plain English.

Here’s the short version: radar fall detection works by bouncing harmless, very low-power radio waves around a room and reading the reflections. From those reflections alone, the sensor can tell a person from a pet, a fall from a sit-down, and breathing from stillness. No camera, no microphone, nothing worn. This page is the plain-English detail: how the sensing works, how radar compares with cameras, wearables, WiFi sensing and floor sensors, and where its honest limits are. If your real question is why families choose a room sensor over a pendant, that’s the won’t-wear problem, and it has its own page.

Radar is just echoes you can measure

Radar is old, proven technology. The name stands for radio detection and ranging, and it’s been finding aircraft in the dark since the 1930s. The idea hasn’t changed: send out a radio wave, and when it hits something, part of it bounces back. Measure what returns and you know where something is and how it’s moving.

The sensor on the wall does exactly that, quietly and constantly. It sends a very low-power radio signal into the room. Walls, furniture and people all reflect a little of it back. Furniture reflects the same way every time. A person doesn’t. Every movement, walking, sitting, reaching, falling, changes the reflection in a distinct, measurable way. Engineers call these movement signatures.

A fall has a signature all of its own: a fast drop in height, then someone low to the ground who stays there. A sit-down is slower, ends at chair height and is usually followed by more movement. A pet is a smaller reflector, lower to the floor, moving in a completely different rhythm. The sensor isn’t guessing from a blurry picture. It’s measuring speed, height and position directly.

Why 60GHz matters

Frequency decides how fine the detail is. The higher the frequency, the shorter the wave, and the smaller the movement it can register. Check On Mum uses 60GHz radar, up in the millimetre-wave band, where the wavelength is about five millimetres. That’s fine enough to register movements of a fraction of a millimetre.

When someone is at rest, the only movement left is the chest rising and falling, and the smaller movement each heartbeat makes. A 60GHz sensor can register both. That’s how the system can tell you, overnight, that Mum is settled and breathing steadily, with nothing on her wrist and no camera in the bedroom. It’s reassurance for the hours you can’t be there, not a medical readout.

Radar vs cameras

Camera-based fall detection genuinely works. The problem isn’t the detection, it’s the camera. A camera makes an image, and an image is something that can be watched, recorded, leaked or hacked. Most parents will not accept a lens in the bathroom or bedroom, and those are exactly the rooms that matter. Cameras also struggle in the dark and in a steamy bathroom. With radar, no image ever exists, so there’s nothing to leak, and radio waves don’t care about darkness or steam.

Radar vs pendants and watches

Wearables detect falls reasonably well while they’re being worn. That last clause is the whole problem. Pendants come off in the shower, sit on the nightstand overnight, run flat, and get quietly retired to a drawer by parents who don’t want to wear a badge that says frail. The weak point isn’t the hardware. It’s asking a person to comply, every hour, for years. A sensor in the room asks nothing of anyone.

Radar vs WiFi sensing

The newest idea: read how a moving body disturbs the WiFi signals already bouncing around a home. The science is real and improving fast. But today it’s coarser than dedicated radar. WiFi runs at much lower frequencies with longer wavelengths, and it was never designed for sensing. It’s decent at knowing someone is moving in the house. Reliably telling a fall from bending down, or a person from a big dog, or reading breathing at rest, is a much harder ask in a real home. One to watch, not one to rely on tonight.

Why not just use WiFi sensing?

Short version: because your router can’t do the impressive part. Commodity WiFi sensing reads the channel-state information a normal router already produces, and off that it tops out at presence, motion and coarse activity. Useful, but not fall-grade. It’s the difference between knowing someone moved and knowing someone fell.

What about the viral clips that seem to draw a skeleton through a wall? Those aren’t running on a home router. They need a coherent multi-channel rig, software-defined radios wired together and carefully calibrated, roughly fifteen hundred dollars and up of lab gear, plus the software to make sense of it. It’s a real research result, not a feature waiting inside the box on your shelf. Reading that back-of-envelope on any given weekend, it’s clearly not something you retrofit into a family home tonight.

That gap is the whole reason purpose-built 60GHz radar exists for fall detection. Rather than borrow a signal designed to carry your internet, it uses a sensor built for one job: measuring how a body moves in a room, finely enough to tell a fall from a sit-down and to register breathing at rest. Same broad idea as WiFi sensing, but the right tool for the job, working reliably in an ordinary home without a rack of lab equipment behind it.

Radar vs floor sensors

Pressure mats and sensor flooring detect an impact where they’re installed, and that’s the catch: only where they’re installed. A mat beside the bed does nothing in the hallway, and a fall against a vanity never hits the floor cleanly. Sensor flooring across a whole home is a renovation, not a retrofit. In an existing family home, one radar sensor high on the wall covers the whole room with no building work.

What radar is genuinely good at

• The hard rooms. Bathrooms full of steam and bedrooms in the dark, the two places cameras are unwelcome and pendants are missing.
• Whole-room coverage with zero compliance. Nothing to wear, charge, press or remember.
• At-rest reassurance. Presence, breathing and heart rate while resting, the stuff overnight peace of mind is made of.
• Privacy by physics. Reflections are measurements, not pictures. There’s no footage to secure because none is ever created.

The honest limits

• One sensor covers one room. Whole-home coverage means a sensor in each room that matters. Most families start with the bathroom, bedroom and lounge.
• Mounting matters. The sensor needs a clear view of the room from the right height and angle. That’s why we install and test it rather than posting you a box.
• No system catches everything. An unusual fall, or one right at the edge of coverage, can be missed. Radar’s advantage is that it’s always on duty, but anyone promising perfection is selling too hard.
• It doesn’t prevent falls. It makes sure the right people find out fast.

Are the radio waves safe?

Yes, and it deserves a straight answer. The sensor transmits at very low power, well below a mobile phone, and the waves are non-ionising, meaning they don’t damage cells the way X-rays can. 60GHz sensing is the same family of technology as the radar in modern cars and the presence sensing built into recent phones and smart devices. At these frequencies the signal barely penetrates skin, let alone a body. You get more radio exposure from your own WiFi router.

Which rooms, and in what order

One sensor covers one room, so the practical question is where radar earns its keep first. For most families the order is: bathroom, bedroom, then the main living area. The bathroom because it combines hard surfaces, water and privacy: the room where falls do the most damage, a camera is unthinkable and the pendant is sitting outside the shower. The bedroom because overnight is when a pendant is most likely to be on the nightstand, and an over-the-bed setup can tell you whether someone is in bed, settled, restless, or up and not back, which we cover honestly in a radar sensor over the bed. And for a parent living with dementia, a sensor covering the hallway or entry does a different job: activity at the front door in the small hours becomes a message on your phone, which is the heart of monitoring a parent who wanders.

What happens when a fall is detected

The sensor registers the fall signature and the alert goes out straight away: a message to the phones of the family members you choose, with what happened and when. Nothing depends on Mum pressing a button or having a phone in reach. From there it’s a human decision: call, drive over, or get help. The full journey, from the first chat to the alert on your phone, is on our how it works page.

One last thing worth saying: for most families, the technology turns out to be the easy part. The harder part is raising it with Mum or Dad in a way that doesn’t sound like surveillance. If that’s the conversation you’re rehearsing, we’ve written how to talk to your parent about monitoring for exactly that moment.

Where this comes from

The primary sources behind the above, so you can check any of it yourself rather than take our word for it:

• Wikipedia: radar, background on how radio detection and ranging works.
• healthdirect: falls, government funded information written for older people and their families.
• healthdirect, the national health information service funded by the Australian, state and territory governments.