It's basically passive radar using the wifi bands as the reflection AFAIK. It doesn't seem to be about the active state of devices, but the deflections in known points. It's creepy.

It doesn't require a WiFi device to work.

> If you’d like to prevent your pet’s movement from causing motion notifications, you can exclude pet motion in your WiFi Motion settings by turning on the Exclude Small Pets feature. > Motion is detected based on the amount of signal disruption taking place between the Xfinity Gateway and your selected WiFi-connected devices, so motion from small pets (around 40 pounds or less) can be filtered out while keeping you notified of large movements more likely to be caused by humans.

I was thinking of attaching a wifi enabled device to a roomba if you wanted to appear to be home when you weren't. I would hope, though, that doing something like this wouldn't be illegal. It's your home, your stuff, etc. Besides, I don't want to get arrested for leaving a rotating fan on or something.

A much easier alternative is to not enable the feature on your router.

It's an opt-in feature. If you don't set it up, they aren't generating the home/away chart like shown in the article.

It's an opt-in feature, for now.

If they find some way to sell the data you'll quickly find it difficult to opt-out of.

Luckily it is still possible to opt out of Comcast.

Not always, depending on where you live

This technology doesn't rely on you actually having a WiFi device on you. It can detect presence/motion by changes to the standing waves of the EM propagation throughout the room.

As the salty water meatbags move from room to room we change how the reflections and scattering patterns of 2.4 and 5GHz waves move. Studying these changes and some calibration, you can even determine small changes (like is the person on the left side of the room breathing, are they standing or prone, etc).

In their docs, they show using the WiFi connection from a printer to determine motion sensing and have the option to exclude pets.

im very skeptical of the accuracy claimed. The layout and complexity of objects in most homes to do this is way to awkward to work reliably.

For someone breathing or a heartbeat you need much higher GHz signal. Usually this is done at 30ghz to 60ghz. The power flux leaving the antenna has an inverse square drop off rate which makes this basically impractical unless your standing directly in front of it.

I have personally tested wifi imaging from a cheap old 2.4Ghz linksys router that was accurate enough to tell if my hand was open or closed, maybe 10 years ago.

Is 60GHz not part of the standard now? Only a matter of consumer hardware support.

I don't think 60GHz is required on WiFi 7 which includes a lot of sensing, but I'm open to be proven wrong.

I do agree some of these claims are pretty extreme. I wonder if it does work what the reliability of things like breathing and heartbeats. FWIW, some of these systems do incorporate 60GHz signals in their analysis, but as you mention dealing with 60GHz is incredibly challenging even in something like a residential building.

I'd really like to actually see it in person to really grasp the limitations.