Comcast turns Xfinity routers into home motion detectors — free Wi-Fi sensing feature tracks RF interference with zero extra hardware required

(Image credit: Comcast) With the pervasiveness of Flock cameras and the public’s backlash against surveillance technology that can track their movements under seemingly lax oversight, Comcast hopes consumers will be more receptive to monitoring activities inside the home. This week, Comcast announced Xfinity Shield, which it claims offers first-of-its-kind “intelligent home protection” courtesy of your seemingly mundane Wi-Fi router.Tom's Hardware Premium RoadmapsWhile the best Wi-Fi routers on the market are supposed to give you higher connection speeds, extended coverage, and enough capacity to handle all of your wireless devices, Comcast is tapping into a little-used aspect of Wi-Fi signals. Called Wi-Fi Motion, it monitors the signal strength and interference between your Wi-Fi router and connected devices. By measuring these frequency signals, it can detect if someone is moving around in your house. When unauthorized activity is detected, the router can instantly send an alert to your phone.You could achieve the same intruder detection using traditional motion sensors in your home, or even an off-the-shelf security camera, but Wi-Fi Motion doesn’t require you to purchase additional hardware to function. However, since it’s only relying on changes in frequency signals, we’d imagine that it won’t offer as much granularity in motion detection, and it could even be more prone to false positives.This isn’t exactly new technology, as we reported on Wi-Fi routers being used to detect humans in a room over three years ago. At the time, researchers at Carnegie Mellon University used a TP-Link Archer AC1750 router to track human movement and positions in a room. (Image credit: Comcast)With that said, we must be clear that this feature is opt-in by default. You will need to use the Xfinity app to enable Wi-Fi Motion, then enable alerts to monitor for suspicious activity. The app also provides three protection modes for monitoring: Home Watch, Away Watch, and Dark Watch.Wi-Fi Motion is just one pillar of Wi-Fi Shield, which is a subset of Xfinity Shield. The other two pillars are Xfinity CyberSecure, which provides automatic protection for devices against phishing attacks and malware, and Family Settings, which allows you to manage screen time for individual devices. Wi-Fi Shield is available free of charge to Comcast customers with Advanced Xfinity Gateways. If you want additional protection, Comcast offers Shield Select for $15/month. Shield Select includes an indoor camera, a window/door sensor, cloud storage for captured video footage, and 24/7 emergency response support.Get Tom's Hardware's best news and in-depth reviews, straight to your inbox. Brandon Hill is a senior editor at Tom's Hardware. He has written about PC and Mac tech since the late 1990s with bylines at AnandTech, DailyTech, and Hot Hardware. When he is not consuming copious amounts of tech news, he can be found enjoying the NC mountains or the beach with his wife and two sons.