Motion Sense on the Pixel 4: How it works and what it can do

Radar on your phone

The Pixel 4 is the first consumer product to incorporate a Soli sensor — a design from Google's ATAP team that uses a type of RADAR to detect very precise and small movements. A Soli sensor lives in the top bezel of every Pixel 4, and though it can't be used in every country due to wireless spectrum regulations, when it is available it drives what Google calls Motion Sense, which is a new way to interact with your phone using gestures.

The Soli sensor itself uses RADAR to watch for movement within its range and it's able to sort out specific types of movement. Early demos have shown it reacting to more than swipes or hand waving, with things like rolling your fingertips as if turning a tiny dial or tapping in the air like you were pressing a virtual button. On the Pixel 4, the gestures we're seeing are a lot less ambitious and wrapped up into Motion Sense.

Motion Sense doesn't really feel all that special. You can use it to silence alarms, dismiss or answer a call, or change tracks in your music player by waving your hand in front of the phone. It can also be used to trigger the camera system for Google's new facial recognition to unlock your phone. We've seen something similar as far back as 2013's Moto X. there is a difference, though, and it's in the capabilities.

Other phones used "air gestures" to do similar things with IR sensors or even through the camera(s) on the front of the phone. None were perfect by any means and that's because the tech used had some limitations. IR sensors or cameras can't detect motion at as high of a resolution as Soli can and it takes more power to keep a camera or bank of IR sensors always on. Soli can definitely do a lot more than Google is showing us so far.

It's probably prudent to start with the most basic set of gestures when releasing new tech like Motion Sense. However, since Soli can also do things like identify the material of an object, count cards as they are dealt, or even identify a product based on its weight, it stands to reason Google can open it up to do a lot more. We expect to see significant improvements to Motion Sense once the Pixel 4 is a bit more mature and Google is sure everything is working as expected.