iPhone How do iPhone know the direction of AirTag ?

April 21, 2021

iPhone How do iPhone know the direction of AirTag ?

How do iPhone know the direction of AirTag ?
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How do iPhone know the direction of AirTag ?

Posted: 21 Apr 2021 02:01 AM PDT

I'm IoT developer and worked in RF location tracking for 15+ years. In Spring Loaded event Apple demonstrated "Precision Finding" feature, that can show the direction and distance. And I'm extremely curious how do they do that.

For RF based tracking technology, distance is easy but direction is an another story. So far all the implementations need antenna array and calculate the received carrier signal phase offset between different antenna sets, so that it can calculate the direction of propagation of a RF wave, a.k.a. Angle-of-Arrival (AoA).

Does iPhone have multiple antennas, or it just do the trick following the old-school wild animal RF tracker way, let user turning around "scanning" signals ?

P.S. On Apple's official page, they claim it's done via UWB and only iPhone 11 or newer can have this feature. So maybe Apple actually implemented AoA ?

P.P.S. In my own experience that RF multi-path kills both ToF (Time-of-fly) and AoA. Very curious how good can Precision Finding work in environment full of metallic surface.

submitted by /u/ulyssesric
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AirTags Feature IP67 Water Resistance, User Replaceable Battery That Lasts a Year

Posted: 20 Apr 2021 12:21 PM PDT