I missed this story on Friday, but it seems particualrly relevant. Joe Rossignol of MacRumors covers how usually-accurate Apple analyst MingChi Kuo says Apple’s rumored tracker device will use Ultra-Wideband (UWB) technology:
The distance between two UWB devices — such as an upcoming iPhone and Apple Tag — can be measured precisely by calculating the time that it takes for a radio wave to pass between the two devices, according to Electronic Design, which notes that UWB is up to 100× more accurate than Bluetooth LE and Wi-Fi: “In practice, UWB signals are able to effectively measure distance between two devicesNo with 5- to 10-cm accuracy, compared to roughly 5-m accuracy for Wi-Fi and Bluetooth. When implemented in a system of fixed beacons tracking tag locations, the locations can be calculated to within 10-cm accuracy.”
This dovetails with an earlier Kuo report from back in February which suggested that this year’s new iPhones would feature built-in UWB.
I’d imagine that any new Apple tracking device would also offer Bluetooth LE, but if you think about it, using UWB would conform with the rumors that Apple is adding an augmented-reality version of Find My that will show you (via the image of a balloon!) exactly where your tracker or other UWB-capable Apple device is located. If UWB really can provide accuracy with an error margin of four inches, that would be entirely possible.
Update: Also worth reading, if you didn’t do so in June (or don’t remember it) is WIRED’s piece about Find My cryptography.