Wideband technology

What Technology Does AirTag Use?

One of the most intriguing devices announced at Apple’s recent ‘Spring Loaded’ event was the AirTag, a sleek tracking device for iPhone users who are serial losers of their keys and wallets. The AirTag uses Bluetooth to communicate with the iPhone, but it also uses Ultra-Wideband (UWB) for location tracking.

Ultra-Wideband (UWB)

The UWB technology that makes Apple’s AirTag locator tags so useful has only been recognized by mainstream society since 2019 thanks to new smartphones equipped with this advanced short-range wireless communication module. What distinguishes UWB from other technologies that determine location, such as Bluetooth and Wi-Fi, is its precise capabilities in locating objects and people.

Unlike Bluetooth, which uses a combination of signals to determine distance and location, UWB relies solely on angle-of-arrival (AoA) technology to pinpoint the exact location of an object or person within a room. This allows the Apple Find My app to locate items with precision down to a few centimeters, which is much more accurate than what Bluetooth can do without a direct line of sight.

AirTags utilize this UWB technology to communicate with iPhones and iPads running iOS 14.5 or later, allowing them to be used as a replacement for a Tile, Samsung SmartTag, or similar item. The only downside is that the device must be in direct line of sight with an iPhone to operate.

Bluetooth Low Energy (BLE)

Bluetooth Low Energy (BLE) is the latest version of the Bluetooth technology that allows electronic devices to connect to one another. It is used in everything from fitness trackers to medical equipment to home automation devices.

AirTags use BLE to transmit encrypted time-sensitive data to iPhones and other BLE-equipped devices that are nearby. The AirTag and an iPhone or other iOS device pair by sharing a crypographic seed during the AirTag’s “provisioning” process. After pairing, the AirTag continuously broadcasts BLE advertising beacons in the 2.4 GHz radio spectrum, sending out time-sensitive encrypted messages that any other iPhone or device that’s nearby can pick up and decode.

Unlike classic Bluetooth connections, which can handle large amounts of data, BLE is optimized for low power consumption and can run on a single battery for a year or more. This is why it’s one of the most widely applied technologies for the Internet of Things and a common feature in smartphones, tablets, laptops, and other consumer electronics.

NFC

The AirTags broadcast their identity as well as the location of their owner to any device that is within range. This is useful but concerns have been raised that it could also facilitate stalking and other forms of abuse.

The nRF52832 chip used by the airtag has a security feature that can be enabled that protects it from being debugged and read out. However, the hardware in the airtag does not appear to have this protection enabled and so secrets (such as a private key pair that generates new identities) are stored in the unprotected internal flash.

The AirTag is powered by a 3V battery and uses a voice coil for sound output when it is energised. It is a small rectangular board with a single antenna that mounts to the top of the plastic shell. Apple’s U1 chip is on the board and very little is known about this custom chip. Apple’s Find My app requires a paired AirTag to be active before it can locate a missing item.

Find My iPhone

AirTag doesn’t use GPS, which would drain its battery and raise privacy concerns. Instead, it sends out scrambled Bluetooth signals that it hopes will find their way to an iPhone that’s listening for them.

This global network of iPhones and Macs can zero in on AirTag’s location at a coarse level, but Apple’s Precision Finding feature gives them the ability to pinpoint the device down to within 50 feet, and even point the user in its direction.

To do this, the devices rely on Bluetooth Low Energy technology that’s built into most modern Apple products, such as iPhones. However, older iPhones without the Ultra-Wideband chip (U1) can still locate an AirTag but not as accurately. And to protect against stalking, Apple made an update to the app that shortened the window of time that it takes for an unknown AirTag to start chirping from three days to 8-24 hours. This also helps to deter people from using the trackers for unsavory purposes.

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