The Magic of Bluetooth AoA/AoD Direction Finding

Tue, 03/31/2020 - 09:46

A Compelling Application – Solved by Bluetooth

The problem of lost or misplaced things is a very old one with a number of high-tech, modern solutions. Just about anything can be tracked to a degree of precision by a GPS/GNSS module, which uses satellite positioning to locate a device within 3 to 4 meters. Further correction can be done to achieve a higher degree of accuracy. But this is a process that demands a bit more power and hardware than is necessarily practical for every IoT application.

If you simply wanted to be able to track down a key fob wirelessly for example, a GPS module might not be the most efficient way to keep track of it. GPS consumes a larger amount of power, in a larger form factor, and it just isn’t practical for this application.

This is where Bluetooth Low Energy (LE) makes such an exciting candidate for tracking services. After all, Bluetooth Low Energy already benefits from extremely low power consumption, sleep and doze modes that can make a coin cell last for years, and tiny form factor that is unobtrusive in most applications.

As of Bluetooth SIG specification version  5.1, Bluetooth direction finding is powered by a methodology known as Angle of Arrival (AoA) / Angle of Departure (AoD), and it’s this method that makes it possible for a device to find another more accurately than prior Bluetooth LE beaconing capabilities for location finding, that used RSSI to estimate distance... So how does it work?