Bluetooth Direction Finding; Technology; Angle Of Arrival (Aoa) - Ublox XPLR-AOA-1 User Manual

XPLR-AOA-1 and XPLR-AOA-2 explorer kits - User guide
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Bluetooth direction finding

Bluetooth direction finding provides a relatively inexpensive and flexible approach to developing
location-related applications for both in indoor and outdoor environments.
Examples of applications for which Bluetooth direction finding technology is most suitable include:
• Asset tracking
• Navigation
• Wayfinding
• Proximity/Direction detection

3.1 Technology

Bluetooth direction finding can be implemented using two different methods, Angle of Arrival (AoA)
and of Departure (AoD).
In each case, protocol-specific control information and user data, transmitted as Bluetooth Protocol
Data Units (PDU), are appended with direction-finding data known as Constant Tone Extension (CTE).
This additional direction-finding data is appended to the end of the packages, as shown in Figure 2.
Figure 2: Bluetooth PDU with Constant Tone Extension
3.1.1

Angle of Arrival (AoA)

In AoA systems, the receiver has an antenna array with multiple antennas. The receiver calculates
the phase shift between these antennas to detect the direction of the tag that it is tracking. An
overview of a system using this method of direction finding is shown in Figure 3.
Figure 3: Angle of Arrival (AoA) system architecture
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