Ublox XPLR-AOA User manual

UBX-21004616 - R02
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XPLR-AOA explorer kits
Bluetooth indoor direction finding
User guide
Abstract
This document describes the XPLR-AOA explorer kits for evaluating Bluetooth 5.1 direction finding
and indoor positioning use cases using Angle-of-Arrival methodology. It serves as a practical guide
that explains how the u-blox modules and software included in the kit are used to explore direction-
finding tags and anchor nodes. The kit contents, setup, configuration, and operation are described.

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Document information
Title
XPLR-AOA explorer kits
Subtitle
Bluetooth indoor direction finding
Document type
User guide
Document number
UBX-21004616
Revision and date
R02
28-Jun-2021
Disclosure restriction
C1 - Public
This document applies to the following products:
Product name
NINA-B4
XPLR-AOA-1
XPLR-AOA-2
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties of this document or any part thereof is only
permitted with the express written permission of u-blox.
The information contained herein is provided “as is” and u-blox assumes no liability for its use. No warranty, either express or
implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent
documents, visit www.u-blox.com.
Copyright © u-blox AG.

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Contents
Document information .............................................................................................................................2
Contents .......................................................................................................................................................3
1Product description............................................................................................................................5
1.1 Kit includes...................................................................................................................................................6
1.2 Evaluation software....................................................................................................................................6
1.3 System requirements ................................................................................................................................6
2Bluetooth direction finding ..............................................................................................................7
2.1 Technology ...................................................................................................................................................7
2.1.1 Angle of Arrival (AoA).........................................................................................................................7
2.1.2 Angle of Departure (AoD) ..................................................................................................................8
2.1.3 Angles of measurement....................................................................................................................8
3XPLR-AOA anchor nodes and tags ................................................................................................9
3.1 Introduction..................................................................................................................................................9
3.2 Overview........................................................................................................................................................9
3.3 C211 anchor nodes...................................................................................................................................10
3.3.1 Overview .............................................................................................................................................10
3.3.2 Connectors.........................................................................................................................................10
3.3.3 Flashing ..............................................................................................................................................13
3.3.4 Configuring the board......................................................................................................................14
3.4 C209 tags ...................................................................................................................................................14
3.4.1 Overview .............................................................................................................................................14
3.4.2 Software and flashing......................................................................................................................16
4System setup .................................................................................................................................... 17
4.1 Anchor node configuration......................................................................................................................17
4.2 Tag configuration......................................................................................................................................17
4.2.1 Configuring advertising interval....................................................................................................17
4.2.2 Enabling/disabling advertising ......................................................................................................18
4.3 Restore Eddystone Instance ID..............................................................................................................18
5Running system................................................................................................................................ 19
Appendix .................................................................................................................................................... 20
AAnchor node AT commands .......................................................................................................... 20
A.1 Direction finding enable +UDFENABLE................................................................................................20
A.1.1 Description.........................................................................................................................................20
A.1.2 Syntax .................................................................................................................................................20
A.1.3 Defined values ...................................................................................................................................20
A.2 Direction finding filter +UDFFILT ..........................................................................................................20
A.2.1 Description.........................................................................................................................................20
A.2.2 Syntax .................................................................................................................................................20
A.2.3 Defined values ...................................................................................................................................21
A.2.4 Notes ...................................................................................................................................................21

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A.3 Configure direction finding +UDFCFG ..................................................................................................21
A.3.1 Description.........................................................................................................................................21
A.3.2 Syntax .................................................................................................................................................21
A.3.3 Defined values ...................................................................................................................................22
A.4 Angle calculation event +UUDF..............................................................................................................23
A.4.1 Description.........................................................................................................................................23
A.4.2 Syntax .................................................................................................................................................23
A.4.3 Defined values ...................................................................................................................................23
A.5 Other supported AT commands ............................................................................................................23
BGlossary .............................................................................................................................................. 24
CLimitations......................................................................................................................................... 24
DC209 schematics.............................................................................................................................. 25
Related documentation......................................................................................................................... 26
Revision history ....................................................................................................................................... 27
Contact....................................................................................................................................................... 28

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1Product description
A Bluetooth "tag" is a small, thin device that can attached to any object to track its whereabouts. An
"anchor node" calculates the position of the tag. Bluetooth tags can attach to keys, wallets, purses,
and other personal property.
u-blox direction finding solutions that leverage this Bluetooth direction finding technology can be
evaluated using two separate explorer kits, as described in Table 1.
Model
Order code
Description
XPLR-AOA-1
XPLR-AOA-1
Bluetooth 5.1 direction finding explorer kit for evaluating Bluetooth 5.1 direction
finding using Angle-of-Arrival methodology. The kit includes a single C211
application board and one C209 tag:
•C211 application boards include a NINA-B411 module and an antenna array that
represents the anchor node for direction finding, using Angle-of-Arrival
methodology. u-connectLocate direction finding software installed on
NINA-B411 delivers angle information for tracked tags to a listening host.
•C209 tags are based on the open CPU NINA-B406 module variant. The tags run
on custom tag software that advertise Eddystone beacons with appended with
Constant Tone Extensions (CTE). The CTE data is used by C211 application
board to calculate the position of the C209 tag.
XPLR-AOA-2
XPLR-AOA-2
Bluetooth 5.1 direction finding explorer kit for evaluating and developing indoor
positioning use cases, using Angle-of-Arrival methodology. The kit includes a four
C211 application boards, four C209 tags and positioning engine client software:
•C211 application boards include a NINA-B411 module and an antenna array that
represents the anchor node for direction finding using Angle-of-Arrival
methodology. u-connectLocate direction finding software installed on
NINA-B411 delivers angle information for tracked tags to a listening host.
•C209 tags are based on the open CPU NINA-B406 module variant. The tags run
on custom tag software that advertise Eddystone beacons with appended with
Constant Tone Extensions (CTE). The CTE data is used by C211 application
board to calculate the position of the C209 tag.
Table 1: u-blox direction-finding explorer kits and ordering codes
☞For further information about the positioning engine client software for Windows, see also the
indoor positioning guide [2] .
Figure 1: u-blox direction-finding explorer kits comprising C211 application board(s) and C209 tag(s)

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1.1 Kit includes
XPLR-AOA-1 direction finding explorer kit for out-of-the-box AoA evaluation includes:
•C211 antenna board with NINA-B411 Bluetooth LE module
•C209 tag with NINA-B406 Bluetooth LE module
•u-connectLocate direction finding software (from u-blox.com)
•C209 tag software example (from Github)
XPLR-AOA-2 indoor positioning explorer kit for out-of-the-box evaluation of indoor positioning
includes:
•Four C211 antenna boards with NINA-B411 module
•Four C209 tags with NINA-B406 module
•u-connectLocate direction finding software (from u-blox.com)
•C209 tag software example (from Github)
•Positioning engine software example to run on a PC
1.2 Evaluation software
Several evaluation packages are available:
•u-connectLocate delivers angle information for tracked tags to a listening host.
Customers install u-connectLocate software on the NINA B411 module mounted on the C211
integration board. C211 integration boards are delivered with bootloader software only.
•s-center software Bluetooth and Wi-Fi evaluation software provides a powerful and easy-to-use
tool for evaluating, configuring, and testing u-blox short range modules
•Sample positioning-engine client that runs on a local Windows workstation (XPLR-AOA-2 only)
1.3 System requirements
•PC with USB interface
•Operating system: Windows 7 onwards

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2Bluetooth 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
2.1 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
2.1.1 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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2.1.2 Angle of Departure (AoD)
In AoD systems, the transmitter has multiple antennas. The receiver calculates the phase difference
between these antennas to determine the direction to the transmitter. By using this data in
combination with angle data from other transmitters, the receiver can estimate its position. An
overview of a system using this method of direction finding is shown in in Figure 4.
Figure 4: Angle of Departure (AoD) system architecture
2.1.3 Angles of measurement
In both AoA and AoD systems, the reported angles of the azimuth and elevation measurements are
compared against a reference plane, as shown in Figure 5.
Figure 5: Azimuth and elevation angles
For further information about Bluetooth direction finding, see the u-blox webinar “Bluetooth for High
Precision Indoor Positioning” available on the u-blox webinar page [8] and Bluetooth SIG technical
overview [1].

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3XPLR-AOA anchor nodes and tags
3.1 Introduction
Both XPLR-AOA-1 and XPLR-AOA-2 explorer kits include both Bluetooth anchor nodes and tags.
☞Although this chapter generally describes these nodes and tags in the context of the XPLR-AOA-1
direction finding system, the concepts it describes are equally applicable to the XPLR-AOA-2
indoor positioning explorer kit. For information about the XPLR-AOA-2 positioning engine, setup,
and configuration, see also the indoor positioning application note [2].
3.2 Overview
u-blox direction finding solutions are comprised of C211 anchor nodes C209 tags, as shown in Figure
6. See also Kit includes. u-blox direction-finding solution supports the Angle of Arrival (AoA)
methodology.
C211 anchor nodes are based on NINA-B4 modules that include support for direction finding.
Anchor nodes are based on NINA-B411 u-connectXpress functionality, whereas C209 tags are based
on NINA-B406 open CPU architecture. For more information about these short-range Bluetooth
modules, see also the respective data sheets [13][14] and product pages [2].
Figure 6 shows several anchor nodes and a host that uses the combined information from the anchor
nodes to calculate the position of the tag. For simple direction finding one anchor node is sufficient.
Figure 6: XPLR-AOA direction-finding solution showing four anchor points tracking a single tag

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3.3 C211 anchor nodes
3.3.1 Overview
C211 application boards are equipped with a NINA-B411 module and an antenna array. These boards
fulfill the role of the anchor node in the XPLR-AOA direction-finding solutions. Anchor nodes run AT
command-based u-connectLocate direction finding software, which delivers AoA data for tracked
beacons to a listening host. Data is transmitted to the host as events over the NINA-B411 UART
interface. See also Anchor node AT commands.
•C211 has an array of five antennas that are used to detect the phase shift for the direction finding
–in both horizontal and vertical levels.
•C211 also has an LED array in the form of a cross. The LEDs indicate the direction of tracked
beacons. In instances where the anchor node tracks several beacons, the LED array tracks the
first C209 tag that is discovered.
Figure 7: C211 antenna side
The C211 board dimensions are 115 (h) x 114 (w) mm.
3.3.2 Connectors
3.3.2.1 UART
The UART connection must be configured for USB connection with jumpers connecting pins 3 to 5
and 4 to 6 on connector J5, as shown in Figure 8.
Figure 8: Jumper settings for UART connection over USB