Building on its Bluetooth direction finding explorer kits launched in 2021, u-blox recently unveiled its ANT-B10 antenna board for Bluetooth direction finding and indoor positioning applications. The board is designed for integration into commercial end products, speeding up the development and testing for a faster time to market.
Bluetooth indoor positioning works by using the angle of arrival (AoA) of a Bluetooth direction finding signal emitted from a mobile tag at several fixed anchor points to calculate the tag’s location in real-time with sub-meter accuracy. Applications include tracking assets in industrial environments such as in warehouses as well as people and things in hospitals, retail environments, or museums. In addition, access control systems deployed in connected buildings can use angle detection to determine which side of a door users are located on.
The need to locate assets indoors is very crucial and it will transform various market segments such as medical, manufacturing, and logistics, said Giorgos Marakis, senior product manager, product strategy short-range radio at u‑blox.
While global navigation satellite system (GNSS) technology has solved the problem of locating assets outdoors, GNSS performs poorly in those indoor environments, Marakis said. “The GNSS satellites are getting blocked by the the walls, the ceilings, and the materials like concrete and steel that are in a building, and there is no current technology that meets the need for low cost and low power consumption, while providing a highly accurate system.”
However, u-blox has selected Bluetooth as the technology of choice for its indoor positioning solution thanks to its low power consumption, high accuracy, and installation cost.
The two key technologies that are trying to tackle the indoor positioning problem are Bluetooth AoA and ultra-wideband (AoA), said Marakis. Bluetooth AoA and UWB are head-to-head when it comes to accuracy, though UWB has a little bit of edge, performing slightly better than Bluetooth AOA, he added.
“They both have an accuracy of below one meter but we should also not overlook the other performance indicators like power consumption, installation cost, and device cost. In these areas, Bluetooth AoA has significant advantages compared to UWB, but it is a very promising technology and in the future we can see it complimenting Bluetooth AoA,” said Marakis.
Click for a larger image. (Source: u-blox)
Another benefit of Bluetooth is its vast ecosystem, he said. “There are millions of Bluetooth devices, so it’s a lot easier to base our research and development efforts on this technology.”
In addition, u-blox already has a wide portfolio of wireless modules that are Bluetooth based. These include both standalone and host-based modules.
These factors led u-blox to create its explorer kits – XPLR-AOA-1 and XPLR-AOA-2 – to evaluate Bluetooth technology for indoor positioning solutions. These kits showcase one of the first complete Bluetooth-based tracking solutions to offer sub-meter-level accuracy in indoor environments.
Marakis said accuracy is very important but customers in industrial environments with big assets like tools and machinery don’t need centimeter accuracy. Below one meter accuracy is more than enough, he said.
One example cited is an eight × six meter room with four anchor points, one at each corner of the room. The test case delivered sub-meter accuracy at 95% probability using the explorer boards. In addition, in 50% of the measurements, the error is below 0.6 meters. The company expects further improvements with the new ANT-B10 antenna board thanks to several enhancements.
Marakis said there are a variety of challenges when it comes to indoor positioning and angle of arrival calculations such as computational efficiency and power consumption.
Compared to the explorer kits, the ANT-B10 offers an increased number of antenna elements in the same PCB footprint and it uses a single RF switch instead of multiple switches for lower losses.
By using a single RF switch there are fewer losses, lower power consumption, and better performance, said Marakis. Phase errors have a direct effect on the performance of the system, so with one switch there are fewer phase errors, resulting in better performance, he added.
The ANT-B10 features an antenna array comprised of eight individual patch antennas and is built around the u‑blox NINA-B411 Bluetooth 5.1 module. The ANT-B10 board concurrently processes incoming signals on all eight patch antennas to determine the AoA for direction finding. The ANT-B10 board now uses a single RF switch from u‑blox partner CoreHW that cycles through the eight antennas at a microsecond timescale, according to the company.
The ANT B-10 is a self-contained Bluetooth sensor board. What makes the ANT B-10 antenna board self-contained is the NINA-B411 module, a Bluetooth 5.1 radio and angle calculation processor that outputs the final angle information “that can go to the application board or to an application processor or a graphical user interface. There’s no further processing required in order to obtain the the angles,” said Marakis.
ANT-B10 antenna board. Click for a larger image. (Source: u-blox)
The NINA-B411 module is programmed with the company’s u-connectLocate embedded software that provides Bluetooth direction finding and angle of arrival. The angle of arrival is a very computational intense measurement, which is accomplished in the embedded MCU of the NINA-B411. Once it outputs the final angle measurement, it’s ready to be used at the application level.
“The AoA algorithm is very efficient in its implementation but at the same time we had to build a mechanism for suppressing the multi-path effects that are present in indoor environments, which gets worse based on the materials that are present such as steel or metal or concrete,” said Marakis.
By using u-connectLocate, which runs on the ANT-B10’s Bluetooth module, solution developers can execute the angle calculation algorithms using AT commands. Together, the solution suite can be integrated directly into an end product.
The software offers an easy-to-command API, which makes it easy to obtain the angles and build an interface between the ANT B-10 and the customer’s application processors, said Marakis. “The ANT-B10 allows our customers to go from proof of concept to mass production, which is the logical next step from the explorer AoA kits.”
The company also unveiled its latest XPLR-AOA-3 explorer kit. It includes an application board to evaluate and test the ANT-B10 antenna board and u‑blox’s direction finding algorithm. The application board features the same off-the-shelf pin header as the antenna board that enables the testing of the ANT-B10 and third-party antenna boards.
The ANT-B10 antenna and and EVB-ANT-1 application board can be connected together to make a simple reference design for a ready-to-use AoA indoor positioning anchor point with full functionality in seconds. “In conjunction with an application board, the ANT-B10 delivers the functionality of an AoA anchor point in a large indoor system deployment,” said Marakis.
The ANT-B10 board is available now. The XPLR-AOA-3 explorer kit will be released later this year.
Advertisement
Learn more about u-blox
