Bluetooth 5.1, released today, comes with radically upgraded proximity and positioning capabilities. This means users of the wireless technology standard can now identify the location of Bluetooth-equipped items at 1cm accuracy. And it’s all thanks to a technique first tested in 1888.
With nearly four billion Bluetooth-enabled devices shipped in 2018 alone, the shortwave UHF technology is used by developers looking to stream audio between devices, transfer data between devices, build asset tracking solutions, or create large device mesh networks.
Bluetooth 5.1: Adds RDS to RSSI
Now radio direction finding (RDF) a technology in use since the early 20th century, has been added to the core specifications of Bluetooth 5.1, meaning devices can determine the direction of a signal being transmitted from another Bluetooth device, sharply improving locational accuracy; typically accurate currently to around one metre.
Location services – think proximity marketing like Point-of-Interest beacons, indoor navigation solutions and a wide range of supply chain asset tracking offerings – typically currently use received signal strength (RSSI) measurements to estimate distance between devices.
Bluetooth 5.1 however now ships with an optional RDF capability that works, in part, by comparing the signal strength of a directional antenna pointing in different directions.
Users can, as a result, use triangulation to improve location accuracy, with the feature supporting two methods for determining the direction of a Bluetooth signal, both of which are based on the use of an antenna array; angle of arrival (AoA) and angle of departure (AoD).
Announcing the release of Bluetooth 5.1, Mark Powell, the executive director of the Bluetooth Special Interest Group (SIG) – a 30,000-member non-profit organisation that oversees development of the standard – said: “Location services is one of the fastest growing solution areas for Bluetooth technology, and is forecasted to reach over 400 million products per year by 2022.”
He added: “This is great traction and the Bluetooth community continues to seek ways to further grow this market with technology enhancements that better address market needs.”
Radio direction finding refers to the practice of determining the direction from which a received signal was transmitted. Radio direction finding has been in practice since the early twentieth century and is used in systems to support everything from aviation and nautical navigation to wildlife tracking.
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“Since the introduction of Bluetooth Low Energy in 2010, developers have been able to leverage Bluetooth to create powerful, low cost location services solutions for a variety of applications spanning across consumer, retail, healthcare, public venues, and manufacturing environments,” said Andrew Zignani, Senior Analyst, ABI Research.
“The new direction finding feature can help Bluetooth better address the varied and evolving needs of the location industry, enabling more flexible, scalable and futureproof deployments that will further accelerate the adoption of Bluetooth for location services in existing markets, while unlocking additional business opportunities for new applications and use cases.”
Top image shows W.G. Wade of the National Bureau of Standards using a large multi-loop antenna to perform RDF in this 1919 photo.