Low-Cost AoA Wayfinding

There’s a new paper (pdf) on a low-cost wayfinder system using Bluetooth’s Angle-of-Arrival (AoA) technology. This system is designed to help visually impaired individuals navigate public spaces, such as airports or shopping centres. The innovation lies in moving the antenna array required for angle measurement onto the user’s device, simplifying the beacon infrastructure. Each beacon becomes a low-cost, single-antenna transmitter, significantly reducing the deployment cost compared to traditional indoor positioning systems.

The prototype, built with Bluetooth 5.1 boards and developed using Python, successfully demonstrated accurate angle and distance measurement. The system achieved a 10° angle accuracy within 15 meters and calculated distance using the Received Signal Strength Indicator (RSSI). For visually impaired users, the system could be extended with a voice notification feature. The ultimate goal is to develop the system into a smartphone app.

Future enhancements include addressing front-and-back signal ambiguities by adding orthogonal antennas and extending the system’s range.

Bluetooth vs WiFi Range

When it comes to wireless connectivity, Bluetooth and WiFi are two of the most widely used technologies. While they serve different purposes, they share some similarities in terms of range and frequency usage. Typically, Bluetooth has similar range as WiFi. Standard Bluetooth connections and WiFi can reach up to 50 meters depending on reflection and blocking.

While standard Bluetooth and WiFi devices have limited ranges, there are special Bluetooth beacons designed for extended range capabilities. These beacons can achieve ranges that surpass typical WiFi connections, sometimes reaching up to 4Km. This extended range is achieved through the use of higher power outputs and additional signal amplifiers. However, it’s important to note that the more extreme long-range beacons are specialised devices requiring power via USB rather than battery and are not representative of typical Bluetooth functionality.

Bluetooth 5 brought significant improvements to the technology, including the potential for extended range. Theoretically, Bluetooth 5 can achieve ranges up to four times that of previous versions in ideal conditions. However, it’s important to understand that most Bluetooth beacons, even those supporting Bluetooth 5, don’t usually utilise these extended range capabilities. This limitation is primarily due to compatibility issues with smartphones.

Most smartphones on the market today don’t support the long-range features of Bluetooth 5. As a result, beacon manufacturers often choose not to implement these extended range capabilities to ensure their devices remain compatible with the widest range of smartphones possible. This decision prioritises broad compatibility over the potential for increased range.

Bluetooth Stickers

The term ‘beacon sticker’ often causes confusion. Here’s an explanation of the origins and misconceptions surrounding this term.

Estimote, a former prominent manufacturer of Bluetooth beacons, popularised the term ‘sticker’ by naming one of their beacon models the Estimote Sticker. This product was a small, thin beacon designed to be easily adhered to surfaces. The name caught on, and many articles and discussions began using the term ‘sticker’ when referring to beacons.

Despite the popularity of the term, there is now no specific product category called ‘beacon stickers’. What people often mean when they ask for beacon stickers are actually small, thin beacons that can be easily attached to surfaces.

Beacons typically come with additional or built-in adhesive layers or can be attached using double-sided stickers. These adhesives, often using special 3M glue for strong fixing, allow beacons to be securely mounted on various surfaces.

Minew i6 Beacon

While Estimote Stickers no longer exist, there are several small, thin beacons such as the K15, E8 and i6 that share characteristics with Estimote’s original Sticker model and come with a 3M double-sided sticker. Stickers are also available separately.

Bluetooth Backward Compatibility

Bluetooth technology is designed to be backward compatible across different versions. Here are the key points about Bluetooth backward compatibility:

General compatibility: Newer Bluetooth versions are typically backward compatible with older versions. This means that devices with newer Bluetooth versions can usually connect to and communicate with devices using older Bluetooth versions.

Classic and Low Energy: There are two main types of Bluetooth: Classic (BR/EDR) and Low Energy (LE). Classic Bluetooth radios are backward compatible with other Classic radios, while LE radios are backward compatible with other LE radios. However, Classic and LE are not directly compatible with each other.

Version-specific compatibility: Bluetooth 5.0 devices can connect to devices using Bluetooth 3.0 and later versions.

Feature limitations: When a newer Bluetooth device connects to an older one, it typically operates at the capabilities of the older device. This means that advanced features of newer versions may not be available when connecting to older devices.

Performance considerations: While backward compatibility ensures basic connectivity, there may be differences in performance, such as audio sync issues or reduced transmission rates when connecting devices with significantly different Bluetooth versions.

Future developments: As Bluetooth technology continues to evolve, backward compatibility remains a priority. For example, the upcoming Bluetooth 6.0 is expected to maintain backward compatibility with previous versions.

It’s important to note that while backward compatibility is a core principle of Bluetooth design, specific device implementations may vary, and some features may require both devices to support the same version and have implemented the relevant part(s) of the specification, for optimal performance.

Bluetooth 6.0

The Bluetooth® Core Specification version 6.0 introduces several key feature enhancements aimed at improving performance, efficiency, and functionality, particularly in Bluetooth Low Energy (LE).

Bluetooth® Channel Sounding: This feature enables secure and accurate distance measurement between two Bluetooth devices, which is essential for applications like digital keys and location tracking.

Decision-Based Advertising Filtering: This enhancement improves scanning efficiency by allowing devices to filter and selectively scan for relevant packets, thereby reducing unnecessary scanning and saving energy.

Monitoring Advertisers: This feature allows observer devices to track when a specific device moves in or out of range, which helps avoid energy waste from scanning for devices that are no longer nearby.

ISOAL Enhancement: Improvements to the Isochronous Adaptation Layer reduce latency in data transmission, making Bluetooth more suitable for time-sensitive applications while also enhancing reliability.

LL Extended Feature Set: The capacity for devices to share information about their supported features has been expanded, accommodating the growing complexity of Bluetooth LE.

Frame Space Update: The previously fixed time interval between packet transmissions is now adjustable, allowing for more flexibility in connection events and isochronous streams, potentially enhancing performance.

But how are future beacons and gateways likely to use the new features introduced in the Bluetooth 6.0?

Specialist sensor beacons are expected to utilise the Channel Sounding feature to estimate distance, potentially offering an alternative to the current beacons that rely on time of flight (TOF) measurements. However, it remains uncertain whether Channel Sounding will outperform existing TOF-based beacons in terms of accuracy and reliability.

Some gateways may adopt Decision-Based Advertising Filtering to improve scanning efficiency. By selectively scanning for relevant packets, these gateways could achieve higher throughput, making them more effective in environments with heavy traffic.

The Monitoring Advertisers feature might find application within smartphones, although this seems unlikely given the lack of a clear use case. While this feature could theoretically help in tracking devices that move in and out of range, the practical benefits for most consumer applications appear limited.

The LL Extended Feature Set is technically interesting but may have limited practical impact. The widespread presence of older beacons and smartphones that do not support this feature could hinder its universal adoption, reducing its overall usefulness in mixed environments.

In summary, while these new features offer exciting possibilities, as with Bluetooth 5.0, their real-world impact will depend on whether and how they are adopted and integrated into future devices, especially considering the existing ecosystem of older Bluetooth devices.

How to Calibrate Temperature Sensor Beacons?

We have several clients using the temperature/humidity sensor beacons in industrial situations. A question we have had is how is the temperature/humidity calibrated? For scenarios that require monitored temperature/humidity, it’s often necessary to show the readings have been calibrated over time.

M52-SA Sensor beacon

Most sensor beacons don’t have a calibration certificate. The long term drift of the sensor is <0.04C/yr and <0.5 RH/yr so in most applications it doesn’t usually need calibration. If you need accuracy better than this you will usually need to calibrate in the software of the phone/device that receives the beacon signal. That is, you will need to periodically measure the real temperature/humidity using another calibrated instrument and apply any offset to the read values.

S5 Sensor beacon

Another option is to use the one beacon, the S5, that does have a temperature/humidity calibration certificate.

Beacons for Spying?

There’s lots of information on Bluetooth beacon security, Bluetooth attacks and using beacons to track individual user data but these are known, small risks we might expect. What about unknown things such as espionage?

Recently, a prospective customer posed a critical question: How can we ensure that purchased beacons are not engaging in activities beyond their intended purpose, such as eavesdropping or transmitting sensitive information? This question becomes even more pertinent when considering beacons manufactured overseas that might be deployed in sensitive locations.

Typically, a single SoC chip on the beacon’s simple Printed Circuit Board (PCB) is responsible for all operations. Upon examination, if there are no additional, unexpected, chips on the PCB, it limits the beacon’s ability to perform unexpected tasks. If the hardware is not compromised, the only factor to consider is the standard, usually Nordic Semiconductor, System on Chip (SoC) used in the beacons. This means that any potential spying would likely be restricted to software in the SoC rather than hardware modifications.

Let’s assume beacons can only exploit the capabilities that the standard SoC chip provides. These usually include Bluetooth, ANT, 802.15.4 and other proprietary and non-proprietary 2.4GHz protocols. Crucially, beacons are designed primarily to send signals rather than receive them. They transmit signals every millisecond, typically every 200ms to 1000ms, to maintain low battery consumption. For a beacon to listen or scan for information, it would require significantly more power, thus drastically reducing battery life. Similarly, relaying, perhaps via covert channels, any gathered information would also deplete the battery swiftly. Therefore, any huge deviation from the expected battery life could be a tell-tale sign of unauthorised activities.

Given that beacons usually only send data, they cannot capture sound or video without additional, noticeable components. When they are listening using the protocols they are designed for, the information they could gather would be limited and lack context, such as identifying what they have seen or the specific location.

While the theoretical possibility of beacons being used for spying exists, it is easily detectable due to the easily examined, simple hardware, limited capabilities of the SoC and the significant power requirements for any additional activities. By understanding the simplicity, limitations and functionalities of these devices, businesses can better safeguard against potential espionage.

Read about our consultancy for more advice

What is the Beacon With the Shortest Range?

A short-range beacon is useful in scenarios where precise proximity detection is crucial. For instance, in retail environments, it can trigger notifications when a customer is near a till or near a specific product. In museums, it can provide detailed information about an exhibit when a visitor is directly in front of it. Short-range beacons are also valuable for security purposes, ensuring access control in restricted areas by detecting when someone is within a specific, confined space.

The range of a beacon can be adjusted by altering its transmission power, known as Tx Power. Tx Power determines the strength of the signal the beacon emits. By reducing the Tx Power, any beacon’s signal strength can be decreased, effectively shortening its range.

Lowering the Tx Power to reduce the beacon’s range significantly improves battery life. Since the beacon is emitting a weaker signal, it consumes less power. This efficiency is beneficial for maintaining the beacon’s operation over longer periods without frequent battery replacements or recharges.

Beacons can generally achieve a minimum range of 2 to 3 metres. However, it’s important to note that the range can fluctuate over time due to the nature of radio signals, which can be affected by environmental factors such as walls, interference from other electronic devices and physical obstructions.

In addition to adjusting the Tx Power, the range can be fine-tuned by using the Received Signal Strength Indicator (RSSI) at the receiving end. RSSI measures the power level of the received signal, allowing devices such as smartphones (iOS and Android) or computers (like Raspberry Pi) to determine how close they are to the beacon. By setting thresholds for RSSI values in the receiving program code, you can define more precise proximity zones, ensuring that actions are triggered only when the device is within the desired range.

What is the Best Beacon Compatible With Our HR System?

The answer to this question is similar to Which Beacons are the Most Compatible (with iOS and Android)? All beacons transmit to Bluetooth standards and use similar, certified, components which means there are no problems with compatibility or ‘best’ beacon for compatibility with an HR system.

Instead, we find the challenges usually lie in setup and getting the HR system to recognise the beacon UUID. Most systems use iBeacon advertising that uses a UUID, major and minor to uniquely identify the beacon. The UUID looks something like 3ce2ef69-4414-469d-9d55-3ec7fcc38520. Some HR systems use upper case for the hexadecimal digits that are letters, some use lower case. Some omit the dashes (-) and some use colons instead. Read your HR user guide to determine the exact format otherwise the beacon won’t be recognised.

Google Find My Device

Google’s “Find My Device” network is a feature designed to help users locate their Android devices and other items using a network of over a billion Android devices. It uses Bluetooth to detect nearby devices and securely send their locations to the Find My Device network.

This network is end-to-end encrypted, meaning that while Google processes location data, it does not have access to the specific locations, which are only visible to the owner of the lost device.

The Find My Device network is only compatible with Bluetooth beacons which are specifically built for this network and have compatible firmware. These tags can help locate everyday items like keys, wallets, or luggage.

Bluetooth beacons from brands like Chipolo and Pebblebee are compatible with Find My Device and beacons from other brands will be available soon.