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Distance Measuring Technologies for COVID-19 Wristbands

Telink Staff

August 12, 2020


Two pedestrians with mobile phones

As stay-at-home orders lift and employees return to work, companies need a smart way to enforce social distancing in the workplace. Bluetooth® technology can help.

As the coronavirus pandemic continues, we’ve seen a number of contact tracing and social distancing solutions hit the market in an effort to stop the spread. Some solutions make use of digital technologies — Amazon’s Distance Assistant, for instance, uses a camera’s depth perception capabilities to gauge whether people are staying a safe distance apart. Other solutions are more bespoke —for instance, attaching pool noodles to your hat to ensure proper distancing.

No matter their approach, employers and businesses will need new tools to help maintain social distancing as lockdowns ease and people return to work. For device-makers looking to contribute, Bluetooth® technologies can be applied in social distancing devices to great effect. Here’s everything you need to know about using Bluetooth LE to measure proximity and help employers and office workers stay safe. 

How Does Bluetooth® Social Distancing Technology Work?

When a Bluetooth device detects and connects to another device, it measures the strength of that signal as RSSI, or received signal strength indicator. The strength of the connection depends on distance — if two devices are in close proximity, the connection will be strong. The connection weakens as the devices move apart. Ordinarily, our mobile devices are constantly scanning for nearby devices, and technologies like social distancing wristbands can use the same method to gauge proximity between two people. Integrated with cloud technologies, wristbands can use the data they gather to analyze how well users are adhering to social distancing requirements over time.

How Bluetooth signal gauges proximity

Wristbands that measure proximity can help enforce social distancing, but it is important to remember that this differs from contact tracing — which often requires pinpointing the point of contact, how close, and for how long. Contact tracing apps use this information to alert the user if they have been in contact with someone who is COVID-19 positive. 

But because contact tracing requires more precision, contact tracing technologies using Bluetooth LE require greater refinement to be consistently accurate. By contrast, social distancing wristbands can reliably indicate whether the user is within a certain distance of another user — but not whether or not they have been exposed. 

3 Ways Bluetooth® LE Measures Distance

As the demand for social distancing technologies increases, developers are exploring different Bluetooth connectivity options for optimum results. Bluetooth LE can be used to measure distance using one of three primary approaches:

1. Bluetooth® LE (RSSI) Alone

This solution relies on the received signal strength indicator (RSSI) to measure the distance between the transmitter and the receiver. RSSI alone is a straightforward way to gauge the distance between two points and it has a low bill of materials (BOM) cost — but it’s not the most accurate solution.

2. Bluetooth® LE with Ultra-wideband (UWB)

Another promising option combines Bluetooth LE with ultra-wideband (UWB). UWB is a low energy radio frequency technology that can transmit short-range, high bandwidth communications over the radio spectrum. UWB is best suited for data collection, location tracking, and short-range indoor application. Combining RSSI with UWB results in highly accurate measurements, but it has a higher BOM cost due to the UWB chip. 

3. Bluetooth® LE Connectivity-Based Proprietary Distance Measurement Technologies

Unlike RSSI alone, Bluetooth LE connectivity-based proprietary technologies can add distance measurement capabilities, making it more accurate and giving Bluetooth LE solutions a wider set of applications. Proprietary technologies can combine Bluetooth LE data packets with constant tone frequency exchanges in order to generate the strong signals needed for more accurate ranging. Bluetooth LE connectivity-based proprietary technologies can also be more accurate than RSSI alone and Bluetooth LE+ UWB — it can also boast a low BOM cost. 

Using BLE-based proprietary technologies to measure distance

For instance, Tharsus’ social distancing solution Bump is an RF-based personal motion system that uses Telink’s Bluetooth LE connectivity-based proprietary technologies to gauge distance in real time. When two devices with Bump sensors come within 6.5 feet of one another, both devices alert their wearers via subtle sound or light warning.    

Stay Safe with Telink 

To stem the spread of COVID-19, event venues, businesses, and workplaces will need to maintain proper social distancing for the foreseeable future. Engineers and tech experts are focused on developing social distancing technologies that are accurate enough to ensure public safety, and affordable enough to be deployed at scale. 

Telink’s advanced chip technology powers Tharsus’ social distancing device Bump — an accurate and secure way to monitor the success of social distancing policies in real time. Our proprietary Bluetooth LE technologies offer a low-power, private, and reliable way to maintain proper distance between users, and our new SoC designs offer advanced, cost-effective solutions for a wide array of wearable devices. Contact us today to learn more.