Configuring RTLS Tags for Social Distancing Proximity Alerts

COVID-19 has affected all walks of life, causing business closures and global economic uncertainty. Industries that are unable to adapt to the so-called new normal cannot maintain pre-coronavirus work patterns which impacts throughput with often severe ramifications to the bottom line. Few market segments have been more affected than the process industries, where strict social distancing requirements are hard to sustain.

Real-time location systems (RTLS) for personnel and asset monitoring have emerged as a potential solution to the challenges of COVID-19 compliance. Many RTLS companies quickly recognised the potential of existing personnel tracking platforms for contact tracing and social distancing. These unique technologies offer a data-driven solution for those industries hardest hit by the pandemic to make safe inroads towards returning profitability.

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RTLS Technologies for Social Distancing

There are various RTLS technologies that can be deployed for social distancing, but Bluetooth low energy (BLE) has emerged as the main front runner in hazardous and harsh industrial environments. BLE has prevailed due to its infrastructural simplicity—despite offering lower accuracy than the likes of ultra-wide band (UWB) systems. Other RTLS technologies suffer from accuracy issues at the sub two metre range. GPS, for example, is affected by horizontal score deviation (HSD), which makes it unreliable for social distancing applications. Wi-Fi triangulation requires extensive infrastructure. LF is short range and therefore unsuitable for two metre accuracy.

The drawbacks of each have conspired to make BLE the prevailing technology for social distancing due to its combination of good accuracy and low infrastructural requirements. Additionally, BLE solutions can be rapidly deployed at low cost compared to other RTLS systems. This means that process managers can quickly and cost-effectively install a robust BLE social distancing system with sub two metre accuracy.

So, once you have selected a BLE RTLS system, how do you configure sub-two metre proximity alerts for social distancing?

BLE Personnel Tags for Social Distancing

BLE does not pair like traditional Bluetooth. Instead, it simply advertises and listens for a response—which uses significantly less energy. A BLE tag emits a signal as part of a window and is receptive to signals during the other part of the window. If and when it receives a transmission from another BLE tag, it measures the RSSI value.

Unlike other RTLS systems, the BLE tag requires no additional infrastructure to determine its location relative to the other device.

Measuring RSSI Values

Determining location via received signal strength indication (RSSI) is a simple process. When the BLE tag detects transmissions from another transmitter, distance is determined as a function of signal strength. Stronger signals indicate closer proximity and vice versa. BLE-based RTLS systems then only need to determine the RSSI value correlating to one- and two-metres for proximity alert configuration.

Once the RSSI values for each distance is known, you can set a threshold value based on the signal strength to define the difference between one metre, two metres, or three metres plus. Social distancing is based on a prescribed two-metre rule. Therefore, you want to use the two- and three-metre plus values as the threshold for proximity alerts.

Although curbing the spread of coronavirus to keep your workforce healthy is the priority, an enduring pain point in process industries is the impact of false positives. It is subsequently vital that your RTLS threshold values are accurate to mitigate unnecessary loss of workforce due to mandatory self-isolation rules.

Triggering Alerts

Configuring the RSSI values to match the advised social distancing measure of two metres means a BLE tag can trigger proximity alerts to the user once that two metre threshold has been crossed. Alerts vary depending on the configuration of the tag. They may be audio-visual or even mechanical, with haptics alerting users to their proximity via vibration. Alerts can be configured to cease as soon as the two-metre distance is restored.

Interested in RTLS systems for contact tracing?

To learn more about BLE for social distancing and personnel tracking systems, simply contact a member of the Extronics team today. Or, you can reach us by email (info@extronics.com) and by phone (+44 845 277 5000).