Social Distancing Wearable TrackerContact tracing made easy

3 months ago, we were not even familiar with the expression ‘social distancing’. But then the coronavirus pandemic began to spread across the world infecting hundreds of thousands of people. With the rising cases in India, we too have been urged to stay home and practice social distancing. Now question comes, what is Social distancing.

Social distancing, also called “physical distancing,” means keeping a safe space between yourself and other people who are not from your household. COVID-19 spreads mainly among people who are in close contact (within about 6 feet) for a prolonged period.

Spread happens when an infected person coughs, sneezes, or talks, and droplets from their mouth or nose are launched into the air and land in the mouths or noses of people nearby. The droplets can also be inhaled into the lungs. Recent studies indicate that people who are infected but do not have symptoms likely also play a role in the spread of COVID-19. Since people can spread the virus before they know they are sick, it is important to stay at least 6 feet away from others when possible, even if you—or they—do not have any symptoms.

Kemsys, the well-known IoT device design house, has designed & developed BLE beacon based wearable device for social distancing and contact tracing, to contrast Covid19 spreading, thanks to ST Microelectronics – BLUENRG (a very low power Bluetooth Low Energy (BLE) single-mode system-on-chip).

Simple, yet Innovative Wearable Tracker Design

These social distancing wearable trackers & applications help users maintain safe distances and minimize the risk of contracting infectious diseases such as COVID-19 by generating an alert when two people come within a minimum set distance of each other, usually 2 meters or less. The application involves wireless Bluetooth® Low Energy (BLE) communication between wearable nodes based on the BlueNRG-1 or BlueNRG-2 systems-on-chip. The nodes simultaneously advertise their presence and scan for the presence of other similar beacons in range, while deploying LowPower Modes during periods of inactivity to conserve battery power. Advertising is performed on three channels and no connection or response packet is required between the devices during advertising and scanning activities (ADV_NONCONN_IND).

  • Alert zone = 2 meters
  • Pre-alert zone = 3 meters
  • Safe zone = more than 3 meters

The tracker is fitted with an onboard accelerometer sensor. If no movement is detected by the accelerometer for DEVICE_HALT_TIME (60 s), it is assumed that the user has removed the band and the device is put to sleep. If the device is tilted more than a threshold value, it is woken up and placed in Normal Mode by the GPIO interrupt (GPIO_Pin_13) connected to the accelerometer interrupt line.

The trackers come with little memory, which is sufficient to store 20 to 100 encounters/samples only, in array format.


(timestamp, target beacon mac id, RSSI, distance),

(timestamp, target beacon mac id, RSSI, distance),

(timestamp, target beacon mac id, RSSI, distance)


Simple, yet Powerful Mobile App for Contact Tracing

It is the responsibility of the user to download these samples from wearable to mobile app, now & then, by pressing a dedicated download button that comes with the wearables. Whenever the user presses this hardware download button, the wearable will move from default “continuous advertise & scan mode” to “download” mode. In this mode, it will pair with the “mobile”. Upon receiving the command from the mobile app for “download samples”, wearables will send “internally stored samples data” to the mobile app, and simultaneously erases the same from internal RAM.

The mobile app offers the following features:

  • Scan and Pair with Wearable BLE Trackers
  • Download sample data from wearable trackers to Mobile top
  • Visualization of Contact Tracing data to Histograms
  • Uploading contact tracing data to Cloud

Learn how IoT is Helping Businesses Adapt to Covid-19 Disruption