Introduction to Bluetooth Beacons
Bluetooth Beacon BLE Beacon is a hardware device based on the Bluetooth Low Energy BLE (Bluetooth 4.0 and above) broadcast protocol. As a BLE device, it is usually installed in a specific location indoors, as the reference point of the indoor location, and continuously broadcasts to the surroundings continuously. It does not need to connect to any host device, and only needs to scan and analyze the host device.
– Low power consumption, long standby time, no external power supply required;
– Easy to install. Use 3M glue or screws to install;
– lower cost and reduced project budget;
– High compatibility and adaptability, compatible with most models on the market.
Relationship between Bluetooth beacon distance and signal strength RSSI
d=10^((ABS(RSSI)-A)/(10*n)) ———— (1)
Where d is the distance in m.
RSSI is the signal strength received by the mobile phone from the Bluetooth beacon, which is a negative number.
A is the absolute value of the received RSSI value when the mobile phone is 1m away from the Bluetooth beacon.
n is the environmental attenuation factor, which requires test correction.
The figure below is a graph made according to A=63, n=1.56:
It can be seen from the above figure that the relationship between RSSI and distance is nonlinear. When the distance exceeds 8 meters, RSSI is not sensitive to the change of distance.
Check-in and time attendance based on Bluetooth beacons
When we use mobile phone applets or APPs to check in and check in, due to differences in the received signal strength of different mobile phones, signal occlusion, signal reflection, etc., we cannot simply use the signal strength of the Bluetooth beacon to be reduced or use a single measurement signal. strength (RSSI), we recommend the following:
- Through the actual test, according to the check-in distance required by the business, the corresponding signal strength value is actually tested, and the signal strength is filtered in the WeChat applet or mobile APP.
- Perform multiple signal measurements, and take the one with the strongest signal strength as the basis for operation (because occlusion and other reasons will only cause the signal to become weaker, and will not cause the signal to become stronger, so the reliability of the stronger signal strength is higher).
Practical application examples
– Use Bluetooth beacon and Bluetooth + NB-IOT work card for automatic punching. When the Bluetooth work card scans the signal of the Bluetooth beacon, it will be sent to the background server through NB-IOT for punching.
– Use Bluetooth beacons combined with WeChat applets or mobile APPs to check in.
– The Bluetooth beacon triggers the body camera, and when the body camera reaches the vicinity of the Bluetooth beacon, the camera function is automatically turned on.
– The Bluetooth beacon triggers other applications. When entering a certain distance near the Bluetooth beacon, it automatically triggers specific operations (such as broadcasting an introduction to cultural relics, etc.
