There’s novel recent research on City Marathon Active Timing System Using Bluetooth Low Energy Technology by Chun-I Sun, Jung-Tang Huang, Shih-Chi Weng and Meng-Fan Chien of Taiwan.
The authors discuss the use of beacons vs RFID and create a system using Received Signal Strength Indicator RSSI and gateways connected to detector mats:
![](https://www.beaconzone.co.uk/blog/wp-content/uploads/2019/10/electronics-08-00252-g004-1024x582.png)
![](https://www.beaconzone.co.uk/blog/wp-content/uploads/2019/10/electronics-08-00252-g010-1024x578.png)
Beacons are carried by athletes. The gateways sync their times via NTP and send data up to a MongoDB database:
![](https://www.beaconzone.co.uk/blog/wp-content/uploads/2019/10/electronics-08-00252-g001-1024x476.png)
An accuracy of ±156 ms was achieved which compares well to the nearest second used to generally record times and resolution accuracy of 0.1s for commercial transponder timing systems.