My own development of a TimeTracker
This system is based on scottgchin's delta5 race timer:
https://github.com/scottgchin/delta5_race_timer
The firmware for Arduino is based on PropNuts Wizardtracker-hardware:
https://github.com/PropNuts/wizardtracker-hardware
It uses an OrangePi, one Arduino an up to 8 RX-Modules