Typical pro-race TSB (Track Side Box) with decoder, N-Tron Network Interface, Battery Mod, Fiber Mod...this is what receives the digital signal from the loop on the track-

An X2 Transponder taped to a rental car (yes...) we use to run a test over the loops before race day-

Pic of an operator console timing FIAWEC...loops on the left, line passings center-

Pic of COTA S/F (loop is the black grooves in the pavement), and Photocell is the hole opposite track used to sync with the decoder timestamp-

Original post about Timekeeping can be found here:
viewtopic.php?f=1&t=9114&p=704403#p704403
Discussion about accuracy of Timekeeping can be found here:
viewtopic.php?f=1&t=9114&p=704403#p704403
Additional images regarding Timekeeping can be found externally here: http://deltaecho5.com/timekeeping-pics/