How do they calculate split second timings in F1?

Answer 1

Time is the main technological challenge facing Tag Heuer, since the performances of the cars, the drivers and the racing teams are measured all at once to the nearest 1/1000th of a second. TAG Heuer's innovative spirit has evolved constantly in this field since 1992, the date when the company was first appointed Official Timekeeper of the FIA Formula 1 World Championship. To eliminate any risk of error, TAG Heuer uses two independent timekeeping systems.

The main system is made of 2 seperate systems (a main and double) which are working independently. The system is made up of 18 antennas setup around the track: three points to measure times and corresponding speeds (finish line, intermediate 1, intermediate 2, with 2 antennas on each point to calculate speed), a strategic point for top speed (with 2 antennas placed at 30 meters distance) and along the pit-lane (checking speeds and measuring times spent in the pits). These antennas receive signals transmitted by the mini-transmitters (transponders) placed in each car and set to different frequencies, which enables the identification of all cars and recording of their times each time they pass the antenna.

For even greater security, this main system has as a back-up a secondary system linked to a double infra-red photocell placed on the finish line. It records the passage of each competitor at each lap. These data are then transmitted to the Timing Tower located above the start/finish line.

Apart from the secondary system managed from the timing tower, the information stemming from all sources via antennas is processed by the mobile Timing Centre. Inside this timekeeping unit, a number of computers perform "live" calculations of split times, lap times, lap number, speeds and time differences. More than 20 engineers are active in this area.

All the data are instantly transmitted by the timing centre to more than 150 monitors interspersed around the site and duly analysed by drivers, officials, media, guests and teams.

Moreover, results and analyses are printed and distributed to teams and available in the press room.
There are also complete and attractive graphics proposed to world-wide TV viewers to help them understanding the evolution of live practice and race sessions, thanks to the numerous television channels which broadcast live, delayed races or news coverage of the Grands Prix, with the TAG Heuer timing logo appearing on screens.

For safety reasons, speed is limited on the pit lanes to 80 km/h during the race and 60 km/h during the practice sessions. Antennae are set up to control speed in the pit lane (pit entrance, pitlane and pit exit). There is also an electronic device to detect possible anticipated start. These systems help marshals to check any possible penalty times imposed on drivers (jump-start, excessive speed in pit-lanes...).

Answer 2

They have electronic sensors in the cars that register as they cross beams in certain sections of the track and the finish line.

They also use timers with three decimal points (eg. 25.456 sec).