How Olympic Timing Works | HowStuffWorks

As you probably know, the Olympic Games are held every two years, alternating between the summer and winter seasons. Because of the differences between these events — from distance considerations to weather considerations — timing technology can vary widely from sport to sport. Let’s start with the summer games.

Athletics/track

In sprint competitions Like the 100-meter dash, which can take less than 10 seconds, timing is critical. That’s why every aspect of the timekeeping is electronic, even the starting gun. And the starting gun sounds less like a gun than it once did, given that security is understandably squeamish about guns at Olympic events. Although it looks like a tag machine, this starting gun is connected to speakers equidistant from each runner, preventing a closer runner from hearing the gun even a millisecond before a runner farther away. But fear not — the sound still mimics a gun (source: Lecher). It’s also integrated with the timing system to eliminate any discrepancies.

On the other side of the race, a laser is projected from one end of the finish line to the other, where a light sensor, also known as a photocell or electric eye, receives the beam. It works by having two photocells (set at different heights to prevent only arm movement being captured) aligned with the finish line. When a runner crosses the line, the beam is blocked and the electric eye sends a signal to the timing console to record the runner’s time.

A serious improvement on the Olympic timing technology used in many events is the Scan’O’Vision camera. It captures that “photo finish” we all crave at a competitive Olympics. Unlike the old film camera, these use digital capture technology. They scan an image through a thin slit up to 2,000 times per second (source: Omega). As the leading edge of each runner’s torso crosses the line, the camera sends an electrical signal to the timing console to record the time. The timing console sends the times to the judges’ consoles and an electronic scoreboard. The images themselves are sent to a computer, which synchronizes them with the timing clock and overlays them side by side on a horizontal time scale, creating a complete picture. The computer also draws a vertical cursor along the leading edge of each runner’s torso at the moment the finish line was crossed. This composite image can then be broadcast on a digital screen within 15 seconds of the end of the race to help decide a close finish {source: Omega).

In longer races, such as the marathon, the clock is also started by an electric gun. However, the large number of participants makes it impossible for all runners to leave the starting line at the same time, and dozens of runners can cross the finish line at the same time. Because of these considerations, marathons require a more individual timing system — RFID tags (radio frequency identification).

Look at any runner’s shoes and you’ll see a small RFID transponder attached to them, which sends out a signal unique radio frequency. Have you ever noticed the mat stretched across the starting line of a marathon? It contains loops of copper wire that act as an antenna, picking up each runner’s signal and sending their identification code and start time to the timing console. Mats track each runner’s progress every 3.1 miles (5 kilometers), with the best times automatically displayed on the scoreboard. Another mat sits at the finish line and records each runner’s finish time. Officials then compare each competitor’s time to the time clock, which is activated by the starting gun.

Major marathons like Boston, New York City and Los Angeles also use this technology, provided by companies like Texas Instruments. It would be interesting to see if the Olympic marathon or other suitable events ever adopt RFID technology or some other type of wearable under the skin.