Measure of the Olympics

-July 30, 2012

In 1948, the first Olympic games since those that followed Jesse Owens’ contradiction of everything Adolf Hitler held dear, they brought 30 hand-held stop watches to London. The Swiss watch company, Omega (now owned by Swatch), handed them out, reminded score keepers to keep them wound, and let the games begin. (You see, in the olden days, watches had to be “wound” by hand. The idea was to apply tension to a spring that would provide energy to a mechanical oscillator, similar in concept to how batteries now provide power to oscillating crystals.)

Omega still provides timing equipment for the Olympics. They even erected a clock in Trafalger Square to countdown 500 days to the Olympics! Though it stopped with 498 days left. It was using GPS timing and succumbed to interference around the crowded intersection. They fixed it within hours. Still, the British Olympics seem destined to provide amusement for the local tabloids.

Race timers, called the “Quantum Timer” and “Quantum Aquatics Timer” were developed by Omega for the Olympis and boast relative accuracy of 1 ms (a millionth of a second) and absolute accuracy of 0.1 parts per million. It’s a 5x improvement since the last games, due to an oscillator developed by Micro-Crystal (also a Swatch subsidiary). Their “Real Time Clock” chip uses a precise 32.768 kHz tuning-fork crystal in a CMOS based oscillator circuit.

Race timing requires more than the start and finish times. False starts have to be detected and penalized. When runners or swimmers get-ready, get-set, and go, they push off starting blocks.

Starting pistols have been replaced by e-guns this year that both flash a light at their tip and provide an audible launch mark from speakers set behind each competitor. Interesting to note that modern TSA regulations can take some credit for the technological advance. Omega Timing’s Peter Hurzeler said, “We had to change the whole thing because today it is forbidden to transport pistols in a plane.” In any case, no millisecond advantage will be gained by being closest to the official who pulls the trigger.

As competitors react to the start signal, the pressure they apply to the starting blocks is measured. They used to measure movement, but runners and swimmers hated having the blocks yield a few millimeters just as they pushed off. The starting blocks attach to piezo-electric crystal force-voltage transducers, also developed by Omega.  

False starts are determined by requiring that athletes demonstrate reaction times no faster than 100 ms (a tenth of a second). Average human reaction time is about 200 ms. Since reaction time is limited by the rate that information can propagate from the eyes or ears to the brain and then from the brain to the muscles, it’s pretty much impossible for a biological system to react much faster. This all adds up to the possibility that an athlete can get a 100 ms jump on the competition. It’s a gamble, though, two false starts lead to disqualification.

With close races becoming more common – the June US Olympics trial featured a third place tie between Jeneba Tarmoh and Allyson Felix, 11.068 s in the 100 m sprint where only the top 3 would be allowed to compete, and in the 2008 games, Michael Phelps beat Milorad Cavic by 0.01 s in the 100 m butterfly resulting in Omega having to hold multiple press conferences to clarify the process – timing resolution has been halved. This year, finish line cameras will shoot at 2000 images per second (2 kHz) so that they can discriminate down to 0.0005 s.

(The author, Ransom Stephens, was nearly arrested at Trafalgar Square in 1983 just prior to viewing Pink Floyd’s The Wall at a nearby cinema. Being that he was in college at the time, his offense could only have been one of two infractions – care to guess? Fortunately, his American accent got him off the hook.)

 

Loading comments...

Write a Comment

To comment please Log In

FEATURED RESOURCES