How does a tiny chip time the runners in the Bay to Breakers race? In this article, I take die photos of the RFID chip used to track athletes during the race.
Bay to Breakers is the iconic San Francisco race, with tens of thousands of runners (many in costume and some in nothing) running 12km across the city. To determine their race time, each runner wears an identification bib. As you can see below, the back of the bib has a small foam rectangle with a metal foil antenna and a tiny chip underneath. The runners are tracked using a technology called RFID (Radio Frequency Identification).
At the beginning and end of the race, the runners cross special mats that contain antennas and broadcast ultra high frequency radio signals. The runner’s RFID chip detects this signal and sends back the athlete’s ID number, which is programmed into the chip. By tracking these ID numbers, the system determines the time each runner took to run the race. The cool thing about these RFID chips is they are powered by the received radio signal; they don’t need a battery.
Mylaps, whose name appears on the foam rectangle, is a company that supplies sports timing systems: the bibs with embedded RFID chips, the detection mats, and portable detection hardware. The detection system is designed to handle large numbers of runners, scanning more than 50 tags per second.
Removing the foam reveals an unusually-shaped metal antenna, the tiny RFID chip (the black dot above the word “DO”, and the barely-visible word “Smartrac”. Studying the Smartrac website reveals that this chip is the Impinj Monza 4 RFID chip, which operates in the 860-960 MHz frequency range and is recommended for sports timing.