Have you ever wondered how chip timing works? Most people don’t know or care as long as they get a time. Sadly, many timers don’t even understand it except to turn it on and hope it all works. Understanding the technology though can help explain issues when things don’t work so well. It’s like understanding why a cell phone doesn’t work in the country or inside a steel structure.
Chip timing or RFID (Radio Frequency ID) timing uses radio waves operating along several specific frequencies governed by the FCC. Most chip timing systems that you will see are what we call passive RFID. This means that the chip itself is inactive until it is activated by radio waves. A timing system disperses these radio waves using one of several technologies. When a chip comes into proximity to the radio wave, it wakes up and runs a little program that then starts communicating with the timing system. The timing chip is actually a very small and specific computer designed only for communicating a small amount of information between the chip and a RFID reader. These radio waves can be interfered by power lines, heart rate monitors, gps watches, and even body mass.
There are several types of timing systems that you will see in actual practice. The oldest is a ground mat that most are familiar with. The original chip timing systems used ground mats with chips that went on a shoe. These chips were originally designed for tracking cattle through feedlots. The ground mats have a fairly weak signal that works because of the close proximity to the chip. Those original race timing systems didn’t work very well, but over time have become fairly reliable. The newer timing systems use overhead antennas with a chip mounted to the bib. These chips actually were originally designed for warehouses and tracking product (think Walmart). The advantage of the overhead or side mounted antennas is that they are very powerful and have a longer range. Rather than a chip being read 2 or 3 feet from the mat, a chip can often be seen as far away as 15 or 20 feet. The actual time of the runner coming across the line is calculated using triangulation and power level detection and is highly accurate.
Companies with investments in ground mats have tried to make bib chips work with their existing systems but the read range of the mats doesn’t lend itself to work very well. This is why you will see multiple mats at a finish line. Timers may have to put as many as 3 or 4 mats just to ensure that all chips get read. The problem with this approach is that only the mat at the finish line is accurate. The rest of the mats are using an offset to approximate the time. Our experience is that a single mat can only get between 90% and 96% of the reads depending on the density of the runners. The rest are caught by the secondary mats as runners slow down. If you ask a timer using mats about this, they may tell you that they get 100%. They are either being disingenuous or their software is handling it and they simply don’t know.
Even overhead or side mounted antennas will miss a read or two depending on the strength of the chip and how the runner is wearing the bib. We’ve seen many events where 100% reads were made with overhead antennas, but it is not flawless and chips can fail.
As timers, we work hard to understand how to properly configure systems and obtain the highest read rates possible. It’s a combination of technology, backups, and awareness to ensure a great race.
If you want to know more please contact us. We’re experts in timing and would love to have a discussion with you.
