In the mid-80s, NASCAR started using active AMD transponders on each car to provide real-time data to viewers and teams.
Active transponders have a battery, a transmitter, and a unique code. The transmitter has a limited range. A wire antenna was installed beneath the pavement at the finish line of each track. The antenna was attached to a receiver/reader.
The reader interprets the unique code and associates it with a time, usually the time of day to the thousandth of a second. That information is passed to a computer that records and reports the information. The computer may also perform calculations, typically reporting the time difference between chip reads.
In the early years, the cost to produce an active transponder exceeded $50 each. Over the years, the costs have been reduced.
The advantages of active transponders are fewer communication collisions and highly accurate times. However, even with reduced costs, a running race with 1000 participants may cost up to $35,000 for transponders, and they can not be discarded, requiring a collection process.
At the same time that active transponders were released, companies were working on passive technology.
Each passive chip has a unique code and an antenna. When a passive chip gets close to a read field, the receiver/reader transmits an electromagnetic signal that provides enough power in the chip to reflect a code to the reader.
Like active systems, the reader records the code and a time, sending the data to a computer for reporting and analysis.
Championchip was the first large-scale use of passive technology in running races in the mid-90s. They used a chip encased in plastic that could be tied into shoelaces or worn with an ankle strap. The initial cost to manufacture a chip was between $15 and $20.
They sold their chips to timing companies for $35 each and charged a $1 royalty for each use. Because of the cost of the chips, they needed to be collected after each race.
Championchip started selling chips directly to participants and waived the royalty fee for participant-owned chips. Races would discount runners who used an owned chip.
The read fields for these chips used UHF frequencies, were up to waist height, and were limited to above the antenna mats. Also, other nearby wireless devices (e.g., DJ Microphones, EMT communications) could prevent the mats from detecting chips.
By the early 2000s, the manufacturing cost of passive chips was 40 cents each. Championchip continued to sell chips for $35.
Around this time, developers were experimenting with VHF systems that used chips embedded in tags attached to bibs. Tag costs were reduced to around 20 cents each. The tags received power from the read antennas and reflected a unique code; they are considered passive systems.
The advantage of these systems was that VHF communications eliminated interference from nearby communications, and the tags no longer needed to be collected for reuse.
A downside is that tags will not record through water, with heavy sweat being an issue.
Many Championchip timers switched to Chronotrack, the first successful disposable chip system. Since those timers were used to pay $1 per chip use, that was carried forward into the tag cost that Chronotrack charged.
Championchip eventually developed its disposable tag system and markets it under the MyLaps brand.
Active systems are still used in triathlons, obstacle and mud events, cross-country skiing, bicycle racing, and auto racing. The cost to manufacture a chip is under $10. But the batteries need to be replaced frequently.
Other uses of passive systems include credit cards, pet chips, automotive toll collection, and product tracking.
What’s the next generation of race timing?