Australian Race-Timing Company Finds Battery-assisted UHF Tags a Winning Solution

Aug 05, 2010Battery-assisted ultrahigh-frequency (UHF) RFID tags will soon replace traditional passive low-frequency (LF) tags for tracking racers in running and cycling events, says Andrew Peterson, the director of RFID Race Timing Systems.

Last October, the Australian company launched its Ultra solution—a UHF RFID system using battery-assisted passive (BAP) EPC Gen 2 tags. UHF has many advantages over traditional LF tags when tracking race competitors, Peterson says, including a greater read range, faster read rates and lower costs. He predicts that UHF could be used in up to 90 percent of racing events within the next few years.

Ultra has already been used in a number of races in Australia, including the Melbourne Marathon, which attracted more than 4,000 competitors, and the Perth Run for a Reason, which drew 8,600 participants. It is also being utilized at this weekend's Avon Descent, Australia's premier whitewater-racing event for paddle crafts and motorboats. Tags will be attached to competitors' helmets and, with a read range of up to 50 meters (164 feet), just one reader with an antenna beaming across the river's width is required at the finishing line in Perth.

Peterson says he first examined the use of UHF RFID for race timing approximately four years ago, because of its potential for improved read rates.

"We have a LF system operating at 134 kHz, but the problem is that you can get tag collision, and require multiple readers at the finishing line to read multiple tags," Peterson explains. "With UHF, we could get faster read rates of up to 300 tags a second. But when we did test it, it did not work too well when next to the human body, because water in the body can detune the tags. UHF was not designed for people-tracking, and LF was the technology of choice."

While RFID Race Timing Systems abandoned UHF in favor of traditional LF tags, companies such as ChronoTrack Systems and MyLaps developed UHF tags that attach to a competitor's shoelace, thereby avoiding the problems caused by the tags coming into contact with the skin (see Gen 2 Tags Track Runner, Motorcycle Speeds and UHF Solution Tracks 42,000 Runners at the New York City Marathon). This, however, was not an ideal solution, Peterson says, as it required sending racers a separate bib and transponder, and the shoe tags were not "idiot-proof."

"With shoe tags, if the transponder is not attached correctly, you will not get a reading," Peterson states. "Sometimes, competitors can push the transponder down the shoe, or under the shoelace. We wanted to be able to place the transponder on the bib before distribution."

At least one other race-timing company, however, had already discovered a way to do just that, using passive EPC Gen 2 tags without batteries. In September 2008, Innovative Timing Systems, a startup firm located in St. Louis, began offering a solution that includes bibs with embedded EPC Gen 2 passive UHF RFID inlays. This system is used for many different events, from canoe races to triathlons (see Startup Offers 'Fail-safe' RFID Race-Timing System). More than a year later, in April 2010, ChronoTrack Systems introduced its B-Tag, a passive batteryless EPC Gen 2 tag that comes attached to a racing bib.

For RFID Race Timing Systems, on the other hand, the breakthrough occurred in 2009, when PowerID introduced its PowerT, a BAP RFID tag designed specifically for racing applications. The PowerT employs an ultra-thin liquid battery that powers the on-board RFID chip, thereby leaving maximum energy backscatter to the reader. Because it is essentially still a passive tag, Peterson notes, it can be manufactured cheaper than an active tag using a coin battery cell. The tag can be built into the back of the bib, thus eliminating the need for racers to attach it.

The tags have a battery life of up to two and a half years, and can still be utilized as a passive UHF tag once the battery is dead.

RFID Race Timing Systems developed its own UHF patch antennas specifically for its readers. According to Peterson, the antennas are embedded in a flexible mat that is easy to position and extremely thin, in order to prevent athletes from tripping over a thick, bulky antenna section. The interrogator is contained in a small, heavy-duty case designed for work outdoors that also contains networking hardware and an industrial computer. With four or eight antenna ports, a single control box can river four or eight antennas to cover a timing point of 4.5 meters (14.8 feet) or 9 meters (30 feet) in width. The company claims its EPC Gen 2 UHF reader is currently the world's most sensitive such device, with a read range up to 70 meters (230 feet) using the BAP tag.

To date, Peterson says, the results have been extremely good. "UHF read rates are as much as 300 tags a second, which is much more than is required," he says. "The biggest issue with UHF tags is readability, and we recorded an accurate read rate of 99.7 percent."

The number of vendors that manufacture UHF tags is greater than for LF tags, meaning that UHF tags are some of the least expensive RFID transponders on the market, owing to manufacturing volumes. This, Peterson says, makes the tags priced low enough to be disposable after use.

"UHF is a step above LF tags, and I believe this will be the tag of choice in running and cycling events," Peterson adds. "UHF may not be the solution for multi-sports, such as triathlon, as the tag is often worn on the ankle under a wetsuit for swimming events, and this is a barrier to UHF. But by this time next year, I believe UHF will make up 60 percent of the running and cycling timing market, and it will be 95 percent the following year."

Damien Hancox, of Tomato Timing, has used the Ultra system for a number of races, the largest of which was a Sri Chinmoy race that attracted 2,300 competitors. The Sri Chinmoy Marathon Team stages running and triathlon events in Melbourne, Sydney, Canberra and other Australian cities.

"I still have the [LF] race-timing system for multi-sport and swim events," Hancox says, "but the convenience of mailing out the race bib with the tag attached, and the fact that the timing tag is disposable, was a big factor in choosing Ultra. Race directors love it, because less staff is needed on the day for registration, no staff is needed for the collection of timing bands and no charge is associated with the non-return of timing bands, which can run into the thousands of dollars for large events."

Hancox adds, "For us, it eliminates incorrect timing bands being handed to the wrong person at registration before the race, and there is no need to check returned chips and rescan for the next race."

In February 2010, MyLaps introduced its BibTag, a battery-powered UHF RFID tag that is integrated with a race bib.