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I am considering building an RFID reader system that can monitor runners times in a foot race. I have read that there are three different types of RFID systems. LF, HF, and UHF. Which one would be best for this application? Has anyone had success building an antenna that can read RFID tags from a distance of a meter or more?

EDIT: Active or Passive? My current thought is to use passive technology. I want to be able to get the tags for as cheap as possible and I don't want there to be a chance of the internal batteries failing.

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    \$\begingroup\$ It would also be useful to know if it will be a passive no battery or an active type with a battery. \$\endgroup\$ – Rex Logan Oct 5 '10 at 13:43
  • \$\begingroup\$ I believe UHF is best and it can be done passive. \$\endgroup\$ – Kellenjb Oct 5 '10 at 14:47
  • \$\begingroup\$ @REX: I am thinking passive \$\endgroup\$ – PICyourBrain Oct 6 '10 at 14:06
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Can you make it compatible with ChampionChip (now merged with MyLaps)? Many runners have their own chips, and that would be a good standard to work from. You can pick up

In response to the comments and answers about the applicability of this technology to racing, I can say that I've run at least two dozen races with RFID tags, and have never had a problem with tag collisions, misses, or accuracy/finish order.

For redundancy, use two mats, and program in the rate at which runners are crossing. Then, if the first mat has a problem, you can use the second and extrapolate the time to cross the line.

Find a race that uses disposable chips, or just keep a pair from your next race, and see what you can come up with. Alternatively, this site sells personalized tags.

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  • \$\begingroup\$ I have seen a 4 mat solution deployed at the last ultra marathon I was at. \$\endgroup\$ – Kortuk Nov 5 '10 at 15:00
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I don't think you need long range (at least not how I categorize long range, like 15-30ft like a highway toll sensor).

At the Boston Marathon this year all the runners got a very small plastic cased passive RFID tag which was designed to be tied into their shoe laces.

At the 11 check points there was a large thin mat across the race track which detected the tag as they ran over it. I don't know the nature of the mat but i imagine it had multiple antennas so the detection distance was maybe 1 foot.

I've also seen some races where the RFID tag was in the bib but i believe there were still using mats for the antennas, the range would just need to be a few feet longer.

In terms of the final results accuracy, long distance races hardly ever end in a "photo finish" situation. If they were to end in that manner I image the judges would have a photo back up of the finish.

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RFID for runners times? Do you think that all tags will trigger at exactly the same distance from tag reader? I don't think so, and that will ruin accuracy a lot. For simplicity, imagine that you have single reader located exactly on the finish line. How will you know if runner is 2m from crossing the line in front of the reader, or just crossing the finish line 2m to the left or right? Do you plan to have more then one reader? I don't think that you have chosen the right technology to solve this problem...

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  • \$\begingroup\$ This technique is actually used for races all over the place including the Olympics and the Boston Marathon. (Do a google search on RFID race timing) I don't know how they pull it off (that's what I am trying to figure out) maybe they use a directional antenna that only communicates straight up. Also, at running speed, 2 meters takes about .5 seconds so if that was the worst case, I could accept that for a 5k race! \$\endgroup\$ – PICyourBrain Oct 6 '10 at 14:02
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    \$\begingroup\$ RFID is also used in triathlons using water proof RFID tags. It allows them to very easily track your time in and out of each stage of the race. \$\endgroup\$ – Kellenjb Oct 6 '10 at 14:49
  • \$\begingroup\$ Then google also for "miss rate" and "tag collision" when googling for "RFID race". I can just laugh at 20 times per second reading scan rate mentioned at respectable company's website: rfidtiming.com/?page=faq. There are so many problems with the technology that a lot of people think that world record will never be certified with such a system. \$\endgroup\$ – avra Oct 6 '10 at 21:01
  • \$\begingroup\$ That is interesting. \$\endgroup\$ – PICyourBrain Oct 7 '10 at 11:07

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