May 16, 2012

Tech Talk – One tag Vs Two?

As there is a lot of confusion out there in the timing world in regard to how many tags are needed to successfully time races with the claim “we are best because we only need one tag” touted by some manufacturers.

So in typical RFID Race Timing fashion we aim to clear the smoke and mirrors that these other manufacturers persist  on using and explain the facts as they are.

Anyone who is involved in timing knows this business centrally revolves around risk management. In any mission critical system, the more layers of redundancy, means the risk of something catastrophic going wrong is reduced. The fact that we employ double lines for mass participant starts, patch antenna in the post finish area, manual backup, etc all aim to get race day read statistics closer to the magic 100%.

No system is 100% and those that claim this, are simply not speaking the truth for one reason – The readability of tags at a particular point in time is influenced by the human participants that are wearing them.

Whether the competitor has decided to wear their bib incorrectly, put it in their pocket, carry it in their hand, or even mount it over a large stomach, all of these actions will reduce the RFID signal and possibly prevent a reliable read. The more chances you have in grabbing a read the less chances of missing athletes! Its as simple as that.

The decision to double tag competitors is also part of this equation. It means that the timer doubles the chance of capturing the athlete. When we analyse the data collected in a double tag event we notice that the reads from tag one will happily deliver us with read percentages around the 99.5% mark. The remaining 0.5% is the human effect. The second tag raises the bar and gets us up to better than 99.95% read  rate. At RFID we are always pushing towards that magic mark of perfection: 100%. That’s why we recommend double tagging and because of the low cost structure of tags it is not that more expensive.

This decision, however is entirely at the discretion of the timers, and they need to assess the risk factors presented to each event. Factors like what are the weather conditions, how many participants, density of participants, hardware setup, manual backup available, even the nature of the competitors.

In a recent news item about a major US Marathon, the manufacturer of the system boasting about using single tags stated, “that they did not miss one athlete….in the elite section”. This was certainly choosing words carefully, the elite being an infinitely smaller field (29 entrants of which 18 posted finish times). The same claim was not extended to the whole field of twenty two thousand other competitors!

How many were missed here?

The difference between 99.5 and 99.95 over the 22,500 participants is 100 people going home without a time. If this is acceptable then one tag is just fine, but if you are the athlete, seriously is an extra 30 cents good insurance against being missed ? (that would of course be $1 plus with the other systems due to their inflated tag prices).

The bottom line is all systems will work with one tag. All the main manufacturers are using quality components and in reality their technical abilities are all reasonably similar. So there is no dramatic advantage of one system over another with regard to tag numbers.

It all depends on what the timer is prepared to live with in regards to missed reads, and what redundancies they have in place. Risk management must take all the factors into account, and if price constraints mean that only one tag is called for then other redundancies must be in place to ensure that tags are read to a satisfactory percentage.

At the end of the race the questions have to be answered to those with missed times.

Are you prepared to tell them it happened because you decided to skimp on 30 cents?


Post note. RFID Race timing has no financial agenda in selling more tags as we sell an open system capable of reading any Gen 2 RFID tag on the market. Our motivation in double tagging is in providing our timers with the knowledge so they can do all in their power to provide an excellent service aiming at perfection.

RFID News, Tech Talk, Uncategorized

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