Timing transponder

Sports shoe with timing transponder

Start number with integrated transponder

A timing transponder is a small transponder that is used at sporting events for timing and route control.

Timing transponders are used at major events such as public and marathon races , triathlon and inline events or bike races. When registering, the participants are assigned a start number, which is either linked to the ID number of a transponder or saved directly on it. This means that individual net and gross timekeeping of thousands of athletes can be carried out during an event.

The times and thus also the presence of the participant are only recorded at discrete locations, the time measuring points. To control compliance with the route, systems for recording intermediate times must be provided at all critical points.

history

RFID running chips were developed in 1993 by students at the University of Nijmegen and tested for the first time at the Zevenheuvelenloop there. The following year they were used in the Berlin Marathon . Due to the simplicity and high measurement accuracy, RFID systems are used for individual time recording even at small events.

technology

The transponder sends its ID number to the timing system. Start, finish and any number of intermediate times can be registered and assigned to the athletes. The data is available in real time to attendees, the press, television and the Internet. In the case of important events, double mats located directly behind one another are usually used for passive systems to ensure greater reliability. This is not necessary with active systems.

Passive RFID systems

All technologies in which the transponder (tag) carried by the participant does not have its own battery are referred to as passive systems. It is supplied with energy by the timing system via induction (mostly 125 kHz or 13.56 MHz) or electromagnetic radiation (UHF, see below). Such tags do not record or process any data during competition, but only announce their presence in the area of the receiving antenna.

UHF Gen2

UHF Gen2 tags, which work at 865.6 ... 867.6 MHz in Germany and can be purchased very cheaply due to their widespread use, have established themselves at popular sports events.

For this purpose, one or two tags (antenna + microchip ) are attached to the back of the start number (bib) . The tags are usually not returnable or subject to a deposit, but can be taken home or disposed of after the event by the participant together with the start number. The start numbers can be ordered directly from the relevant providers with preprogrammed chips and glued-on tags, so that the timekeeper's work on site is limited to setting up the system and issuing the start numbers.

For events with water contact (e.g. triathlon), reusable, encapsulated tags such as the one that are usually worn on the leg are still used.

Proprietary Systems

Opened 125 kHz RFID tag from mika: timing GmbH. Outside diameter of the coil: 24 mm.

Before the triumph of UHF Gen2, the market was split between many individual providers. Due to the production costs for individual transponders, these mostly had to be bought by the participants or rented for specific events. For this purpose, a one-time purchased transponder could be used at all events that used systems from the same manufacturer.

The so-called ChampionChip (company mika: timing GmbH) was the market leader for a long time. However, due to the better detection performance and easier handling of UHF systems, their low-frequency systems are slowly being displaced from the market.

Active transponders

Active transponders are increasingly used for high-level competitions. They contain a battery.

Active tags

Active transponder

Active systems usually work on two frequencies, a low frequency for the detection line (the so-called loop , e.g. 125 kHz) to trigger the detection, and a high frequency with a longer range for the actual communication with the timing system (e.g. 2.4 GHz ). This offers advantages such as higher temporal accuracy and more reliable triggering, as well as partially extended functions. Depending on the system, these include:

Intermediate timekeeping in the transponder: at a remote point without internet access or mobile phone network, a clock can be started in the transponder, and the transponder thus confirms the crossing of the point along with the time the next time it crosses a regular time measuring point.
Increased detection reliability: the transponder transmits the point in time when the detection was triggered until the timing system has confirmed receipt. Thus, no release can be lost.
No collisions: With passive systems, all transponders on the detection line transmit at the same time. In active systems, when the channel is occupied, detections can still be transmitted seconds after crossing the detection line, which means that several 100 transponders can be triggered simultaneously.

There are transponders with rechargeable batteries, fixed batteries (with a service life of up to 7 years) and, for vehicles, transponders with an external connection for the supply voltage.

Systems using GPS

Systems that use the Global Positioning System (GPS) are sometimes used, but have so far not been able to establish themselves. The high energy consumption and the associated frequent charging, the costs for the trackers as well as the overloading of the cellular networks with thousands of transponders in one network cell at the same time are problems that have not yet been solved.

advantages

The time measurement transponder enables fully automatic time recording and evaluation. The result lists can be created as soon as each participant crosses the finish line, human errors are avoided.

The net time measurement is only possible with transponders, since this is the only way to determine the time for each participant when crossing the start line. For award ceremonies, the gross time still counts (time elapsed since the starting shot), as it has the lowest potential for abuse.

The individual antenna mats ( similar in form and function to a cable bridge , equipped with wire loops or antenna elements depending on the system) can be used in a modular manner, i.e. they can be used at different points and in different widths. For example, system widths of up to 16 meters (across the direction of movement) are currently used in the Berlin Marathon. In this way, a large number of athletes can cross a certain time measurement point at the same time. Waiting times in the start area or delays at checkpoints and in the finish area that often occur during mass runs are avoided.

disadvantage

Problems often arose with the first passive systems. If the receiver coil is perpendicular to the transmitter coil of the antenna mat or too far away from it, no voltage is induced and the chip remains silent. The problem arose especially when the tag was worn on the body rather than on the shoe or ankle. However, when worn on the shoe or ankle, the runner's torso is not measured, as prescribed by IAAF rules.

With UHF Gen2, the power is sufficient to ensure reliable detections even at head height. The polarization direction of the antennas in the transponder and the antenna mat on the floor must, however, still match.

In current active systems, a 3-D coil ensures that they can trigger completely independently of the orientation.

In addition, a target camera is still used for high-class events, also to ensure a rating through redundancy in any case.

providers

Most providers offer active and passive systems. Widespread on the market include:

MYLAPS with ChampionChip , ChipX (passive) and TranX (active)
race | result with the race | result passive system (UHF Gen2) and race | result active system (active)
Micro Talk Systems with J-Chip (active)
Smartrac transponder ( DogBone ) as a producer of Gen2 UHF chips that can be programmed as required.

gallery

Rod-shaped RFID transponder from ChampionChip , weight approx. 4 g
Exposed chip with ferrite rod antenna
Flat RFID chip, 38 mm diameter, weight around 3 g.
System for the Ironman Germany 2007 marathon. The transponder is attached to the black and red ribbon on the ankle
Target system of the Berlin Marathon 2003 with the marathon world record by Paul Tergat (Kenya) in 2:04:55 hours