Control of Road Races Timing Systems. How do they work

Current popular race timing systems, or road races, are popularly referred to as chip timing. Its correct technical name is Timing Systems by Transponder, and not by chip.

What is a transponder?

A transponder is an element that emits a answer when excited with some type of wavelength.

So within this category we have from the barcodes that reflect the laser light that it is applied over them by an exciter, and the barcode receiver can then read the printed alphanumeric values ​​that make up the code. Until, for example in Formula One, to obtain a greater precision the transponder is excited by a laser that coincides with the finish line and returns the dorsal of the car.

EIn the case of timing popular races are electronic circuits that are subjected to magnetic fields that produce an electric flow in them that will feed the emission of a radio signal that will be captured by the receiving antennas of the system. This emission will be either the athlete’s bib number or a number that identifies univocally the chip, known as the ID of the antenna.

Types of transponders.

Champion Chip, creator of the first transponder system for racing timing, design two types of systems, one active and one passive. The active system is more used in official competitions, while the passive is used in crowned races where the main participants are popular athletes, although they are also official races.

In active systems, the chip has a small adjoining battery that generates enough electricity for the emission of a radio signal, although it only emits this signal when the chip detects that it is subjected to a magnetic field. And in passive systems the electric flow is generated by the magnetic field itself and the attached battery is not necessary. Therefore, the active system is more effective because with a light magnetic field the chip already returns a valid signal, while the passive system is cheaper to save the battery.

Within the passive systems, chips exist in different types of frequencies, being today the UHF chips the most extended since they are the cheapest disposable chips in the market.

Therefore, we will focus this time on how passive chips work.

Excitation and reception systems.

As we have already writen a timing system by transponder will have three key elements: the exciter of the chip, the receiver and the decoder.

Both the exciter and the receiver are usually encapsulated in the same device: the antenna, and the decoder is a suitcase or device that interprets and stores the detections made.

In this way, the antenna is constantly emitting a magnetic field in order to excite the chips that cross that field. When the chip captures enough energy when subjected to the magnetic field, it emits a radio signal. This radio signal will be picked up by the antenna and sent to the decoder. The decoder will obtain the number (bib number or identifier of the chip) and will assign the current step time, the time that at that moment marks the clock of the decoder.

Explained for less technical people, the exciter creates a magnetic field, which does not other thing that a constant flow of electrons rotating from the positive pole to the negative constantly. When the transponder enters in this flow, its electrons also begin to move inside it, which in fact it is an electric flow, when the electrons move with sufficient speed inside the chip, the radio that is integrated inside, begins to transmit a unique signal that is not other thong that a numeric identifier. It's as if the transponder started shout 501!, 501!, 501!

The antenna also has an ear (receiver) listening to everything that is shouted inside the magnetic field, once the signal is captured it sends it to the brain (decoder) that interprets it and assigns it the time at which it was heard.

Therefore, two scenarios occur:

  • The transponder must be in the magnetic field long enough so that its electric flow is enough to turn on the radio. If an athlete will cross very, very fast, the finish line the chip would never send its identifier. This is the reason why in official competitions the active chip is used because that should not wait to send the signal until the electric flow is obtained from a battery.
  • Once the emitision starts, the antenna identifier is sent multiple times, and only one must be registered. For that reason, the current decoders wait to register the detection time of a chip to stop listening to it, and then record the time of the time that I listen most clearly because it was closer.

How to certify the best precision of the systems

With the emergence of timing systems by chip is often questioned without even if athletics judges have still usefull in road races with using transponder timing systems.

The answer without a doubt is, YES, the judges are still necessary but now we have better systems to control the events. The work of the judges will be a task of control and certification of the results.

Timing companies alone do not have the power to certify the accuracy of a time, only provide the electronic systems, and the operation of these. Finally, they will provide the judges lists of results that we will have to compare to validate their accuracy.

There are few issues that must be checked to be able to certify that the results provided by a timing system by transponder.

In my opinion they are:

      1. Location of the systems

        The first task will be to verify, with the homologation report of the circuit, the correct placement of the timing devices in each kilometric point of control, in such a way that the athlete is not detected before that points. It must be detected at the exact point, or later approximate.

        Note: It must be considered that the transponder systems do not detect the athlete on an exact line (such as the finish line), but can detect it in an ellipsoid magnetic field with several centimeters with.

        As the current systems assign the final time with the sharpest signal received, determining the antenna should be placed coinciding with the finish line. EYE! The antenna, not the set of carpet or cable grommet that contains it.

      2. Synchronization of timing systems

        Most approved timing systems do not have an automatic start-up system, and less than the intermediate points; therefore, they must be synchronized before the start of the race.

        The first task of the judges, before the start of the race, will be to check the perfect synchronization of all the timing points, and in a coordinated way pass a chip through all the control points after a fictitious start-up of the system. The Electronic Timekeeping Judge, in a central computer (normally placed in the finish line), must verify that all the systems registered said chip in the same second. This registered time may be expressed in the system's own clock time, or in a mark after the fictitious start-up.

        In the absence of an automatic start-up system, the valid time must be synchronized with the judges' chronometer correctly started. In systems without automatic start-up, the time of the electronic timing systems that do not coincide with those of the judges will not be valid. It is understood that it is normal for the rounded time taken by the judge to differ by more or less one second (never more), due to the rounding up and the differences in tenths that may occur between the judge's act of taking the time, and the Transponder detection by the system.

        If the detection devices are correctly located, the time indicated by the electronic system must be equal to or greater than the time taken by the judges, rarely less.

      3. Tiebreaks

        As we have already mentioned, the magnetic field where the transponder is excited and as a result emits a signal to be detected, is not a straight line. In addition, it is necessary specially when teh transponder it is placed on foot (for any systems).

        Both points cause that the detection time is not exactly the time when the body of the athlete crosses the finish line. For this reason, ties can be drawn that will hardly be broken with the timing system. While the time taken by a transponder system is accepted by the IAAF, the determination of the positions of arrival is still full power of the judges. Given that with the use of transponders, no longer control corridors of arrival to determine the positions, I recommend that the judges make the video recording of the arrivals to later be able to attend claims of the arrival posts. These will be easily located in the video from the time of recording, and the results of the electronic arrival system.

        The detection times in case of a tie should not be considered as irrefutable proof of the position of the athletes, especially when it is adjusted.

      4. Control of categories and sex.

        The transponders allow the detection of data of the bib number assigned to a transponder, they do not detect ages (categories), nor sexes.

        There are also cases of athletes who carry more than one transponder because they sell their results to other athletes for their later participation in more important classics. (The result determines a better or worse position of exit). The judges must have specially care with this type of fraud.

        One of the simplest controls is the control of the first women in arrival, and in the kilometric points, that later together with the operator of the timing system we will have to check in the results sheets.

      5. Control of passage and start-ups.

        The placement of a detection system at the star line, nothing contributes to the certification of results in terms of the accuracy of them. But if it provides evidence of possible fraud at the time of completing the circuit.

        Although it seems obvious regarding the classifications, I must insist that the time between the detection of the athlete at the start line and the detection of the athlete on finish line, is not an official time that should appear on the final page of official results.

        The judge responsible for the electronic timekeeping should check the list of athletes who were not detected at the start, or any intermediate kilometer point of control, in order to validate their result obtained at the finish line.

        For the controversy remains if an athlete not detected at some point should be disqualified, which I think is safe, is that without other evidence, the result should not be estimated as valid for the ranking.

        Should you disqualify in this case? It remains in the judgment of the Referee of the Race after reviewing the available evidence.

        No electronic timing system by transponder ensures 100% of detections with correct use. In addition to this uncertainty (close to 1% in all systems), the uncertainty of the incorrect use of transponders by athletes is added: Do not carry the transponder, carry it but incorrectly, manipulate the transponder (break), or failure of the electronic circuit due to poor preservation of the circuit between its delivery and its use.


The judges are the guarantors of the correct drafting of the results sheets and certification of the results obtained and their tasks are:

Check the placing and synchronization of the timing systems at each control point.

Check the accuracy of the times, and in the systems without automatic start-up, set the time of the first classified with their manual chronometers. Once the time of the first classified is right, control with random times that the time differences are saved with the rest of the classifieds plus / minus one second.

Be especially attentive to women and if possible at a glance to the categories, as well as verify "randomly" behind finish line if athletes carry more than one transponder.

Check the athletes that have not been detected at the start, or any other kilometer point, to indicate that their result should not be considered in the ranking, or even if there is certainty of fraud, disqualify it.

And all this reflect in reports attached to the results sheets that certify the validity of the results.

All these tasks must be carried out without obstructing the arrival of the athletes with lines to take their bib numbers, and making the organizers and operators of the system aware that the judges are there as necessary collaborators, and not fiscal.

That is to say, it is not little work that remains to the judges, although some think that they are no longer necessary.

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