HK1245521B - Method and apparatus of determining the passing time of a moving transponder - Google Patents

Description

Method and apparatus for determining the passage time of a mobile transponder

Technical Field

The present invention relates to determining the transit time of a transponder through a detector antenna and, in particular but not exclusively, to a method and system for determining the transit time of a mobile transponder, a transponder for enabling the determination of the transit time of a mobile transponder, a timing module for determining the transit time of a mobile transponder through a detection antenna of a base station, a transponder for enabling the determination of the transit time, and a computer program product for using such a method.

Background Art

Sports events (such as car or motorcycle racing, track and field sports, and ice skating) often require accurate and fast time registration for tracking participants during the event. Such timing systems are often based on a transmitter-detector solution, where each participant in the event is provided with a transmitter (transponder). The transmitter can be configured to transmit packets at a certain frequency and insert a unique identifier into the packet so that the detector can associate the packet with a certain transmitter.

Each time a transmitter passes through the detector's loop antenna, the detector receives several data packets associated with the transmitter. The signal strength (RSSI) associated with each received data packet is a function of the transmitter's distance from the antenna and the specific configuration of the transmitter and detector antennas. Therefore, by assigning timestamp information and evaluating the signal strength associated with each data packet, the detector can determine when a transponder passes the detector antenna.

Examples of such timing systems are described in US5091895 and US20120087421. When such a system is used to determine the passing time of a car or bicycle, the transponder is mounted on the chassis or frame of the vehicle. In this case, the angle between the transponder and the ring detector embedded in the road is fixed and known, for example, 0 degrees or 90 degrees depending on the type of transponder. A simple implementation of the passing time algorithm is to find the time when the signal strength (e.g., RSSI) is maximum or minimum.

However, in certain situations, such as when the transponder is worn on the chest of an athlete (e.g., a runner), the angle between the transponder and the loop may vary. The runner may lean forward and/or sideways, causing the angle to not remain at a fixed, predetermined angle. In such situations, an algorithm that assumes a fixed angle will produce significant errors when determining transit times. Therefore, as can be seen from the above, there is a need in the art for an improved timing system that allows for accurate determination of transit times even when the angle between the transponder and the antenna is variable.

Summary of the Invention

As will be appreciated by those skilled in the art, aspects of the present invention may be embodied as a system, method, or computer program product. Thus, aspects of the present invention may take the form of a fully hardware embodiment, a fully software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which are generally referred to herein as "circuits," "modules," or "systems." The functions described in this disclosure may be implemented as algorithms executed by a microprocessor of a computer. Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer-readable media having a computer-readable program code embodied (e.g., stored) thereon.

Any combination of one or more computer-readable media may be utilized. A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media would include the following: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program used by or in conjunction with an instruction execution system, apparatus, or device.

A computer-readable signal medium may include a propagated data signal having computer-readable program code embodied therein (e.g., in baseband or as part of a carrier wave). Such a propagated signal may take any of a variety of forms, including, but not limited to, electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium that is not a computer-readable storage medium and that can communicate, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device.

The program code embodied in the computer-readable medium can use any suitable medium transmission, and this medium includes but is not limited to, wireless, wired line, optical fiber, cable, RF etc., or aforesaid any suitable combination.The computer program code that is used to carry out the operation of each aspect of the present invention can be written with any combination of one or more programming languages, comprises object-oriented programming language (such as, Java (TM), Smalltalk, C++ etc.) and conventional procedural programming language (such as, " C " programming language or similar programming language).Program code can be performed on the user's computer completely, partly on the user's computer, is performed as an independent software package, partly on the user's computer and partly on a remote computer, or is performed completely on a remote computer or server.Under a kind of latter scenario, the remote computer can be connected to the user's computer by any type of network (comprising local area network (LAN) or wide area network (WAN)), or can (for example, use internet service provider to pass through the internet) be connected to an external computer.

Aspects of the present invention are described below with reference to the flowchart illustrations and/or block diagrams of the methods, devices (systems) and computer program products according to embodiments of the present invention. It will be understood that each box in the flowchart illustrations and/or block diagrams and the combination of boxes in the flowchart illustrations and/or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor (especially a microprocessor or central processing unit (CPU)) of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine so that the instructions executed by the processor of the computer, other programmable data processing device or other device produce equipment for implementing the function/action specified in one or more boxes in the flowchart and/or block diagram.

These computer program instructions may also be stored in a computer-readable medium, which may instruct a computer, other programmable data processing apparatus, or other device to operate in a specific manner, so that the instructions stored in the computer-readable medium produce a product that includes instructions for implementing the functions/actions specified in one or more blocks in the flowchart and/or block diagram.

The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operating steps are performed on the computer, other programmable apparatus, or other device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide a process for implementing the functions/actions specified in one or more blocks in the flowchart and/or block diagram.

The flow chart and block diagrams in the figure illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present invention.In this regard, each box in the flow chart or block diagram can represent a part of a module, fragment, or code, which includes one or more executable instructions for realizing (one or more) specified logical functions.It should also be noted that in some alternative implementations, the function shown in the box can occur in a different order than that shown in the figure.For example, two boxes shown as continuous can actually be performed substantially simultaneously, or depending on the functions involved, the box can sometimes be performed in the opposite order.It should also be noted that each box in the block diagram and/or flow chart description and the combination of the boxes in the block diagram and/or flow chart description can be realized by a special hardware-based system that performs a specified function or action, or can be realized by a combination of special hardware and computer instructions.

It is an object of the present invention to reduce or eliminate at least one disadvantage known in the prior art.In a first aspect, the present invention may relate to a method of determining a transit time of a mobile transponder past a detection antenna of a base station.

In a first embodiment, the method may include: exchanging a first signal (sequence) between a first transponder coil and the detection antenna and exchanging a second signal (sequence) between a second transponder coil and the detection coil during the passage; associating the first signal and/or the second signal with a time instance indicating the time when the first signal and/or the second signal was exchanged between the transponder and the base station; and determining the passage time of the at least one transponder based on the signal strength of the first signal and the second signal and the time instance.

The present invention aims to provide an accurate transit time that is corrected for errors caused by changes in the angular orientation of the transponder relative to the detection antenna. This correction is based on the signal strength of two different signal sequences exchanged between the transponder and the base station during the transit. In this process, the signal strength values can be time-stamped so that these values can be linked to a timeline. The inventors have discovered that the signal strength of the two different signal sequences is correlated with the angular orientation of the transponder coil relative to the detection antenna. Analysis of the signal strengths of the first and second signal sequences exchanged during the transit of the transponder allows the transit time to be determined that is corrected for the angular orientation of the transponder coil relative to the detection antenna. In this way, errors in the transit time can be eliminated or at least significantly reduced. Therefore, the present invention makes it possible to determine a more accurate transit time than timing systems known from the prior art. The present invention is simple and does not require additional hardware in the transponder, such as an accelerometer. Furthermore, the present invention is independent of the speed at which the transponder passes the detection antenna.

In an embodiment, the magnetic axis of the first transponder coil is oriented differently from the magnetic axis of the second transponder coil. In another embodiment, the magnetic axis of the first transponder coil may be oriented perpendicular to the magnetic axis of the second transponder coil. Thus, the first signal and the second signal are exchanged between the transponder and the base station based on the transponder coils being oriented differently relative to the detection antenna (typically a detection coil embedded in the track or above the track using, for example, a mat antenna).

In an embodiment, the transit time may be determined based on at least one time instance associated with at least one maximum field strength value of the first signal and at least one time instance associated with at least one minimum field strength value of the second signal. Thus, the extreme values in the field strength values of the first and second signals may be used to accurately determine the transit time corrected for errors due to variations in the angular orientation of the transponder relative to the detection antenna.

In an embodiment, the time instance may indicate the time at which the first signal and/or the second signal is received by the base station. In such an embodiment, upon receipt, the signal may be time stamped by the base station in order to provide a time basis for measuring the field strength.

In an embodiment, the method may further include: using the first transponder coil to receive the first signal transmitted by the detection antenna; and using the second transponder coil to transmit the second signal to the detection antenna, wherein the second signal includes a first signal strength value of the first signal. In such an embodiment, the field strength of the first signal received by the transponder is determined by the transponder.

In an embodiment, the method may further include: the transponder determining a first signal strength value associated with the first signal. In another embodiment, the method may further include: if the signal strength value is above a predetermined threshold, then the transponder determining that the second signal includes the signal strength value for transmission to the detection antenna. In such an embodiment, if the signal strength of the signal transmitted by the base station is sufficiently strong (i.e., the transponder is within a certain distance from the detection antenna), then the transmitter unit in the transponder may be triggered.

In an embodiment, the method may further comprise: detecting the second signal; and associating the second signal with a second field strength value.

In an embodiment, the method may further include: the transponder using the first transponder coil for transmitting the first signal to the detection antenna; and using the second transponder coil for transmitting the second signal to the detection antenna.

In an embodiment, the method may further comprise: detecting the first signal and the second signal; and associating the first signal and the second signal with a first field strength value and a second field strength value, respectively.

In an embodiment, the method may further include: determining at least a first time instance _T1 when the signal strength of the first signal has at least one minimum signal strength value and at least a second time instance _T2 when the signal strength of the second signal has at least one maximum signal strength value; and determining a passing time _Tp by correcting _T1 or _T2 based on a difference between _T1 and _T2 .

In an embodiment, the first signal and/or the second signal may comprise an identifier for identifying the transponder.

In another aspect, the present invention may relate to a timing system for determining a passage time of a mobile transponder through at least one detection antenna of a base station, the system being configured to: exchange a first signal sequence between a first transponder coil and the detection antenna and a second signal sequence between a second transponder coil and the detection coil during the passage of at least one transponder; associate the first signal and/or the second signal with a time instance indicating the time when the first signal and/or the second signal was exchanged between the transponder and the base station; and determine the passage time of the at least one transponder based on the signal strengths of the first signal and the second signal and the time instance.

In yet another aspect, the present invention may relate to a base station configured to determine a passage time of a mobile transponder passing a detection antenna. In an embodiment, the base station may be configured to: during the passage of at least one transponder, transmit a first signal sequence to a first transponder coil via the detection antenna and receive a second signal sequence transmitted by a second transponder coil to the detection antenna, the second signal comprising a signal strength value of the first signal; associate the first signal and/or the second signal with a time instance indicating a time when the first signal and/or the second signal were exchanged between the transponder and the base station; and determine the passage time of the transponder based on the signal strengths of the first and second signals and the time instance.

In another embodiment, the base station may be configured to: receive a first signal sequence transmitted by a first transponder coil and receive a second signal sequence transmitted by a second transponder coil during a passage of at least one transponder; associate the first signal and/or the second signal with a time instance indicating a time when the first signal and/or the second signal was exchanged between the transponder and the base station; and determine a passage time of the transponder based on signal strengths of the first signal and the second signal and the time instance.

In a further aspect, the present invention may relate to a timing module for determining a passage time of a mobile transponder passing a detection antenna of a base station, wherein the module may be configured to: receive a first signal strength value associated with a first signal sequence exchanged between at least one transponder and the base station; and receive a second signal strength value associated with a second signal sequence exchanged between at least one transponder and the base station; wherein the first strength value and the second strength value are associated with time instances when the first signal and/or the second signal are exchanged between the transponder and the base station; determine at least a first time instance _T1 when the signal strength of the first signal has at least one minimum signal strength value and at least a second time instance _T2 when the signal strength of the second signal has at least one maximum signal strength value; and determine a passage time _Tp by correcting _T1 or _T2 based on a difference between _T1 and _T2 .

In yet another aspect, the present invention may relate to a transponder for exchanging signals with a timing system, the timing system being configured to determine a passage time when the transponder passes through a detection antenna of the timing system, wherein the transponder may include: a detector unit, which uses a first transponder coil for detecting a first signal transmitted to the transponder by the timing system at a first carrier frequency; a transmitter unit, which uses a second transponder coil for transmitting a second signal to the detection antenna at a second carrier frequency; wherein the magnetic axis direction of the first transponder coil is different from the magnetic axis direction of the second transponder coil; and wherein the magnetic axis direction of the first transponder coil is different from the magnetic axis direction of the second transponder coil.

In an embodiment, the first (carrier) frequency may be selected in the range between 10 and 1000 kHz (preferably between 50 and 250 kHz). In an embodiment, the second (carrier) frequency may be selected in the range between 5 and 500 MHz. In another embodiment, the second (carrier) frequency may be selected in the range between 0.5 and 6 GHz.

The signal strength of the signal exchanged between the transponder and the timing system will depend on the electromagnetic coupling between the transponder coil and the detection antenna. Therefore, when the transponder moves towards the detection antenna, the electromagnetic coupling between the transponder coil and the detection coil - and therefore the signal strength of the exchanged signal - will vary as a function of the distance between the transponder and the detection antenna. This function (distance function) can be used to accurately determine the transit time, i.e. the time instance at which the transponder passes through the timing line. However, the distance function also depends on the (angular) orientation of the (one or more) transponder coils relative to the detection ring. Only for certain predetermined orientations of the transponder coil relative to the detection coil can the maximum magnetic coupling or minimum coupling with the detection antenna be achieved directly above the timing line. In this case, the transit time can be determined by an algorithm that monitors the signal strength of the transponder signal during the passage and detects at which time instance the minimum or maximum value of the signal strength occurs. This time instance is then determined as the transit time.

However, in many cases, the angular orientation of the transponder coil and the detection antenna deviates from this ideal. The angular orientation is not fixed, but rather variable and depends on the orientation of the athlete's (or vehicle's) body (or the vehicle's) as it passes the timing line. Consequently, in many cases, the location of the extreme values in the signal strength signal no longer coincides with the transponder's passage across the timing line.

The transponder according to the present invention makes it possible to determine the transit time of the transponder for different (angular) orientations relative to the detection antenna. In particular, the transponder makes it possible to determine the transit time for different transponder orientations due to the fact that the magnetic axis of the transponder coil is oriented in different directions, so that—at a certain distance between the transponder and the detection antenna—the electromagnetic coupling between the transponder and the base station will be different.

The inventors discovered that the distance function associated with the first and second transponder coils is dependent on the angular orientation of the transponder coils and the detection antenna. Consequently, analysis of the signal strengths of the first and second signal sequences exchanged during a transponder's passage allows for the determination of a transit time corrected for the angular orientation of the transponder coils relative to the detection antenna. This eliminates or at least significantly reduces errors in the transit time. Consequently, the present invention enables the determination of a more accurate transit time than with timing systems known from the prior art.

In an embodiment, the magnetic axis direction of the first transponder coil may be substantially perpendicular to the magnetic axis direction of the second transponder coil.

In an embodiment, the transponder may further include a transponder processor configured to measure the signal strength of the second signal, provide one or more data packets, insert the one or more measured signal strength values of the second signal as a payload into the one or more data packets, and provide the one or more data packets to the transmitter unit for transmitting the first signal including the one or more data packets to the detection antenna.

In an embodiment, the sequence in which two or more signal strength values are inserted into the payload of at least one of said data packets is determined by the order in which the transponders have detected the first signal.

In an embodiment, the transponder processor may be configured to activate the receiver unit and/or the transmitter unit if the signal strength of the second signal is above a predetermined signal strength threshold, or if the second signal comprises a predetermined modulation pattern.

In a further aspect, the present invention may relate to a sports bib comprising: a support sheet attachable to clothing and/or the body to support a transponder, preferably comprising a printed identifier on a front side of the support sheet; and a transponder as described above. In an embodiment, the transponder may be attached to the support sheet such that one of the magnetic axes of the first transponder coil or the second transponder coil is oriented substantially parallel to the plane of the support sheet, and one of the magnetic axes of the first transponder coil or the second transponder coil is oriented substantially perpendicular to the plane of the support sheet.

The invention may also relate to a computer program or a computer program suite comprising at least one software code portion, or a computer program product storing at least one software code portion, configured for performing a method according to one or more of the above methods when the software code portion is run on a computer system.

The present invention will be further described with reference to the accompanying drawings, which schematically show embodiments according to the present invention. It will be understood that the present invention is not limited in any way to these specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 schematically depicts a motion timing system according to an embodiment of the present invention.

2 depicts a schematic diagram of at least a portion of a timing system according to an embodiment of the present invention.

3A and 3B depict the signal strength of the transponder passing through the detection antenna for a first angular orientation of the transponder coil relative to the detection ring.

4A and 4B illustrate the signal strength of a transponder passing through a detection antenna as a function of the distance between the transponder and the timing wire for a particular coil configuration.

5A and 5B illustrate the signal strength of a transponder passing through a detection antenna as a function of the distance between the transponder and the timing wire for other coil configurations.

FIG6 illustrates the signal strength of a transponder passing through a detection antenna and the signal strength values used to determine the passage time as a function of the distance between the transponder and the timing line for a particular coil configuration.

7A and 7B depict the dependency of the increment Δ on the angular orientation of the transponder plane and the linear dependency of the increment on the error introduced by the angular orientation of the transponder plane.

FIG8 shows the error in transit time as a function of angle.

9 depicts a flow chart of a process for determining a mobile transponder's transit time, according to an embodiment of the present invention.

10A and 10B depict a transponder-base station configuration according to an embodiment of the present invention.

11A and 11B depict an embodiment of a timing system that allows signals to be exchanged between a transponder and a base station based on at least two different coil configurations.

12 depicts a block diagram illustrating an exemplary data processing system that may be used in the systems and methods as described herein.

DETAILED DESCRIPTION

FIG1 schematically illustrates a timing system according to an embodiment of the present invention. Specifically, FIG1 schematically illustrates a timing system 100 that can be used for timing a mobile transponder. For example, the timing system can be used at sporting events, such as motorcycle and bicycle races, marathons, and triathlons, where participants 102 of the event can wear a transponder 106 associated with a unique identifier. In an embodiment, the transponder can be attached to the participant's clothing or harness 104 or the participant's vehicle. The harness can include a support sheet that can be secured to clothing and/or the body for supporting the transponder, wherein the support sheet includes a printed identifier on the front side of the support sheet.

The timing system may also include a base station 112 connected to one or more base station detection antennas 110 (e.g., one or more detection rings) that may be embedded in the ground or arranged on or next to the track. For example, in an embodiment, one or more detection rings may be implemented as carpet antennas. The detection antennas may be aligned with a timing line 108 (e.g., a terminal plane, etc.) serving as a reference marker for a passing time (i.e., a time instance at which a particular portion of a participant passes (crosses) the timing line). The base station and the transponder may be configured to exchange signals so as to enable accurate determination of the passing time.

For this reason, the base station may include a receiver 118 for detecting transponder signals 116. In the case of two-way communication between the transponder and the base station, the base station may also include a transmitter 119 for transmitting the base station signal 114 to the transponder via a detection antenna or another antenna. During the time the transponder passes over the timing line, the base station receiver may detect the transponder signal sequence. The base station may also determine signal timing information (e.g., reception time) and the signal strength information associated with the received transponder signal. The base station processor 120 may determine the passing time based on the transponder signal and the associated signal timing and signal strength information. A portion of the data processing may be completed remotely by a data processing module 122 hosted on a server. In this case, the base station may be configured to transmit information to the data processing module via one or more networks 124. A database 126 connected to the server may be used to store the passing time for later use.

The signal strength of the transponder signal received by the base station will depend on the electromagnetic coupling between the transponder coil and the detection antenna. Therefore, when the transponder moves towards the detection antenna, the electromagnetic coupling between the transponder coil and the detection coil - and therefore the signal strength of the detected transponder signal - will change as a function of the distance between the transponder and the detection antenna. This function, which may be referred to as the distance function below, can be used to accurately determine the transit time, i.e. the time instance at which the transponder passes through the timing line. However, the distance function also depends on the (angular) orientation of the (one or more) transponder coils relative to the detection ring. Only for certain predetermined angular orientations of the transponder coil relative to the detection coil can the maximum magnetic coupling or minimum coupling with the detection antenna be achieved directly above the timing line. In this case, the transit time can be determined by an algorithm that monitors the signal strength of the transponder signal during the transit and detects at which time instance the minimum or maximum value of the signal strength occurs. This time instance is then determined as the transit time.

In some embodiments, the angle of transponder coil and detection antenna is oriented to the direction of the detection antenna. However, in many cases, the angle of transponder coil and detection antenna is oriented to deviate from the above-mentioned ideal situation. The angle is not fixed but variable, and depends on the direction of his or her body (or the direction of vehicle) when the athlete (vehicle) passes through the timing line. Therefore, in many cases, the position of extreme value is no longer consistent with the passing through of transponder on the timing line in the signal strength signal. The angle of transponder can cause the significant error in the passing time determined with respect to the detection ring. Therefore, in order to ensure accurate time measurement, it is necessary to consider that the passing time algorithm of transponder with respect to the angle of detection antenna is oriented.

To enable correction for these angular effects, the timing system in Figure 1 is configured to exchange a first signal sequence and a second signal sequence during the passage of the transponder over the detection coil, wherein the first signal sequence is exchanged based on a first transponder coil/detection coil configuration (first coil configuration) and the second signal sequence is exchanged based on a second transponder coil/detection coil configuration (second coil configuration). In an embodiment, the coil configuration can be formed by two different transponder coils and a detection coil connected to a base station. For example, the first coil configuration can include a first transponder coil and a detector coil, and the second coil configuration can include a second transponder coil and a detector coil, wherein the magnetic axes of the first transponder coil and the second transponder coil have different orientations. Based on the signal strengths of the first and second signal sequences exchanged during the passage of the transponder, a passage time corrected for the angular orientation of the transponder coil relative to the detection antenna can be determined. In this way, errors in the passage time can be eliminated or at least significantly reduced. The details of the timing system will be described in more detail below.

Fig. 2 depicts a schematic diagram of at least a portion of a timing system according to an embodiment of the present invention. In particular, Fig. 2 depicts a transponder module 202 and a base station 204 connected to a detection antenna 206 (e.g., a detection loop), wherein the detection antenna can be aligned with a timing line 205 (e.g., parallel to the y-axis). In this particular embodiment, the timing system is configured to exchange data bidirectionally between the transponder and the base station. To this end, the transponder can include a transmitter unit 208 for transmitting a first (transponder) signal 210 containing a data packet 230 to the base station and a receiver unit 212 for receiving a second (base station) signal 214 from the base station. Similarly, the base station can include a receiver unit 216 for receiving a signal from a transponder within the range of the detection antenna and a transmitter unit 220 for transmitting a transponder signal to the transponder. The base station can include a (real-time) clock so that the received signal and/or the transmitted signal can be time stamped when received or transmitted.

The transponder may include a power source in the form of a battery or the like. In an embodiment, the receiver unit of the transponder may be implemented as a low-power wake-up receiver, such that the receiver unit will only be activated if it receives a wake-up signal. In this way, the life of the power supply may be significantly extended. In an embodiment, the wake-up signal may be a signal having a predetermined carrier frequency and a signal strength, wherein the signal strength is greater than a predetermined signal strength threshold. In another embodiment, the wake-up signal may be a base station signal having a predetermined carrier frequency and a predetermined modulation mode. The predetermined modulation mode may be used to distinguish the carrier frequency from surrounding white noise.

The processors 222 and 224 in the transponder and base station can be configured to control the transmitter unit and the receiver unit so as to transmit and receive (exchange) signals based on a suitable data transmission scheme. Examples of such data transmission schemes may include quadrature amplitude modulation (QAM), frequency shift keying (FSK), phase shift keying (PSK), and amplitude shift keying (ASK). To this end, the processors in the transponder and base station can be configured to generate data packets in a certain data format that conforms to the data transmission scheme. The data packet may include a header and a payload. The header information may include a (unique) transponder identifier so that a receiver (e.g., a receiving unit in a base station) can link a transponder signal including one or more data packets to a specific transponder. The processors in the transponder and base station may also include a modulator for converting the data packets in the RF data signal and a demodulator for converting the RF data signal received by the transponder's detection unit into a data packet. The decoder in the processor can extract information from the data packet, e.g., header information and/or payload, which can be used by a transit time algorithm when determining transit time. To avoid collisions, an anti-collision scheme, e.g., a TDMA scheme, can be used. Typical transmission periods are in the range of 1 and 10 milliseconds, and typical data signal lengths may range between 50 and 300 microseconds.

The transponder may also include at least two magnetic coils arranged on a planar substrate 226 that defines a transponder plane. A first (receiver) coil 228 may be connected to the transponder's receiver unit, wherein the first coil has a magnetic axis 230 oriented in a first direction (e.g., in the transponder plane). The first receiver coil and the detection coil may form a first coil configuration for exchanging signals between the transponder and the base station. A second (transmitter) coil 232 connected to the transponder's transmitter unit may have its magnetic axis 234 oriented in a second direction (e.g., perpendicular to the transponder plane). The second transponder coil and the detection coil may form a second coil configuration for exchanging signals between the transponder and the detection coil. The coils may be implemented in various ways, for example, as dipole-type thin film or wire-wound coils (either with or without a ferrite core). The distance function will depend on the type of antenna used by the transponder.

The transmitter unit of the base station can transmit the transponder signal at a first (carrier) frequency (e.g., 125kHz) (the wake-up frequency of the transponder's receiver unit), but other frequencies are also conceivable. For example, in an embodiment, the first (carrier) frequency can be selected in the range between 10 and 1000kHz, preferably in the range between 50 and 250kHz. As the athlete moves toward the timing line, the transponder will move toward the transmitting detection coil so that the transponder coil can begin to pick up the base station signal at the first carrier frequency. The transponder processor can determine the signal strength of the received base station signal, and if the signal strength is above a signal strength threshold, it can begin to store the signal strength value of the detected base station signal in a buffer. In addition, the transponder processor can switch the transmitter unit from sleep mode to active mode. During active mode, the transponder processor can generate data packets in a predetermined data format and transmit these data packets to the base station in a transponder signal.

In an embodiment, the transponder signal may be transmitted to the base station at a second (carrier) frequency (e.g., 6.78 MHz) that is different from the first carrier frequency. However, other frequencies are also contemplated. For example, in an embodiment, the second (carrier) frequency may be selected from a range between 5 and 500 MHz. Alternatively, the second (carrier) frequency may be selected from a range between 0.5 and 6 GHz. The transponder processor may generate a data packet including a header 232 that includes, among other things, a transponder ID for enabling the base station to identify the source of the data packet. In addition, the transponder processor may insert one or more signal strength values 234 _1-3 of the detected base station signal into the payload of the data packet. In an embodiment, the data packet sent to the base station in the transponder signal may include one signal strength value. In another embodiment, the data packet may include two, three, four, or more signal strength values. The order in which the signal strength values are inserted into the payload of the data packet may determine the order in which the transponder detects the base station signal.

In an embodiment, when the detector unit of the transponder determines that the signal strength of the received base station signal is above a certain threshold, the transponder processor can start a counter. The counter can be increased or decreased until a certain final value is reached. During the counting period, the transponder can transmit a transponder signal. When the counter reaches its final value, the transponder processor can return the transmitter unit in the transponder to its sleep mode. Thereafter, the transponder processor can activate the transmitter unit if it still receives a base station signal with a signal strength above the threshold. Thus, the counter ensures that the transmitter unit is switched after a predetermined time. In this way, the transmitter unit is only in active mode when the base station signal is above a predetermined signal strength threshold (i.e., within a certain range of the detector antenna).

When the base station detects a transponder signal, it determines the signal strength (eg, RSSI) of the received transponder signal, converts the signal into digital data packets including one or more signal strength values as a payload, and assigns a time stamp to the data packets.

The signal strength of the transponder signal received by the base station will depend on the electromagnetic coupling between the transponder coil and the detection antenna. As the transponder moves toward the detection antenna, the electromagnetic coupling—and therefore the signal strength of the detected transponder signal—will vary as a function of the distance between the transponder and the detection antenna. The signal strength of the base station signal (transmitted by the detection coil and received by the transponder's first (receiver) coil) and the signal strength of the transponder signal (time stamp) determined during the transponder's passage over the detection coil (transmitted via the second (transmitter) coil and received by the base station) are used to accurately determine the transponder's passage time.

Figures 3A and 3B depict the measured signal strength of a transponder through a detection antenna for a particular orientation of the transponder coil relative to the detection loop. In particular, Figures 3A and 3B depict situations in which the angular orientation of the transponder coil relative to the detection coil provides maximum magnetic coupling or minimum coupling with the detection antenna when the transponder is located above the timing line. Figure 3A depicts the orientation of the transponder relative to the detection coil in more detail. The transponder 302 moves toward the detection coil in the z-axis direction at a certain speed. Ideally, the transponder plane is oriented in the x, y plane, and the detection coil is arranged in the x, z plane, with the longitudinal side of the detection coil substantially parallel to the z-axis (and the timing line). In the transponder configuration of Figure 3A, the magnetic axis of the first transponder coil 308 is parallel to the y-axis, and the magnetic axis of the second transponder coil 310 is parallel to the z-axis.

3B depicts the signal strength values (indicated by circles) exchanged between the first transponder coil 308 and the detection coil 306, and the signal strength values (indicated by triangles) exchanged between the second transponder coil 310 and the detection coil 306 versus the distance between the transponder and the timing line (where zero corresponds to a position on the timing line). It should be noted that although the x-axis refers to the distance between the transponder and the timing line, it actually represents the time measured by the base station, and in particular, the time at which the transponder signal is received by the base station.

3B shows that for this transponder configuration, the electromagnetic coupling between the first transponder coil 308 and the detection coil 306 can be given by a first distance function 320, wherein the signal strength exhibits a maximum 322 when the transponder is located above the timing line, and exhibits a minimum at a location where the transponder is located above a portion of the coil oriented parallel to the timing line (not shown). In contrast, the electromagnetic coupling between the second transponder coil 310 and the detection coil 306 is given by a second distance function 312, which exhibits a minimum signal strength 318 when the transponder is located above the timing line, and exhibits a minimum at a location where the transponder is located above a portion of the coil oriented parallel to the timing line (not shown).

Therefore, by measuring the signal strength of the signal exchanged between the first transponder coil and the base station and between the second transponder coil and the base station, two distance functions can be obtained. The signal strength measured can be associated with time by the signal exchanged between the transponder and the base station by timestamp, so that the time instance associated with the minimum value in the first distance function and/or the maximum value in the second distance function can be determined as through time. As mentioned above, Fig. 3 A and 3B describe ideal conditions, wherein when the transponder is on the timing line, maximum/minimum coupling is achieved between the transponder coil and the detection coil. But, when the athlete passes through the timing line, there is a great chance that the situation corresponding to drawing in Fig. 3 A and 3B is not present towards (particularly the direction of the transponder coil with respect to the detection ring).

Figures 4A and 4B illustrate the signal strength of a transponder passing through a detection antenna as a function of the distance between the transponder and the timing line, where the orientation of the transponder coil relative to the detection loop differs from the situation illustrated in Figures 3A and 3B. Specifically, Figure 4A depicts a situation similar to that of Figure 3A, except that transponder 402 includes a first coil 408 and a second coil 410 rotated by an angle θ 418 of 15 degrees about the x-axis (i.e., the angle between the normal n 416 to the transponder plane and the z-axis is θ). This rotation results in a distance function that differs from the distance function shown in Figure 3B. As shown in Figure 4B, the rotation of the transponder about the x-axis results in first and second distance functions 418 and 422, where the maximum signal strength 420 of the first distance function and the minimum signal strength 424 of the second distance function no longer coincide with the transponder's position above the timing line. Figures 4A and 4B illustrate that deviations from the "ideal" transponder orientation shown in Figures 3A and 3B can lead to errors in determining the transit time.

5A and 5B show first and second distance functions 502 _1,2 , 504 _1,2 for other angular orientations between the transponder coil and the detection coil (i.e., the transponder is rotated 30 degrees and 45 degrees around the x-axis, respectively). As shown in the figure, the rotation will result in a further shift in the position of the extreme values in the signal strength relative to the position of the timing line and relative to each other. The functional relationship of the extreme value positions of the two distance functions is therefore related to the position of the transponder coil relative to the detection coil. This correlation will be described in more detail with reference to FIG6 and 7A and 7B and can be used in a transit time algorithm for accurately determining a transit time that corrects for (angular) deviations in the orientation of the transponder coil relative to the detection ring.

FIG6 depicts a first distance function and a second distance function 602, 604 similar to those described with reference to FIG4B. Thus, during the passage of the transponder over the detection coil, the timing system can measure the signal strength of the first signal sequence and the second signal sequence exchanged between the transponder and the base station. Based on the measured signal strength values, the first distance function and the second distance function can be derived for use by a transit time algorithm to determine the transit time. The transit time algorithm may include the steps of determining:

a first time instance T ₁ when the first distance function 602 has a maximum signal strength value 608 ;

a second time instance T ₂ when the second distance function 604 has a minimum signal strength value 610 ;

- parameter increment Δ defined as the difference between T ₁ and T ₂ ;

- The transit time _Tp by calculating _T1 -Δ*K, where K is a constant depending on the height of the transponder and the ring width.

The ring width can be a fixed parameter of approximately 50 to 100 cm. The transponder height is a system parameter estimated to be approximately 150 cm. FIG7A depicts the relationship between the angular orientation of the transponder plane and the increment Δ. This graph shows that the difference between the location of maximum signal intensity for the first distance function and the location of minimum signal intensity for the second distance function is substantially linearly related to the angular orientation of the transponder plane. Furthermore, FIG7B depicts a substantially linear relationship between the increment and the error introduced by the angular orientation of the transponder plane. Thus, as the angular orientation of the transponder plane increases, the error increases.

The transit time algorithm can use _T1 as the initial transit time and correct this time value by multiplying the delta value by K. For example, in FIG7A , the transit time can be determined as: _Tp = _T1 - Δ*2.7. FIG8 shows the error in transit time as a function of angle. This graph shows that the error in timing line position due to angle effects can be kept very low. Furthermore, the algorithm is independent of speed. Although the transit time is determined based on _T1 in the transit time algorithm described above, it will be apparent to those skilled in the art that _T2 can also be used as the basis for determining the transit time.

Figure 9 depicts a flow chart of a process for determining the transit time of a mobile transponder according to an embodiment of the present invention. Here, the process can begin with the base station transmitting a base station signal to the transponder at a first (carrier) frequency (step 902). When the detector is within the range of the base station, the transponder can detect the base station signal, and if the signal strength of the base station signal is above a certain threshold and/or a certain modulation mode is detected (step 904), the transponder can be triggered to send a transponder signal to the base station at a second (carrier) frequency, wherein the transponder signal includes a transponder identifier and the signal strength of the base station signal (step 906). The transponder signal including the signal strength and transponder ID can be detected by the base station. Upon detection, the base station can determine the signal strength of the received transponder signal and the reception time of the transponder signal (step 908). As long as the signal strength of the base station signal received by the transponder is above the threshold, process steps 902-908 (steps 910-924) can be repeated. In this way, the signal strength of the first signal sequence (the signal strength of the base station signal) and the signal strength of the second signal sequence (the signal strength of the transponder signal) can be determined. This signal strength may define a first distance function and a second distance function which may be used by a time transit algorithm for determining a transit time corrected for the angular orientation of the transponder relative to the detection antenna.

Figures 10A and 10B depict a transponder-base station configuration according to another embodiment of the present invention. In particular, Figure 10A depicts a transponder 1002 including a processor 1004, a receiver unit 1006, and a transmitter unit 1008. The transponder also includes three magnetic coils 1010, 1012, 1014, wherein the magnetic axis of each coil 106, 1018, 1020 is oriented in a different direction (e.g., the first coil has a magnetic axis in the y-direction, the second coil has a magnetic axis in the x-direction, and the third coil has a magnetic axis in the z-direction).

As depicted in FIG10B , the orientation of the transponder plane relative to the x, y, and z axes can be described based on spherical coordinates comprising a tilt angle θ and an azimuth angle, wherein the tilt angle is defined relative to the z axis (the axis perpendicular to the (top) surface of the wavelength conversion layer), and wherein the azimuth angle is defined relative to either the x or y axis. As the transponder moves toward the detection antenna, the electromagnetic coupling between the detection coil and each of the transponder coils will vary as a function of the distance between the transponder and the detection antenna. The three differently oriented coils can be corrected for angular deviations in the two angular directions θ and φ using a similar scheme as described in detail with reference to FIG1-9 above.

A process for determining the signal strength of a first signal sequence exchanged between a transponder and a base station based on a first coil configuration (e.g., a first transponder coil and a detection coil) and a second coil configuration (e.g., a second transponder coil and a detection coil) can be implemented in various ways. For example, Figures 11A and 11B depict an embodiment of a timing system that allows signals to be exchanged between a transponder and a base station based on at least two different coil configurations. For example, in the embodiment of Figure 11A, two alternating transponder coils 1110 and 1112 can be used to exchange first and second signals 1114 and 1116 between a transponder ₁₁₀₂ and a base station 1108, wherein the magnetic axis directions of the first transponder coil and the magnetic axis directions of the second transponder coil have different orientations. Thus, during the passage of a mobile transponder over a timing line, once the transponder enters the range of a detection antenna, the transponder transmits a first signal sequence and a second signal sequence that are detected by the detection antenna 1106. The base station 1108 can detect the first and second signals, determine their signal strengths, and determine a time instance indicating when the base station received the signals. A transit time algorithm in the base station may then calculate the transit time based on the signal strength and the associated time instance.

FIG11B depicts another embodiment in which a transponder coil 1113 and at least two differently oriented detection antennas 1106 _{1, 2} can be used to exchange first and second signals 1114, 1116 between a transponder 1102 ₂ and a base station 1108. Thus, during a mobile transponder's transit over a timing line, the transponder can alternately receive a first signal transmitted by a first detection antenna 1106 ₁ , determine the signal strength of the received first signal, and then transmit a second signal to a second detection antenna 1106 ₂ , where the second signal includes a signal strength value associated with the first signal. Base station 1108 can detect the second signals, determine their signal strengths, and determine a time instance indicating when the base station received the second signals. A transit time algorithm in the base station can then calculate a transit time based on the signal strength values of the first and second signals and the associated time instances.

Figure 12 depicts a block diagram of an exemplary data processing system that can be used in the system and method described with reference to Figures 1-11. Data processing system 1200 may include at least one processor 1202 coupled to memory element 1204 by system bus 1206. Therefore, the data processing system can store program code in memory element 1204. In addition, processor 1202 can execute the program code accessed from memory element 1204 via system bus 1206. In one aspect, the data processing system can be implemented as a computer suitable for storing and/or executing program code. However, it should be appreciated that the data processing system can be implemented in the form of any system comprising a processor and memory that can perform the function described in this specification.

Memory element 1204 may include one or more physical memory devices, such as, for example, local memory 1208 and one or more mass storage devices 1210. Local memory may refer to random access memory or (one or more) other non-persistent memory devices typically used during the actual execution of program code. Mass storage devices may be implemented as hard drives or other persistent data storage devices. The processing system may also include one or more cache memories (not shown) that provide temporary storage of at least some program code to reduce the number of times program code must be retrieved from mass storage devices 1210 during execution.

Input/output (I/O) devices, depicted as input devices 1212 and output devices 1214, may optionally be coupled to the data processing system. Examples of input devices may include, but are not limited to, for example, a keyboard, a pointing device (such as a mouse), etc. Examples of output devices may include, but are not limited to, for example, a monitor or display, a speaker, etc. Input devices and/or output devices may be coupled to the data processing system either directly or through an intermediate I/O controller. A network adapter 1216 may also be coupled to the data processing system to enable the data processing system to be coupled to other systems, computer systems, remote network devices, and/or remote storage devices through an intermediate private or public network. A network adapter may include a data receiver for receiving data transmitted to the data processing system by the system, device, and/or network, and a data transmitter for transmitting data to the system, device, and/or network. Modems, cable modems, and Ethernet cards are examples of different types of network adapters that may be used with a data processing system.

As shown in FIG12 , memory element 1204 can store application 1218. It should be appreciated that data processing system 1200 can also execute an operating system (not shown) that can facilitate the execution of applications. Applications implemented in the form of executable program code can be executed by data processing system 1200 (e.g., by processor 1202). In response to executing the application, the data processing system can be configured to perform one or more operations that will be described in further detail herein.

In one aspect, for example, data processing system 1200 may represent a client data processing system. In this case, application 1218 may represent a client application that, when executed, configures data processing system 1200 to perform the various functions described herein with reference to a "client." Examples of a client may include, but are not limited to, a personal computer, a portable computer, a mobile phone, and the like.

The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when used in this specification, the term "comprising" specifies the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

All equipment or steps in the claims below plus the corresponding structure, materials, actions and equivalents of functional elements are intended to include any structure, material or action that performs the function in combination with other claimed elements for which protection is specifically claimed. The description of the present invention is given for the purpose of illustration and description, but is not intended to be exhaustive or limit the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments have been chosen and described in order to best explain the principles and practical applications of the invention and to enable others of ordinary skill in the art to understand the various embodiments of the invention with various modifications suitable for the intended specific use.

Claims (18)

1. A method for determining the passage time of a mobile transponder through a detection antenna of a base station, the method comprising: During the passage, a first signal sequence is exchanged between the first transponder coil and the detection antenna, and a second signal sequence is exchanged between the second transponder coil and the detection antenna; Associate the first signal in the first signal sequence and/or the second signal in the second signal sequence with a time instance indicating the time when the first signal and/or the second signal are exchanged between the transponder and the base station; and The transit time of the transponder is determined based on the signal strengths of the first and second signals and the time instance, wherein the magnetic axis direction of the first transponder coil is different from that of the second transponder coil. 2. The method according to claim 1, wherein the magnetic axis direction of the first transponder coil is substantially perpendicular to the magnetic axis direction of the second transponder coil. 3. The method of claim 1 or 2, wherein the passage time is determined based on at least one time instance associated with at least one maximum field strength value of the first signal and at least one time instance associated with at least one minimum field strength value of the second signal. 4. The method of claim 1 or 2, further comprising: The first transponder coil is used to receive the first signal transmitted by the detection antenna; and, The second transponder coil is used to transmit the second signal to the detection antenna, wherein the second signal includes a first signal strength value of the first signal. 5. The method of claim 4, further comprising: Determine a first signal strength value associated with the first signal; Insert one or more of the first signal strength values as payloads into the data packets; and, A second signal, including the data packets, is transmitted to the detection antenna. 6. The method of claim 4, further comprising: Detect the second signal; The second signal is correlated with the second field intensity value. 7. The method of claim 1 or 2, further comprising: The transponder uses the first transponder coil to transmit the first signal to the detection antenna; and uses the second transponder coil to transmit the second signal to the detection antenna. 8. The method of claim 1 or 2, further comprising: Detect the first signal and the second signal; Determine a first field intensity value associated with the intensity of the first signal and a second field intensity value associated with the intensity of the second signal. 9. The method of claim 1 or 2, further comprising: Determine at least a first time instance _T1 when the signal strength of the first signal has at least a minimum signal strength value and at least a second time instance _T2 when the signal strength of the second signal has at least a maximum signal strength value; Based on _T1 and _T2 , the transit time _Tp is determined by correcting _{either T1} or _T2 . 10. A timing system for determining the passage time of a mobile transponder through at least one detection antenna of a base station, the system comprising: The base station connected to the at least one detection antenna is configured to exchange a first signal sequence between a first transponder coil and the detection antenna and a second signal sequence between a second transponder coil and the detection antenna during the passage of at least one transponder, wherein the magnetic axis direction of the first transponder coil is different from that of the second transponder coil; and Wherein, the base station is further configured to associate a first signal in the first signal sequence and/or a second signal in the second signal sequence with a time instance indicating the time when the first signal and/or the second signal are exchanged between the transponder and the base station; and, The system further includes a base station processor of the base station, which is configured to determine the transit time of the at least one transponder based on the signal strength of the first signal and the second signal and the time instance. 11. A base station for determining the passage time of a mobile transponder through a detection antenna, the base station comprising: A transmitter unit, configured to transmit a first signal sequence to a first transponder coil via the detection antenna during the passage of at least one transponder; and A receiver unit configured to receive, during the passage of at least one transponder, a second signal sequence transmitted to the detection antenna by a second transponder coil, wherein the magnetic axis direction of the first transponder coil is different from that of the second transponder coil, and the second signal in the second signal sequence includes the signal strength value of the first signal in the first signal sequence; and Wherein, the base station is further configured to associate the first signal and/or the second signal with a time instance indicating the time when the first signal and/or the second signal are exchanged between the transponder and the base station; and, The base station further includes a base station processor, which is configured to determine the transit time of the transponder based on the signal strengths of the first signal and the second signal and the time instance. 12. A base station for determining the passage time of a mobile transponder through a detection antenna, the base station comprising: A receiver unit configured to receive, during the passage of at least one transponder, a first signal sequence transmitted by a first transponder coil and a second signal sequence transmitted by a second transponder coil, wherein the magnetic axis direction of the first transponder coil is different from that of the second transponder coil; and Wherein, the base station is configured to associate a first signal in the first signal sequence and/or a second signal in the second signal sequence with a time instance indicating the time when the first signal and/or the second signal are exchanged between the transponder and the base station; and, The base station further includes a base station processor, which is configured to determine the transit time of the transponder based on the signal strengths of the first signal and the second signal and the time instance. 13. A timing module for determining the passage time of a mobile transponder through a detection antenna of a base station, the module comprising: A base station processor configured to receive from a receiver unit a first signal strength value associated with a first signal sequence exchanged between a first transponder coil of at least one transponder and the base station, and a second signal strength value associated with a second signal sequence exchanged between a second transponder coil of the at least one transponder and the base station, wherein the magnetic axis direction of the first transponder coil is different from that of the second transponder coil; wherein the first signal strength value and the second signal strength value are associated with a time instance when a first signal in the first signal sequence and/or a second signal in the second signal sequence is exchanged between the at least one transponder and the base station; and The base station processor is configured to determine at least a first time instance _T1 when the signal strength of the first signal has at least a minimum signal strength value and at least a second time instance _T2 when the signal strength of the second signal has at least a maximum signal strength value; and the base station processor is configured to determine the passage time _Tp based on _T1 and _T2 by correcting _T1 or _T2 . 14. A transponder for exchanging signals with a timing system, the timing system being configured to determine the transit time when the transponder passes through a detection antenna of the timing system, the transponder comprising: A detector unit that uses a first transponder coil to detect a first signal transmitted to the transponder by a timing system at a first carrier frequency; A transmitter unit that uses a second transponder coil to transmit a second signal to a detection antenna at a second carrier frequency; The magnetic axis direction of the first transponder coil is different from that of the second transponder coil. 15. The transponder of claim 14, further comprising: A transponder processor configured to measure the signal strength of the second signal, to provide one or more data packets, to insert one or more measured signal strength values of the second signal as a payload into the one or more data packets, and to provide the one or more data packets to the transmitter unit for transmitting a first signal including the one or more data packets to the detection antenna. 16. The transponder of claim 15, wherein the transponder processor is configured to activate the detector unit and/or the transmitter unit if the signal strength of the second signal is higher than a predetermined signal strength threshold, or if the second signal includes a predetermined modulation pattern. 17. A sports harness, the sports harness comprising: Support plate, which can be secured to clothing and/or the body for supporting the transponder; and, The transponder as claimed in any one of claims 14-16, wherein the transponder is attached to the support plate such that one of the magnetic axis directions of the first transponder coil or the second transponder coil is substantially parallel to the plane of the support plate, and one of the magnetic axes of the first transponder coil or the second transponder coil is substantially perpendicular to the plane of the support plate. 18. A computer-readable storage medium storing at least one portion of software code, which, when running on a computer system, is configured to perform the method as described in any one of claims 1-9.