EP3461716A1

EP3461716A1 - Transponder for train control applications

Info

Publication number: EP3461716A1
Application number: EP17194154.5A
Authority: EP
Inventors: Bhabani NAYAK; Karsten Rahn
Original assignee: Siemens Mobility GmbH
Current assignee: Siemens Mobility GmbH
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2019-04-03

Abstract

It is proposed to provide a transponder system for a rail application comprising a first radiation unit forming a first beam that radiates at a first angle with reference to a railway track, a second radiation unit forming a second beam that radiates at a second angle with reference to the railway track, wherein the first angle and the second angle are different. This allows the transponder to determine the position of a rail vehicle with high accuracy, it allows to cancel cross-talk and it allows determining the direction of movement. The transponder system may be used as or within a balise. Also, a method is provided to utilize this transponder in an efficient way.

Description

The invention relates to a method and to a device for train control applications. The invention in particular relates to a transponder that can be used in or as a balise to improve the detection of a rail vehicle.
A balise is known to be an electronic beacon or transponder placed between the rails of a railway as part of an automatic train protection (ATP) system (see, e.g., en.wikipedia.org/wiki/Balise). Balises constitute an integral part of the European Train Control System (ETCS), where they serve as "beacons" giving the exact location of a train. For further details regarding ETCS, reference is made to, e.g., en.wikipedia.org/wiki/European_Train_Control_System.
A detection of a balise is currently subject to some uncertainty with regard to the actual position of the balise. However, a detection of a balise position at a high accuracy is a general motivation to enable applications like supervision of platform screen doors or station stopping of a rail vehicle.
In addition, cross-talk has a strong impact on detecting the position of a balise. Such cross-talk may stem from signals that are radiated from other balises of the same track and/or from balises of neighboring tracks. For example, telepowering may activate balises on the same track or on adjacent tracks. These activated balises emit signals that may interfere with the signal that should be detected by the rail vehicle. These unwanted signals are referred to as cross-talk. Based on cross-talk, the rail vehicle may determine a wrong position, because it receives a signal from a wrong balise (i.e. a balise that is not being passed over by the rail vehicle).
It is also a disadvantage, that the information provided by a balise to the rail vehicle does not suffice to determine a direction of travel. In fact, the rail vehicle needs to pass multiple balises on the same track in order to determine its direction.
The objective is thus to overcome the disadvantages stated above and in particular to provide a solution that allows improving existing balises and therefore improving the detection of rail vehicles.
This problem is solved according to the features of the independent claims. Further embodiments result from the depending claims.
In order to overcome this problem, a transponder system for a rail applications is provided, the transponder system comprising

a first radiation unit forming a first beam that radiates at a first angle with reference to a railway track,
a second radiation unit forming a second beam that radiates at a second angle with reference to the railway track,
wherein the first angle and the second angle are different.

The solution presented in particular allows for an optimized transponder (e.g., in a balise) that conveys uplink signals towards a rail vehicle. Due to the beam directions of the first and second beams, the rail vehicle is able to detect the signals conveyed via the beams at different times. This enables an improved detection of the balise and it allows reducing the cross-talk. Also, based on the different signals, the direction of the rail vehicle crossing the balise can be determined.
In an embodiment, the first angle and the second angle differ by at least 25 degrees.
In an embodiment, the first angle amounts to Φ and the second angle amounts to -Φ, wherein Φ may be in the range from 30° to 80°.
It is noted that the absolute values of the first angle and the second angle may be different from each other. The first angle may in particular be in a range between 30° and 80° and the second angle may be in a range between -30° and -80° irrespective of the value of the first angle.
In an embodiment, each of the first and second transponder unit comprises a phase shifter and an antenna, wherein the phase shifter introduces the respective first or second angle and the antenna enables emitting the respective beam.
The antenna may be realized as a loop.
In an embodiment, the first radiation unit sends a first information towards the railway track and the second radiation unit sends a second information towards the railway track.
In an embodiment, the transponder system is part of a balise that is located adjacent to or within the railway track.
It is in particular an option that the balise comprises only the transponder.
Also, a balise is suggested that is comprising the transponder system as described herein.
Further, a method is suggested for monitoring a rail vehicle, wherein the rail vehicle comprises a receiver that is arranged to receive at least one signal from a balise as described herein, wherein the method comprises:

receiving a first information via the first beam and receiving a second information via the second beam,
determining the position of the rail vehicle based on the first information and the second information.

In an embodiment, the first information has a first time-stamp and the second information has a second time-stamp.
The time-stamp may comprise a time of emission by the respective transponder and/or a time of the reception at the rail vehicle.
Hence, by receiving the information from the balise for more than once, the position of the rail vehicle can be determined at a higher accuracy and/or higher reliability.
For example, after having received the first and second information, the position of the balise is determined by calculating the middle point in time (i.e. the arithmetic middle between the first and second time stamps), or any point in time between the two time stamps based on the angle of the two beams.
In an embodiment, the method comprises:

determining the presence of the balise based on the first information and the second information.

Hence, if the first and the second information are received by the rail vehicle, the rail vehicle can determine that the actual balise is present.
In an embodiment, the method comprises:

determining a direction based on the succession of receiving the first information and the second information.

In an embodiment, the method comprises:

cancelling cross-talk based on the first information and the second information.

As the first information and the second information identify the actual balise to be detected, any cross-talk signal from another balise can be rejected. In other words, if the first information is detected together with a third information and then the second information is detected, the third information can be discarded as cross-talk or interference, because the first and second information defines the balise which is actually being passed.
In an embodiment, the method comprises:

determining a velocity of the rail vehicle based on the first information and the second information.

In an embodiment, the method utilizes at least one of the following frequency ranges:

a high-frequency range from 3MHz to 30 MHz,
a very-high-frequency range from 30MHz to 300MHz,
an ultra-high-frequency range from 300MHz to 3GHz
a frequency range above 3GHz.

Also, a rail vehicle is suggested comprising a processing unit, wherein the processing unit is arranged to execute the steps of the method as described herein.
It is noted that the steps of the method stated herein may be executable on this processing unit as well.
It is further noted that said processing unit can comprise at least one, in particular several means that are arranged to execute the steps of the method described herein. The means may be logically or physically separated; in particular several logically separate means could be combined in at least one physical unit.
Said processing unit may comprise at least one of the following: a processor, a microcontroller, a hard-wired circuit, an ASIC, an FPGA, a logic device.
The solution provided herein further comprises a computer program product directly loadable into a memory of a digital computer, comprising software code portions for performing the steps of the method as described herein.
In addition, the problem stated above is solved by a computer-readable medium, e.g., storage of any kind, having computer-executable instructions adapted to cause a computer system to perform the method as described herein.
The aforementioned characteristics, features and advantages of the invention as well as the way they are achieved will be further illustrated in connection with the following examples and considerations as discussed in view of the figures.

Fig.1: shows an exemplary balise that is arranged to emit different signals via different beams;
Fig.2: shows an exemplary scenario utilizing the balise shown in Fig.1 in combination with a rail vehicle 201 crossing this balise;
Fig.3: shows an exemplary scenario of the rail vehicle moving from right to left thereby crossing two balises of the type introduced in Fig.1;
Fig.4: shows an exemplary scenario of the rail vehicle moving from right to left thereby crossing the balise in the presence of cross-talk.

Examples described herein in particular refer to a transponder for train control applications. The transponder may be used in a balise (i.e. as a balise transponder) to enhance the performance of a balise. Such enhancement may comprise at least one of the following:

an improvement of an accuracy of a balise localization;
an improvement of a crosstalk detection, which may in particular facilitate a reduction of detrimental crosstalk effects;
a recognition of a travel direction via a single balise;
a calculation of a velocity, in particular during detection of the balise.

Embodiments suggested in particular comprise a balise loop design for an uplink signal (towards a rail vehicle) to send two different signals in two different directions utilizing different beam directions, e.g., +45° and -45°. It may in particular be advantageous for each balise to send via the different beams two different signals to differentiate between different balises and/or crosstalk.
Fig.1 shows an exemplary balise 101 that is arranged to emit a signal M1 via a beam 106 and a signal M2 via a beam 111.
An analog-to-digital converter 102 converts an analog signal M1 to a digital signal M1, which is conveyed to a phase shifter 104. The phase shifter 104 supplies a weight W and a phase offset Φ to the digital signal M1, which is then radiated via a loop 105.
Accordingly, an analog-to-digital converter 107 converts an analog signal M2 to a digital signal M2, which is conveyed to a phase shifter 109. The phase shifter 109 supplies a weight W and a phase offset -Φ to the digital signal M2, which is then radiated via a loop 110.
Due to the phase shifting supplied by the phase shifters 104 and 109, the radiated signals M1 and M2 are phase shifted, wherein the phase offset Φ may amount to, e.g., 30°, 45° or 50° (hence the phase offset -Φ may amount to -30°, -45° or - 50°) .
The signals M1 and M2 may in particular comprise a balise information, which may comprise an identification (ID) of the balise.
A power unit 112 supplies telepowering to the phase shifters 104 and 109.
A telepowering signal is sent from an antenna of the rail vehicle (e.g., the on-board antenna 202 sown in Fig.2) to activate the balise 101 and accordingly the phase shifters 104 and 109. Hence, the phase shifters 104 and 109 will be activated when the balise is tele-powered.
The power unit 112 is a source to generate power for the phase shifters 104, 109, the analog-to- digital converts 102, 107 and the radiating loops 105, 110. The power unit 112 is activated by a telepowering signal from the rail vehicle (i.e. the on-board antenna 202).
Hence, telepowering may, e.g., refer to an activation of the balise via an on-board antenna of a rail vehicle with a 27 MHz flux that results in the corresponding uplink balise current Iu2 (as defined by UNISIG).
The functionality of a phase shifter is described, e.g., in Jayaprakash Selvaraj, "Phase shifter design & Research study and verification of wide band phase shifter circuits", 2012.
Fig.2 shows an exemplary scenario utilizing the balise 101 as shown in Fig.1. A rail vehicle 201 may move in a direction 203 (in the example shown in Fig.2 from the right hand side to the left hand side). The rail vehicle 201 comprises an on-board antenna 202 to detect a signal transmitted by the balise 101.
The rail vehicle may detect the balise upon receiving the signals M2 and M1 (when moving along the direction 203) via its on-board antenna 202.
At a time T0, the rail vehicle 201 detects the signal M2. At a later time T1 the rail vehicle 201 detects the signal M1. T0 and T1 may be timestamps. A middle between the timestamps T0 and T1 can be determined. If the distance 141 (see Fig.1) between the beams 106 and 111 is known and a height 204 between the balise 101 and the on-board antenna 202 is known (with some uncertainty), a velocity v can be approximated as follows: $v = \frac{s}{t} = \frac{d}{T 1 - T 0},$
wherein d is the distance 141 between the beams 106 and 111, wherein d may be further calculated as follows: $d = \frac{2 h}{tanΦ},$
wherein h is the height 204 and Φ is the angle between the track and the beam.
It is also possible to determine the direction of movement: If the on-board antenna receives first the signal M2 then the signal M1, the rail vehicle 201 moves in direction 203. If the on-board antenna receives first the signal M1 then the signal M2, the rail vehicle 201 moves in the direction opposite to the direction 203.
Also, the signals received by the rail vehicle 201 can be compared with a configured balise orientation stored in a track database. The succession of the signals M1 and M2 (or vice versa) may be compared with the track database to determine whether the rail vehicle 201 (in this example) moves from left to right or from right to left.
Fig.3 shows an exemplary scenario of the rail vehicle 201 (comprising the on-board antenna 202) moving from right to left (see: movement direction 301) thereby crossing first a balise 121 and then the balise 101.
It is noted that the balise 121 has the same structure as the balise 101. Contrary to the balise 101, the balise 121 emits a signal M3 via a beam 122 (instead of the signal M1) and a signal M4 via a beam 123 (instead of the signal M2).
Hence, the rail vehicle 201 moving along direction 301 detects the following signals (in a timely order, i.e. T3 > T2 > T1 > T0) :

At a time T0, the rail vehicle 201 detects the signal M4.
At a time T1, the rail vehicle 201 detects the signal M3. Hence the rail vehicle 201 can confirm that it has passed the balise 121. Also, the rail vehicle 201 is able to determine that it moves in the direction 301 (in this example: from right to left). Based on the signals detected, the rail vehicle may also determine that no crosstalk is present.
At a time T2, the rail vehicle 201 detects the signal M2.
At a time T3, the rail vehicle 201 detects the signal M1. Hence the rail vehicle 201 can confirm that it has passed the balise 101. Also, the rail vehicle 201 is able to determine that it moves in the direction 301. Based on the signals detected, the rail vehicle may also determine that no crosstalk is present.

Fig.4 shows an exemplary scenario of the rail vehicle 201 (comprising the on-board antenna 202) moving in direction 301 from right to left thereby crossing the balise 101 in the presence of cross-talk.
The rail vehicle 201 crossing the balise 101 detects the following signals (in a timely order, i.e. T1 > T0):

At a time T0, the rail vehicle 201 detects the signal M2 and the signal M3.
At a time T1, the rail vehicle 201 detects the signal M1.

In particular due to the adverse polarizations, the rail vehicle 201 will not receive the signal M4 after having crossed the middle of the balise 101. Hence, at the time T1, the rail vehicle 201 by only receiving the signal M1 is able to identify that the balise 101 has been passed and that the signal M3 at the time T0 was no valid information, but cross-talk. Hence, at the time T1, the rail vehicle 201 is able to determine that the signal M3 was based on cross-talk and should be discarded.
As stated before, at the time T1 the rail vehicle 201 can confirm that it has passed the balise 101. Also, the rail vehicle 201 is able to determine that it moves in the direction 301.

Advantages and further embodiments

The proposal suggested herewith in particular allows localizing the balise with an increased precision. This allows for an enhanced performance of train control applications. Also, the direction of the train can be determined at a high reliability utilizing signals from a single balise. Another advantage is the possibility to remove cross-talk and hence to improve the performance of the signal processing.
This concept further allows for a localization of a balise without additional odometric information.
The approach hence improves the localization of the rail vehicle, because the moving direction can be detected and validated at each single balise.
It is another advantage that existing balises may be updated to provide the functionality described herein. The on-board antennas of the rail vehicle may not require any changes and are therefore fully compatible with the improved balises as suggested herein.
Although the invention is described in detail by the embodiments above, it is noted that the invention is not at all limited to such embodiments. In particular, alternatives can be derived by a person skilled in the art from the exemplary embodiments and the illustrations without exceeding the scope of this invention.

Claims

A transponder system for a rail application comprising
- a first radiation unit forming a first beam (106; 122) that radiates at a first angle with reference to a railway track,

- a second radiation unit forming a second beam (111; 123) that radiates at a second angle with reference to the railway track,

- wherein the first angle and the second angle are different.
The transponder system according to claim 1, wherein the first angle and the second angle differ by at least 25 degrees.
The transponder system according to any of the preceding claims, wherein the first angle amounts to Φ and the second angle amounts to -Φ, wherein Φ may be in the range from 30° to 80°.
The transponder system according to any of the preceding claims, wherein each of the first and second transponder unit comprises a phase shifter (104, 109) and an antenna (105, 110), wherein the phase shifter introduces the respective first or second angle and the antenna enables emitting the respective beam.
The transponder system according to any of the preceding claims, wherein the first radiation unit sends a first information (M1; M3) towards the railway track and the second radiation unit sends a second information (M2; M4) towards the railway track.
The transponder system according to any of the preceding claims, which is part of a balise (101; 121) that is located adjacent to or within the railway track.
A balise (101; 121) comprising the transponder system according to any of the preceding claims.
A method for monitoring a rail vehicle (201), wherein the rail vehicle comprises a receiver that is arranged to receive at least one signal from a balise according to claim 7, the method comprising:
- receiving a first information (M2) via the first beam (111) and receiving a second information (M1) via the second beam (106),

- determining the position of the rail vehicle based on the first information and the second information.
The method according to claim 8, wherein the first information has a first time-stamp (TO) and the second information has a second time-stamp (T1).
The method according to any of claims 8 or 9, wherein the method comprises:
- determining the presence of the balise based on the first information and the second information.
The method according to any of claims 8 to 10, wherein the method comprises:
- determining a direction (203; 301) based on the succession of receiving the first information and the second information.
The method according to any of claims 8 to 11, wherein the method comprises:
- cancelling cross-talk based on the first information and the second information.
The method according to any of claims 8 to 12, wherein the method comprises:
- determining a velocity of the rail vehicle based on the first information and the second information.
The method according to any of claims 8 to 13, wherein the method utilizes at least one of the following frequency ranges:
- a high-frequency range from 3MHz to 30 MHz,

- a very-high-frequency range from 30MHz to 300MHz,

- an ultra-high-frequency range from 300MHz to 3GHz

- a frequency range above 3GHz.
Rail vehicle (201) comprising a processing unit, wherein the processing unit is arranged to execute the steps of the method according to any of claims 8 to 14.
A computer program product directly loadable into a memory of a digital computer, comprising software code portions for performing the steps of the method according to any of claims 8 to 14.