A balise comprising a monitoring circuit for testing the function of the balise

Abstract

The present invention discloses a balise (100) being configured for transmitting a train control signal (102) to an onboard unit of a rail vehicle, comprising: - a control unit (116) being configured for receiving train control data and converting the train control data into the respective train control signal, - an electronic driver unit comprising an LC resonator (106) configured to transmit the train control signal via a transmitting coil of the LC resonator (116) to a vehicle antenna (104) aligned with the onboard unit of the rail vehicle; - a monitoring unit (112) comprising a signal generation circuit (a) configured for generating a test signal and further comprising a signal transmitting antenna (b) for transmitting the test signal (B(t)) thereby inducing a response signal (b(t)) in the transmitting coil of the LC resonator (106); - said monitoring unit (112) further comprising a receiving antenna (c) configured for receiving the response signal (b(t)), said response signal inducing an output signal in the receiving antenna (c); and - said monitoring unit (112) further comprising an evaluation unit (f) configured to evaluate the output signal with respect to its frequency and / or amplitude. Thus, the monitoring unit performs a frequency and quality supervision of the resonance of the LC resonator. This measure permits to send a feedback, optionally in addition of more information of the configuration and the orders received from the control unit that controls the balise, thereby enabling the emission of more restrictive orders in case of balise failures detected by the monitoring unit integrated into the balise, and in this way avoiding rail accidents.

Description

[0001] The present invention relates to a balise that is configured for transmitting a train control signal to an onboard unit of a rail vehicle.

[0002] In order to transmit a train control signal to an onboard unit of a rail vehicle, various equipment is known throughout the world. In many European Countries, the train control data is transferred by Balise systems to the onboard unit.

[0003] In Spain, the Digital ASFA System is the evolution of the current ASFA System, which allows, by digital technology, to interpret the signal information from the railway signal, and transmit it to the ASFA Onboard Equipment. The Balise is the trackside equipment of the Digital ASFA System that transmits this information to the onboard equipment. The Balise is based on an analog balise, but additional control signals and new functionalities can be added also in digital technology to safeguard for example the required properties imposed by the national rail authorities and / or to improve the efficiency in the use of the railway tracks.

[0004] In the Digital ASFA system, the transmission of the train control data is carried out by the Balise acting as interface between the trackside equipments and the antenna of the onboard unit of the train vehicle. The transmission is realized by an oscillating circuit implemented in the Balise which transmits the train control data as an AC magnetic signal which induces an AC electric signal in the receiver antenna (coil) of the onboard unit. With the correct coupling of the transmitted signal and the receiver antenna and an appropriate amplification in the onboard unit, the train control data can be interpreted by the train driver.

[0005] Thus, the Balise comprises an oscillating circuit LC which requires the condition that the oscillation of the LC circuits is effective on or close to its resonance frequency. This frequency is determined by: f R = 1 / 2 π √ LC

[0006] The induced electric voltage thereby significantly depends on the factors: i) the current in the LC circuit; and ii) the mutual impedance M of the transmitter and receiver antennas.

[0007] The bigger both factors are the higher is the probability that the signal emitted by the inductance L of the LC circuit is received by the receiver antenna on the rail vehicle during the short period of time when the rail vehicle passes over the transmitter antenna of the LC circuit of the Balise.

[0008] For receiving the train control data from the balise, the train side antenna works with two coils. One transmitter coil to generate an AC control signal, and a receiver coil to receive the signal coupled from the transmitter coil. When the onboard antenna circulating on the rail passes over a balise, the resonance frequency of the balise couples to the onboard antenna and forces the change of the AC control signal of the onboard equipment, by the resonance frequency of the balise, Thus, this frequency is interpreted by the onboard equipment as a train control data.

[0009] Unfortunately, there does not exist any means for the monitoring of the correct function of the Balise when eventually placed in the railway track.

[0010] Therefore, it is an objective of the present invention to provide a means for controlling the correct function of the Balise that can be easily implemented in the Balise and is robust in terms of the specific demand on the resilience to the very diverse implications of the position between the rails of the railway track, such as snow, rain, hot sun, humidity etc.

[0011] These objectives are achieved according to the present in invention by a Balise being configured for transmitting a train control signal to an onboard unit of a rail vehicle, comprising: a control unit being configured for receiving train control data and converting the train control data into the respective train control signal, an electronic driver unit comprising an LC resonator configured to transmit the train control signal via a transmitting coil of the LC resonator to a vehicle antenna aligned with the onboard unit of the rail vehicle; a monitoring unit comprising a signal generation circuit configured for generating a test signal and further comprising a signal transmitting antenna for transmitting the test signal thereby inducing a response signal in the transmitting coil of the LC resonator; said monitoring unit further comprising a receiving antenna configured for receiving the response signal, said response signal inducing an output signal in the receiving antenna; and said monitoring unit further comprising an evaluation unit configured to evaluate the output signal with respect to its frequency and / or intensity.

[0012] Thus, the monitoring unit performs a frequency and quality supervision of the resonance of the LC resonator. This measure permits to send a feedback to the equipment in charge of transmitting the information detected from the railway signals to the ASFA Balise, in addition to more information of the configuration and the orders received from the control unit that controls the Balise. Thereby, the control unit can be enabled for the emission of more restrictive orders (lower speed, lower range of movement, etc.) in case of balise failures detected by the monitoring unit in the Balise thereby strongly support the railway security functionalities implemented for avoiding rail accidents.

[0013] Advantageously, the signal generation circuit is configured to generate a pulse of very short duration and great amplitude. The answer to this pulse allows the monitoring circuit to observe the course of the output signal that is the response to the oscillating quality and frecuency of the LC resonator

[0014] For interpreting the output signal the evaluation unit apply a Fast Fourier transform (FFT) to the output signal. The result of this FFT represents the distribution of frequency components present in the output signal thus also allowing a determination of the frequency and quality of resonance of the LC resonator.

[0015] Advantageously, the signal generation circuit can be is configured to generate an AC pulse having a length of less than 1 sec and a frequency in the range from 5 to 500 kHz, preferably in the range from 50 to 150 kHz. This measure allows the monitoring circuit to observe the course of the output signal that is the response to the oscillating quality of the LC resonator for the specific frequency of the AC pulse. Thus, by varying the frequency and / or the intensity of the AC pulse, the monitoring unit is enabled to generate a clear picture of the quality of resonance in the LC resonator.

[0016] A further criterion that is helpful for the interpretation of the output signal can be realized when the evaluation unit is configured to apply a Fast Fourier transform (FFT) to the output signal. The result of this FFT represents the distribution of frequency components present in the output signal thus also allowing a determination of the quality of resonance of the LC resonator.

[0017] In a further preferred embodiment of the present invention, the evaluation unit can be configured to compare the output signal against a predetermined threshold signal and to send a warning signal in case of a deviation of the output signal from the threshold signal exceeding a predetermined tolerance.

[0018] Further aspects of the present invention will be better understood through the following drawings, wherein like numbers designate like objects and which depict in: Fig. 1 a schematic illustration of a general balise; Fig. 2 a schematic illustration of a monitoring unit present in the Balise of Figure 1; and Fig. 3 a schematic illustration of an output signal and its FFT analysis performed by the monitoring unit of Figure 2. Description of Examples

[0019] Figure 1 schematically shows the architecture of a balise 100 for transmitting train control data 102 from the balise 100 to a receiving antenna 104 of an onboard unit of a rail vehicle (not shown). The balise 100 comprises an LC resonator 106 wherein the inductivity of the LC resonator 106 transmits the train control data / signal as AC magnetic signal B(t). The balise 100 further comprises a connector 108 for receiving the commands from an interlocking system 110 and transmitting information from a monitoring unit 112 connected via a balise interface 114 to the connector 108. For transmitting the different train control data, the balise 100 comprises train control data selector 116 which is enabled to connect various capacitors to the LC resonator in order to adapt the resonance frequency of the LC resonator to the respective train control signal that needs to be transmitted to the receiving antenna 104. Further, the balise 100 comprises a configurator interface 118 for the configuration of the various components of the balise 100.

[0020] The monitoring unit and its functioning as schematically shown in Figure 2 comprises substantially the excitation of the LC resonator 106 with a sinusoidal signal and the following detection of the response signal 120 of this excitation in terms of the phase and amplitude of this response signal (output signal in Figure 2). Usually in this embodiment, the frequency sampling of the monitoring unit 112 is operated for test signals at the typical signal bandwidth for ASFA balises in Spain that are operated between 50 and 120 kHz (see Table 1). For each of the frequencies of the test signals the output signal of the receiving antenna 104 is registrated and analysed in this frequency bandwidth. The processing in the monitoring unit 112 allows the determination of the oscillation frequency of the balise on the track, its quality factor and the communication of the values of this oscillation to the specific device in charge of transmitting the information detected from the railway signals to the ASFA Balise. Table 1: List of the signal frequencies which are transmitted by the Balise system to the onboard unit of the train vehicle for various train control data for SICVA and AVE high speed train onboard unit in SpainTrain control data Frequencies SICVA (Hz) Frequencies AVE (Hz) f inferior f central f superior f inferior f central f superior FP109909111104112298109909111104112298L1593556000360650596566030360949L2633326402164709635836427164958L3675766831069044677766851069244L47210372.87673649722527302173790L5769337777578617770197785378686L6820888298183873821018299083879L7876268898390340877768913390489L8945149597897442946699613297595L9101970103522105074102471104430106388

[0021] Figure 2 now schematically shows the scheme of the flow of pulses at the balise 100 with respect to the specific functionalities implemented by the monitoring unit 112. How it can be seen, the monitoring unit 112 comprises the following modules (a) to (h). (a) is a module for the generation of the test signal (test signal pulse) which provides this test signal of short duration to a digital signal amplifier (d) which receives and amplifies the test signal and which comprises a power source (g). The amplified test signal is then directed to an excitation antenna (b) which substantially comprises a coil for generating an AC magnetic field B(t). This AC magnetic field B(t) is capable of inducing a signal in the magnetic coil of the LC resonator (h) - known as LC resonator 106 from Figure 1 - of the balise system 100. The response signal b(t) of the LC resonator (h) is detected by a magnetic field sensor (c) which substantially comprises a magnetic coil. The response signal that is induced in this magnetic field sensor (c) is then amplified by an amplifier (e) and the amplified response signal is eventually directed to a digital signal processing unit (f) which finally generates an analyse signal. This digital signal processing unit (f) is enabled to determine the frequency of the response signal coming from the LC resonator (h), the quality of the response signal b(t) and (when installed in the rail way track) the transmission value for the oscillation in the receiving antenna 104 of the onboard unit of the train vehicle.

[0022] While Figure 1 schematically shows the architecture of the balise 100 which can be used to transmit train control data (a train control signal) according to predetermined format and content of the train control data, such as signalling aspects L1, L2, L3 and L7. Table 2 summarizes the descriptive experimental parameters which are inherently realized by the monitoring unit 112. Table 3 shows the respective results of the analysis of the test signals that have been generated by the module for signal generation (a). Table 2: Descriptive parameters of the laboratory operation of the monitoring circuit in the ASFA Balise system for the frequency sampling Train Control f initial f final δf f 0 Q Response / real part / data ASFA (kHz) (kHz) (kHz) (kHz) (kHz) imaginary partExperimental Parameter Value / Description Number of registered signals20Test Balise system and train control data consideratedBalise ASFA SIEMENS, Train control data L1, L2, L3 and L7Range of frequencies evaluated59.3 to 69.3 kHzTime required for monitoring and data analysis< 60 sec Table 3: Some representative results of the monitoring measurements for the train control data L1, L2 and L3; f initial , f final , δf, f 0 and Q are the initial and final frequency of the frequency sampling, the pass of frequency, the resonance frequency and the factor of the signal quality. L150700.02060.2188.2L250700.02064.2200.7L3501000.05068.5171.4

[0023] Thus, the present monitoring unit that can be exemplarily realized as a PCB (Printed Circuit Board) with two antennas, one for emission (b) and the other for reception (c), allows to generate the test pulses and to injects them into the transmitter antenna (b). These pulses are coupled with the LC resonator and the receiving antenna (c) receives the response pulses and its replicas in a cushioned manner as this is shown in Figure 3, upper part. The micro controller in the digital signal processing unit (f) of the monitoring unit 112 performs the FFT (fast Fourier transform) of the response signal received by the receiver antenna (c) and amplified by the amplifier (e). The time separation between the pulses and / or the replicas gives the value of the resonance frequency. The enveloping curce of the replicas provides the value of the resonance quality. Figure 3 bottom part shows the determination of the prevailing frequency in the response signal which is the actual resonance frequency of the LC resonator with the respective aligned capacity that frequency-wise determines the signalling aspect that has to be transmitted by the balise 100 to the vehicle antenna 104.

[0024] Additionally, the monitoring unit 112 obtains the information of the configuration of the LC resonator and signalling orders received by the balise 100 through optocouplers and send this information to the controller unit that is then enabled to verify whether the signalling order transmitted to the balise 100 has been correctly attended to by the balise 100. In case of a mismatch, the controller unit can act in consequence to this mismatch by sending an even more restrictive signalling order to the onboard units of the passing train in order to protect the passengers and the trains. This functionality lifts the balise 100 according to the present invention onto an extra safety level.

Claims

1. A balise (100) being configured for transmitting a train control signal (102) to an onboard unit of a rail vehicle, comprising: - a control unit (116) being configured for receiving train control data and converting the train control data into the respective train control signal, - an electronic driver unit comprising an LC resonator (106) configured to transmit the train control signal via a transmitting coil of the LC resonator (116) to a vehicle antenna (104) aligned with the onboard unit of the rail vehicle; - a monitoring unit (112) comprising a signal generation circuit (a) configured for generating a test signal and further comprising a signal transmitting antenna (b) for transmitting the test signal (B(t)) thereby inducing a response signal (b(t)) in the transmitting coil of the LC resonator (106); - said monitoring unit (112) further comprising a receiving antenna (c) configured for receiving the response signal (b(t)), said response signal inducing an output signal in the receiving antenna (c); and - said monitoring unit (112) further comprising an evaluation unit (f) configured to evaluate the output signal with respect to its frequency and / or amplitude.

2. The balise (100) according to claim 1, wherein the signal generation circuit (a) is configured to generate an AC pulse having a length of less than 1 sec and a frequency in the range from 5 to 500 kHz, preferably in the range of 50 to 150 kHz.

3. The balise (100) according to claim 1 or 2, wherein the evaluation unit (f) is configured to apply a Fast Fourier transform to the output signal.

4. The balise (100) according to any of the preceding claims wherein the evaluation unit (f) is configured to compare the output signal against a predetermined threshold signal and to send a warning signal in case of a deviation of the output signal from the threshold signal exceeding a predetermined tolerance.

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