AU2014221300A1 - Device for determining a signalling state for a plurality of electrical railway signalling units, associated system and method - Google Patents

Abstract

This device for determining a signalling state for a plurality of electrical railway signalling units, each signalling unit having one signalling state out of a plurality of predetermined signalling states, comprises, for each signalling unit : - measurement means for measuring at least one variable parameter relating to a current capable of flowing through the signalling unit, and - computing means connected to the measurement means and capable of generating a signal indicating the signalling state of the signalling unit. At least one variable parameter measured is the intensity of the current flowing through the said signalling unit. Figure 2

Description

Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Device for determining a signalling state for a plurality of electrical railway signalling units, associated system and method The following statement is a full description of this invention, including the best method of performing it known to me/us: 5102 BACKGROUND OF THE INVENTION The present invention relates to a determination device for determining a signalling 5 state for a plurality of electrical railway signalling units, each signalling unit having one signalling state out of a plurality of predetermined signalling states, the device comprising, for each signalling unit: - measurement means for measuring at least one variable parameter relating to a current capable of flowing through the signalling unit, and 10 - computing means connected to the measurement means and capable of generating a signal indicating the signalling state of the signalling unit. The present invention also relates to a signalling system including such a determination device. The invention also relates to a method for determination implemented by such a 15 determination device. The field of the invention concerns that of railway signalling systems comprising electrical signalling units, such units being intended, via the transmission of signals, for transmitting either to a train driver or to the train itself, an information element that may be used to control the train. In particular, in the event where the signals emitted by the signalling 20 units are transmitted to the train itself, this transmission is performed by safety equipment units installed on the ground. In order to ensure proper performance of critical safety functions required for the railway signalling system, all component equipment units constituting the signalling system must thus meet security requirements, such requirements being defined by the railway safety standards. 25 From the document WO 2011/139727 Al a signal determination device of the aforementioned type is already known. Such a device is used within a signalling system comprising a current source, a plurality of signalling units, and a plurality of electrical relays, each relay being connected in series with one of the signalling units and being capable of controlling the signalling state of this signalling unit. The current source supplies an electric 30 current intended to provide the power supply for all the signalling units. The measurement means include current sensors capable of measuring the intensity of the current supplied by the current source, and voltage sensors. Each voltage sensor is connected to a terminal, connected on the one hand to one of the relays and on the other hand to one of the signalling units. The combination of the measurements of intensity taken by the current 35 sensors and the measurements of voltage taken by the voltage sensors makes it possible for 2 the computing means to determine the value of the signal indicating the signalling state of each signalling unit. However, such a signal determination device is not very compact by virtue of the fact that the components forming the device are relatively widely dispersed within the system. 5 Such a device also requires certain measurement means to be connected to the electrical relays, in order to measure the voltage across the terminals of each of these relays. This creates constraints linked to the positioning of these measurement means over the signalling system, which adds to the level of complexity of and weighs down in particular the architecture of this system. 0 SUMMARY OF THE INVENTION One object of the invention is therefore to provide a determination device for determining a signalling state for a plurality of electrical railway signalling units that provide the ability to overcome the constraints related to the positioning of the measurement means, 5 while presenting greater compactness. For this purpose, the invention relates to a signal determination device of the aforementioned type wherein at least one variable parameter measured is the intensity of the current flowing through the said signalling unit. According to other advantageous aspects of the invention, the determination device .0 comprises one or more of the following characteristic features, taken into consideration individually or in accordance with any technically possible combinations : - the only variable parameter measured is the intensity of the current flowing through the said signalling unit; - the computing means include at least one data acquisition channel, each data 25 acquisition channel comprising a conversion module for converting an analog signal into a digital signal and a programmable module, connected in series, the programmable module being connected to the measurement means and being capable of executing, in accordance with a test procedure, one or more test(s) on the operation of the measurement means; - the measurement means are capable of performing a plurality of measurements of 30 the intensity of the current over the course of a predetermined time period, and the computing means are capable of calculating the value of the signal indicating the signalling state of the signalling unit based on the results of the plurality of measurements; - the computing means are further capable of comparing each value of the intensity measured to at least one predetermined threshold value of intensity, and of calculating the 35 value of the signal indicating the signalling state of the signalling unit based on the results of these comparisons; 3 - each programmable module is in addition capable of time stamping each intensity value measured by the measurement means, and the computing means are capable of calculating at least one parameter that is characteristic of a signalling state of the signalling unit, based on the time stamp values related to the said measured values; 5 - the computing means include a first data acquisition channel, a second data acquisition channel, a first data processing unit and a second data processing unit, and the measurement means include a first and a second current sensors, the first and second current sensors being connected in series, the first, and the second data acquisition channels respectively, being connected in series between respectively the first, and the 0 second current sensors, and respectively the first, and the second data processing units, each data processing unit being capable of calculating the value of the signal indicating the signalling state of the signalling unit, the first data processing unit being connected to the second data processing unit and being capable of generating the said signal, the value of the signal generated being dependent upon the existence of an equality between the values of 5 signals calculated by the first and second data processing units. The object of the invention also relates to a signalling system comprising a plurality of electrical railway signalling units and a determination device for determining a signalling state for each signalling unit, each signalling unit having one signalling state out of a plurality of predetermined signalling states, wherein the said determination device is as defined here .0 above. The object of the invention also relates to a determination method for determining a signalling state for a plurality of electrical railway signalling units, each signalling unit having one signalling state out of a plurality of possible signalling states, the method being implemented by a device comprising, for each signalling unit, the 25 measurement means for measuring at least one variable parameter relating to a current capable of flowing through the signalling unit, and the computing means connected to the measurement means and capable of generating a signal indicating the signalling state of the signalling unit, the method including, for each signalling unit, the following steps: 30 - measuring, by the measurement means, of the said at least one variable parameter relating to a current capable of flowing through the signalling unit, - determining, by the computing means, of the signalling state of the signalling unit, and - transmitting, by the computing means, of the signal indicating the signalling state of 35 the signalling unit, 4 in which at least one variable parameter measured is the intensity of the current flowing through the said signalling unit. According to other advantageous aspects of the invention, the method includes one or more of the following characteristic features, taken into consideration individually or in 5 accordance with any technically possible combination : - the step of measuring comprises a plurality of measurements of the intensity of the current flowing in the signalling unit, the said measurements being performed by the measurement means over a predetermined time period; - the step of determining includes: 0 - comparison of each value of the intensity measured to at least one predetermined threshold value of intensity, and - calculation of the value of the signal indicating the signalling state of the signalling unit based on the results of these comparisons. 5 BRIEF DESCRIPTION OF THE DRAWINGS These characteristic features and advantages of the invention will become apparent upon reviewing the description which follows, provided purely by way of non limiting example, and with reference being made to the accompanying drawings, in which: - Figure 1 is a schematic view of a signalling system according to the invention, .0 - Figure 2 is an electrical circuit diagram of the signalling system shown in Figure 1, including twelve, electrical railway signalling units and a signal determination device according to the invention, the determination device comprising twelve data processing channels, - Figure 3 is an operational block diagram of a data processing channel shown in 25 Figure 2 according to a first embodiment of the invention, - Figure 4 is a flowchart showing a determination method according to the invention, and - Figure 5 is a view similar to that in Figure 3 according to a second embodiment of the invention. 30 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In this present document, the term "electrical railway signalling unit" is understood to refer to any unit capable of providing, over a railway network, a signal intended to inform either the driver of a railway vehicle moving over the network, or the railway vehicle itself.

5 The term "variable parameter relating to a current" is understood to refer to any electrical parameter characteristic of this current, such as the electrical current intensity or the electrical voltage, for example. Figure 1 shows a train 10 traveling on a railway network 12, and a signalling system 5 14 in conformity with the invention. The signalling system 14 includes at least two electrical railway signalling units 16 and a device 17 for determining a signalling state for each signalling unit 16. In the example of Figures 1 and 2, the signalling system 14 is formed of two electrical assemblies 14A, each electrical assembly 14A comprising of a signalling element 18 having six signalling units 16. 10 Each electrical assembly 14A in addition comprises six current sources 19, only two of which are shown in the Figure 2. In the example of Figure 2, each electrical assembly 14A also includes six relays 20, only two of which are shown in Figure 2. Each relay 20 is capable of controlling a signalling unit 16. Each electrical assembly 14A also includes a disconnector 21 provided with two terminals. For each electrical assembly 14A, each signalling unit 16 is 15 connected in series to a current source 19, a control relay 20, as well as to the disconnector 21. Alternatively, not shown, each electrical assembly 14A comprises of a single current source 19, connected to each of the signalling units 16. According to this alternative, each electrical assembly 14A includes six relays 20, each relay 20 being capable of controlling a 20 signalling unit 16. Further alternatively, the signalling system 14 does not include any control relay 20. Further alternatively or additionally, the signalling system 14 does not include a disconnector 21. As illustrated in the Figures 1 and 2, each signalling unit 16 is formed for example of a 25 signalling lamp. Each signalling lamp 16 includes for example several light emitting diodes, not shown in the figures for reasons of clarity. By way of a variant, each signalling lamp 16 is an incandescent lamp. In a general sense, each signalling unit 16 is an electrical charge. Each signalling unit 16 has one signalling state out of a plurality of predetermined signalling states. In the example of Figures 1 and 2, each lamp 16 presents three possible 30 light states corresponding to various different physical states of the lamp: a "lamp lit" state, a "lamp off' state, and a "flashing lamp" state. Each lamp 16 moreover also presents one signalling state from out of four signalling states: a first signalling state ES1 corresponding to the lighting state "lamp on", a second signalling state ES2 corresponding to the lighting state "lamp off", a third signalling state ES3 corresponding to the lighting state "flashing lamp" and 35 a fourth signalling state ES4 corresponding to a state "fault" and not corresponding to a particular lighting state. In its third signalling state ES3, the lamp 16 flashes based on a time 6 period T and a duty cycle ratio a. The fourth signalling state ES4 is a "fictional" state assigned to the lamp 16. This fourth state ES4, necessary for responding to the requirements of railway safety, corresponds either to the presence of an electrical fault situated on the exterior of the determination device 17, or to an internal fault in the device 17 and detectable 5 by the latter, as detailed here below. The fourth state ES4 does not correspond to a lamp 16 that is materially out of service. In the example of Figures 1 and 2, the lamps 16 of a same signalling element 18 present first, second, third and fourth signalling states ESI, ES2, ES3, ES4 that are identical. By way of a variant, the lamps 16 of the same signalling element 18 present distinctly 0 different first signalling states ES1, and second, third and fourth signalling states ES2, ES3, ES4 that are identical. More precisely, the lamps 16 of a same signalling element 18, for example, emit light signals of different wavelengths, each light signal associated with a lamp 16 corresponding to the first signalling state ES1 associated with this lamp. Alternatively, the lamps 16 of a same signalling element 18 present first, second, third and fourth signalling 5 states ES1, ES2, ES3, ES4 that are distinctly different. As illustrated in Figure 2, the determination device 17 is formed of a housing comprising, for each signalling element 18, a module 24 for data processing. In the example of Figure 2, each module 24 is connected between the current sources 19 and the signalling units 16 of an electrical assembly 14A, in parallel to one of the disconnectors 21. This .0 provides the ability to advantageously reduce the size encumbrance of the device 17. Each data processing module 24 includes at least one data processing channel 26. More precisely, each module 24 includes as many data processing channels 26 as there are signalling units 16 arranged within the electrical assembly 14A to which the module 24 is connected. Thus, in the example of Figure 2, each module 24 includes six data processing 25 channels 26, not shown in the figure for reasons of clarity. One of the six data processing channels 26 is shown in Figure 3. Each data processing channel 26 is connected in parallel with the associated disconnector 21 and is connected to one of the signalling units 16. Each data processing channel 26 thus forms, with the signalling unit 16 to which it is connected, an electrical circuit 27. Each circuit 27 is electrically independent of the other circuits 27. 30 As illustrated in the Figure 3, each data processing channel 26 comprises the means 28 for measuring at least one variable parameter relating to a current capable of flowing in the associated signalling unit 16, and computing means 30. The determination device 17 thus includes, for each signalling unit 16, the measurement means 28 and the computing means 30. 35 The measurement means 28 only include at least one current sensor 32. According to the example of Figure 3, the measurement means 28 for each processing channel 26 7 comprise a single current sensor 32. The current sensor 32 is connected in parallel with the disconnector 21, within the associated circuit 27. Thus, in accordance with the invention, at least one variable parameter measured by the measurement means 28 associated with a signalling unit 16 is the intensity of the current 5 flowing through this unit 16. Preferably, the only variable parameter measured by the measurement means 28 associated with a signalling unit 16 is the intensity of the current flowing through this unit 16. Advantageously, the current sensor 32 is a magnetic sensor, capable of emitting a measurement signal for measuring the intensity of the current flowing through the signalling 0 unit 16. This makes it possible to obtain a determination device that is very minimally intrusive 17 within the electrical assembly 14A. Furthermore, such a magnetic sensor may be used to measure both the intensity of a direct electric current as well as the intensity of an alternating electric current. The magnetic current sensor is for example a torus arranged around an electrical conductor, not shown, that enables the circulation of the said current. By 5 way of a variant, the current sensor 32 is a "shunt" effect sensor, or a Hall effect sensor, or even a current probe. The measurement means 28 are advantageously capable of carrying out several measurements of the intensity of the current over the course of a predetermined time period. More precisely, the current sensor 32 of each data processing channel 26 is capable of 0 measuring in a continuous and ongoing manner the intensity of the current flowing within the associated signalling unit 16, over the course of a time period D. In the example of Figures 1 to 3, the time period D is greater than the time period T elapsing between two flashes of the lamp 16. The computing means 30 are connected to the measurement means 28 and are 25 capable of generating a signal indicating the signalling state of the associated signalling unit 16. This signal is referred to as the signal S in the following sections of this document. In the example of Figures 1 to 3, the signal S is able to assume four different values, each corresponding to a respective signalling state ES1, ES2, ES3, ES4 of the associated signalling unit 16. 30 The computing means 30 comprise at least one data acquisition channel 34 and at least one data processing unit 36. According to the example of Figure 3, the computing means 30 comprise a data acquisition channel 34 and a data processing unit 36, connected to the channel 34. As shown in the Figure 3, the data acquisition channel 34 comprises of a logic circuit 35 38, referred to in subsequent sections as PGA (English acronym for Programmable Gain 8 Amplifier), a conversion module 40 for converting an analog signal into a digital signal, and a programmable module 42, connected in series in this order. The PGA 38 is connected to the current sensor 32 and is capable of applying a programmable gain to the measurement signal transmitted by the current sensor 32. The 5 PGA 38 moreover is also capable of enabling the selection of a type of predetermined test signal, originating from the programmable module 42, as detailed here below. By way of a variant, the channel 34 does not include a PGA 38. According to this variant, the conversion module 40 is connected directly to the current sensor 32. The conversion module 40 comprises an analog data processing unit 44, known per 0 se and connected to the PGA 38, and an analog digital converter 46, connected to the analog data processing unit 44. The programmable module 42 is advantageously a programmable logic circuit, in subsequent sections referred to as FPGA (the English acronym for Field-Programmable Gate Array). The FPGA 42 is connected between the analog digital converter 46 and the 5 data processing unit 36. The FPGA 42 is also connected, on the one hand, to the current sensor 32, and on the other hand, to the PGA 38. The FPGA 42 is advantageously capable of executing, in accordance with a predetermined test procedure, one or more test(s) on the operation of the measurement means 28. In the example of Figure 3, the FPGA 42 is capable of transmitting to the current .0 sensor 32, either periodically or at the request of the data processing unit 36, at least one test signal intended for testing the operation of this current sensor 32. The FPGA 42 is also capable of transmitting to the PGA 38 a plurality of sinusoidal signals of distinct amplitudes. The FPGA 42 is also capable of transmitting to the PGA 38 a command signal for ordering a type of test. The command signal allows the PGA 38, upon receiving a command from the 25 FPGA 42, to select the type of test signal used for testing of the conversion module 40. The FPGA 42 is advantageously capable of transmitting to the data processing unit 36 a sampled signal, and of time stamping the value of each sample of that signal. Each sample of the signal transmitted by the FPGA 42 to the processing unit 36 corresponds to an effective value of the current intensity measured by the current sensor 32. 30 The data processing unit 36 is, for example, formed by a processor associated with a memory storage. The processing unit 36 is capable of calculating the value of the signal S as a function of the values of samples of the signal transmitted by the FPGA 42, and of transmitting the signal S. More particularly, in the example of Figure 3, the data processing unit 36 is capable of comparing the value of each sample of the signal transmitted by the 35 FPGA 42 to at least one intensity threshold value stored in the memory, and calculating the value of the signal S as a function of the results these comparisons. The processing unit 36 9 is advantageously capable of comparing the value of each sample of the signal transmitted by the FPGA 42 to a first threshold value stored in the memory, and then to a second threshold value stored in the memory, strictly greater than the first threshold value. This double comparison helps ensure the absence of any confusion between the first signalling 5 state ES1 of the lamp 16 and the second signalling state ES2 of the lamp 16. The threshold values may be configured by a user. The processing unit 36 is also capable of calculating, based on the time stamp values relating to the values of samples of the signal transmitted by the FPGA 42, the time period T elapsed between two flashes of the lamp 16, as well as the duty cycle ratio a that is 10 associated with this flash. The processing unit 36 is then capable of deriving the value of the signal S based on the results of this calculation. The processing unit 36 is advantageously capable of transmitting to the FPGA 42 a request for launching of a predetermined test procedure. Each test procedure is, for example, stored in the memory of the processing unit. Each test procedure includes in 15 particular the issuance by the data processing unit 36, to the FPGA 42, of one or more test commands associated with the procedure. Besides the test procedures and the first and second intensity threshold values, the reference values T1, a1 respectively, corresponding to the theoretical time period elapsing between two flashes of the lamp 16, and to the theoretical duty cycle ratio, respectively, are 20 stored in the memory of the processing unit 36. At least one configuration parameter is also stored in the memory of the data processing unit 36. Advantageously several configuration parameters are stored in this memory. The reference values T1 and a1 may be configured by a user. The configuration parameters may be used by a user so as to be able to configure on 25 the one hand, the data processing unit 36, the PGA 38 and the FPGA 42 depending upon the intensity of the nominal current circulating within the signalling unit 16 and on the other hand, the data processing unit 36 based on the first and second threshold values. This ensures the ability of obtaining a determination device 17 that may be reconfigured, and thus is capable of operating, safely, with many types of signalling units 16. This characteristic 30 feature thus allows for the performing of accurate measurements of current intensity, and covering a wide range of potential currents. In the example of Figures I to 3, the signal determination device 17 is capable of transmitting to the train 10 a message reflecting the values of the signals S transmitted by all of the data processing units 36 associated with a signalling element 18, indicating the 35 signalling state of this signalling element 18.

10 Each current source 19 provides a power supply current to one of the signalling elements 18. In the example of Figures 1 and 2, each current source 19 provides a direct electric current to one of the signalling elements 18. By way of a variant, each current source 19 supplies an alternating electric current to one of the signalling elements 18, 5 The operation of the determination device 17 according to the invention will now be explained. In the Figure 4 are shown the steps of a determination method according to the invention, implemented by the signal determination device 17. Only one of the data processing channels 26, as well as the circuit 27 and the 0 signalling unit 16 asso ciated thereto, will be considered in subsequent sections below. Indeed, the operation of the other data processing channels 26 being analogous and each processing channel 26 operating independently of the others, the steps of the method implemented by the other data processing channels 26 will not be described in more detail. During an initial step 54, the measurement means 28 measure at least the intensity of 5 the current flowing through the signalling unit 16 in the example of Figure 3, the sensor 32 measures the intensity of the current flowing in the signalling unit 16. More precisely, the current sensor 32 performs, over the course of the time period D, several measurements of the intensity of the current flowing in the signalling unit 16. For each measurement performed during the time period D, the sensor 32 then transmits to the PGA 38 a signal for measuring .0 the intensity of the current flowing in the signalling unit 16. For reasons of clarity, in the remainder of this description only the measurements performed by the sensor 32 during the course of the time period D shall be considered. During a subsequent step 56, the PGA 38 applies a predetermined gain to each measurement signal transmitted by the current sensor 32 and transmits each resulting 25 analog signal to the analog to digital conversion module 40. During a subsequent step 58, the digital analog conversion module 40 converts each analog signal transmitted by the PGA 38 into a digital signal, and then transmits each digital signal to the FPGA 42. During a subsequent step 60, the FPGA 42 transmits to the processing unit 36 a 30 sampled signal, having previously time stamped the value of each sample of this signal. Each sample of the signal transmitted to the data processing unit 36 corresponds to an effective value of the current intensity measured by the current sensor 32. During a subsequent step 62, the data processing unit 36 calculates the value of the signal S based on the values of samples of the signal transmitted by the FPGA 42, 35 This step 62 of determining the value of the signal S includes a first sub-step 62A, in which the data processing unit 36 compares the value of each sample of the signal 11 transmitted by the FPGA 42 to at least one intensity threshold value stored in the memory of the data processing unit 36. In the example of Figure 3, the processing unit 36 compares the value of each sample to the first threshold value stored in the memory, then to the second threshold value stored in the memory. 5 The step 62 of determining includes a second sub-step 62B, in which the processing unit 36 calculates, via its processor, the value of the signal S as a function of the results of the comparisons performed in the first substep 62A. More specifically, if all of the values of samples are greater than the second threshold value, the processing unit 36 determines the value of the signal S as being the one 10 corresponding to the first signalling state ESI of the signalling unit 16. If all of the values of samples are less than the first threshold value, the data processing unit 36 determines the value of the signal S as being the one corresponding to the second signalling state ES2 of the signalling unit 16. If each sample value is either greater than the second threshold value or less than the 15 second threshold value, and if at least two sample values are distinctly different, the signalling unit 16 examines the time stamp values associated with these sample values. The processor of the processing unit 36 then uses these time stamp values to calculate the time period T elapsing between two flashes of the lamp 16 as well as the duty cycle ratio a associated with this flash. If the calculated time period T is equal to the theoretical time ?0 period T1 stored in the memory of the data processing unit 36, the data processing unit 36 determines the value of the signal S as being the one corresponding to the third signalling state ES3 of the signalling unit 16. If the calculated time period T is less or greater than the theoretical time period T1 stored in the memory of the data processing unit 36, the data processing unit 36 determines the value of the signal S as being the one corresponding to 25 the fourth signalling state ES4 of the signalling unit 16. By way of a variant, if the calculated time period T is greater than the theoretical time period T1 stored in the memory of the data processing unit 36, the data processing unit 36 determines the value of the signal S as the one corresponding to the first or to the second signalling state ES1, ES2 of the signalling unit 16. 30 In all other distinct cases, separate from the preceding cases, the data processing unit 36 determines the value of the signal S as being the one corresponding to the fourth signalling state ES4 of the signalling unit 16. During a subsequent step 64, the processing unit 36 transmits the signal S. In the example of Figures 1 to 3, in a final step, not shown, the signal determination 35 device 17 transmits to the train 10 two messages. Each message reflects the values of the 12 signals S transmitted by all of the data processing units 36 associated with one of the signalling elements 18, indicating the signalling state of this signalling element 18. Additionally, during a step 66 carried out in parallel with the steps 54 to 64, the data processing unit 36 transmits to the FPGA 42, for example periodically, a request to launch a 5 test procedure. The processing unit 36 transmits to the FPGA 42 in particular one or more test commands associated with the test procedure. The FPGA 42 then executes, according to the test procedure, one or more test(s) on the operation of the data processing channel 34. More specifically, the FPGA 42 transmits to the PGA 38 a signal for commanding a type of test. The FPGA 42 then transmits to the current sensor 32 a test signal. The steps 54 to 0 62 are then carried out for this test signal, and the processing unit 36 analyses the results obtained during a subsequent step 68. During the step 68, if the results obtained are in accordance with the pre-recorded theoretical results within the processing unit 36, the step 66 is performed again. Otherwise, the data processing unit 36 determines the value of the signal S as being the one 5 corresponding to the fourth signalling state ES4 of the signalling unit 16, and the final step 64 is carried out. By way of a variant, the step 66 is carried out periodically by the FPGA 42. In this case, the data processing unit 36 does not transmit to the FPGA 42 the request to launch a test procedure, but only the one or more test signals associated with the test procedure. 0 The testing step 66 provides the ability to perform a continuous test of the entire processing channel 26 and to detect any latent defects within this channel 26. Figure 5 illustrates a second embodiment of the invention for which the elements similar to the first embodiment previously described above, are identified by identical reference numerals and thus shall not be described again. 25 Unlike the first embodiment, the measurement means 28 for each processing channel 26 comprise a first current sensor 32A and a second current sensor 32B. In addition, the computing means 30 for each processing channel 26 include a first data acquisition channel 34A, a second data acquisition channel 34B, a first data processing unit 36A and a second data processing unit 36B. 30 The first and second current sensors 32A, 32B are connected in series between the current source 19 and the signalling units 16, in parallel with the disconnector 21, within the associated circuit 27. Each of the first and second current sensors 32A, 32B is, for example, structurally identical to the current sensor 32 of the first embodiment. The first data acquisition channel 34A, and the second channel 34B respectively, are 35 connected in series respectively between the first current sensor 32A, and the second current sensor 32B, and respectively the first data processing unit 36A, and the second data 13 processing unit 36B. Each of the first and second acquisition channels 34A, 34B is structurally analogous to the acquisition channel 34 of the first embodiment. The first data processing unit 36A is connected to the second data processing unit 36B. Each data processing unit 36A, 36B is structurally analogous to the data processing 5 unit 36 of the first embodiment previously described above. Each data processing unit 36A, 36B is thus capable of calculating a value Sa, Sb of the signal indicating the signalling state of the associated signalling unit 16, based on the values of samples of the signal transmitted by the FPGA 42 to which it is connected. Each data processing unit 36A, 36B is in addition capable of transmitting to the other 10 data processing unit 36A, 36B the value Sa, Sb of the signal that it has calculated, and testing the existence of an equality between the calculated values Sa, Sb of the signal. Only the first data processing unit 36A is capable of transmitting the signal S. The operation of the signal determination device 17 according to the second embodiment will now be explained. 15 The steps 54 to 68 of the determination method according to the second embodiment of the invention are identical to those of the determination method according to the first embodiment of the invention, and therefore will not be described in further detail. The determination method according to the second embodiment further includes, between the step of determining 62 and the final stage 64, a step of transmitting, by each data processing 20 unit 36A, 36B to the other data processing unit 36A, 36B, of the value Sa, Sb of the signal that it has calculated in the course of the step of determining 62. The determination method also includes, upon completion of this transmitting step, a step of testing, by each data processing unit 36A, 36B, of the existence of an equality between the calculated values Sa, Sb of the signal. 25 If, during the step of testing, each of the two data processing units 36A, 36B determines the existence of an equality between the values Sa, Sb, the first data processing unit 36A assigns as value to the signal S the value Sa, and outputs the signal S during the final step 64. Otherwise, the first data processing unit 36A assigns as value to the signal S the value corresponding to the fourth signalling state ES4 of the signalling unit 16, and 30 outputs the signal S during the final step 64. Compared to signal determination device according to the first embodiment of the invention, the device according to the second embodiment of the invention provides the ability to detect the internal faults and defects within the processing channel 26, that are undetectable in the first embodiment. This contributes to increasing the safety of the 35 signalling system 14.

14 The other advantages of this second embodiment of the determination device are identical to those of the first embodiment, and therefore shall not be described again. The person skilled in the art will of course understand that the invention is applicable in the same manner by using, for each processing channel, a number N of current sensors, 5 of data acquisition channels and data processing units, where N is an integer greater or equal to three. The same treatment processes are then performed in each of the N groups of components, then a "majority vote" is taken or a strict equality is tested in order to assign to the signal S its value. Thanks to the time stamping by the FPGA of each transmitted signal value, the signal 10 determination device 17 according to the invention provides the ability to detect a state of "flashing" of each signalling unit, and to determine the characteristic parameters of this flashing. The determination device 17 according to the invention also provides the ability to detect the signalling state of each signalling unit of the signalling system, in compliance with 15 the safety requirements necessary for this system. Furthermore, unlike the devices described in the prior art, the signal determination device 17 according to the invention, and regardless of whatever be the embodiment, has been created in the form of an integrated housing unit, which in particular greatly improves the compactness of the device. The device according to the invention moreover also has a 20 simpler design, especially due to the fact that it does not impose the requirement of jointly measuring currents and voltages in order to be operational. For each signalling unit whose signalling state must be determined, one single measurement of current by means of the device is sufficient. The device according to the invention does also does not require the presence of any control relay within the signalling system in order to be operational. 25 Unlike the devices described in the prior art, the signal determination device 17 according to the invention ensures the ability to measure in an independent manner the intensity of the current flowing through each signalling unit of a signalling element. This further makes it possible, with regard to the overall architecture of the signalling system, to test the processing channels independently of each other. 30 It may thus be conceived that the signal determination device 17 according to the invention overcomes the constraints related to positioning of the measurement means and to the control architecture of signalling units, while presenting significantly greater compactness. Throughout this specification and the claims which follow, unless the context requires 35 otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not 15 the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or 5 known matter forms part of the common general knowledge in the field of endeavour to which this specification relates,

Claims (9)

1. -A determination device for determining a signalling state for a plurality of electrical railway signalling units, each signalling unit having one signalling state out of a plurality of 5 predetermined signalling states, the device comprising, for each signalling unit: - measurement means for measuring at least one variable parameter relating to a current capable of flowing through the signalling unit, and - computing means connected to the measurement means and capable of generating 10 a signal indicating the signalling state of the signalling unit, wherein at least one variable parameter measured is the intensity of the current flowing through the said signalling unit, wherein the computing means include at least one data acquisition channel, each data acquisition channel comprising a conversion module for converting an analog signal into 15 a digital signal and a programmable module, connected in series, the programmable module being connected to the measurement means and being capable of executing, in accordance with a test procedure, one or more tests on the operation of the measurement means, and wherein each programmable module is in addition capable of time stamping each intensity value measured by the measurement means, and wherein the computing means 20 are capable of calculating at least one parameter that is characteristic of a signalling state of the signalling unit, based on the time stamp values related to the said measured values.

2. -A device according to claim 1, wherein the only variable parameter measured is the intensity of the current flowing through the said signalling unit. 25

3. -A device according to claim 1, wherein the measurement means are capable of performing a plurality of measurements of the intensity of the current over the course of a predetermined time period, and wherein the computing means are capable of calculating the value of the signal indicating the signalling state of the signalling unit based on the results of 30 this plurality of measurements.

4. -A device according to claim 3, wherein the computing means are further capable of comparing each value of the intensity measured to at least one predetermined threshold value of intensity, and of calculating the value of the signal indicating the signalling state of 35 the signalling unit based on the results of these comparisons. 17

5. -A device according to claim 1, wherein the computing means include a first data acquisition channel, a second data acquisition channel, a first data processing unit and a second data processing unit, and in that the measurement means include a first and a second current sensors, the first and second current sensors being connected in series, the 5 first, and the second data acquisition channels respectively, being connected in series between respectively the first, and the second current sensors, and respectively the first and the second data processing units, each data processing unit being capable of calculating the value of the signal indicating the signalling state of the signalling unit, the first data processing unit being connected to the second data processing unit and being capable of 10 generating the said signal, the value of the signal generated being dependent upon the existence of an equality between the values of signals calculated by the first and second data processing units.

6. -A signalling system comprising a plurality of electrical railway signalling units and 15 a determination device for determining a signalling state for each signalling unit, each signalling unit having one signalling state out of a plurality of predetermined signalling states, wherein the signal determination device is in accordance with claim 1.

7.-A determination method for determining a signalling state for a plurality of 20 electrical railway signalling units, each signalling unit having one signalling state out of a plurality of possible signalling states, the method being implemented by a device comprising, for each signalling unit, measurement means for measuring at least one variable parameter relating to a current capable of flowing through the signalling unit, and computing means connected to the 25 measurement means and capable of generating a signal indicating the signalling state of the signalling unit, the method including, for each signalling unit, the following steps: - measuring, by the measurement means, of the said at least one variable parameter relating to a current capable of flowing through the signalling unit 30 - determining, by the computing means, of the signalling state of the signalling unit, and - transmitting, by the computing means, of the signal indicating the signalling state of the signalling unit, wherein at least one variable parameter measured is the intensity of the current 35 flowing through the said signalling unit, 18 wherein the computing means include at least one data acquisition channel, each data acquisition channel comprising a conversion module for converting an analog signal into a digital signal and a programmable module, connected in series, the programmable module being connected to the measurement means and being capable of executing, in accordance 5 with a test procedure, one or more tests on the operation of the measurement means, and wherein the method further includes time stamping, by each programmable module, of each value measured by the measurement means, and calculation, by the computing means, of at least one parameter that is characteristic of a signalling state of the signalling unit, based on the time stamp values related to the said measured values. 10

8. -A method according to claim 7, wherein the step of measuring comprises a plurality of measurements of the intensity of the current flowing in the signalling unit, the said measurements being performed by the measurement means over a predetermined time period. 5

9. - A method according to claim 8, wherein the step of determining includes: - comparison of each value of the intensity measured to at least one predetermined threshold value of intensity, and - calculation of the value the signal indicating the signalling state of the signalling unit .0 based on the results of these comparisons.