JP5055955B2 - Railway vehicle transmission equipment - Google Patents

Description

  The present invention relates to a railway vehicle transmission device on a network that transmits and receives data between control and display devices in a train, and particularly suitable for improving communication reliability between vehicles. About.

  Various communication devices are used in trains to communicate information for operation control, display information for providing information to passengers, and the like. When the signal lines are laid for each different information, the amount of the signal lines increases. Therefore, as described in [Patent Document 1], the wiring is reduced by networking.

  In addition, when a train is networked, if a dedicated communication line is used as a line connecting between vehicles, it becomes expensive and difficult to automatically connect, so a conventional lead-through line is used. When the transmission speed is increased, the communication frequency is increased, and therefore, increase in attenuation of the lead-through line and noise mixing are problematic. For this reason, as described in [Patent Document 2], there is an example in which communication is performed by raising the signal voltage level between vehicles from the communication signal voltage in the vehicle.

  In addition, a plurality of vehicles are connected to form a single train, but the communication direction of information is controlled as described in [Patent Document 3] so that a smooth network can be constructed even when vehicles are connected and disconnected. Possible transmission repeaters are being considered.

Japanese Patent No. 373080 Japanese Patent No. 3720326 JP 2005-168126 A

  The amount of information to be communicated is increasing with the enhancement of train operation control and passenger service functions, and as described in [Patent Document 1], it is necessary to reduce the number of wires by networking. Although a coaxial cable and an optical cable can be laid for the communication line in the vehicle, it is difficult to use these cables for the vehicle connecting portion in terms of cost and workability. Therefore, as described in [Patent Document 2], when a lead-through line used in a train is used as a communication line, there is a method of increasing the signal voltage to compensate for signal attenuation. In addition, there is a problem that a plurality of lead-through lines are bundled and may interfere with other lines and cause noise.

  Further, as described in [Patent Document 3], when Ethernet (registered trademark), which is widely used as a transmission protocol, is used for transmission between vehicles by a transmission repeater, CDMA / CD (Carrier Sense Multiplex). (Access with Collision Detect) method, it is necessary to monitor data collision, and there is a problem that collision detection is difficult because the lead-in line is attenuated and noise is mixed. In other words, Ethernet and RS422 used for communication within a train are baseband communications in which digital data is converted into a signal voltage for communication. Since 0 or 1 of the data is determined based on the voltage level, there is a risk that the data is erroneously determined due to waveform distortion due to noise, reflection from a signal line connecting portion between vehicles, or signal attenuation frequency characteristics.

  An object of the present invention is to provide a railway vehicle transmission apparatus having high communication performance with respect to signal attenuation and noise between vehicles, which are problems when an information network is constructed in a train.

  In order to achieve the above object, the railway vehicle transmission apparatus of the present invention modulates digital data at a specific frequency and transmits it, and demodulates it at the frequency on the receiving side. Further, the communication stability can be improved by adopting OFDM (Orthogonal Frequency Division Multiplexing) as a modulation system and performing communication avoiding a frequency region where reflection and attenuation are large.

  Also, the transmission timing is one-to-one communication with an adjacent transmission device, and the transmission timing is ping-pong transmission performed after the other party's transmission is completed, and the transmission is performed alternately even when there is no data to be transmitted. is there.

  The transmission frame is modulated and transmitted to an adjacent transmission device only when the transmission frame of the in-vehicle network is sent to a terminal connected to the network of another vehicle.

  According to the present invention, since data is modulated and transmitted by one-to-one communication, it is resistant to signal attenuation and noise, and communication is stable even in a lead-in line that is a signal line between vehicles between trains. Can be improved. In addition, since data collision does not occur during transmission between vehicles, waiting time is small, efficient transmission is possible, and separation and connection of vehicles can be easily handled.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the configuration of a railway vehicle transmission apparatus according to this embodiment.

  As shown in FIG. 1, a terminal 2 that is a control device, a sensor, a display device, or the like is connected to a hub 1 by a LAN communication line 6, and a network is formed in one vehicle 5. The hub 1 is connected to the relay device 3 via the LAN communication line 6, and the relay device 3 is connected to the relay device 3 of an adjacent vehicle by a lead-through line 4.

When data is transmitted from the terminal 2a of the vehicle 5a to the terminal 2b, the data is transmitted via the hub 1a. When transmitting from the terminal 2a to the terminal 2d of the other vehicle 5b, the transmission is performed via the hub 1a, the relay device 3a, the relay device 3b, and the hub 1b. For transmission between terminals, widely used communication protocols such as Ethernet and RS422 are adopted. However, transmission between the relay devices 3 modulates and demodulates communication frame data from the hub 1 by one-to-one communication. Do it.

  FIG. 2 is a configuration diagram of the relay apparatus according to the present embodiment. An IF circuit 7 (abbreviation of interface circuit 7) is connected to the LAN communication line 6, and an address selection reception buffer 8 and a transmission buffer 17 are connected to the IF circuit 7. A modulator 9, a switching circuit 11, and a transmission amplifier 12 are sequentially connected to the address selection reception buffer 8, and a demodulator 16 and a reception amplifier 14 are sequentially connected to the transmission buffer 17. A transmission / reception control circuit 18 connected to the memory 10, the modulator 9 and the demodulator 16 is connected to the switching circuit 11. The transmission / reception control circuit 18 is connected to a connection line between the demodulator 16 and the reception amplifier 14 via the synchronization detection circuit 15. The transmission amplifier 12 and the reception amplifier 14 are connected to the coupler 13.

  The case where communication is performed between the terminals 2 between vehicles by the relay device 3 configured as described above will be described.

  Communication frame data transmitted from the terminal 2 via the hub 1 and the LAN communication line 6 is received by the IF circuit 7 of the relay device 3 via the hub 1. The reception data is identified by the address selection reception buffer 8 and stored in the address selection reception buffer 8 if it is determined that the data should be relayed from the destination address of the reception data.

  FIG. 3 is a configuration diagram of a communication frame on the LAN communication line 6 and a communication frame on the lead-in line 4 according to this embodiment.

  The communication frame configuration shown in (b) of FIG. 3 shows the frame configuration on the LAN communication line 6 and includes a header that is communication control information and a payload that transmits and receives data used by the terminal. As shown in FIG. 3A, the header stores a transmission address, a destination address, information indicating the frame length, and the like. Using the destination address information, the address selection reception buffer 8 of the relay device 3 determines whether or not the data is to be transmitted by the relay device 3.

  The communication frame configuration shown in (c) of FIG. 3 shows the communication frame configuration on the lead-in line 4, and has a configuration in which a synchronization signal indicating the head of data is added before the header during modulation communication. . Since the communication is one-to-one, a destination address is not necessary for the header information, and information on a transmission address and a frame length is stored.

  The reception data stored in the address selection reception buffer 8 is controlled by the switching circuit 11 by the transmission / reception control circuit 18, and the synchronization signal stored in the memory 10 is transferred to the switching circuit 11, the transmission amplifier 12, the coupler 13, and the lead-through line. 4 is transmitted to the relay device 3 of the adjacent vehicle, the header information generated by the transmission / reception control circuit 18 is then modulated by the modulator 9, and the switching circuit 11 is switched to transmit the modulated header information to the switching circuit 11. The data is transmitted to the relay device 3 of the adjacent vehicle via the amplifier 12, the coupler 13, and the lead-through line 4. Finally, the reception data stored in the address selection reception buffer 8 is modulated by the modulator 9, and the switching circuit 11 is switched to convert the reception data modulated to a specific frequency into the switching circuit 11, the transmission amplifier 12, the coupler 13, and the subtraction. It transmits to the relay apparatus 3 of an adjacent vehicle via the through line 4.

When receiving data from the relay device 3 of the adjacent vehicle via the lead-in line 4, the synchronization detection circuit 15 does not include a synchronization signal for the signal received via the coupler 13 and the reception amplifier 14. To detect. When a synchronization signal is detected, the transmission / reception control circuit 18 is notified, and a modulated signal such as a header and data is sequentially received following the synchronization signal. Is output. The IF circuit 7 transmits the data stored in the transmission buffer 17 to the LAN communication line 6 at an appropriate timing.

  Thus, since the relay device 3 modulates and demodulates the communication frame data transmitted through the LAN communication line 6, the probability of occurrence of a communication error with respect to noise and signal attenuation is reduced, and reliability is improved. it can. Reliability can be improved by applying a single carrier to the modulation scheme, but if OFDM modulation, which is a multi-carrier scheme, is applied, data can be communicated using a wide frequency band, and the following effects are obtained. First, since the frequency bandwidth is wide, the transmission voltage per unit frequency can be lowered, and electromagnetic interference with other devices can be reduced. The second point enables stable communication. In other words, since the lead-through line is connected by a connector at the connecting part between the vehicles, the impedance of this connecting part is different, and reflection attenuation may occur. However, in OFDM, data is allocated and transmitted to multiple carriers in the band. Therefore, when a signal of a specific carrier is attenuated by reflection attenuation, it is possible to avoid allocating data to the carrier, and stable communication is possible without being affected by reflection attenuation.

  FIG. 4 is a diagram schematically illustrating a transmission state of a modulated signal between relay devices. Reference numerals 3a and 3b described on the synchronization signal and the header are relays on which the data is transmitted. Indicates the device. As shown in FIG. 4, the relay devices 3a and 3b alternately transmit a synchronization signal and header information. When there is no data to be transmitted at the time of transmission, there is no payload and only the synchronization signal and header are transmitted. In this case, by setting the length of the header to 0, the receiving side relay device can know that there is no payload.

  CDMA / CD adopted in Ethernet or the like is a method for transmitting data when transmission data is generated. In this case, if data is transmitted simultaneously by both relay apparatuses, there is a possibility that data collides and communication becomes impossible. For this reason, it is necessary to confirm that no other device is transmitting before transmission (carrier sense) and to constantly monitor whether the transmitted data has collided. Since it is necessary to carry out carrier sense for a certain period of time, the pause period between transmissions becomes longer and the efficiency decreases. In addition, since the attenuation is large in the lead-through line, when the reception signal level is lowered, it is difficult to detect the transmission signal and the reception signal on the transmission side, and there is a possibility that the conventional method misses the collision.

  On the other hand, in the present embodiment, since the transmission is performed alternately, there is no need for carrier sense, the pause period can be shortened, and the efficiency is improved.

  The operation when the vehicle 5c is disconnected at a station or the like will be described using the example shown in FIG.

  FIG. 1 shows an example in which three vehicles are connected, and the relay device 3b of the center vehicle is connected to the relay devices 3a and 3c of the left and right vehicles. As shown in FIG. 4, the relay device 3c and the relay device 3d transmit alternately even when there is no transmission data from the hub 1.

  In this state, when the vehicle 5c is disconnected, data from the relay device 3d is not received by the relay device 3a. Therefore, the relay device 3a is in a state where the relay device 3d is disconnected or cannot transmit due to a failure. I can know that. As described above, since the transmission is performed alternately between the relay devices regardless of the presence or absence of the transmission data, even when the vehicle is disconnected, it is possible to know the existence and state of the counterpart relay device.

  In addition, when data is not transmitted from the other relay device after the set period has elapsed, the data is transmitted again from the relay device 3a, so that when the vehicle 5c is connected, the data from the relay device 3d is transmitted. Since there is transmission, the relay device 3a can know that it is connected. Even if the connected vehicle is a new vehicle, the relay device of the present embodiment receives one-to-one communication regardless of the transmission address, and therefore can communicate without problems.

  As described above, according to the present embodiment, adjacent relay apparatuses transmit one another in one-to-one communication, and transmit again when the transmission from the other party is not within the set period. Can be easily accommodated.

  Further, the communication in the vehicle has a star type network configuration via a hub, and the example in which the relay device is connected to the hub has been described. However, as shown in FIGS. 5 and 6, the network configuration in the vehicle is a bus type. , It may be a ring type, and the entire train can be easily networked by connecting a relay device to the network.

  In this embodiment, digital data is modulated and transmitted at a specific frequency, and the reception side demodulates at the above frequency, so that the influence on noise can be reduced. Further, the communication stability can be improved by adopting OFDM (Orthogonal Frequency Division Multiplexing) as a modulation system and performing communication avoiding a frequency region where reflection and attenuation are large. In OFDM, the transmission spectrum is flat with respect to frequency, so the transmission voltage per frequency can be reduced compared to the conventional method of boosting and transmitting the signal voltage of baseband communications, thus reducing interference with other signal lines. it can.

  Further, the communication is one-to-one communication with an adjacent transmission apparatus, and the transmission timing is ping-pong transmission performed after the transmission of the other party is completed. Even when there is no data to be transmitted, the transmission is alternately performed. For this reason, data collision does not occur, and when the transmission frame of the in-vehicle network is modulated and transmitted to an adjacent transmission device, communication can be performed with the shortest waiting time.

  In addition, only when sending a transmission frame of an in-vehicle network to a terminal connected to a network of another vehicle, the transmission frame is modulated and transmitted to an adjacent transmission device, so unnecessary data is transmitted and received between the transmission devices. Therefore, the use efficiency of the transmission line is high. In addition, since the communication is one-to-one with an adjacent transmission device, it is possible to easily cope with the division and connection of a plurality of vehicles.

  The railway vehicle transmission device of the present invention can be applied to applications for relaying between networks when the attenuation of the transmission path between the networks is large and noise is mixed.

The block diagram of the transmission apparatus for rail vehicles which is one Example of this invention. The block diagram of the relay apparatus of a present Example. The block diagram of the communication frame on the LAN communication line of a present Example, and the communication frame on a lead-in line. The figure which showed typically the transmission condition of the modulated signal between the relay apparatuses of a present Example. The block diagram of the transmission apparatus for rail vehicles which uses a bus type for the network in a vehicle of a present Example. The block diagram of the transmission apparatus for rail vehicles which uses a bus type for the network in a vehicle of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hub 2 Terminal 3 Relay apparatus 4 Lead-through line 5 Vehicle 6 LAN communication line 7 IF circuit 8 Address selection reception buffer 9 Modulator 10 Memory 11 Switching circuit 12 Transmission amplifier 13 Coupler 14 Reception amplifier 15 Synchronization detection circuit 16 Demodulator 17 Transmission buffer 18 Transmission / reception control circuit

Claims (7)

A relay device installed in each of a plurality of connected vehicles;
A terminal in each vehicle connected to the relay device via a network;
A lead wire connecting a relay device between adjacent vehicles,
The relay device is data added after the header, regardless of whether the communication signal includes data to be relayed from the terminal in the vehicle,
A railway vehicle transmission device that alternately transmits and receives the communication signal by one-to-one communication with a relay device mounted on an adjacent vehicle. A relay device installed in each of a plurality of connected vehicles;
A terminal in each vehicle connected to the relay device via a network;
A lead wire connecting a relay device between adjacent vehicles,
The relay device is data added after the header including the destination address , regardless of whether the communication signal includes data used by the terminal in each vehicle.
A railway vehicle transmission device that alternately transmits and receives the communication signal by one-to-one communication with a relay device mounted on an adjacent vehicle. In the railway vehicle transmission device according to claim 1 or 2,
The transmission device for a railway vehicle, wherein the relay device transmits again when the communication signal from the relay device mounted on the adjacent vehicle that has transmitted is not received within a set period. In the railway vehicle transmission device according to any one of claims 1 to 3,
The communication signal, the transmission system for a railway vehicle, which comprises at least synchronization signal. In the railway vehicle transmission device according to any one of claims 1 to 4,
The relay device modulates and transmits the communication signal at a specific frequency,
A transmission apparatus for a railway vehicle, wherein the modulated communication signal is received and demodulated. The railway vehicle transmission device according to claim 5,
A railway vehicle transmission apparatus, wherein the modulation is a multi-carrier system including OFDM. The railway vehicle transmission device according to any one of claims 1 to 6,
The relay apparatus, the relay destination address included in the communication signal received is connected to the communication signal only if other than the terminal in the vehicle connected to the network of the relay device in the pull through line device A transmission device for a railway vehicle, characterized by being transmitted to

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