Dual network and dual optical data link based signal transmission system

Abstract

A signal transmission system based on a dual network and a dual optical data link is disclosed. A signal transmission system for managing vehicle traffic according to the present disclosure comprises at least one interlocking system and a gateway device including an active gateway device and a standby gateway device. The interlocking system transmits the same control signal to the active gateway device and the standby gateway device. The active gateway device converts the received control signal into a preset standard frame. The active gateway device and the standby gateway device receive the same control signal from the interlocking system and exchange their respective status data to verify the normal state of each of the active gateway device and the standby gateway device or the normal state of each network. When an abnormality is detected in the state of the active gateway device or the network of the active gateway device, the standby gateway device performs the role of the active gateway device in place of the active gateway device.

Description

Technology Field

[0001] The present disclosure relates to the field of signal control technology for managing vehicle traffic, and more specifically, to a dual network-based and dual optical data link-based signal transmission system that improves the integrity, safety, and communication reliability of control signals by duplicating the network layer and the optical physical layer, respectively, in the process of converting control signals generated by a control device or an interlocking system into standardized frames through a gateway device and transmitting them to an optical signal transmission device, and the optical signal transmission device transmitting the control signals to a field control device through an optical data link. Background Technology

[0002] Generally, signal transmission systems controlling vehicle traffic ensure the safety and continuity of the overall traffic flow by transmitting control commands generated by control units or interlocking devices to field control units via gateway devices, and by feeding back the operation results or status information of field equipment to higher-level control units. In such signal transmission systems, the system must operate stably even in situations such as control command delays, erroneous transmission, data loss, or path interruptions; furthermore, in safety-critical environments such as railways, the reliability and redundancy of communication paths are essential.

[0003] However, conventional signal control systems are mostly configured based on a single network or a single optical transmission path, which presented a problem where the entire control system was immediately affected if a failure occurred in a specific section. For instance, it was common practice to configure a redundant path for only one of the upper or lower control sections, such as by duplicating only the communication between the interlocking device and the gateway device, or by duplicating only the optical data link. In such partial redundancy structures, a failure in a specific section causes a bottleneck, disrupting the entire control command flow and, in severe cases, posing a risk of field equipment malfunction.

[0004] In particular, devices that directly control actual field equipment (signals, switches, track circuits, etc.), such as Trackside Functional Modules (TFMs), are sensitive to the integrity and timing of control commands; therefore, in a single-transmission-path based structure, it is difficult to effectively prevent problems such as optical signal loss, jitter, and transmission path failures. Furthermore, even if some conventional systems are equipped with active and standby devices, they lack sufficient functions for exchanging status information between devices or determining network normality, leading to issues where failover does not occur in a timely manner or unnecessary switching takes place. Prior art literature

[0005] Published Patent Application No. 10-2022-0007031 The problem to be solved

[0006] The present invention aims to solve the problems of the conventional technology described above by duplicating the signal transmission path between the interlocking device and the gateway device into a first network and a second network, thereby ensuring that the same control signal is stably transmitted through the other path even if a failure occurs in one path, and thus improving the reliability of the upper control section.

[0007] In addition, the purpose is to minimize problems such as delay, signal loss, and interference that may occur in the physical communication section by converting the control signal transmitted from the gateway device to the field control device into an electrical signal and then transmitting it in parallel to the field control device via a dual optical data link using multiple optical signal transmission devices.

[0008] The purposes of the present disclosure are not limited to those mentioned above, and other purposes and advantages of the present disclosure not mentioned may be understood from the following description and will be more clearly understood from the embodiments of the present disclosure. Furthermore, it will be readily apparent that the purposes and advantages of the present disclosure can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0009] A signal transmission system for managing vehicle traffic according to the present embodiment includes at least one interlocking device and a gateway device including an Active Gateway device and a Standby Gateway device, wherein the interlocking device transmits the same control signal to the Active Gateway device and the Standby Gateway device, the Active Gateway device converts the received control signal into a preset standard frame, the Active Gateway device and the Standby Gateway device receive the same control signal from the interlocking device and exchange their respective status data to verify the normal state of each of the Active Gateway device and the Standby Gateway device or the normal state of each network, and the Standby Gateway device can perform the role of the Active Gateway device in place of the Active Gateway device when an abnormality is detected in the state of the Active Gateway device or the network of the Active Gateway device.

[0010] Here, the interlocking device can transmit the same control signal to the Active gateway device and the Standby gateway device through the first network and the second network, respectively.

[0011] At this time, the Active gateway device can convert each of the control signal received through the first network and the control signal received through the second network into the preset standard frame.

[0012] At this time, the device further includes a first optical signal transmission device that communicates with the gateway device and a second optical signal transmission device that communicates with the gateway device, and the Active gateway device can perform at least one of a first operation of converting the converted control signal into a first electrical signal and transmitting it to the first optical signal transmission device and a second operation of converting the converted control signal into a second electrical signal and transmitting it to the second optical signal transmission device.

[0013] Here, the gateway device includes a Field Programmable Gate Array (FPGA), and through the FPGA, generates an electrical signal by performing at least one of Manchester encoding, Non-Return-to-Zero (NRZ), Return-to-Zero (RZ), Bi-phase method, 4B / 5B encoding, PWM-based encoding, and Binary Phase Shift Keying (BPSK)-based electrical signal modulation algorithms on the converted control signal, and can transmit the generated electrical signal to the first optical signal transmission device or the second optical signal transmission device.

[0014] Herein, the apparatus further includes a third optical signal transmission device that communicates with the first optical signal transmission device and a fourth optical signal transmission device that communicates with the second optical signal transmission device, wherein the first optical signal transmission device converts the first electrical signal into an optical signal to generate a first optical signal and transmits the first optical signal to the third optical signal transmission device via a first optical data link or transmits the first electrical signal to the third optical signal transmission device, and the second optical signal transmission device converts the second electrical signal into an optical signal to generate a second optical signal and transmits the second optical signal to the fourth optical signal transmission device via a second optical data link or transmits the second electrical signal to the fourth optical signal transmission device, and the third optical signal transmission device converts the first optical signal received from the first optical signal transmission device into an electrical signal to generate a third electrical signal, and the fourth optical signal transmission device converts the second optical signal received from the second optical signal transmission device into an electrical signal to generate a fourth electrical signal.

[0015] In this case, the system further includes a field control device that controls at least one field equipment device, and the field control device can receive at least one of the first electric signal or the third electric signal from the third optical signal transmission device and the second electric signal or the fourth electric signal from the fourth optical signal transmission device.

[0016] In addition, the field control device may determine that the first electric signal and the second electric signal, or the third electric signal and the fourth electric signal, are normal signals if the difference in reception times between the first electric signal and the second electric signal, or between the third electric signal and the fourth electric signal, is within a threshold value.

[0017] Alternatively, when at least one of the first electrical signal, the second electrical signal, the third electrical signal, and the fourth electrical signal is received, the field control device generates a response signal for each and transmits it to the third optical signal transmission device or the fourth optical signal transmission device; when the third optical signal transmission device receives the response signal, it transmits the response signal to the first optical signal transmission device; when the fourth optical signal transmission device receives the response signal, it transmits the response signal to the second optical signal transmission device; and the gateway device can determine whether each optical signal transmission device is normal based on the response signal received by the first optical signal transmission device from the third optical signal transmission device or the response signal received by the second optical signal transmission device from the fourth optical signal transmission device. Effects of the invention

[0018] The signal transmission system for managing vehicle traffic according to the present invention enables continuous transmission of control signals even if a failure occurs in a specific network section by duplicating the control signal transmission path between a control device or interlocking device and a gateway device into a first network and a second network.

[0019] In addition, by configuring the gateway device into an Active gateway device and a Standby gateway device, and by detecting a mismatch in the control signals or an abnormal state within the device to perform automatic switching, it is possible to prevent the signal transmission system from being interrupted due to a failure of the gateway device itself.

[0020] In addition, by duplicating the signal transmission between the gateway device and the field control device using a first optical data link and a second optical data link, and simultaneously transmitting the same control signal in the form of an optical signal, it is possible to prevent incorrect control signals from being reflected in the field device even in failure situations such as optical link disconnection, signal attenuation, or noise ingress. Brief explanation of the drawing

[0021] Aspects, features, and advantages of specific embodiments of the present disclosure will become more apparent from the following description with reference to the accompanying drawings. FIG. 1 is a drawing for schematically illustrating a signal transmission system according to one embodiment of the present disclosure. FIG. 2 is a diagram illustrating a signal transmission path of a signal transmission system according to one embodiment of the present disclosure. FIG. 3 is a block diagram illustrating the configuration of a gateway device according to one embodiment of the present disclosure. FIG. 4 is a sequence diagram for explaining the operation of a control device, a gateway device, and a first optical signal transmission device according to one embodiment of the present disclosure. FIG. 5 is a sequence diagram for explaining the operation of a first optical signal transmission device, a third optical signal transmission device, and a field control device according to one embodiment of the present disclosure. FIG. 6 is a diagram illustrating the operation of a gateway device transmitting a signal through an optical data link according to one embodiment of the present disclosure. FIG. 7 is a flowchart illustrating an algorithm for determining a received electrical signal as a normal signal by a field control device according to one embodiment of the present disclosure. Specific details for implementing the invention

[0022] Before specifically describing the present disclosure, the method of description in the specification and drawings is described.

[0023] First, the terms used in this specification and claims have been selected based on general terms considering their functions in the various embodiments of this disclosure. However, these terms may vary depending on the intent of those skilled in the art, legal or technical interpretations, and the emergence of new technologies. Additionally, some terms have been arbitrarily selected by the applicant. Such terms may be interpreted according to the meanings defined in this specification; in the absence of specific definitions, they may be interpreted based on the overall content of this specification and common technical knowledge in the relevant field.

[0024] In addition, the same reference numbers or symbols described in each drawing attached to this specification represent parts or components that perform substantially the same function. For convenience of explanation and understanding, the same reference numbers or symbols are used to describe different embodiments. That is, even if components having the same reference number are all depicted in multiple drawings, the multiple drawings do not imply a single embodiment.

[0025] Additionally, in this specification and claims, terms including ordinal numbers, such as "first," "second," etc., may be used to distinguish between components. These ordinal numbers are used to distinguish identical or similar components from one another, and the meaning of the terms should not be limited by the use of such ordinal numbers. For example, the order of use or arrangement of components combined with such ordinal numbers should not be restricted by the number. If necessary, each ordinal number may be used interchangeably.

[0026] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "consisting of" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0027] In the embodiments of the present disclosure, terms such as "module," "unit," "part," etc. are used to refer to a component that performs at least one function or operation, and such component may be implemented in hardware or software, or in a combination of hardware and software. Additionally, a plurality of "modules," "units," "parts," etc. may be integrated into at least one module or chip and implemented as at least one processor, except where each needs to be implemented in specific individual hardware.

[0028] Furthermore, in the embodiments of the present disclosure, when a part is described as being connected to another part, this includes not only a direct connection but also an indirect connection through another medium. Additionally, the meaning that a part includes a certain component implies that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0029] In the present disclosure, the expression “at least one of a, b, or c” may refer to “a”, “b”, “c”, “a and b”, “a and c”, “b and c”, “a, b, and c all”, or variations thereof.

[0030] The terms used in this disclosure have been selected to be as widely used and general as possible, taking into account their functions within this disclosure; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been selected at the applicant's discretion, and in such cases, their meanings will be described in detail in the relevant explanatory sections. Therefore, terms used in this disclosure should be defined not merely by their names, but based on their meanings and the overall content of this disclosure.

[0031] Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art as described in this specification. Additionally, terms including ordinal numbers, such as "first" or "second," used in this specification may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another.

[0032] When a part of a specification is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "part" or "module" as used in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0033] Embodiments of the present disclosure are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present disclosure in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0034] Here, the artificial intelligence model included in the present disclosure may be constructed by considering the application field of the recognition model, the purpose of learning, the form of the processing data, or the computational performance of the device.

[0035] An artificial intelligence model may be based on a neural network and may include multiple nodes (neurons) that simulate the human neural network. Each node has a weight and is connected to others to perform signal transmission processes similar to synapses.

[0036] Artificial intelligence models can include various structures such as Deep Neural Networks (DNN), Convolutional Neural Networks (CNN), Recurrent Neural Networks (RNN), Restricted Boltzmann Machines (RBM), Deep Belief Networks (DBN), Bidirectional Recurrent Deep Neural Networks (BRDNN), and Reinforcement Learning-based Q-Networks (DQN); recently, hybrid models that combine or modify these structures are also being utilized.

[0037] In addition to supervised learning, unsupervised learning, semi-supervised learning, and reinforcement learning, self-supervised learning techniques are being widely applied. Self-supervised learning can be utilized by performing pretraining using large-scale unstructured data, followed by fine-tuning or instruction-based learning to suit a specific domain.

[0038] FIG. 1 is a drawing for schematically illustrating a signal transmission system (1) according to one embodiment of the present disclosure.

[0039] The signal transmission system (1) according to the present disclosure may be a system configured to ensure the continuity of the control signal even in the event of a system failure, by duplicating the transmission path of the control signal in an environment where a number of field devices must be safely controlled, such as railway signal control, road traffic control, or industrial equipment control.

[0040] Referring to FIG. 1, the signal transmission system (1) according to the present embodiment may include an interlocking device (100), a gateway device (200), a first optical signal transmission device (300a), a third optical signal transmission device (300b), a field control device (400), and a field equipment device (500).

[0041] The interlocking device (100) may be a central control server, a traffic control server, or a higher-level control system for controlling traffic flow or managing the operating status of a train or vehicle.

[0042] For example, the interlocking device (100) may be implemented as an Electronic Interlocking Equipment (EIE) or Centralized Traffic Control (CTC) server in the case of a railway signaling system, and may be implemented as a Traffic Signal Controller server in the case of a road traffic management system.

[0043] The interlocking device (100) can acquire and analyze traffic control data such as operation schedule, train location information, track occupancy information, signal status information, and turnout direction information, and generate commands such as train operation control or signal status control based on the analysis results, and transmit control signals corresponding to each command to each gateway device (200).

[0044] The interlocking device (100) can communicate with the gateway device (200) through an Ethernet-based wired network and can monitor the control status of each field control device (400) through field status information or response signals received from the gateway device (200).

[0045] The gateway device (200) may be a relay device for converting a control signal received from the interlocking device (100) into a frame format that can be processed by the field control device (400) and transmitting it. The gateway device (200) may be implemented, for example, as a railway control communication gateway, an industrial control protocol converter, or a redundant network relay unit.

[0046] At this time, the gateway device (200) includes two or more Ethernet-based communication ports, so that it can communicate simultaneously with the interconnected device (100) through multiple networks.

[0047] The gateway device (200) can convert a control signal received from the interlocking device (100) into a preset standard frame (e.g., SSI, TCP / IP, UDP, or a dedicated railway signal standard) through an internal processor or control module, and the converted frame can then be transmitted to the first optical signal transmission device (300a) after undergoing a signal conversion process.

[0048] Meanwhile, the optical signal transmission device (300a, 300b) is an intermediate control device that manages signal conversion and optical data communication between the gateway device (200) and the field control device (400), and can convert an electrical signal received from the gateway device (200) into an optical signal and transmit it to the field control device (400), or convert an electrical signal received from the field control device (400) into an optical signal and transmit it to the gateway device (200).

[0049] An optical signal transmission device can be implemented as an ODLM (Optical Data Link Module) and can perform communication in pair with other optical signal transmission devices. The signal transmission system (1) according to the present disclosure may include a plurality of optical signal transmission devices and can ensure the continuity of the control signal despite physical link disconnection or signal attenuation by simultaneously transmitting the same control signal through a plurality of optical data links.

[0050] Meanwhile, the optical signal transmission device (300a, 300b) acts as a main controller that controls optical communication of the entire system and can manage the data transmission cycle, encoding specifications, and signal verification criteria (e.g., threshold) between the gateway device (200) and the field control device (400). Accordingly, the optical signal transmission device (300a, 300b) can perform real-time synchronization and fault detection in a redundant optical communication-based signal transmission system.

[0051] The field control device (400) may be a device that controls field equipment based on control signals received from optical signal transmission devices (300a, 300b) or monitors the status of field equipment and reports it to the gateway device (200).

[0052] The field control device (400) can be implemented, for example, as a Trackside Functional Module (TFM) of a railway signaling system, a Signal Control Module, a Point Machine Control Unit, or a Field Signal Controller of a road traffic control system.

[0053] The field control device (400) and the optical signal transmission device (300a, 300b) can receive the transmitted signal and perform an operation corresponding to the control command.

[0054] Additionally, the field control device (400) transmits a self-generated response signal (Ack signal) to the gateway device (200), thereby enabling the gateway device (200) to verify the normality of each optical data link or each network. Here, the response signal may include various information such as the internal control result of the field control device (400), sensor status, voltage level of the input / output port, relay driving result, etc.

[0055] The field control device (400) may include a plurality of control modules (e.g., UM (Universal Module), PM (Point Module), etc.), and each control module may be responsible for controlling railway equipment such as specific signals, switches, or track circuits.

[0056] The field control device (400) can communicate with the gateway device (200) through optical signal transmission devices (300a, 300b), and at this time, the first optical signal transmission device (300a) can be connected to the gateway device (200) and the third optical signal transmission device (300b) can be connected to the field control device (400).

[0057] The optical signal transmission device (300a, 300b) can perform the function of converting a received optical signal into an electrical signal or converting an internally generated electrical signal into an optical signal, and communication can be performed between the optical signal transmission devices in the form of an electrical signal or an optical signal. Accordingly, bidirectional communication between the gateway device (200) and the field control device (400) can be performed in the form of an electrical signal or an optical signal.

[0058] The field equipment unit (500) is a physical device that is controlled by the field control unit (400) and is a real field driving unit (Field Equipment Unit) in which control commands transmitted from the electronic interlocking unit (100) are finally executed.

[0059] The field equipment device (500) can be implemented, for example, in the case of a railway signal control system, as a signal light unit, a point machine, a track circuit, a level crossing controller, etc. In addition, in the case of a road traffic system, it can be a vehicle signal light controller, a pedestrian signal controller, a control node of an intersection-responsive signal system, or a vehicle detection unit, etc.

[0060] The field equipment device (500) can drive a relay, motor, solenoid, lamp, or switching circuit according to a control signal received from the field control device (400) to light up a signal, change the direction of a turnout, or change the energized state of a track circuit.

[0061] Additionally, the field equipment device (500) may include a state detection sensor for detecting the operation result itself, and through this sensor, can convert state information such as whether the light is on, whether the operation is completed, and whether current is flowing into an electrical signal and feed it back to the field control device (400).

[0062] For example, when the field equipment device (500) receives a control signal to turn on the red light of the signal, it can close the power circuit of the signal and detect the lighting state, generate the corresponding state information as a response signal, and then transmit it to the field control device (400).

[0063] Through this structure, it is possible to verify in real time whether the command transmitted from the linkage device was accurately executed at the site, and as a result, closed-loop control of the entire signal transmission system (1) can be implemented.

[0064] FIG. 2 is a diagram illustrating a signal transmission path of a signal transmission system (1) according to one embodiment of the present disclosure.

[0065] Referring to FIG. 2, in the signal transmission system (1) according to the present embodiment, a control signal generated by the interlocking device (100) can be transmitted to a gateway (200) device through a plurality of networks via a network switch (Network(N / W) Switch).

[0066] Here, the interlocking device (100) may be configured to be redundant with an Active interlocking device and a Standby interlocking device, and the Active interlocking device performs the generation and transmission of control commands in a normal state, and the Standby interlocking device may immediately switch to Active mode according to a failover trigger when a failure occurs in the Active control device.

[0067] The interlocking device (100) can generate main control commands to perform traffic control functions such as train operation, signal control, switch state switching, and track circuit monitoring, and transmit them to the gateway device (200).

[0068] At this time, the interlocking device (100) communicates simultaneously with the gateway device (200) through each of the multiple networks (first network (A-Net) and second network (B-Net)), thereby maintaining the continuity of the control signal even if a failure occurs in one of the networks.

[0069] Additionally, the interlocking device (100) can monitor the operating status of each field control device (400) and field equipment device (500) in real time based on field feedback data received from the gateway device (200). Accordingly, the interlocking device (100) can ensure the stability and continuity of traffic signal control for the entire system even if a network or gateway failure occurs.

[0070] Referring to FIG. 2, the gateway device (200) is a relay device for transmitting a control signal received from the interlocking device (100) to the field control device (400), and may be composed of an Active gateway device (GW-1) and a Standby gateway (GW-2) device.

[0071] The Active Gateway (GW-1) device acts as the main control node during normal operation and can convert the same control signal received from the interconnection device (100) through multiple networks (A-Net, B-Net) into a frame of a preset standard and then transmit it to the field control device (400).

[0072] The standby gateway device (GW-2) receives the same control signals as the active gateway (GW-1) device, but may remain in a standby state until an internal state abnormality or a mismatch in the control signals is detected in the active gateway (GW-1) device, and may receive the same data as the active gateway device (GW-1).

[0073] The Active Gateway Device (GW-1) and the Standby Gateway Device (GW-2) receive the same control signal from the interconnection device (100) and can verify the normal state of each gateway device or the network state of each gateway device by exchanging their respective status data. If a discrepancy occurs during the exchange of status data between the gateway devices (e.g., a problem occurs in the Active Gateway Device or a problem occurs in the network of the Active Gateway Device), the Standby Gateway Device (GW-2) can perform the role of the Active Gateway Device instead of the Active Gateway Device (GW-1). In this case, the Standby Gateway Device (GW-2) can convert the control signal received from the interconnection device (100) into a preset standard frame and transmit it to the optical signal transmission device (300a) instead of the Active Gateway Device (GW-1).

[0074] As described above, the optical signal transmission device (300a) can be implemented as an ODLM, is provided on the side of the gateway device (200), and may be configured in multiple units according to one embodiment. The gateway device (200) performs encoding on the received control frame and can transmit the encoded electrical signal to the optical signal transmission device (300a) or, if configured in multiple units, to each of the optical signal transmission devices (300a).

[0075] According to one embodiment, the optical signal transmission device (300a) converts a received electrical signal into an optical signal and can transmit the converted optical signal to an optical signal transmission device (300b) corresponding to each optical signal transmission device (300a) through an independent optical network (e.g., A-Net(III), B-Net(III)) corresponding to each optical signal transmission device. The optical signal transmission device (300b) is provided on the side of the field control device (400) and can be implemented to perform communication in pair with each optical signal transmission device (300a). According to another embodiment, the optical signal transmission device (300a) may transmit the received electrical signal to the optical signal transmission device (300b) in the form of an electrical signal without converting it into an optical signal.

[0076] Accordingly, the gateway device (200) performs network redundancy (Active / Standby switching) and the optical signal transmission device (300) performs optical conversion and transmission redundancy, thereby ensuring continuous transmission of control signals through another path even if a failure or loss of optical signal occurs in one of the communication paths.

[0077] Referring again to FIG. 2, the field control device (400) may be a terminal control device for receiving a control signal transmitted from the gateway device (200) and driving a signal or equipment to be controlled at an actual traffic site.

[0078] The optical signal transmission device (300b) located on the side of the field control device (400) can convert the received optical signal into an electrical signal through an optical data link connected to the optical signal transmission device (300a) located on the side of the gateway device (200) and transmit it to the internal control module of the field equipment device (400), and can convert the electrical signal generated in the field control device (400) back into an optical signal and transmit it to the optical signal transmission device (300a) located on the side of the gateway device (200).

[0079] As described above, a plurality of optical signal transmission devices (300a) may be provided on the side of each gateway device (200), and a plurality of corresponding optical signal transmission devices (300b) may be provided on the side of the field control device (400). Through such an optical communication method, a redundant communication path can be maintained.

[0080] In particular, the gateway device (200) according to the present disclosure may have a multiple connection structure connected through multiple networks and multiple optical links. Referring to FIG. 2, the Active gateway device (GW-1) and the Standby gateway (GW-2) may each have a dual connection structure connected to a plurality of optical signal transmission devices (300a).

[0081] Conventional gateways are often connected to only a single ODLM or a single optical data path, which caused the entire signal transmission system to be interrupted when a specific gateway or specific optical data path failed. However, in the multi-connection structure according to the present disclosure, since each gateway device is directly connected to a plurality of optical signal transmission devices, stable signal transmission can continue through the same optical path from the Standby gateway device even if a failure occurs in the Active gateway device.

[0082] This structure ensures not only the switching of gateway devices but also the redundancy of the optical data path itself, thereby enabling complete redundancy in both the network layer (first and second networks) and the optical signal transmission layer (A-Net(III), B-Net(III)). Consequently, since a single component or single path failure can fundamentally prevent the entire control system from being interrupted, it becomes possible to realize high-reliability, high-availability signal transmission required in safety-critical environments such as railways or roads. Meanwhile, the field control device (400) determines that the difference in reception time of the electric signals received from multiple optical signal transmission devices (300b) is within a preset threshold value, and can control the driving parts such as traffic signals, track switches, and circuit breakers according to the corresponding control command.

[0083] Meanwhile, the gateway device (200) can control multiple field control devices (400) in parallel, and according to one embodiment, control of up to 64 field control devices (400) may be possible. Each field control device (400) is branched and controlled according to unique identification information, and the gateway device (200) can monitor the communication status of individual devices through the response signal of each link.

[0084] Additionally, the gateway device (200) may periodically or non-periodically transmit status information indicating its own operating status or network status to the interlocking device (100). The status information may include the operating mode (Active / Standby) of the gateway device (200), whether the internal module is functioning properly, the connection quality and failure status of each network, the communication status with each optical signal transmission device, frame verification results, etc.

[0085] The method of reporting status information to the linkage device (100) can be implemented in various ways. According to one embodiment, only the Active gateway device can transmit status information to the linkage device (100), and according to another embodiment, both the Active gateway device and the Standby gateway device can be configured to transmit their respective status information to the linkage device (100). Through this, the linkage device (100) can identify the operating status and network environment of each gateway device in real time and perform rapid failover in the event of a failure.

[0086] Additionally, the gateway device (200) can receive response signals, feedback signals, or measurement signals reflecting the operating status of field equipment devices received in reverse from the field control device (400) and transmit them to the interlocking device (100). These response signals or measurement signals may include the results of executing control commands transmitted through the optical signal transmission device (300), information on changes in the status of field equipment devices, information on whether there is a fault, and time synchronization information. The gateway device (200) can filter or verify the received signals and transmit them to the interlocking device (100), thereby supporting the upper control layer to monitor the field situation in real time. Through this, the interlocking device (100) can check whether the control command has been executed and, if necessary, quickly execute a re-command or fault response procedure.

[0087] In this way, the signal transmission system (1) according to the present disclosure can provide a highly reliable control environment in which a control signal generated by a control device or an interlocking device (100) can be continuously transmitted even in the event of a single path failure or communication disconnection through a redundant communication structure through a plurality of networks and an Active / Standby type gateway.

[0088] In addition, the same control signal is transmitted to a field control device (400) via multiple optical data links in parallel through multiple optical signal transmission devices (300), and by verifying the synchronization and consistency of the electrical signals received from each path, malfunctions caused by incorrect signal transmission or data loss can be prevented. Therefore, while responding to failures in the network and optical communication sections, the integrity and real-time nature of the control signal are maintained, thereby ensuring a high level of stability and reliability in safety-critical control environments such as railway signal control.

[0089] FIG. 3 is a block diagram for explaining the configuration of a gateway device (200) according to one embodiment of the present disclosure.

[0090] Referring to FIG. 3, the gateway device (200) may include a memory (210), a communication interface (220), and a processor (230). However, the configuration of the gateway device (200) is not limited to that described above, and additional separate configurations may be provided or some configurations may be omitted.

[0091] First, regarding the configuration of the gateway device (200), the memory (210) of the gateway device (200) is configured to store various instructions or data related to the operating system (OS) for controlling the overall operation of the gateway device (200) and the components of the gateway device, and can perform the role of maintaining and managing core control data of the gateway device.

[0092] The memory (210) may include non-volatile memory such as ROM (Read Only Memory) and flash memory, and volatile memory such as DRAM (Dynamic Random Access Memory), and may additionally include auxiliary storage devices such as a hard disk or SSD (Solid State Drive) as needed.

[0093] Additionally, the memory (210) may store control signal data received from the linkage device (100), Active / Standby status information of the gateway device (200), a comparison reference value for determining whether the control signal is matched, and failover trigger occurrence conditions and history data.

[0094] In particular, the memory (210) stores standard frame format information for converting control signals, network-specific identification information (A-Net, B-Net), and setting parameters for each communication interface, thereby enabling the processor (230) to perform signal verification, conversion, or retransmission procedures depending on the situation.

[0095] Accordingly, the memory (210) enables the gateway device (200) to reliably process control signals in a redundant network environment and maintain data transmission integrity to the optical signal transmission device (300).

[0096] The communication interface (220) is configured for the gateway device (200) to transmit and receive data with an external interlocking device (100) and an optical signal transmission device (300), and can perform data exchange and control signal transmission between multiple communication paths within the signal transmission system (1).

[0097] The communication interface (220) can support both wired and wireless communication methods, and specifically, can be connected to each device via a private line, serial communication, or fiber optic network, centered on an Ethernet-based wired network. In addition, the communication interface (220) can operate by distinguishing between a first network (A-Net) and a second network (B-Net), thereby supporting the parallel transmission of the same control signal through multiple paths.

[0098] In the case of a wired communication interface, a physical connection may be made using a pair cable, a coaxial cable, or an optical fiber cable, and multiple ports may be provided to support a network redundancy structure. Additionally, the communication interface (220) may be linked with an internal processor (230) of the gateway device (200) to perform control signal processing, such as verifying the frame specifications of a received control signal, identifying a network path, and requesting data conversion.

[0099] The gateway device (200) is not limited to including only one communication interface (220), but includes multiple communication interfaces (220A, 220B) corresponding to network A and network B, respectively, so that data transmission and reception can continue through another path even if one network path is lost. Accordingly, the communication interface (220) can ensure stable transmission of control signals and continuous operation of the system even in the event of network failure or disconnection.

[0100] The processor (230) is a core component for controlling the overall operation of the gateway device (200) and controlling the data flow between the interlocking device (100) and the optical signal transmission device (300). The processor (230) is connected to the memory (210) and can control each component of the gateway device (200) and perform the processes of receiving, verifying, and converting control signals by executing control commands or programs stored in the memory (210).

[0101] The processor (230) can dynamically perform different roles depending on whether the gateway device (200) operates in Active mode or Standby mode. In Active mode, it performs real-time conversion and transmission of control signals, and in Standby mode, it monitors the status information of the Active gateway and can immediately take over control authority when a failover trigger occurs.

[0102] The processor (230) may internally include a plurality of functional modules. Referring to FIG. 3, the processor (230) may include a signal receiving module (231), a signal verification module (233), a data conversion module (235), an encoding module (235), and a signal conversion module (239). Each of these modules corresponds to a functional unit module that can be implemented in software or hardware.

[0103] The signal receiving module (231) receives control signals transmitted equally from the interlocking device (100) through the first network (A-Net) and the second network (B-Net), and can analyze the arrival time, format, identifier, etc. of the received signals and store them in memory (210). In addition, the signal receiving module (231) monitors the communication status for each network and can generate a retry signal if packet loss or transmission delay is detected.

[0104] The signal verification module (233) can determine whether the control signals are aligned by comparing and analyzing whether the control signals of the first network and the second network obtained by the signal receiving module (231) are identical. If the alignment result is inconsistent, the signal verification module (233) can determine the inconsistent state as an internal abnormal state and generate a switching trigger signal to transmit to the Standby gateway.

[0105] In addition to verifying whether control signals received through the first network and the second network are aligned, the signal verification module (233) can determine whether each gateway device is operating normally by analyzing status information exchanged between the Active gateway device and the Standby gateway device. Here, status information is information exchanged to evaluate the operational stability of the gateway device and the normality of the communication path, and may include at least one of internal status data of the gateway device and network status data.

[0106] The signal verification module (233) can periodically exchange status information or based on received events to check in real time whether each gateway device or the network to which the gateway device is connected is abnormal. Through this, if an internal fault occurs in the Active gateway device or if it is determined that one of the networks to which the gateway device is connected is in an abnormal state, the Standby gateway device can automatically perform failover to take on the role of Active.

[0107] The data conversion module (235) can convert a control signal received from a control device or an interlocking device into a transmission format suitable for communication with an optical signal transmission device (300). The data conversion module (235) can convert raw control data or non-formatted data provided by the control device or an interlocking device into transmission-formatted data according to a preset standard frame (e.g., transmission command frame, status report frame, safety protocol frame, etc.).

[0108] The data conversion module (235) can perform packaging into a standardized frame structure including a header, payload, checksum, sequence number, etc. of a control signal, data mapping in accordance with protocol specifications (e.g., a dedicated protocol for railway signaling) or inter-device interface specifications, combination and alignment of control commands and metadata (timestamp, signal class, channel information, etc.), or detection of abnormal data (missing, corrupted, format error) and error correction.

[0109] The structured data for transmission generated by the data conversion module (235) is subsequently digitally encoded in the encoding module (237) and converted into an electrical signal form that can be processed by the optical signal transmission device (300) in the signal conversion module (239), thereby enabling the performance of an intermediate layer conversion function that connects the upper control signal to a lower physical layer in a form suitable for the lower physical layer.

[0110] The encoding module (237) can perform encoding to convert structured control signal data generated by the data conversion module (235) into a transmission signal format that can be processed by the optical signal transmission device (300).

[0111] Specifically, the encoding module (237) can perform Manchester coding on the input bit sequence to improve the synchronization and transmission quality of the transmitted data. Manchester coding is an encoding method that includes level switching within each bit interval, which facilitates maintaining clock synchronization between transmission and reception and can provide the effect of reducing the impact of signal distortion or noise that may occur during the data transmission process. Accordingly, the encoding module (237) can generate a Manchester code according to waveform switching rules corresponding to logic 1 and logic 0 and provide it as a transmission signal.

[0112] Additionally, the encoding module (237) may selectively apply other forms of digital encoding standards, such as NRZ (Non-Return-to-Zero), RZ (Return-to-Zero), Bi-phase method, 4B / 5B encoding, PWM-based encoding, or BPSK-based electrical signal modulation algorithms, depending on the system settings or transmission environment.

[0113] In addition, the encoding module (237) can generate an error detection code (e.g., parity bit, checksum, CRC) to verify data integrity and add it to the transmission frame, and can insert a preamble or flag to identify the beginning and end of the frame.

[0114] The signal conversion module (239) can perform the function of converting the encoding signal generated in the encoding module (237) into an optical signal that can be transmitted in an optical signal transmission device.

[0115] More specifically, the signal conversion module (239) can adjust the electrical waveform of the encoded electrical signal into a form capable of optical modulation and control the waveform to be converted into an optical signal by transmitting it to a transmitting element (e.g., LED (Light Emitting Diode) or LD (Laser Diode)) included in the optical signal transmission device (300). In this conversion process, the signal conversion module (239) can normalize the level, timing, and waveform of the electrical signal to match the standard specifications required by the optical transmitting element, and can apply preset modulation standards such as NRZ-based optical modulation and Manchester-based optical modulation depending on the modulation characteristics.

[0116] Additionally, the signal conversion module (239) can monitor the operating state or optical output state of the optical signal transmission device and adjust the electrical input signal in real time to maintain the required optical output intensity (Opitcal Intensity) or optical modulation quality.

[0117] Each module may operate independently, but depending on the implementation form, they may be combined or separated to perform their functions. Additionally, the present invention may include other modules not described herein, and these modules may also contribute to the operation of the electronic device (100).

[0118] To this end, the processor (130) may be implemented as a general-purpose processor such as a CPU (Central Processing Unit) or AP (Application Processor), a graphics-dedicated processor such as a GPU (Graphic Processing Unit) or VPU (Vision Processing Unit), or an artificial intelligence-dedicated processor such as an NPU (Neural Processing Unit). The processor (160) may include volatile memory such as SRAM.

[0119] One or more processors (130) may be implemented as a single core processor including one core, or as one or more multicore processors including multiple cores (e.g., homogeneous multicore or heterogeneous multicore).

[0120] When one or more processors (130) are implemented as multi-core processors, each of the multiple cores included in the multi-core processor may include internal processor memory such as on-chip memory (110), and a common cache shared by multiple cores may be included in the multi-core processor.

[0121] Additionally, each of the multiple cores (or some of the multiple cores) included in the multi-core processor may independently read and execute program instructions for implementing the method according to one embodiment of the present disclosure, or all (or some of) of the multiple cores may be linked together to read and execute program instructions for implementing the method according to one embodiment of the present disclosure.

[0122] In the case where a method according to one embodiment of the present disclosure includes a plurality of operations, the plurality of operations may be performed by a single processor or by a plurality of processors.

[0123] For example, when the first operation, the second operation, and the third operation are performed by the method according to one embodiment, the first operation, the second operation, and the third operation may all be performed by the first processor, and the first operation and the second operation may be performed by the first processor (e.g., a general-purpose processor) and the third operation may be performed by the second processor (e.g., an artificial intelligence dedicated processor).

[0124] FIG. 4 is a sequence diagram for explaining the operation of an interlocking device (100), a gateway device (200), and a first optical signal transmission device (300a) according to an embodiment of the present disclosure. The operation process of the signal transmission system (1) can be performed through a stepwise signal processing procedure between the interlocking device (100), the gateway device (200), and the first optical signal transmission device (300a).

[0125] First, the interlocking device (100) can generate control signals related to traffic control, track switching, or traffic light control of a vehicle (S400). At this time, the interlocking device (100) operates in an Active and Standby configuration, and can generate the same control signals in parallel through a redundant network (A-Net, B-Net).

[0126] The interlocking device (100) is a central control server or operation management system that collects real-time train location, track occupancy information, signal light status, onboard communication data, etc., and can calculate operation control commands for each section based thereon. For example, depending on the approach distance and speed information of the train, it can generate a command signal to control the signal lights of a specific section to a 'stop' or 'proceed' state, or a switching command signal to control a point switch.

[0127] According to one embodiment, the generated control signal may be formed as a structure including multiple control parameters rather than a single signal. The control signal may include an ID (identifier) ​​of a control command, a timestamp, identification information (device ID) of a controlled device, a mode flag, etc.

[0128] In addition, the interlocking device (100) can parallelize the packet structure at the time of signal generation so that the same signal is transmitted simultaneously through each of a plurality of networks (first network (A-Net), second network (B-Net)) for the redundancy of the control signal.

[0129] The interlocking device (100) can transmit the generated control signal to the gateway device (200) (S410). The control signal is transmitted in the form of an electrical signal in packet units, and the gateway device (200) receives it, temporarily stores it in internal memory (210), and can determine whether it is the same signal through a signal verification module.

[0130] The interlocking device (100) can transmit the same control signal to both Active and Standby gateway devices. In this case, the interlocking device (100) can transmit the generated control signal in parallel to each gateway device through each of the multiple networks (first network (A-Net), second network (B-Net)). Each network is configured with mutually independent physical paths or switching routing paths, and has a redundancy structure so that the same signal can be transmitted through the other network even if one network fails.

[0131] When the interlocking device (100) transmits a control signal, it assigns a unique identifier and a frame sequence number to each packet, thereby enabling the gateway device (200) to identify whether the signals are identical. Additionally, each control signal may include additional information such as a command execution time (timestamp), a network identification flag, and a checksum for error detection.

[0132] The gateway device (200) receives a control signal transmitted from the interlocking device (100) and can verify the reception time and data matching of the signals input from the first network and the second network, respectively. If it is determined that the signals received from the two networks are identical, the gateway device (200) can recognize the signal as a normal control signal and perform a frame conversion procedure.

[0133] If part or all of the control signal is lost or a transmission delay occurs, the gateway device (200) may make a retransmission request to the interconnection device (100), and if the same signal is not received within a certain period of time, the network may be determined to be an abnormal link.

[0134] Meanwhile, the gateway device (200) can convert the received control signal into a preset standard frame (S420). The active gateway device (200) can ensure communication compatibility by converting the received control signal into a standardized frame structure.

[0135] According to one embodiment, when the gateway device (200) receives the same control signal from the interlocking device (100) through the first network and the second network, it can determine whether the control signals input through the two networks match and be controlled to immediately generate a standardized frame or to generate a standardized frame only when the control signals are the same.

[0136] In the frame generation process, the gateway device (200) can analyze the payload of the received control signal to generate a frame structure consisting of a header, a data field, an error detection field (checksum or CRC), and a frame end portion (trailer). The header may include an identifier (ID) of the control command, a data length, the address of the interconnected device, the address of the destination device, network path information, etc., and the data field may include actual control commands (e.g., point control, signal control, field equipment operation command, etc.).

[0137] Additionally, the gateway device (200) may generate a verification code, such as a Cyclic Redundancy Check (CRC), a parity bit, or a checksum, when creating a frame to detect data integrity and errors, and insert it into the frame. The error verification field can be used to detect data distortion or transmission errors that may occur during long-distance communication through an optical data link.

[0138] Subsequently, the gateway device (200) can convert frame data into an electrical signal to transmit the generated preset standard frame to the optical signal transmission device (300) (S430). Specifically, the gateway device (200) can modulate digital data in the form of a frame into an electrical waveform suitable for the transmission standard, and can adjust the signal to satisfy electrical conditions of the physical layer for optical conversion, such as electrical level, timing, and pulse width.

[0139] Specifically, the gateway device (200) can convert a bit sequence of frame data into an electrical signal suitable for transmission standards by performing at least one of Manchester Encoding, NRZ (Non-Return-to-Zero), RZ (Return-to-Zero), Bi-phase method, 4B / 5B encoding, PWM-based encoding, or BPSK (Binary Phase Shift Keying)-based electrical signal modulation algorithms through an encoding module.

[0140] The converted electrical signal may be in a form suitable for the transmitting element (e.g., LED or LD) of the optical signal transmission device (300) to convert into an optical signal. Additionally, the gateway device (200) can minimize signal distortion or loss that may occur during optical conversion by adjusting the voltage and current strength of the output electrical signal to match the input specifications of the optical signal transmission device.

[0141] These various encoding and modulation methods can be selected and applied depending on the system environment, the electrical characteristics of the transmission path, or the signal recovery algorithm of the field control device, and each method can be usefully utilized to ensure signal synchronization, improve noise immunity, or optimize transmission quality.

[0142] In addition, the gateway device (200) can monitor or correct the rise / fall time, jitter, signal-to-noise ratio (SNR), etc. of the signal to ensure transmission stability during the electrical signal conversion process, and thereby output a high-quality electrical signal that can be stably transmitted even in a long-distance optical data link environment.

[0143] And, the gateway device (200) can transmit the generated electrical signal to at least one of a plurality of optical signal transmission devices (300a) so that optical-based transmission is possible (S440). Specifically, the gateway device (200) can transmit the electrical signal to a first optical signal transmission device (300a) and a second optical signal transmission device (300a) that communicate via independent optical data links to ensure redundancy of the transmission path and communication stability.

[0144] The gateway device (200) can output a converted electrical signal by selecting a path according to the network in which the control signal is received from the interlocking device (100). Specifically, the gateway device (200) can transmit an electrical signal (first electrical signal) associated with the control signal to the first optical signal transmission device (300a) when the control signal is received through the first network (A-Net), and can be configured to transmit an electrical signal (second electrical signal) to the second optical signal transmission device when the control signal is received through the second network (B-Net). Through this, consistency for each network path can be maintained, and safety based on path separation can be enhanced in the event of a network failure.

[0145] In addition, since the gateway device (200) maintains an independent transmission path for each of the first network and the second network, control signals received from different networks can be transmitted to the corresponding optical signal transmission device without crossing each other. This prevents cross-path interference on the optical data link and enables stable determination of the time synchronization of the first optical signal and the second optical signal received from the field control device.

[0146] Additionally, the gateway device (200) may apply a parallel transmission method that simultaneously transmits the converted electrical signal to the first optical signal transmission device (300a) and the second optical signal transmission device (300b). The parallel transmission method provides a basis for the field control device (400) to determine whether the signal is normal by comparing the difference in arrival times between the two paths when receiving the electrical signal, and can maintain system safety even in failure situations such as delays, short circuits, or breaks in the optical data link.

[0147] Meanwhile, since the gateway device (200) operates in an Active / Standby redundancy structure, the Active gateway (GW-1) basically performs data transmission, and if an internal abnormality or link disconnection is detected, the Standby gateway (GW-2) is immediately activated by a switching trigger to transmit the same data. As described above, the gateway device (200) can determine whether each gateway device is operating normally by checking whether control signals received through the first network and the second network match, and by analyzing the status information exchanged between the Active gateway device and the Standby gateway device.

[0148] The status information may include the CPU load rate of the gateway device, memory usage, power status or internal fault flag, packet loss rate of the first network and the second network respectively, latency, whether the link is disconnected, control signal reception period or whether a signal is missing, or synchronization information between Active / Standby, timestamp error, and exchange period.

[0149] The gateway device (200) can periodically exchange status information or based on received events to check in real time whether each gateway device or the network to which the gateway device is connected is abnormal. Through this, if an internal fault occurs in the Active gateway device or if it is determined that one of the networks to which the gateway device is connected is in an abnormal state, the Standby gateway device can automatically perform a failover to take on the role of Active.

[0150] The gateway device (200) can transmit converted data in parallel through each of a plurality of network paths (first network (A-Net), second network (B-Net)), and the two networks can be configured with independent routing or physical lines.

[0151] Additionally, the gateway device (200) assigns a sequence number and a timestamp to each frame during the transmission process, so that the optical signal transmission device (300a) can determine the order and synchronization status of the received signals.

[0152] The optical signal transmission device (300a) receives data input from the gateway device (200) and can perform integrity verification of the received frame. Additionally, if the same frame is received from multiple networks, the optical signal transmission device (300a) can determine the normal path by comparing whether the data is consistent and can disable the data link with the error.

[0153] Meanwhile, the gateway device (200) can monitor whether the transmitted control data has arrived and the delay time by periodically receiving an acknowledgment signal or link status feedback from the optical signal transmission device (300a).

[0154] Through this, the gateway device (200) can detect problems such as latency, packet loss, or out-of-order errors that may occur in the network transmission section in real time, and perform re-transmission or link switching.

[0155] Next, we examine the process of the optical signal transmission device (300) transmitting the signal received from the gateway device (200) to the field control device (400).

[0156] FIG. 5 is a sequence diagram for explaining the operation of a first optical signal transmission device (300a), a third optical signal transmission device (300b), and a field control device (400) according to one embodiment of the present disclosure.

[0157] The first optical signal transmission device (300a) can convert an electrical signal input from the gateway device (200) into an optical signal suitable for transmission via an optical data link (S500). Specifically, the first optical signal transmission device (300a) can modulate the waveform of the input electrical signal into the form of light intensity or pulses using an optical conversion element (e.g., LED or LD) and an optical modulation circuit provided internally.

[0158] Additionally, the first optical signal transmission device (300a) can correct or stabilize the electrical signal to satisfy the signal conditions required for optical conversion based on the level, frequency, waveform, and rise / fall time of the input electrical signal. Through this, the optical signal transmission device (300a) can minimize signal loss and maintain the transmission quality of the optical signal above a certain level even in an optical cable or optical fiber-based transmission environment.

[0159] Subsequently, the first optical signal transmission device (300a) can transmit the electrical signal converted into an optical signal (first optical signal) to the third optical signal transmission device (300b) through the first optical data link (S510). At this time, the first optical data link can be configured to enable unidirectional or bidirectional optical communication, and can satisfy high speed and low latency characteristics by using an optical fiber cable or an equivalent optical transmission medium.

[0160] Additionally, the second optical signal transmission device can also transmit the optical signal (second optical signal) converted from the gateway device (200) to the fourth optical signal transmission device via the second optical data link. The first optical signal transmission device (300a) and the second optical signal transmission device may be positioned on the side of the gateway device (200), whereas the third optical signal transmission device (300b) and the fourth optical signal transmission device may be positioned on the side of the field control device (400), so that stable optical signal communication can be performed between each other via each optical data link.

[0161] In this way, through a structure in which the first / second optical signal transmission device and the third / fourth optical signal transmission device correspond to each other in a 1:1 manner, a control signal generated from the gateway device (200) can be transmitted to the field control device (400) along two independent optical transmission paths, and even if a failure occurs in a specific optical data link, the control signal can be transmitted normally through another path.

[0162] The third optical signal transmission device (300b) can inversely convert an optical signal (first optical signal) input from the first optical signal transmission device (300a) through the first optical data link into an electrical signal (third electrical signal) (S520).

[0163] Specifically, the third optical signal transmission device (300b) can convert the intensity change or blinking pattern of the received optical signal (first optical signal) into an electrical voltage or current signal by using an internally included optical-to-electrical converter (O / E Converter) or photodiode. The third optical signal transmission device (300b) can detect the optical signal received through the optical fiber cable using a light receiving element (e.g., PIN photodiode, APD (Avalanche Photodiode)). The received optical signal can be converted into an analog or digital electrical signal (third electrical signal) corresponding to the intensity of light or the on / off pattern according to the photoelectric conversion principle of the photodiode. The fourth optical signal transmission device can also convert the optical signal (second optical signal) received from the second optical signal transmission device into an electrical signal (fourth electrical signal) in the same manner.

[0164] Afterwards, the third optical signal transmission device (300b) can restore the converted third electrical signal into a stable digital signal form by performing amplification, shaping, and noise filtering processes on the converted third electrical signal.

[0165] According to another embodiment, the third optical signal transmission device (300b) can perform decoding based on a Manchester encoding pattern or an NRZ modulation pattern, etc., performed in the gateway device (200) to generate a restored third electrical signal containing original data (payload) and control commands.

[0166] Meanwhile, as described in steps S500 to S520 above, the optical signal transmission device (300a, 300b) can perform signal transmission through conversion between an electrical signal and an optical signal, but depending on the system installation environment, wiring distance, and communication reliability requirements, it may also perform communication using the electrical signal itself without an optical conversion procedure. For example, in sections where the physical distance between the gateway device (200) and the field control device (400) is short or the impact of electromagnetic interference (EMI) is low, signals can be exchanged by directly applying an electrical signal-based serial communication method (RS-485, LVDS, etc.) between the optical signal transmission devices.

[0167] In this case, the first optical signal transmission device (300a) can transmit the first electrical signal to the third optical signal transmission device (300b). Likewise, the second optical signal transmission device can transmit the second electrical signal to the fourth optical signal transmission device.

[0168] In addition, the optical signal transmission device can selectively use either an electric signal mode or an optical signal mode depending on the system settings; the optical signal mode may be advantageously applied in long-distance transmission or high-noise environments, while the electric signal mode may be advantageously applied in short-distance and low-interference environments. As such, the optical signal transmission device can selectively perform at least one of electric signal-based transmission and optical signal-based transmission depending on installation conditions, cable configuration, and system design policies, thereby providing a flexible communication structure optimized for various environments.

[0169] The third optical signal transmission device (300b) or the fourth optical signal transmission device can convert the optical signal into an electrical signal and then transmit the converted electrical signal to the field control device (400) (S530).

[0170] Specifically, the third optical signal transmission device (300b) can verify whether the electrical signal restored through the decoding and signal shaping process is suitable for a reference signal specification (e.g., Manchester decoding result, NRZ baseband signal, or system-defined data format) and then transmit it to the input port of the field control device (400). To ensure the reliability of the electrical signal, the optical signal transmission device (300b) can transmit it after performing signal amplification, waveform correction, level normalization, etc. Additionally, the transmission of the electrical signal can be done through a serial communication interface (e.g., RS-485, UART, LVDS) with the field control device (400) or through a dedicated signal line.

[0171] At this time, the electrical signal being transmitted may include a control command generated by the interlocking device (100), a frame structure converted from the control signal by the gateway device (200), payload data restored through an encoding / decoding process, a check code or status flag for error detection, etc.

[0172] After receiving the third electric signal (or first electric signal) transmitted from the third optical signal transmission device (300b), the field control device (400) can generate a response signal based on whether the third electric signal is normal and the result of internal data verification (S540). Similarly, after receiving the fourth electric signal (or second electric signal) transmitted from the fourth optical signal transmission device, the field control device (400) can generate a response signal based on whether the fourth electric signal is normal and the result of internal data verification.

[0173] Specifically, the field control device (400) can analyze control commands, error verification codes (e.g., checksum, CRC), data identifiers (ID), and timestamps included in the received electrical signal, and if it is determined that the electrical signal has been received normally, it can generate a normal acknowledgment signal (ACK). On the other hand, if data corruption, frame mismatch, decoding failure, or uninterpreted commands are detected, it can generate a negative acknowledgment signal (NACK).

[0174] Additionally, the field control device (400) checks the status information (e.g., sensor value, operation status, presence of fault, etc.) of the field equipment device being managed internally in real time, and can include such information in the response signal if required. The response signal may be composed of an extended response packet that includes not only simple reception acknowledgment but also equipment status reports, data verification results, etc.

[0175] Subsequently, the field control device (400) can transmit the generated response signal to the third optical signal transmission device (300b) (S550). Specifically, the field control device (400) can provide response data in the form of an electrical signal to the third optical signal transmission device (300b) through an internal communication interface, and in this process, the data format, voltage level, timing specifications, etc. of the response signal can be adjusted to be suitable for the input specifications of the optical signal transmission device. Likewise, the field control device (400) can transmit the generated response signal to the fourth optical signal transmission device.

[0176] Additionally, the field control device (400) can perform signal integrity verification (FCS verification, checksum verification, etc.) for the accurate transmission of the response signal, and then transmit only the normally generated response signal to the third optical signal transmission device (300b). The electrical signal transmitted from the field control device (400) can subsequently be converted into an optical signal by the optical signal transmission device (300b) and transmitted to the gateway device (200).

[0177] The third optical signal transmission device (300b) can convert the response signal input from the field control device (400) into an optical signal (third optical signal) (S560). Likewise, the fourth optical signal transmission device can convert the input response signal into an optical signal (fourth optical signal).

[0178] Specifically, the third optical signal transmission device (300b) can form an optical pulse corresponding to a response signal by analyzing the logic level or data pattern of the input electrical signal and generating a driving current corresponding to an internal optical transmission element.

[0179] In addition, the third optical signal transmission device (300b) can perform optical modulation control to stabilize signal characteristics such as optical output strength, pulse width, and waveform shape during the optical conversion process, and can correct the optical output to be maintained constant by taking into account the transmission distance, cable attenuation, and changes in ambient temperature.

[0180] And, the third optical signal transmission device (300b) can transmit the third optical signal to the first optical signal transmission device (300a) through the first optical data link (S570). Likewise, the fourth optical signal transmission device can transmit the fourth optical signal to the second optical signal transmission device through the second optical data link. The third optical signal transmission device (300b) can output a signal using an optical coupler, an optical interface (e.g., LC, SC connector), and a transmission port so that the optical signal passes stably through the optical data link.

[0181] The first optical signal transmission device (300a) can receive a response optical signal transmitted from the third optical signal transmission device, and then convert the optical signal into an electrical signal through an internal optical-to-electric converter (O / E Converter) or photodiode and transmit it to the gateway device (200). The converted response signal can be processed by a signal verification module of the gateway device (200) and used to determine whether the optical data link is normal and the operating status of the field control device (400).

[0182] Meanwhile, similarly, the response signal generated by the field control device (400) may be directly communicated in the form of an electrical signal by omitting the optical conversion process depending on the system environment. For example, in an environment where the installation distance between the optical signal transmission devices (300a, 300b) is short or the electrical interference factor is low, the third optical signal transmission device (300b) may be configured to directly transmit the response signal in the form of an electrical serial signal.

[0183] In this way, the optical signal transmission device can selectively perform at least one of an electrical signal-based communication mode and an optical signal-based communication mode according to the system settings, and thus, by supporting various communication methods according to field installation conditions, communication quality requirements, and cable configuration, the flexibility and reliability of the entire signal transmission path can be improved.

[0184] Meanwhile, according to another embodiment, the gateway device (200) can determine the signal transmission method (optical signal, electrical signal, or hybrid transmission method) between optical signal transmission devices (300) using an artificial intelligence model. Here, the artificial intelligence model is a model that predicts data transmission quality and can calculate the reliability of each transmission method by receiving at least one data quality indicator as input.

[0185] Data quality indicators input into an artificial intelligence model may include the Signal-to-Noise Ratio (SNR) of electrical signals, jitter, electromagnetic interference (EMI) levels, voltage fluctuations, changes in resistance / impedance, optical power of optical signals, attenuation (loss), Manchester code error rate, inverse conversion error rate, historical error rate history per link, delay patterns, and environmental changes over time (temperature, vibration, humidity, etc.).

[0186] At this time, each data quality metric can be converted into a unit score before being input into an artificial intelligence model. The unit score is a normalization process intended to eliminate differences in the physical units or measurement ranges of each quality metric, and can be calculated based on a threshold, standard deviation, minimum / maximum value, or historical cumulative statistical value for each metric. For example, SNR can be converted into a quality degradation score between 0 and 1 depending on the degree of reduction in the signal-to-noise ratio, jitter can be converted into a time-normalized score based on the delay deviation, and optical intensity can be calculated into a loss score based on the reduction rate of optical intensity.

[0187] Regarding the reliability calculation method, the artificial intelligence model can calculate a quality prediction value that predicts the transmission quality at the next time point by taking unit scores of data quality indicators calculated for multiple previous frames as input through a time series prediction structure such as LSTM (Long Short-Term Memory), GRU (Gated Recurrent Unit), or Temporal Convolution Network.

[0188] The artificial intelligence model can independently calculate quality prediction values ​​for electrical signal-based transmission methods and optical signal-based transmission methods, respectively, and calculate the reliability for each transmission method by combining weight factors for each data quality indicator with the calculated quality prediction values.

[0189] In this case, the weights for each quality indicator can be dynamically updated as the AI ​​model learns historical transmission data, reflecting the correlation between the unit score and the quality prediction value, and can be automatically adjusted to reflect the relative influence of specific indicators on transmission performance. The reliability calculated in this way can be used as a criterion to select the transmission method that provides higher transmission reliability at a given point in time by comparing electrical signal-based transmission methods with optical signal-based transmission methods.

[0190] In addition, the artificial intelligence model can apply reliability not only at the frame level but also at the segment (bit segment) level. The artificial intelligence model can determine criteria for dividing a transmission frame into multiple segments by learning not only the temporal variability of signal quality but also patterns in which quality rapidly degrades in specific sections. Subsequently, for each segment, the reliability of the electrical signal-based transmission method and the optical signal-based transmission method can be independently calculated, and a transmission method suitable for the corresponding segment can be selected. Depending on the selected transmission method, the optical signal transmission device (300) can perform segment-based distributed transmission.

[0191] Furthermore, to ensure the stability of the transmission method switching, the gateway device (200) may additionally consider the segment interval to be switched as a switching determination criterion. The gateway device (200) can determine whether the transmission method switching impairs the stability of the segment structure by analyzing the segment interval, segment length, modulation stability of the segment boundary, and boundary quality variation pattern. If the segment interval is below a predetermined threshold, the gateway device (200) may delay or suspend the switching because the possibility of transmission errors occurring at the boundary increases during the switching. Conversely, if the segment interval is above the threshold and the boundary quality variability is within an allowable range, the switching can be performed by determining that point in time as a stable point where the transmission method switching is possible.

[0192] In addition, the artificial intelligence model includes not only quality indicators but also the interval between segments as input features to learn error patterns occurring at segment boundaries and can predict the optimal transition section where changes in the transmission method can be performed stably. Accordingly, the gateway device (200) can maintain stable transmission quality while preventing problems such as increased transmission delay, boundary loss, and frame reassembly failure in advance by combining quality-based transition judgment and segment structure-based transition judgment.

[0193] In this way, by utilizing an artificial intelligence model to predict the transmission quality of electrical and optical signals respectively and automatically switching transmission modes in a highly reliable manner, it becomes possible to deliver control signals that are stable and error-resistant even amidst environmental changes. Furthermore, by minimizing quality degradation across transmission sections through segment-level selection and switching stabilization techniques, the real-time performance and reliability of the entire system can be enhanced.

[0194] As seen in FIG. 5, the control signal converted from the gateway device (200) can be reliably transmitted to the field control device (400) through two independent optical data links, and the response signal generated from the field control device (400) can also be returned to the gateway device (200) along the same dual path. This dual optical path-based communication structure can improve the reliability and fault tolerance of the entire signal transmission system by allowing signal transmission to continue through another path even if a failure such as attenuation, disconnection, or noise ingress occurs in a specific optical data link.

[0195] FIG. 6 is a diagram illustrating the operation of an optical signal transmission device (300) transmitting a signal through an optical data link according to one embodiment of the present disclosure.

[0196] In a signal transmission system (1) according to one embodiment of the present disclosure, optical signal transmission devices (300a, 300b) can perform an optical conversion process to transmit a control signal transmitted from a gateway device (200) to a field control device (400) through each optical data link.

[0197] The gateway device (200) may include an internal Field Programmable Gate Array (FPGA), and can generate an electrical signal by performing at least one of Manchester encoding, Non-Return-to-Zero (NRZ), Return-to-Zero (RZ), Bi-phase method, 4B / 5B encoding, PWM-based encoding, and BPSK-based electrical signal modulation algorithms on a control signal received from the interlocking device (100) through the FPGA. Through such a method, an electrical signal that can be converted into an optical signal through an optical signal transmission device (300a, 300b) can be generated.

[0198] Here, Manchester encoding is an encoding method that includes data bits and clock signals simultaneously through the rise or fall of signal voltage within one bit cycle. Specifically, by expressing the logical value ('1' or '0') of the data bit in the form of a signal voltage change, the clock signal and data signal can be transmitted simultaneously. Through this, the optical signal transmission device (300) can ensure signal synchronization stability by enabling stable reception synchronization without the separate transmission of a synchronization signal during optical signal transmission, and can minimize phase delay or data loss that may occur in a long-distance transmission environment.

[0199] Accordingly, the gateway device (200) can simultaneously achieve accurate timing of the signal and improved error detection reliability during optical data link transmission by encoding the control signal through the FPGA to generate a modulated electrical signal.

[0200] The electrical signal encoded in this way can be converted into an optical signal through an optical signal transmission device (300a). The optical signal transmission devices (300a, 300b) can be implemented as ODLMs, and each ODLM can convert the electrical signal generated through the FPGA into an optical signal.

[0201] The first electrical signal can be converted into a first optical signal through the first optical signal transmission device (300a), and the second electrical signal can be converted into a second optical signal through the second optical signal transmission device. Each converted optical signal can be transmitted in parallel to independent optical cables (A-Link, B-Link) through each optical signal transmission device. Therefore, a redundancy structure can be implemented so that even if a failure occurs in one optical link, the signal can be continuously transmitted through another path.

[0202] The converted optical signal can be transmitted to each optical signal transmission device (300) provided at the gateway device (200) and to each optical signal transmission device provided at the field control device (400), and the field control device (400) can receive it, convert it back into an electrical signal, and then execute a control command corresponding to each control node (T1~T63).

[0203] As shown in FIG. 6, a high-reliability, high-precision, real-time optical data transmission system can be implemented through an encoding-based electrical signal-to-optical signal conversion structure and a dual ODLM communication path, and can provide the effect of minimizing data distortion or delay during transmission.

[0204] FIG. 7 is a flowchart illustrating an algorithm for determining a received electrical signal as a normal signal by a field control device (400) according to one embodiment of the present disclosure.

[0205] As described above in FIG. 5, the field control device (400) can receive the third electric signal and the fourth electric signal or the first electric signal and the second electric signal, respectively, from each of the optical signal transmission devices (300) provided at the field control device (400) (S710).

[0206] The third electrical signal (or the first electrical signal) may be received via a network or optical data link connected through the third optical signal transmission device (300b), and the fourth electrical signal (or the second electrical signal) may be received via a network or optical data link connected through the fourth optical signal transmission device. Each electrical signal contains the same control command data, but a minute time difference may occur depending on the physical length of the transmission path, optical fiber loss, or the state of the intermediate repeater.

[0207] The field control device (400) can use the difference in arrival times between the two received electrical signals (the third electrical signal and the fourth electrical signal or the first electrical signal and the second electrical signal) as reference data to determine whether the signal is normal.

[0208] Specifically, the field control device (400) can calculate the time difference for each received electrical signal and determine whether the difference is within a threshold (S720).

[0209] Here, the threshold is a pre-set reference value considering factors such as the difference in path length between optical data links, transmission delay, or internal processing delay between optical conversion modules (ODLMs), and corresponds to an allowable error range for determining whether the two signals have been received in normal synchronization.

[0210] If the difference in reception time between the two electrical signals is found to be below a threshold value, the field control device (400) can determine that synchronization has been successfully achieved by considering that the two electrical signals are based on the same control command.

[0211] Accordingly, if the difference in reception time between the two calculated electrical signals is determined to be within a threshold value, the field control device (400) determines that both electrical signals have been received in normal synchronization, determines that the signals are normal signals, and determines that the operation of the optical signal transmission device is normal (S730).

[0212] At this time, an electrical signal determined to be a normal signal means that a control command transmitted from each optical signal transmission device (300) has reached the field control device (400) without error, and the field control device (400) can perform a control operation corresponding to a field equipment device (500) (e.g., signal, track switch, etc.) based on this.

[0213] In addition, electrical signals determined to be normal are stored as log data and can be utilized for network status diagnosis or maintenance; furthermore, if only normal signals are received continuously for a certain period, it can be considered a synchronization hold state that guarantees system stability.

[0214] If it is determined that the difference in reception time of each received electrical signal exceeds a preset threshold, the field control device (400) may determine that the signal is an abnormal signal (S740).

[0215] Such abnormal judgment may occur when signal synchronization is broken due to delay, signal loss, reflection, or conversion errors of the ODLM module in any path of the optical data link.

[0216] If the field control device (400) determines that the received electrical signal is an abnormal signal, it does not use the signal to perform a control command, generates an error log, or transmits an error notification signal to an optical signal transmission device (a third or fourth optical signal transmission device).

[0217] In addition, if abnormal signals are continuously detected in the same path for a certain period of time, the corresponding optical data link can be switched to a fault isolation state to prevent malfunction of the entire control system.

[0218] In this way, the field control device (400) according to the present disclosure can verify in real time whether there is a delay or loss between communication paths by comparing the arrival times of electrical signals received through a plurality of optical data links.

[0219] According to another embodiment, the gateway device (200) can determine whether each optical signal transmission device (300a, 300b) or the corresponding link or network is faulty by simultaneously transmitting and receiving data through independent optical data links through each of the plurality of optical signal transmission devices (300a).

[0220] Specifically, the gateway device (200) transmits the same command data or test pattern in parallel to the first optical signal transmission device (300a) and the second optical signal transmission device, and can determine whether there is a fault in either of the two optical signal transmission paths by comparing the arrival status, arrival time, and the normality of the Cyclic Redundancy Check (CRC) bit included in the response signal received from each device.

[0221] For example, if the gateway device (200) does not receive a response signal from the first or second optical signal transmission device within a certain period of time, or if an error is detected in the CRC verification result of the received response signal, it can determine that a physical failure (e.g., cable disconnection, connector failure, ODLM itself malfunction, etc.) has occurred in the optical signal transmission device or the optical data link or network. On the other hand, if a normal response is continuously received in the path of another optical signal transmission device, the gateway device (200) can diagnose that there is a partial link failure in the path of a specific optical signal transmission device rather than a total network failure, thereby accurately identifying the point of failure.

[0222] Additionally, the gateway device (200) monitors the response cycle of each of the multiple optical signal transmission devices, and if response delays or missing responses occur continuously only in a specific path, it can record the path as an “abnormal state” and reflect it in the status bit. This fault identification function can provide the effect of improving the availability of the entire signal system by detecting physical problems that may occur in the field early, such as single ODL blockage, optical connector contamination, and optical module aging.

[0223] As seen in the preceding drawings, the signal management system (1) according to the present disclosure can prevent malfunctions and improve the reliability of the entire control command by rapidly detecting and excluding abnormal signals even if a failure occurs in a part of the network, optical data link, or part of the optical signal transmission device. Accordingly, communication stability, fault tolerance, and safety integrity of the optical signal-based control network can be effectively secured.

[0224] Meanwhile, the various embodiments described above may be implemented by combining two or more embodiments, provided that they do not conflict or contradict each other.

[0225] Specifically, each of the multiple operations, steps, and configurations for implementing one embodiment may be embodied in another embodiment, or the operations and steps of another embodiment may be followed by the last operation or step of one embodiment, but are not limited thereto.

[0226] Meanwhile, computer instructions or computer programs for performing processing operations of each device, device, terminal, computer, processor, module, or engine, etc., according to the various embodiments of the present disclosure described above, may be stored on a non-transitory computer-readable medium. When such computer instructions or computer programs stored on the non-transitory computer-readable medium are executed by the processor of a specific device, they cause the specific device described above to perform processing operations according to the various embodiments described above.

[0227] A non-transient computer-readable medium refers to a medium that stores data semi-permanently and can be read by a device, unlike media that store data for a short period of time such as registers, caches, and memory. Specific examples of non-transient computer-readable media include CDs, DVDs, hard disks, Blu-ray discs, USBs, memory cards, and ROMs.

[0228] According to one embodiment, the method according to the various embodiments disclosed herein may be provided by being included in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0229] Although preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the present disclosure as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present disclosure. Explanation of the symbols

[0230] 1: Signal transmission system 100: Electronic interlocking device 200: Gateway device 210: Memory 220: Communication interface 230: Processor 231: Signal receiving module 233: Signal verification module 235: Data conversion module 237: Encoding module 239: Signal conversion module 300a: First optical signal transmission device 300b: Third optical signal transmission device 400: Field control unit 500: Field Equipment

Claims

Claim 1 In a signal transmission system for managing vehicle traffic, at least one interlocking system; a gateway device including an active gateway device and a standby gateway device; a first network forming a communication path between each of the active gateway device and the standby gateway device and the interlocking system; a second network forming a communication path between each of the active gateway device and the standby gateway device and the interlocking system; a field control device controlling at least one field equipment device; a first optical signal transmission device forming a communication path between each of the active gateway device and the standby gateway device and the field control device; and a second optical signal transmission device forming a communication path between each of the active gateway device and the standby gateway device and the field control device.A signal transmission system comprising: an interlocking device that transmits the same control signal to the Active Gateway device and the Standby Gateway device; the Active Gateway device that converts the received control signal into a preset standard frame; the Active Gateway device and the Standby Gateway device that receive the same control signal from the interlocking device and exchange their respective status data to verify the normal state of each of the Active Gateway device and the Standby Gateway device or the normal state of each network; and when an abnormality is detected in the state of the Active Gateway device or the network of the Active Gateway device, the Standby Gateway device performs the role of the Active Gateway device in place of the Active Gateway device, wherein even when the Standby Gateway device does not perform the role of the Active Gateway device in place of the Active Gateway device, it receives the same control signal from each of the first network and the second network in the same manner as the Active Gateway device, and even when the Standby Gateway device does not perform the role of the Active Gateway device in place of the Active Gateway device, it receives a response signal from the field control device through each of the first optical signal transmission device and the second optical signal transmission device in the same manner as the Active Gateway device. Claim 2 delete Claim 3 In claim 1, the Active gateway device is a signal transmission system that converts each of the control signal received through the first network and the control signal received through the second network into the preset standard frame. Claim 4 A signal transmission system according to claim 1, wherein the Active gateway device performs at least one of a first operation of converting the converted control signal into a first electrical signal and transmitting it to the first optical signal transmission device, and a second operation of converting the converted control signal into a second electrical signal and transmitting it to the second optical signal transmission device. Claim 5 In claim 4, the active gateway device comprises a Field Programmable Gate Array (FPGA), and through the FPGA, generates an electrical signal by performing at least one of Manchester encoding, Non-Return-to-Zero (NRZ), Return-to-Zero (RZ), Bi-phase method, 4B / 5B encoding, PWM-based encoding, and Binary Phase Shift Keying (BPSK)-based electrical signal modulation algorithms on the converted control signal, and transmits the generated electrical signal to the first optical signal transmission device or the second optical signal transmission device, a signal transmission system. Claim 6 In claim 4, a third optical signal transmission device that communicates with the first optical signal transmission device; A signal transmission system further comprising: a fourth optical signal transmission device that communicates with the second optical signal transmission device; wherein the first optical signal transmission device converts the first electrical signal into an optical signal to generate a first optical signal and transmits the first optical signal to the third optical signal transmission device via a first optical data link or transmits the first electrical signal to the third optical signal transmission device; the second optical signal transmission device converts the second electrical signal into an optical signal to generate a second optical signal and transmits the second optical signal to the fourth optical signal transmission device via a second optical data link or transmits the second electrical signal to the fourth optical signal transmission device; the third optical signal transmission device converts the first optical signal received from the first optical signal transmission device into an electrical signal to generate a third electrical signal; and the fourth optical signal transmission device converts the second optical signal received from the second optical signal transmission device into an electrical signal to generate a fourth electrical signal. Claim 7 In claim 6, the field control device is a signal transmission system that receives at least one of the first electric signal or the third electric signal from the third optical signal transmission device and the second electric signal or the fourth electric signal from the fourth optical signal transmission device. Claim 8 In claim 7, the field control device is a signal transmission system that determines the first electric signal and the second electric signal or the third electric signal and the fourth electric signal as normal signals if the difference in reception time between the first electric signal and the second electric signal or the third electric signal and the fourth electric signal is within a threshold value. Claim 9 In claim 7, the field control device generates a response signal for each of the first electrical signal, the second electrical signal, the third electrical signal, and the fourth electrical signal when at least one of them is received and transmits it to the third optical signal transmission device or the fourth optical signal transmission device; the third optical signal transmission device transmits the response signal to the first optical signal transmission device when the response signal is received; the fourth optical signal transmission device transmits the response signal to the second optical signal transmission device when the response signal is received; and the gateway device determines whether each optical signal transmission device is normal based on the response signal received by the first optical signal transmission device from the third optical signal transmission device or the response signal received by the second optical signal transmission device from the fourth optical signal transmission device.

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