A beidou-based train unified time service system and method

Abstract

The application discloses a train unified time service system and method based on Beidou, which comprises a time service unit, a communication unit and an information interface unit. The communication unit and the information interface unit are multiplexed based on a locomotive safety information comprehensive monitoring device and communicate through an RS485 bus. The time service unit is used for generating a reliable clock reference. The communication unit is used for providing a reliable clock information transmission channel. The information interface unit is used for realizing data interaction between the train and the on-board equipment. The interface and the communication protocol between the information interface unit and the on-board equipment are compatible with the locomotive safety information comprehensive monitoring device. The method is mainly implemented based on the above system. The application has the advantages of simple structure, low cost, easy implementation, high time service precision and the like.

Description

Technical Field

[0001] This invention mainly relates to the field of rail transit technology, specifically a unified train timing system and method based on BeiDou. Background Technology

[0002] With the rapid development of rail transit technology, the number of onboard devices used for train control and condition monitoring is increasing. However, many onboard devices currently use relatively outdated time synchronization methods and lack a safe, reliable, and unified time reference.

[0003] Because the real-time time is not synchronized between different onboard devices, the timestamps when the devices interact with each other will not be on a unified time baseline, which may cause insufficient train accuracy or even control errors. Furthermore, when the operation data files recorded locally by each device are used for post-event linkage analysis, the inconsistent timelines will make it impossible to comprehensively discover the correlation between the operation data of different devices, resulting in the failure to detect potential safety hazards of the train in a timely and accurate manner, which may lead to safety accidents.

[0004] In existing technologies, the following methods are mainly used for time synchronization of train onboard equipment:

[0005] 1) Manually calibrate the time using a handheld device;

[0006] For example, the Train Control Unit (LKJ), as a railway traffic safety control device, may malfunction if a time error occurs, potentially affecting train control and posing serious safety hazards. Currently, the railway industry generally uses IC cards or handheld terminals to synchronize the time with a ground-based satellite master clock, followed by manual time synchronization and verification of the LKJ by personnel on board the train, relying on a local clock chip for timekeeping.

[0007] The advantage of this scheme is that it involves rigorous manual verification, avoiding occasional time errors that may occur with automatic time synchronization. The disadvantage is that manual operation is inefficient and requires periodic checks to eliminate accumulated time errors in the local clock; otherwise, LKJ time errors could lead to safety incidents.

[0008] 2) Automatic time synchronization using GNSS satellite time;

[0009] Vehicle-mounted equipment such as the China Locomotive Remote Monitoring and Diagnostic System (CMD), the Locomotive Integrated Wireless Communication Equipment (CIR), and the Locomotive Signaling Device directly receive navigation messages from GNSS satellites, perform time calculations, and then use GNSS time to calibrate the local time.

[0010] The advantage of this method is its accuracy. However, its disadvantage lies in the complex electromagnetic environment of high-speed train operations. Errors in navigation message reception or bugs in the PNT algorithm can lead to occasional time discrepancies, resulting in significant deviations from the actual time. If this time is provided to control equipment, it can cause malfunctions or even safety accidents. Therefore, this method cannot be used as a reliable clock reference.

[0011] 3) The time is obtained periodically from the train control system;

[0012] Equipment such as TAX (Locomotive Safety Information Integrated Monitoring Device) and LMD (LKJ Equipment Operation Monitoring and Management System) periodically obtain time from the LKJ train control system to correct the time of their local clock chip, using it as their own time reference.

[0013] The advantage of this approach is that the LKJ train control system is the central hub for train control, ensuring time accuracy. Therefore, choosing the LKJ train control system's time as the time reference is a reasonable choice. The disadvantage is that it inherits the accumulated clock error of the LKJ system and does not eliminate the time of fixed communication cycles and bus communication delays, resulting in a fixed time deviation.

[0014] 4) The cycle time is obtained from the TAX device;

[0015] Equipment such as voice recording devices, locomotive onboard safety protection systems (6A), pantograph-catenary detection devices, and track detection devices do not have direct communication interfaces with the LKJ train control system. Instead, they indirectly obtain LKJ time by communicating with the TAX (Locomotive Safety Information Integrated Monitoring Device) to correct their local time. LKJ serves as the primary clock source, while TAX acts as the secondary clock source.

[0016] The advantages of this scheme are that it maintains a unified time dimension with the LKJ train control system and utilizes the existing communication bus transmission channel, requiring no hardware or software modifications to the on-board equipment, making it easy to implement. The disadvantages are that the existing TAX system uses a broadcast RS485 bus to broadcast LKJ time, lacking effective access authentication mechanisms and control measures. Unordered access by external devices, or any non-standard or faulty communication interface at any access node, can affect the security and reliability of TAX bus data transmission and may cause errors in time information during transmission.

[0017] In summary, current train onboard equipment timing systems and methods lack a reliable clock reference, a convenient and reliable clock information transmission channel, and a clock synchronization mechanism between devices, which is insufficient to support the needs of train control and train health monitoring data linkage analysis. Summary of the Invention

[0018] The technical problem to be solved by this invention is to provide a unified train timing system and method based on BeiDou that is simple in structure, low in cost, easy to implement, and has high timing accuracy, in response to the technical problems existing in the prior art.

[0019] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0020] A unified train timing system based on BeiDou Navigation Satellite System includes: a timing unit, a communication unit, and an information interface unit; the communication unit and the information interface unit reuse a locomotive safety information integrated monitoring device and communicate via an RS485 bus; the timing unit is used to generate a reliable clock reference; the communication unit is used to provide a reliable clock information transmission channel; the information interface unit is used to realize data interaction with the train's onboard equipment; the interface and communication protocol between the information interface unit and the train's onboard equipment are compatible with the locomotive safety information integrated monitoring device.

[0021] As a further improvement to the system of the present invention, the timing unit adopts a multi-source clock verification mechanism to ensure the accuracy and availability of time.

[0022] As a further improvement to the system of the present invention: the timing unit includes a BeiDou timing module, a mobile communication module, and a main processing module; the BeiDou timing module is used to receive and process satellite signals and navigation messages, calculate BeiDou time in real time, and send it to the main processing module; the main processing module is used to determine the number of available satellites and the valid positioning identifier in the BeiDou time information; the mobile communication module is used to dial up to the network, establish a remote data transmission channel for the main processing module, and realize data interaction with the network clock server.

[0023] As a further improvement to the system of the present invention: during the processing, if the number of available BeiDou satellites is greater than a set threshold and the positioning quality is valid, the main processing module determines that the BeiDou time is available.

[0024] As a further improvement to the system of the present invention: the main processing module pre-configures multiple network clock server addresses, sends NTP time requests to all servers through the mobile network, and receives a time response from any server within a set threshold time. The two parties then interact according to the NTP protocol. The main processing module acquires the NTP time and eliminates the local clock difference and communication delay error of the time synchronization unit. If no response is received from any server within the specified time, the acquisition of NTP time is considered to have failed.

[0025] As a further improvement to the system of the present invention: after the main processing module obtains the BeiDou time and NTP time information, it performs time comparison logic judgment. If the time difference between the two is within the threshold range, it is determined that the clock source is reliable and the local time of the BeiDou time correction and timing unit is used as the reliable clock for output. Otherwise, an invalid time is output.

[0026] As a further improvement to the system of the present invention: the main processing module uses BeiDou satellite time as a basis and adopts multi-source clock verification and signal interference filtering measures to generate a reliable clock source.

[0027] As a further improvement to the system of the present invention: after the communication unit completes self-test upon power-on, it receives information from the timing unit in real time; when it is determined that the clock information output by the timing unit is valid, it uses the NTP protocol to obtain the time from the communication unit, corrects the local clock, eliminates the delay and local clock difference in the communication process, and sets the time valid flag.

[0028] As a further improvement to the system of the present invention: the communication unit adopts access authentication and data encryption measures; the information interface unit sends an access authentication request to the communication unit, the communication unit queries the device information database to see if the information interface unit is a legitimate device, if it is legitimate, the authentication is passed, and the communication unit broadcasts the encrypted locomotive safety information to the information interface unit in real time; if the authentication fails, the communication unit informs the authentication result and disconnects the connection.

[0029] As a further improvement to the system of the present invention: the communication unit adopts a primary and backup redundancy design. After power-on, machine A is the primary machine and machine B is the backup machine by default. Both machines obtain time from the time synchronization unit and correct their local clocks.

[0030] As a further improvement to the system of the present invention: the host machine A is responsible for data interaction with the information interface unit, while the standby machine B is only responsible for listening to the information; machine A and machine B periodically send master and standby status information to each other. When the standby machine B receives the master fault information or communication timeout, it automatically upgrades to the master and is responsible for broadcasting locomotive safety information to the outside world. When machine A recovers to normal, it works in the standby state.

[0031] As a further improvement to the system of the present invention: after the information interface unit receives valid information from the communication unit, it transmits it to the external vehicle-mounted device. The vehicle-mounted device continuously detects a certain amount of data. If the time identifier is determined to be valid and the time information contained in the data packet flows forward continuously, it is considered valid and the local time is corrected.

[0032] This invention further provides a unified train timing method based on BeiDou, the process of which includes:

[0033] Multiple network clock server addresses are pre-configured. NTP time requests are sent to all servers via the mobile network. A time response is received from any server within a specified time. The two parties interact according to the NTP protocol.

[0034] Obtain NTP time and eliminate local clock differences and communication delay errors of the time synchronization unit; if no response is received from any server within the specified time, the NTP time acquisition is considered to have failed.

[0035] After obtaining BeiDou time and NTP time information, a time comparison logic is performed. If the time difference between the two is within the threshold range, the clock source is determined to be reliable, and the local time of the BeiDou time correction and timing unit is used as the reliable clock for output. Otherwise, an invalid time is output.

[0036] It receives information from the timing unit in real time; when it determines that the clock information output by the timing unit is valid, it uses the NTP protocol to obtain the time from the communication unit, corrects the local clock, eliminates the delay and local clock difference in the communication process, and sets the time valid flag.

[0037] As a further improvement to the method of the present invention: access authentication and data encryption measures are adopted during the communication process; the information interface unit sends an access authentication request to the communication unit, and the communication unit queries the device information database to see if the information interface unit is a legitimate device. If it is legitimate, the authentication is passed, and the communication unit broadcasts the encrypted locomotive safety information to the information interface unit in real time; if the authentication fails, the communication unit informs the authentication result and disconnects the connection.

[0038] As a further improvement to the method of the present invention: the communication unit adopts a primary and backup redundancy design. After power-on, unit A is the primary unit and unit B is the backup unit by default. Both units obtain time from the time synchronization unit and correct their local clocks. The primary unit is responsible for data interaction with the information interface unit, while unit B is only responsible for listening to information. Units A and B periodically send primary and backup status information to each other. When the backup unit receives a primary unit failure message or communication timeout, it automatically upgrades to the primary unit and is responsible for broadcasting locomotive safety information. When unit A recovers, it operates in the backup unit state.

[0039] Compared with the prior art, the advantages of the present invention are as follows:

[0040] 1. The Beidou-based unified train timing system and method of the present invention has a simple structure, low cost, easy implementation, and high timing accuracy. It can provide a unified time reference for many on-board devices of the train and provide the necessary prerequisites for precise train control and train health status linkage analysis.

[0041] 2. The BeiDou-based unified train timing system and method of the present invention has a precise and reliable clock source: The present invention uses high-precision BeiDou time as the timing reference. At the same time, in order to avoid introducing erroneous time data output when the BeiDou signal encounters electromagnetic interference or when the BeiDou module PNT algorithm has a bug, NTP time is used for automatic verification to ensure the precision and reliability of the clock source and eliminate safety hazards caused by time errors.

[0042] 3. The BeiDou-based unified train timing system and method of the present invention are easy to implement, low in cost, and highly scalable: The present invention uses the existing Locomotive Safety Information Integrated Monitoring Device (TAX) as the time information transmission platform, without the need to add a separate timing system device. The present invention does not change the connection relationship of the on-board equipment in terms of hardware, and does not require changes to the communication protocol in terms of software. It only upgrades the internal bus architecture. Moreover, the existing communication protocol between TAX and each on-board device already includes time information, so it will not affect the software of each on-board device. Therefore, the solution has high feasibility and low cost. At the same time, the TAX platform has strong scalability by increasing the number of information interface unit plug-in configurations and interfaces, which can meet the needs of subsequent applications.

[0043] 4. The Beidou-based unified train timing system and method of the present invention ensures the security and reliability of the timing information transmission channel: The present invention adopts a primary and backup redundancy mechanism for communication units, so that a single communication failure or channel failure will not affect the reliable transmission of time information; the system has external device access authentication function to block unauthorized device access, and has data encryption function to prevent time information from being maliciously tampered with during transmission.

[0044] 5. The Beidou-based unified train timing system and method of the present invention proposes a point-to-point gateway RS485 bus to replace the existing broadcast RS485 bus, which solves the problems of communication deadlock, frame loss or frame error caused by the RS485 bus being easily interfered with by the communication terminals of each node when multiple nodes communicate. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the topological structure of the system of the present invention.

[0046] Figure 2 This is a schematic diagram of the topological structure of the timing unit in a specific application example of the present invention.

[0047] Figure 3 This is a schematic diagram of the workflow of the time synchronization unit in a specific application example of the present invention.

[0048] Figure 4 This is a schematic diagram illustrating the workflow of the communication unit and information interface unit in a specific application example of the present invention. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0052] In this application, unless otherwise expressly specified and limited, the terms "assembly," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0053] like Figure 1 and Figure 2 As shown, the BeiDou-based unified train timing system of the present invention is designed based on the Locomotive Safety Information Integrated Monitoring Device (TAX), including: a timing unit, a communication unit, and an information interface unit; the communication unit and the information interface unit reuse the existing TAX, and the two communicate via an RS485 bus; the timing unit is used to generate a reliable clock reference; the communication unit is used to provide a reliable clock information transmission channel; the information interface unit is used to realize data interaction between the system of the present invention and the train on-board equipment; the interface and communication protocol between the information interface unit and the train on-board equipment are compatible with the existing TAX.

[0054] In specific application examples, the timing unit adopts a multi-source clock verification mechanism to ensure the accuracy and availability of time.

[0055] In a specific application example, the timing unit includes a BeiDou timing module, a mobile communication module, and a main processing module. The BeiDou timing module is used to receive and process satellite signals and navigation messages, calculate the BeiDou time in real time, and send it to the main processing module. The main processing module is used to determine the number of available satellites and the valid positioning identifier in the BeiDou time information. The mobile communication module is used to dial up to the network, establish a remote data transmission channel for the main processing module, and realize data interaction with the network clock server.

[0056] In a specific application example, if the number of available BeiDou satellites is greater than 8 (configurable) and the positioning quality is valid during the processing, the main processing module determines that the BeiDou time is available, thus avoiding the use of poorly received satellite signals for train timing.

[0057] See Figure 3 In a specific application example, the main processing module pre-configures multiple network clock server addresses and sends NTP time requests to all servers via the mobile network. Within a specified time (default 2 seconds), it receives a time response from any server, and the two parties interact according to the NTP protocol. The main processing module acquires the NTP time, eliminating local clock errors and communication delays in the time synchronization unit. If no response is received from any server within the specified time, the NTP time acquisition is considered a failure. For example, the NTP time acquisition operation continues in a 3-minute (default) cycle until the NTP time is successfully acquired.

[0058] In a specific application example, after the main processing module obtains the BeiDou time and NTP time information, it performs a time comparison logic judgment. If the time difference between the two is within the threshold range (default 1s), the clock source is determined to be reliable, and the local time of the BeiDou time correction and timing unit is used as the reliable clock for output. Otherwise, an invalid time is output.

[0059] In specific application examples, the main processing module uses BeiDou satellite time as a basis and adopts measures such as multi-source clock verification and signal interference filtering to generate a reliable clock source.

[0060] In a specific application example, after the communication unit completes its self-test upon power-on, it receives information from the timing unit in real time. When it is determined that the clock information output by the timing unit is valid, the time is obtained from the communication unit using the NTP protocol to correct the local clock, eliminate the delay and local clock difference in the communication process, and set the time validity flag.

[0061] See Figure 4In a specific application example, the communication unit has multiple RS485 bus interfaces. To improve the reliability of communication between the communication unit and the information interface unit, both parties adopt access authentication and data encryption measures. The information interface unit sends an access authentication request to the communication unit. The communication unit queries the device information database to determine if the information interface unit is a legitimate device. If legitimate, authentication is successful, and the communication unit broadcasts encrypted locomotive safety information to the information interface unit in real time. The information includes time information and a valid identifier. If authentication fails, the communication unit informs the information interface unit of the authentication result and disconnects the connection.

[0062] In a specific application example, the communication unit adopts a primary / backup redundancy design. After power-on, unit A is the primary unit and unit B is the backup unit by default. Both units obtain time from the timing unit via RS485 bus and calibrate their local clocks. The primary unit is responsible for data interaction with the information interface unit, while unit B is only responsible for listening for information. Units A and B periodically send primary / backup status information to each other. When the backup unit receives a primary unit failure message or a communication timeout, it automatically becomes the primary unit and is responsible for broadcasting locomotive safety information (including time information and valid identifiers). When unit A recovers, it operates in backup mode.

[0063] In a specific application example, after the information interface unit receives valid information from the communication unit, it transmits it to the external vehicle-mounted equipment. The vehicle-mounted equipment continuously detects a certain number of data packets (e.g., 5 packets). If the time identifier is determined to be valid and the time information contained in the data packet flows forward continuously, it is considered valid, and the local time is corrected.

[0064] As shown above, this invention utilizes the Train Safety Information Integrated Monitoring Device (TAX), a public information platform, to broadcast real-time train clock information externally, providing a unified clock reference for all onboard equipment. Furthermore, this invention proposes a point-to-point gateway-type RS485 bus architecture, replacing the existing multi-node RS485 communication method of TAX, and is compatible with the existing TAX RS485 hardware interface and software protocol. It also proposes methods for redundancy switching of communication units and authentication of information interface units during clock information transmission, ensuring reliable clock information transmission. Further, this invention utilizes a trusted clock source generation method, based on BeiDou time synchronization and NTP time verification, to ensure the accuracy and availability of the time reference.

[0065] It is understood that in the above-described scheme of the present invention, the clock source generation scheme further employs a multi-core design using BeiDou time, GPS time, and NTP time, which can further improve the reliability of the clock source. It can also address the issue of NTP time being unavailable by using BeiDou time and GPS time comparison measures to improve system availability. This should be within the scope of protection of the present invention.

[0066] This invention further provides a unified train timing method based on BeiDou. Taking the system based on the above invention as an example, the process includes:

[0067] Multiple network clock server addresses are pre-configured. NTP time requests are sent to all servers via the mobile network. Within a specified time (default 2s), a time response is received from any server, and the two parties interact according to the NTP protocol.

[0068] Obtain NTP time to eliminate local clock differences and communication delay errors of the time synchronization unit; if no response is received from any server within the specified time, the NTP time acquisition is considered to have failed; for example, continue the next round of NTP time acquisition operation with a period of 3 minutes (default) until the NTP time is successfully acquired.

[0069] After obtaining BeiDou time and NTP time information, a time comparison logic is performed. If the time difference between the two is within the threshold range (default 1s), the clock source is determined to be reliable, and the local time of the BeiDou time correction and timing unit is used as the reliable clock for output. Otherwise, an invalid time is output.

[0070] It receives information from the timing unit in real time; when it determines that the clock information output by the timing unit is valid, it uses the NTP protocol to obtain the time from the communication unit, corrects the local clock, eliminates the delay and local clock difference in the communication process, and sets the time valid flag.

[0071] In specific application examples, access authentication and data encryption measures are implemented during communication. The information interface unit sends an access authentication request to the communication unit. The communication unit queries the device information database to determine if the information interface unit is a legitimate device. If legitimate, authentication is successful, and the communication unit broadcasts encrypted locomotive safety information to the information interface unit in real time. This information includes time information and a valid identifier. If authentication fails, the communication unit informs the user of the authentication result and disconnects the connection.

[0072] In a specific application example, the communication unit adopts a primary / backup redundancy design. After power-on, unit A is the default primary unit and unit B is the backup unit. Both obtain time from the timing unit via RS485 bus and calibrate their local clocks. The primary unit is responsible for data interaction with the information interface unit, while unit B is only responsible for listening for information. Units A and B periodically send primary / backup status information to each other. When the backup unit receives a primary unit failure message or a communication timeout, it automatically becomes the primary unit and is responsible for broadcasting locomotive safety information (including time information and valid identifiers). When unit A recovers, it operates in backup mode.

[0073] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A unified train timing system based on BeiDou, characterized in that, include: The system includes a timing unit, a communication unit, and an information interface unit; the communication unit and information interface unit reuse the locomotive safety information integrated monitoring device and communicate via an RS485 bus. The timing unit is used to generate a reliable clock reference; the communication unit is used to provide a reliable clock information transmission channel; the information interface unit is used to realize data interaction with the train's onboard equipment; the interface and communication protocol between the information interface unit and the train's onboard equipment are compatible with the locomotive safety information integrated monitoring device; the timing unit includes a BeiDou timing module, a mobile communication module, and a main processing module; the BeiDou timing module is used to receive and process satellite signals and navigation messages, calculate BeiDou time in real time, and send it to the main processing module; the main processing module is used to determine the number of available satellites and valid positioning identifiers in the BeiDou time information; the mobile communication module is used to dial up to the network, establish a remote data transmission channel for the main processing module, and realize data interaction with the network clock server; The main processing module is pre-configured with multiple network clock server addresses and sends NTP time requests to all servers via the mobile network. Within a set threshold time, it receives a time response from any server, and the two parties interact according to the NTP protocol. The main processing module acquires the NTP time, eliminating local clock errors and communication delays in the timing unit. If no response is received from any server within the specified time, the NTP time acquisition is considered a failure. After acquiring the BeiDou time and NTP time information, the main processing module performs a time comparison logic judgment. If the time deviation is within the threshold range, the clock source is deemed reliable, and the local time of the timing unit is corrected using BeiDou time and output as a reliable clock; otherwise, an invalid time is output. After power-on and completing self-test, the communication unit receives information from the timing unit in real time. Once the clock information output by the timing unit is determined to be valid, the time is obtained from the communication unit using the NTP protocol, the local clock is corrected, the delay and local clock error during the communication process are eliminated, and the time validity flag is set.

2. The BeiDou-based unified train timing system according to claim 1, characterized in that, During the processing, if the number of available BeiDou satellites is greater than a set threshold and the positioning quality is valid, the main processing module determines that the BeiDou time is available.

3. The BeiDou-based unified train timing system according to claim 1, characterized in that, The main processing module uses BeiDou satellite time as a basis and employs multi-source clock verification and signal interference filtering measures to generate a reliable clock source.

4. The BeiDou-based unified train timing system according to claim 1, characterized in that, The communication unit adopts access authentication and data encryption measures. The information interface unit sends an access authentication request to the communication unit. The communication unit queries the device information database to see if the information interface unit is a legitimate device. If it is legitimate, the authentication is passed. The communication unit then broadcasts encrypted locomotive safety information to the information interface unit in real time. If authentication fails, the communication unit will inform the user of the authentication result and disconnect the connection.

5. The BeiDou-based unified train timing system according to claim 1, characterized in that, The communication unit adopts a primary and backup redundancy design. After power-on, machine A is the primary machine and machine B is the backup machine by default. Both machines obtain time from the time synchronization unit and correct their local clocks.

6. The BeiDou-based unified train timing system according to claim 5, characterized in that, The main unit A is responsible for data interaction with the information interface unit, while the standby unit B is only responsible for listening to the information. Units A and B periodically send primary and standby status information to each other. When the standby unit B receives a fault message from the main unit or a communication timeout, it automatically becomes the main unit and is responsible for broadcasting locomotive safety information. When the main unit A returns to normal, it operates in standby mode.

7. The BeiDou-based unified train timing system according to any one of claims 1-6, characterized in that, After receiving valid information from the communication unit, the information interface unit transmits it to the external vehicle-mounted equipment. The vehicle-mounted equipment continuously detects a certain amount of data. If the time identifier is determined to be valid and the time information contained in the data packet flows forward continuously, it is considered valid and the local time is corrected.

8. A train unified time synchronization method based on any one of claims 1-7, characterized in that, The process includes: Multiple network clock server addresses are pre-configured. NTP time requests are sent to all servers via the mobile network. A time response is received from any server within a specified time. The two parties interact according to the NTP protocol. Obtain NTP time and eliminate local clock differences and communication delay errors of the time synchronization unit; if no response is received from any server within the specified time, the NTP time acquisition is considered to have failed. After obtaining BeiDou time and NTP time information, a time comparison logic is performed. If the time difference between the two is within the threshold range, the clock source is determined to be reliable, and the local time of the BeiDou time correction and timing unit is used as the reliable clock for output. Otherwise, an invalid time is output. It receives information from the timing unit in real time; when it determines that the clock information output by the timing unit is valid, it uses the NTP protocol to obtain the time from the communication unit, corrects the local clock, eliminates the delay and local clock difference in the communication process, and sets the time valid flag.

9. The BeiDou-based unified train timing method according to claim 8, characterized in that, During the communication process, access authentication and data encryption measures are taken; the information interface unit sends an access authentication request to the communication unit, and the communication unit queries the device information database to see if the information interface unit is a legitimate device. If it is legitimate, the authentication is passed, and the communication unit broadcasts encrypted locomotive safety information to the information interface unit in real time. If authentication fails, the communication unit will inform the user of the authentication result and disconnect the connection.

10. The BeiDou-based unified train timing method according to claim 8, characterized in that, The communication unit adopts a primary and backup redundancy design. After power-on, unit A is the primary unit and unit B is the backup unit by default. Both units obtain time from the time synchronization unit and correct their local clocks. The primary unit is responsible for data interaction with the information interface unit, while unit B is only responsible for listening to information. Units A and B periodically send primary and backup status information to each other. When the backup unit receives a primary unit failure message or communication timeout, it automatically becomes the primary unit and is responsible for broadcasting locomotive safety information. When unit A recovers, it operates in backup unit mode.

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