Railway satellite-ground communication performance test system using low-orbit satellite

Abstract

The invention discloses a railway satellite-ground communication performance test system using a low-orbit satellite. The system comprises a central controller, a satellite signal analyzer, a wide-narrow band satellite converged communication terminal, a satellite communication service quality test unit, a railway broadband trunking communication test unit, a railway application function test unit and time-space synchronization equipment. According to the method, the blank of a low-orbit satellite railway satellite-ground data communication performance test scheme is filled, tests can be carried out in the aspects of satellite network coverage, satellite network service quality, indexes of satellite communication bearing railway application services and the like, powerful support is provided for optimization and upgrading of a railway communication system, and the test efficiency is improved through the comprehensive and systematic test scheme. The performance of satellite communication in a railway environment can be accurately evaluated, and a scientific basis is provided for development and application of a railway communication technology.

Description

Technical Field

[0001] The present invention relates to the field of railway communication technology, and in particular to a railway satellite-to-ground communication performance test system using a low-orbit satellite. Background Art

[0002] Satellite Internet is a new type of communication method that has emerged in recent years. It uses low-orbit broadband satellites to form a constellation to achieve global signal coverage and directly provide broadband communication services to ground users. Satellite communication can form an independent network without relying on the ground network and provide various communication services directly to end users.

[0003] Satellite internet, with its advantages of wide coverage, unrestricted geographic presence, and easy installation, can be integrated and complemented with existing railway communication networks, expanding their coverage and application scope. This is particularly valuable for railways in remote areas with limited communications and power infrastructure, or those prone to natural disasters. However, to ensure the efficient and stable application of satellite communications in railway environments, comprehensive and accurate performance testing is essential.

[0004] In view of the lack of standardized testing solutions for low-orbit satellite-railway satellite-to-ground data communications in the current market, which limits the in-depth application of satellite communication technology in the railway field, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a railway satellite-to-ground communication performance test system using low-orbit satellites. The system aims to accurately evaluate the various performances of satellite communications in the railway environment by building a comprehensive and systematic test framework to carry out tests from aspects such as satellite network coverage, satellite network service quality, and indicators of satellite communications carrying railway application services.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A railway satellite-to-ground communication performance test system using low-orbit satellites includes: a central controller, a satellite signal analyzer, a wide- and narrow-band satellite converged communication terminal, a satellite communication service quality test unit, a railway broadband trunking communication test unit, a railway application function test unit, and a time-space synchronization device; wherein:

[0008] The central controller is used to arrange test tasks according to the set railway test scenarios, and control any one or any combination of satellite signal analyzers, satellite communication service quality test units, railway broadband trunking communication test units, and railway application function test units according to the test tasks to perform corresponding test tasks and collect test results; wherein the satellite communication service quality test units, railway broadband trunking communication test units, and railway application function test units perform corresponding test tasks in collaboration with the wide- and narrow-band satellite converged communication terminal and the time-space synchronization equipment;

[0009] The satellite signal analyzer is used for general spectrum analysis and interference analysis of satellite signals;

[0010] The broadband and narrowband satellite fusion communication terminal has narrowband satellite communication and broadband satellite communication capabilities, and is used to realize satellite-based data transmission and reception;

[0011] The satellite communication service quality testing unit is used to test the communication service quality of the satellite communication network in combination with the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment;

[0012] The railway broadband trunking communication test unit is used to test the railway broadband trunking communication service carried by satellite communication by combining the broadband and narrowband satellite integrated communication terminal and the time and space synchronization equipment to obtain the corresponding technical indicators;

[0013] The railway application function test unit is used to test the railway application function carried by satellite communication by combining the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment to obtain the corresponding technical indicators;

[0014] The time-space synchronization device is used to collect train position and speed information in real time, and send it to the satellite communication service quality test unit, the railway broadband cluster communication test unit and the railway application function test unit in real time.

[0015] It can be seen from the technical solution provided by the above-mentioned present invention that the present invention fills the gap in the performance test scheme for low-orbit satellite-railway satellite-to-ground data communications, provides strong support for the optimization and upgrading of railway communication systems, and through a comprehensive and systematic test scheme, can accurately evaluate the performance of satellite communications in the railway environment, providing a scientific basis for the development and application of railway communication technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of a railway satellite-to-ground communication performance test system using a low-orbit satellite provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of a wide- and narrow-band satellite converged communication terminal provided by an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of the logic composition of a satellite communication service quality test provided by an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of the railway broadband trunking communication test logic provided by an embodiment of the present invention;

[0021] Figure 5 A schematic diagram of the logic composition of railway application function testing provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] First, the following terms may be used in this article:

[0024] The terms "include," "comprises," "contains," "has," or other similar expressions should be interpreted as non-exclusive. For example, "including certain technical features (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products, or manufactured articles, etc.) should be interpreted as including not only the technical features explicitly listed, but also other technical features known in the art that are not explicitly listed.

[0025] The term "consisting of" excludes any technical features not explicitly listed. If used in a claim, this term renders the claim closed, excluding any technical features other than those explicitly listed, except for conventional impurities associated with them. If this term appears only in a clause of a claim, it limits only the elements explicitly listed in that clause; elements listed in other clauses are not excluded from the claim as a whole.

[0026] Unless otherwise specified or limited, the terms "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this document based on specific circumstances.

[0027] The following describes in detail a railway satellite-to-ground communication performance testing method and system provided by the present invention. Any information not described in detail in the examples of the present invention represents prior art known to those skilled in the art. Where specific conditions are not specified in the examples of the present invention, the test was conducted in accordance with conventional conditions in the art or the conditions recommended by the manufacturer. Reagents or instruments used in the examples of the present invention, where the manufacturer is not specified, are commercially available conventional products.

[0028] Example 1

[0029] The embodiment of the present invention provides a railway satellite-to-ground communication performance test system using a low-orbit satellite. Figure 1 As shown, it mainly includes: central controller, satellite signal analyzer, wide- and narrow-band satellite fusion communication terminal, satellite communication service quality test unit, railway broadband cluster communication test unit, railway application function test unit and time and space synchronization equipment.

[0030] (1) The central controller is used to arrange test tasks according to the set railway test scenario, and control any one or any combination of satellite signal analyzers, satellite communication service quality test units, railway broadband cluster communication test units, and railway application function test units according to the test tasks to perform corresponding test tasks and collect test results; wherein, the satellite communication service quality test unit, railway broadband cluster communication test unit, and railway application function test unit perform corresponding test tasks under the cooperation of the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment.

[0031] (2) The satellite signal analyzer is used to implement general spectrum analysis and interference analysis of satellite signals.

[0032] Preferably, the general spectrum analysis includes: measuring the frequency of the satellite signal by scanning technology, measuring the power of the satellite signal by fast Fourier transform, and then using vector signal analysis technology to analyze the signal in frequency domain, modulation domain and code domain.

[0033] Preferably, the interference analysis includes: comprehensively adopting waterfall diagram measurement and receiving strength change measurement methods to observe the change of satellite signals in the satellite operating frequency band over time, thereby evaluating the impact of the interference signal and assisting in locating the interference source.

[0034] (3) The broadband and narrowband satellite fusion communication terminal has narrowband satellite communication and broadband satellite communication capabilities, and is used to realize satellite-based data transmission and reception.

[0035] Preferably, the broadband and narrowband satellite fusion communication terminal includes: a broadband transceiver antenna, a narrowband transceiver antenna, a satellite Internet broadband communication module, a narrowband satellite communication module, an industrial computer module, a first data transmission interface and a second data transmission interface; wherein: the broadband transceiver antenna, the satellite Internet broadband communication module, the industrial computer module and the first data transmission interface are connected in sequence; the narrowband transceiver antenna, the narrowband satellite communication module, the industrial computer module and the second data transmission interface are connected in sequence; and it can realize L-band narrowband satellite communication and Ka-band broadband satellite communication.

[0036] (4) The satellite communication service quality testing unit is used to test the communication service quality of the satellite communication network in combination with the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment.

[0037] Preferably, the satellite communication service quality testing unit measures the carrying capacity of the satellite communication network from the perspective of end-to-end data transmission application, and the tested communication service quality includes: data packet transmission delay, packet loss rate and data throughput; data packet transmission delay reflects the effectiveness of data transmission time in the satellite communication network; packet loss rate reflects the reliability of data transmission in the satellite communication network; data throughput reflects the data throughput capacity of the satellite communication network.

[0038] (5) Railway broadband cluster communication test unit, which is used to test the railway broadband cluster communication service carried by satellite communication by combining the broadband and narrowband satellite integrated communication terminal with the time and space synchronization equipment to obtain the corresponding technical indicators.

[0039] Preferably, the testing of the railway broadband trunking communication service carried by satellite communication includes: call function testing, MCX performance testing and voice quality testing.

[0040] (6) Railway application function test unit, which is used to test the railway application function carried by satellite communication by combining the wide- and narrow-band satellite integrated communication terminal with the time-space synchronization equipment to obtain the corresponding technical indicators.

[0041] Preferably, the testing of the satellite communication function of carrying railway applications includes: CTCS-3 level train control service testing and dispatching command service testing.

[0042] (7) The time-space synchronization device is used to collect train position and speed information in real time and send it to the satellite communication service quality test unit, the railway broadband cluster communication test unit and the railway application function test unit in real time.

[0043] In the embodiment of the present invention, the satellite communication service quality test unit, railway broadband trunking communication test unit, and railway application function test unit can be in the form of software, which can run in a separate device or in a central controller.

[0044] The solution provided by the embodiments of this invention fills a gap in the field of low-orbit satellite-railway satellite-to-ground data communication performance testing, providing strong support for the optimization and upgrade of railway communication systems. Through a comprehensive and systematic testing solution, the performance of satellite communications in railway environments can be accurately evaluated, providing a scientific basis for the development and application of railway communication technology.

[0045] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with reference to specific embodiments below.

[0046] 1. Overall overview of the plan.

[0047] In order to understand the network indicators and service performance of low-orbit satellite communications in the railway environment and evaluate the application efficiency of low-orbit satellite communications in the railway industry, it is necessary to design reasonable test scenarios, select reasonable test plans, and use dedicated test equipment to conduct tests from aspects such as satellite network coverage, satellite network service quality, and indicators of satellite communications carrying railway application services. To this end, an embodiment of the present invention provides a railway satellite-to-ground communication performance test system for low-orbit satellite railway satellite-to-ground data communication testing. It has signal reception and analysis functions and can accurately measure physical signal strength, service quality parameters, and business communication indicators. Specifically:

[0048] (1) Measuring physical signal strength: It can test the satellite signal coverage performance and electromagnetic environment of the satellite operating frequency band in different areas of the railway, including signal strength, coverage range, etc.

[0049] (2) Measuring service quality parameters: focusing on the performance of the satellite communication network itself, such as access performance, mobility performance, and channel maintenance performance, and testing the main communication indicators such as bandwidth, latency, and packet loss rate of satellite communication carrying railway application services.

[0050] (3) Measuring business communication indicators: Testing the application functions carried by satellite communications, for example, testing the application functions of key railway businesses such as railway dispatching communications, CTCS-3 (China Train Control System Level 3) train control system, and train wireless integrated communications carried by satellite communications.

[0051] 2. The overall structure of the plan.

[0052] See also Figure 1The system provided by the present invention mainly includes: a central controller, a satellite signal analyzer, a wide- and narrow-band satellite fusion communication terminal, a satellite communication service quality test unit, a railway broadband cluster communication test unit, and a railway application function test unit.

[0053] 1. Central controller.

[0054] In the embodiment of the present invention, the central controller is the core control unit of the system, which is mainly responsible for the arrangement of test tasks and controls other parts of the system to perform test tasks and test data analysis. Specifically, after the test is completed, the test results are collected, a test result report is generated, and subsequent analysis work is carried out.

[0055] 2. Satellite signal analyzer.

[0056] In the embodiment of the present invention, the satellite signal analyzer mainly implements general spectrum analysis and interference analysis of satellite signals. The satellite signal analyzer uses a high-performance spectrum scanner to support the measurement of satellite L-band and Ka-band wireless signals.

[0057] (1) General spectrum analysis: The frequency, power and other parameters of the signal are measured by scanning and fast Fourier transform respectively, and the signal frequency domain, modulation domain and code domain analysis are completed using vector signal analysis technology.

[0058] (2) Interference monitoring: A combination of waterfall chart measurement and RSSI measurement is used to observe how the signal within the satellite operating frequency band changes over time, assess the impact of interference signals, and assist in locating interference sources.

[0059] (3) It can capture the I / Q (in-phase component / quadrature component) data of the signal in real time and store it in the internal core processor for subsequent signal analysis and processing, such as modulation quality analysis, spectrum analysis, phase noise analysis, etc.

[0060] 3. Wide- and narrow-band satellite fusion communication terminal.

[0061] In an embodiment of the present invention, the broadband and narrowband satellite fusion communication terminal supports L-band narrowband satellite communication and Ka-band broadband satellite communication, has the characteristics of multi-system, multi-function and integration, can be connected to the low-orbit satellite network, and has a data transmission interface.

[0062] like Figure 2The figure shows a schematic diagram of a broadband and narrowband satellite fusion communication terminal, which mainly includes: a broadband transceiver antenna, a narrowband transceiver antenna (the antennas are all located on the top of the train), a satellite Internet broadband communication module, a narrowband satellite communication module, an industrial computer module (controls the satellite Internet broadband communication module and the narrowband satellite communication module, mainly realizing network connection management, data transceiver control and external device interface control functions.), a first data transmission interface and a second data transmission interface, which can support the satellite Internet Ka-band broadband system and L-band narrowband system; the above-mentioned broadband and narrowband satellite fusion communication terminal has an automated and portable fusion terminal prototype with broadband beam automatic satellite tracking, multi-satellite automatic optimization and link bandwidth adaptive adjustment, and has a broadband and narrowband data transmission Ethernet interface (corresponding to Figure 2 The first data transmission interface and the second data transmission interface at the bottom).

[0063] like Figure 2 As shown, the broadband and narrowband satellite fusion communication terminal includes a broadband test channel and a narrowband test channel, which can collaborate with related test units to complete corresponding test tasks.

[0064] 4. Satellite communication service quality testing unit.

[0065] In this embodiment of the present invention, a satellite communication service quality testing unit tests the service quality of data communications between the railway satellite and the ground, including throughput, latency, and packet loss rate. Specifically, the satellite communication service quality testing unit measures the carrying capacity of the satellite communication network from the perspective of end-to-end data transmission applications. Its service quality is comprehensively evaluated based on three indicators: data packet transmission latency, packet loss rate, and data throughput. Combined with train position and speed information during testing, the satellite communication service quality under different railway positions and speed levels can be determined. Data packet transmission latency and packet loss rate reflect the time effectiveness and reliability of satellite communication data transmission. Data throughput, including peak throughput and average throughput, reflects the data throughput capacity of the satellite communication network.

[0066] In the embodiment of the present invention, the satellite communication service quality test unit can test the service quality of broadband satellite communication and narrowband satellite communication respectively. Its logical structure is as follows: Figure 3 shown.

[0067] The test methods for the three indicators of data packet transmission delay, packet loss rate, and data throughput are as follows:

[0068] (1) Testing method for data packet transmission delay and packet loss rate.

[0069] The satellite communication service quality test unit generates UDP data frames of a set length and, with the assistance of a wide- and narrow-band satellite converged communication terminal, transmits them to a ground-based test server via the satellite communication network. It also receives UDP data frames looped back from the ground-based test server. Half the time interval between the start of sending a UDP data frame and the receipt of the same UDP data frame is used as the packet transmission delay. The packet loss rate is calculated as the ratio of the number of UDP data frames that were not successfully looped back to the total number of UDP data frames sent.

[0070] (2) Data throughput test method.

[0071] The FTP service is enabled on the ground test server. With the assistance of the wide- and narrow-band satellite converged communication terminal, the satellite communication service quality test unit tests the downlink and uplink throughput via the satellite communication network using FTP download and upload.

[0072] 5. Railway broadband cluster communication test unit.

[0073] In the embodiment of the present invention, the railway broadband trunking communication test unit is used to evaluate and optimize the quality of voice call services provided on the low-orbit satellite communication network. Through a real communication environment, combined with the train position and speed information during the test, the actual application of railway broadband trunking communication is tested, including call quality, connection speed, stability, etc. The logical structure is as follows: Figure 4 shown.

[0074] The railway broadband trunking communication test unit is responsible for the following tests:

[0075] (1) Call function test: The MCX client implements the call control function of the MCX protocol. With the assistance of the broadband and narrowband satellite converged communication terminal, the satellite communication network is used to implement call initiation, answering, hanging up, holding, and resuming operations. The MCX client initiates individual voice calls, group voice calls, and railway emergency calls, and combines the train position and speed information during the test to implement call function testing. Among them, MCX is a critical business communication. The MCX client here is a software module, which is part of the railway broadband trunking communication test unit.

[0076] (2) MCX performance test, including: testing the call establishment time, call success rate and call drop rate under the corresponding train position and speed; among them, the call establishment time is tested by recording the time difference between the call request and the successful establishment of the call, the call success rate is tested by counting the proportion of calls initiated within a set time that are successfully established, and the call drop rate is tested by counting the proportion of calls dropped among calls successfully established within a set time.

[0077] (3) Speech quality test: An auditory model is used to simulate the human auditory system, and the POLQA (Perceptual Objective Listening Quality Analysis) algorithm recommended by ITU-T is used to evaluate the speech quality at the corresponding train position and speed. The speech quality is evaluated by analyzing the characteristics of the speech signal.

[0078] 6. Railway application function test unit.

[0079] In the embodiment of the present invention, the railway application function test unit can test the railway application function carried by satellite communication under different geographical locations and different speed levels. For example, the service quality of CTCS-3 level train control services and dispatching command services can be tested. Its logical structure is as follows: Figure 5 As shown, in addition to the test control part, the railway application function test unit also has two parts: a dispatching command test terminal and a simulated train automatic protection device, which are used for corresponding business tests.

[0080] (1) CTCS-3 level train control service test, including: service transmission delay and success rate; with the assistance of the wide- and narrow-band satellite fusion communication terminal, the sending entity sends a TCP / IP data frame to the responding entity according to the specified data packet length and starts timing, the responding entity verifies the received data frame and sends a response frame, the sending entity calculates the service transmission delay under the corresponding train position and speed based on the time when the response frame is received, and calculates the success rate under the corresponding train position and speed based on the number of correctly received response frames and the total number of frames; wherein, the responding entity and the sending entity are one-to-one corresponding, if the sending entity is a simulated train automatic protection device, the responding entity is a simulated wireless block center on the ground, conversely, if the sending entity is a simulated wireless block center on the ground, the responding entity is a simulated train automatic protection device.

[0081] (2) Dispatch command service tests include: testing the dispatch command transmission success rate and the train wireless train number transmission success rate; with the assistance of the wide-band and narrowband satellite fusion communication terminal, the dispatch command ground server sends the dispatch command to the dispatch command test terminal, and after receiving the dispatch command, the dispatch command test terminal returns the automatic receipt and manual receipt to the dispatch command ground server, so as to calculate the dispatch command transmission success rate under the corresponding train position and speed; the dispatch command test terminal periodically sends the train wireless train number to the dispatch command ground server, and calculates the train wireless train number transmission success rate under the corresponding train position and speed based on the ratio of the number of dispatch command ground server successfully received and the total number of dispatch command test terminal transmissions.

[0082] 7. Space-time synchronization equipment.

[0083] The time and space synchronization equipment supports the train network control system interface and satellite interface (for example, Beidou positioning interface). The train network control system interface complies with the Ethernet train backbone network protocol specified in GB / T 28029. It can obtain train speed information from the process data packets broadcast in the train network control system and obtain the train's latitude and longitude and time information in real time through the satellite interface.

[0084] When the satellite signal meets the requirements (good signal), the system uses the longitude and latitude information of the train as the basis to query the pre-established database to obtain the corresponding train kilometer mark. When the satellite signal does not meet the requirements (signal loss or interference), the train position is estimated by dead reckoning based on the speed information obtained from the train network control system.

[0085] In the embodiments of the present invention, the terms "low-orbit satellite," "narrowband satellite," and "broadband satellite" are all commonly used technical terms in the field of satellite communications. For example, a low-orbit satellite generally refers to a satellite operating in a low Earth orbit (LEO), which generally refers to an orbital range of approximately 200 to 2000 kilometers above the Earth's surface. A narrowband satellite refers to a satellite system that uses a relatively small frequency range for communication. In contrast to narrowband, a broadband satellite uses a wider frequency range for communication. The distinction between narrowband and broadband is primarily based on the frequency bandwidth used for communication.

[0086] Through the description of the above embodiments, those skilled in the art will clearly understand that the above embodiments can be implemented through software or by using software plus a necessary general-purpose hardware platform. Based on this understanding, the technical solutions of the above embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, a USB flash drive, a mobile hard disk, etc.) and includes a number of instructions for causing a computer device (such as a personal computer, a server, or a network device) to execute the methods described in the various embodiments of the present invention.

[0087] Those skilled in the art will clearly understand that for the convenience and brevity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the system can be divided into different functional modules to complete all or part of the functions described above.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art.

Claims

1. A railway satellite-to-ground communication performance test system using a low-orbit satellite, characterized in that: include: Central controller, satellite signal analyzer, broadband and narrowband satellite converged communication terminal, satellite communication service quality test unit, railway broadband trunking communication test unit, railway application function test unit and time and space synchronization equipment; including: The central controller is used to arrange test tasks according to the set railway test scenarios, and control any one or any combination of satellite signal analyzers, satellite communication service quality test units, railway broadband trunking communication test units, and railway application function test units according to the test tasks to perform corresponding test tasks and collect test results; wherein the satellite communication service quality test units, railway broadband trunking communication test units, and railway application function test units perform corresponding test tasks in collaboration with the wide- and narrow-band satellite converged communication terminal and the time-space synchronization equipment; The satellite signal analyzer is used for general spectrum analysis and interference analysis of satellite signals; The broadband and narrowband satellite fusion communication terminal has narrowband satellite communication and broadband satellite communication capabilities, and is used to realize satellite-based data transmission and reception; The satellite communication service quality testing unit is used to test the communication service quality of the satellite communication network in combination with the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment; The railway broadband trunking communication test unit is used to test the railway broadband trunking communication service carried by satellite communication by combining the broadband and narrowband satellite integrated communication terminal and the time and space synchronization equipment to obtain the corresponding technical indicators; The railway application function test unit is used to test the railway application function carried by satellite communication by combining the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment to obtain the corresponding technical indicators; The time-space synchronization device is used to collect train position and speed information in real time, and send it to the satellite communication service quality test unit, the railway broadband cluster communication test unit and the railway application function test unit in real time.

2. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The general spectrum analysis includes: measuring the frequency of satellite signals through scanning technology, measuring the power of satellite signals through fast Fourier transform, and then using vector signal analysis technology to analyze the signal frequency domain, modulation domain and code domain.

3. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The interference analysis includes: A comprehensive method of waterfall diagram measurement and receiving strength change measurement is used to observe how satellite signals within the satellite operating frequency band change over time, thereby assessing the impact of interference signals and assisting in locating interference sources.

4. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The broadband and narrowband satellite fusion communication terminal includes: a broadband transceiver antenna, a narrowband transceiver antenna, a satellite Internet broadband communication module, a narrowband satellite communication module, an industrial computer module, a first data transmission interface and a second data transmission interface; wherein: the broadband transceiver antenna, the satellite Internet broadband communication module, the industrial computer module and the first data transmission interface are connected in sequence; the narrowband transceiver antenna, the narrowband satellite communication module, the industrial computer module and the second data transmission interface are connected in sequence; and it can realize L-band narrowband satellite communication and Ka-band broadband satellite communication.

5. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The satellite communication service quality testing unit is used to test the communication service quality of the satellite communication network by combining the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment, and includes: The satellite communication service quality test unit measures the carrying capacity of the satellite communication network from the perspective of end-to-end data transmission applications. By combining the train position and speed information during the test, it can obtain the satellite communication service quality under different positions and speed levels. The communication service quality tested includes: data packet transmission delay, packet loss rate and data throughput; Data packet transmission delay reflects the effectiveness of data transmission time in the satellite communication network; packet loss rate reflects the reliability of data transmission in the satellite communication network; data throughput reflects the data throughput capacity of the satellite communication network.

6. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The data packet transmission delay and packet loss rate are tested in the following ways: The satellite communication service quality test unit generates a UDP data frame of a set length, sends it to a ground test server via a satellite communication network with the assistance of a wide- and narrow-band satellite fusion communication terminal, and receives the UDP data frame looped back by the ground test server; The half of the time interval between the start of sending a UDP data frame and the reception of the same UDP data frame is used as the data frame transmission delay; The packet loss rate is calculated by the ratio of the number of UDP data frames that are not successfully looped back to the total number of UDP data frames sent.

7. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The stated data throughput was tested using the following methods: The FTP service is enabled on the ground test server. With the assistance of the wide- and narrow-band satellite converged communication terminal, the satellite communication service quality test unit tests the downlink and uplink throughput via the satellite communication network using FTP download and upload.

8. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The railway broadband trunking communication test unit is used to test the railway broadband trunking communication service carried by satellite communication by combining the broadband and narrowband satellite integrated communication terminal and the time and space synchronization equipment, including: Railway broadband trunking communication testing uses a real communication environment, combined with train position and speed information during testing, to test call functions, MCX performance, and voice quality. Call function test: The MCX client within the railway broadband trunking communication test unit implements the call control function of the MCX protocol. With the assistance of the broadband and narrowband satellite converged communication terminal, call initiation, answering, hanging up, holding, and resuming operations are achieved via the satellite communication network. Individual voice calls, group voice calls, and railway emergency calls are initiated through the MCX client, and call function tests are implemented in conjunction with train position and speed information during testing. MCX is a critical business communication. The MCX performance test includes testing the call setup time, call success rate, and call drop rate under the corresponding train position and speed. Specifically, the call setup time is tested by recording the time difference between the call request being issued and the call being successfully established. The call success rate is tested by counting the proportion of calls initiated within a set time that are successfully established. The call drop rate is tested by counting the proportion of calls dropped among successfully established calls within a set time. Speech quality test: An auditory model is used to simulate the human auditory system. A perceptually objective speech quality assessment algorithm is used to analyze the characteristics of speech signals to evaluate speech quality at corresponding train positions and speeds.

9. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The railway application function test unit is used to test the railway application function carried by satellite communication by combining the wide- and narrow-band satellite integrated communication terminal and the time-space synchronization equipment, including: The railway application function test unit can perform service tests on satellite communication-based railway application functions under different geographical locations and speed levels. It is equipped with a dispatching command test terminal and simulated train automatic protection equipment for corresponding service tests. CTCS-3 train control service tests include: service transmission delay and success rate; with the assistance of a wide- and narrow-band satellite converged communication terminal, the sending entity sends a TCP / IP data frame to the responding entity according to the specified data packet length and starts timing. The responding entity verifies the received data frame and sends a response frame. The sending entity calculates the service transmission delay for the corresponding train position and speed based on the time the response frame is received, and calculates the success rate for the corresponding train position and speed based on the number of correctly received response frames and the total number of frames. If the sending entity is a simulated train automatic protection device, the responding entity is a simulated radio block center on the ground; if the sending entity is a simulated radio block center on the ground, the responding entity is a simulated train automatic protection device. Dispatching command service tests include: testing the dispatching command transmission success rate and the train wireless train number transmission success rate; with the assistance of the wide- and narrow-band satellite fusion communication terminal, the dispatching command ground server sends the dispatching command to the dispatching command test terminal, and after receiving the dispatching command, the dispatching command test terminal returns automatic signature and manual signature to the dispatching command ground server to calculate the dispatching command transmission success rate under the corresponding train position and speed; the dispatching command test terminal periodically sends the train wireless train number to the dispatching command ground server, and calculates the train wireless train number transmission success rate under the corresponding train position and speed based on the ratio of the number of dispatching command ground server successfully received and the total number of dispatching command test terminal transmissions.

10. The railway satellite-to-ground communication performance test system using a low-orbit satellite according to claim 1, characterized in that: The real-time acquisition of train position and speed information includes: The train speed information is obtained through the process data packets broadcast in the train network control system, and the longitude and latitude information and time information of the train are obtained in real time through the satellite interface. When the satellite signal meets the requirements, the longitude and latitude information of the train is obtained as the basis, and the pre-established database is queried to obtain the corresponding train kilometer mark. When the satellite signal does not meet the requirements, the speed information obtained from the train network control system is used for dead reckoning to estimate the train position.

Images