Secondary radar equipment for rail transit application and distance measuring method of secondary radar equipment

Abstract

The invention discloses a rail transit application-oriented secondary radar device and a distance measurement method thereof, and the device comprises a first digital signal processing module which is used for receiving a control instruction sent by a train control system, generating a pseudo-random code modulation baseband interrogation signal with known codes and sending the pseudo-random code modulation baseband interrogation signal to the first radio frequency transceiving component; the first radio frequency transceiving component is used for performing digital-to-analog conversion, filtering, amplification and frequency mixing on the transmitted baseband digital signal and generating a finally transmitted radio frequency signal; the second digital signal processing module is used for carrying out baseband signal processing and active response on the inquiry signal from the vehicle-mounted radar terminal, and carrying out information interaction with a ground train control system; and the second radio frequency assembly is used for performing down-conversion processing on an inquiry radio frequency signal transmitted by the vehicle-mounted radar terminal to obtain a second intermediate frequency signal and sending the second intermediate frequency signal to the second digital signal processing module. According to the invention, the driving safety capability of the train is improved, and the accident occurrence probability is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of rail transit, and in particular to a secondary radar device and a ranging method thereof for rail transit applications. Background Art

[0002] With the expansion and crisscrossing of the railway network, the increasingly smaller train intervals and the ever-increasing train speeds have posed a huge challenge to the safety of rail transit. Therefore, it is necessary to equip independent systems to monitor the positions between trains and provide early warnings to drivers.

[0003] Currently, train control systems primarily utilize satellite-based positioning for train-assisted collision avoidance. However, these systems can be challenging to locate in areas with low satellite visibility (such as tunnels), areas with severe multipath reflections (such as urban high-rise buildings), and areas with significant electromagnetic interference. Furthermore, these systems address issues such as positioning when satellite signal reception is poor, correcting and obtaining precise positions when stopping at switches and platforms, and resuming operations after eliminating trackside equipment such as axle counters and track circuits, should system or individual train communications be disrupted. Furthermore, these issues can be addressed in mixed modes with both faulty and healthy trains. These issues can help improve train safety and reduce the probability of accidents. Summary of the Invention

[0004] In view of this, the present application provides a secondary radar device and a ranging method thereof for rail transit applications.

[0005] The present application discloses a secondary radar for rail transit applications, which includes an on-board radar terminal installed on a train and a trackside radar terminal installed beside the track; the on-board radar terminal communicates with the train operation control system and has three basic working modes: inquiry, response, and data transmission; the trackside radar terminal communicates with the ground control system and has two basic working modes: response and data transmission;

[0006] The vehicle-mounted radar terminal includes a first digital signal processing module and a first radio frequency transceiver component. The first digital signal processing module is used to generate a baseband interrogation signal modulated by a known pseudo-random code after receiving a control instruction from the train control system and send it to the first radio frequency transceiver component. The first radio frequency transceiver component is used to perform digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted radio frequency signal. It is also used to receive the response radio frequency signal from the trackside radar terminal, perform down-conversion processing, obtain a second intermediate frequency signal, and send it to the first digital signal processing module.

[0007] The trackside radar terminal includes a second digital signal processing module and a second radio frequency transceiver component; the second digital signal processing module is used to perform baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively respond, and exchange information with the ground train control system; the second radio frequency component is used to down-convert the interrogation radio frequency signal transmitted by the vehicle-mounted radar terminal to obtain a second intermediate frequency signal and send it to the second digital signal processing module, and is also used to perform digital-to-analog conversion, filtering, amplification, and mixing on the baseband digital signal generated by the second digital signal processing module to generate the final transmitted radio frequency signal; the baseband digital signal includes a ranging response signal and a digital transmission signal;

[0008] The first digital signal processing module is also used to receive the response signal sent by the trackside radar terminal. After the response signal is frequency-converted by the first RF transceiver component, it is parsed and a pseudo-code sequence is generated in the first digital signal processing module, the cross-correlation is calculated, the distance between the vehicle-mounted radar terminal and the trackside radar terminal is calculated, or the digital transmission data frame is parsed and reported.

[0009] Furthermore, the on-board radar terminal has a built-in operating system, which communicates with the train control system through the operating system, obtains and processes the response information sent by the trackside radar terminal, uploads the processing results to the train control system, and generates a digital transmission signal according to the digital transmission instructions of the train control system; the trackside radar terminal has a built-in operating system, which communicates with the ground train control system through the operating system, obtains and processes the query information sent by the on-board radar terminal, uploads the processing results to the ground train control system, and generates a digital transmission signal according to the digital transmission instructions of the ground train control system;

[0010] The train control system is used to send control instructions to the first signal processing module in the vehicle-mounted radar terminal;

[0011] The first signal processing module is used to forward the received control instruction to the physical layer through the processor, and perform corresponding calculation and processing on the signal to be transmitted according to the control instruction.

[0012] Furthermore, the first signal processing module includes a baseband signal generating module and a response signal receiving module;

[0013] The baseband signal generation module is used to receive instructions from the ranging module or the data transmission module, and based on the known transmission mode and information, perform RS coding calculation and CRC check calculation to obtain the information pulse code, combine it with the interrogation pulse synchronization header spread spectrum code, use DPSK modulation to obtain the pseudo-random code with the known code to modulate the interrogation baseband signal and send it to the first RF transceiver component;

[0014] The response signal receiving module is used to receive the second intermediate frequency signal after frequency conversion processing by the first RF transceiver component, and perform low-pass filtering and down-sampling on it to generate a response baseband signal. It uses the template matching method to identify the response signal, detect the positioning data pulse, demodulate and interpret the data pulse, obtain a random ID number and random transmission delay, and send the relevant data to the ranging module.

[0015] Furthermore, the second digital signal processing module includes a baseband signal generating module and a response signal transmitting module;

[0016] The baseband signal generation module is used to parse the inquiry baseband signal sent by the response signal transmission module, compose the relevant information obtained from the analysis into a response information packet, and generate a response baseband signal in conjunction with the synchronization header pulse and send it to the response signal transmission module. Alternatively, based on the known transmission mode and information, the module performs RS coding and CRC check calculation to obtain the information pulse code, combines the inquiry pulse synchronization header spread spectrum code, and uses DPSK modulation to obtain the baseband signal and send it to the response signal transmission module. The relevant information includes a random ID number and a random response delay.

[0017] The response signal transmission module is used to receive the second intermediate frequency signal after frequency conversion processing by the second RF transceiver component, and perform low-pass filtering and down-sampling on it to generate an inquiry baseband signal transmitted by the vehicle-mounted radar terminal and send it to the baseband signal generation module; it is also used to transmit the baseband signal generated by the baseband signal generation module to the second RF component for transmission.

[0018] Furthermore, the first radio frequency transceiver component and the second radio frequency transceiver component each include a frequency conversion module, a first mixer, and a second mixer;

[0019] The frequency conversion module is used to receive the interrogation baseband signal, filter and amplify it, and then send it to the first mixer and the second mixer in sequence, or process the down-converted signals output by the first mixer and the second mixer, and output them to the first digital signal processing module;

[0020] The first mixer is used to generate a local oscillator signal and mix it with the information output by the frequency conversion module to output a fixed second intermediate frequency signal. If the mixing is up-conversion, it is output to the second mixer; otherwise, it is output to the digital signal processing module;

[0021] The second mixer is used to mix the signal amplified by the response signal transmission module to output a radio frequency signal of a specified frequency band, or receive the response radio frequency signal and down-mix it to output a fixed first intermediate frequency signal to the first mixer for further down-conversion processing.

[0022] Furthermore, the first digital signal processing module further includes a ranging module;

[0023] The ranging module is used to receive the ranging instructions sent by the train control system and forward them to the baseband signal generation module. At the same time, it receives the data sent by the response signal receiving module, obtains the propagation delay by generating a pseudocode sequence and calculating the cross-correlation, and calculates the distance between the on-board radar terminal and the trackside radar terminal.

[0024] Furthermore, the ranging module is specifically used to:

[0025] When the vehicle-mounted radar terminal transmits a radio frequency signal, a timing pulse is triggered to start timing. When the response signal returned by the trackside radar terminal is received, the peak value is solved according to relevant calculations, and the timing pulse stops timing. The timing pulse can be used to measure the propagation delay from the vehicle-mounted radar terminal to the trackside radar terminal, thereby measuring the distance between the vehicle-mounted radar terminal and the trackside radar terminal. The radio frequency signal transmitted by the vehicle-mounted radar terminal is a signal modulated by a pseudo-random code with a known code.

[0026] Furthermore, the first digital signal processing module further includes a data transmission module;

[0027] The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the train control system into multiple basic packets, and send them to the first digital signal processing module to generate baseband signals for transmission to the trackside radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the trackside radar terminal, and report them to the train control system.

[0028] Furthermore, the second digital signal processing module further includes a data transmission module;

[0029] The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the ground train control system into multiple basic packets, and send them to the second digital signal processing module to generate baseband signals, which are transmitted to the on-board radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the on-board radar terminal, and report them to the ground train control system.

[0030] This application also discloses a secondary radar device ranging method for rail transit applications, which is applicable to the aforementioned secondary radar for rail transit applications and includes:

[0031] After receiving the control command from the train control system, the first digital signal processing module of the on-board radar terminal generates a baseband interrogation signal modulated by a known pseudo-random code and sends it to the first RF transceiver component. The first RF transceiver component performs digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted RF signal. At the same time, it receives the response RF signal from the trackside radar terminal, performs down-conversion processing, obtains a second intermediate frequency signal, and sends it to the first digital signal processing module.

[0032] The second digital signal processing module performs baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively responds, and exchanges information with the ground train control system; the second RF component down-converts the interrogation RF signal transmitted by the vehicle-mounted radar terminal to obtain an intermediate frequency signal and sends it to the second digital signal processing module. At the same time, the baseband digital signal generated by the second digital signal processing module is subjected to digital-to-analog conversion, filtering, amplification, and mixing to generate the final transmitted RF signal; the baseband digital signal includes a ranging response signal and a digital transmission signal;

[0033] The first digital signal processing module receives the response signal sent by the trackside radar terminal. After frequency conversion processing by the first RF transceiver component, the first digital signal processing module parses and generates a pseudo code sequence, calculates the cross-correlation, calculates the distance between the vehicle-mounted radar terminal and the trackside radar terminal, or parses the digital data frame and reports it.

[0034] Due to the adoption of the above-mentioned technical solution, the present application has the following advantages: based on the application scenario of real-time monitoring of the line of sight information between the train and other surrounding trains during the train operation, it solves the problems of how to communicate with the faulty vehicle when the traditional train collision avoidance system has poor satellite signal reception, insufficient positioning accuracy, and vehicle-ground communication interruption, which helps to improve the train's driving safety capabilities and reduce the probability of accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0036] Figure 1 This is a block diagram of a vehicle-mounted radar terminal according to an embodiment of the present application;

[0037] Figure 2 This is a block diagram of a trackside radar terminal according to an embodiment of the present application;

[0038] Figure 3 This is a flow chart of a secondary radar device ranging method for rail transit applications according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] The present application is further described with reference to the accompanying drawings and embodiments. The embodiments described are only a part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0040] See also Figures 1 to 3The present application provides an embodiment of a secondary radar device for rail transit applications, which includes an on-board radar terminal installed on a train and a trackside radar terminal installed next to the track; the on-board radar terminal communicates with the train operation control system and has three basic operating modes: inquiry, response, and data transmission; the trackside radar terminal communicates with the ground control system and has two basic operating modes: response and data transmission;

[0041] The vehicle-mounted radar terminal includes a first digital signal processing module and a first radio frequency transceiver component. The first digital signal processing module is used to generate a baseband interrogation signal modulated by a known pseudo-random code after receiving a control instruction from the train control system and send it to the first radio frequency transceiver component. The first radio frequency transceiver component is used to perform digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted radio frequency signal. It is also used to receive the response radio frequency signal from the trackside radar terminal, perform down-conversion processing, obtain a second intermediate frequency signal, and send it to the first digital signal processing module.

[0042] The trackside radar terminal includes a second digital signal processing module and a second radio frequency transceiver component; the second digital signal processing module is used to perform baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively respond, and exchange information with the ground train control system; the second radio frequency component is used to down-convert the interrogation radio frequency signal transmitted by the vehicle-mounted radar terminal to obtain a second intermediate frequency signal and send it to the second digital signal processing module, and is also used to perform digital-to-analog conversion, filtering, amplification, and mixing on the baseband digital signal generated by the second digital signal processing module to generate the final transmitted radio frequency signal; the baseband digital signal includes a ranging response signal and a digital transmission signal;

[0043] The first digital signal processing module is also used to receive the response signal sent by the trackside radar terminal. After the response signal is frequency-converted by the first RF transceiver component, it is parsed and a pseudo-code sequence is generated in the first digital signal processing module, the cross-correlation is calculated, the distance between the vehicle-mounted radar terminal and the trackside radar terminal is calculated, or the digital transmission data frame is parsed and reported.

[0044] Optionally, the on-board radar terminal has a built-in operating system, communicates with the train control system through the operating system, obtains and processes the response information sent by the trackside radar terminal, uploads the processing result to the train control system, and generates a digital transmission signal according to the digital transmission instruction of the train control system; the trackside radar terminal has a built-in operating system, communicates with the ground train control system through the operating system, obtains and processes the inquiry information sent by the on-board radar terminal, uploads the processing result to the ground train control system, and generates a digital transmission signal according to the digital transmission instruction of the ground train control system;

[0045] The train control system is used to send control instructions to the first signal processing module in the vehicle-mounted radar terminal;

[0046] The first signal processing module is used to forward the received control instruction to the physical layer through the processor, and perform corresponding calculation and processing on the signal to be transmitted according to the control instruction.

[0047] Optionally, the first signal processing module includes a baseband signal generating module and a response signal receiving module;

[0048] The baseband signal generation module is used to receive instructions from the ranging module or the data transmission module, and based on the known transmission mode and information, perform RS coding calculation and CRC check calculation to obtain the information pulse code, combine it with the interrogation pulse synchronization header spread spectrum code, use DPSK modulation to obtain the pseudo-random code with the known code to modulate the interrogation baseband signal and send it to the first RF transceiver component;

[0049] The response signal receiving module is used to receive the second intermediate frequency signal after frequency conversion processing by the first RF transceiver component, and perform low-pass filtering and down-sampling on it to generate a response baseband signal. It uses the template matching method to identify the response signal, detect the positioning data pulse, demodulate and interpret the data pulse, obtain a random ID number and random transmission delay, and send the relevant data to the ranging module.

[0050] Optionally, the second digital signal processing module includes a baseband signal generating module and a response signal transmitting module;

[0051] The baseband signal generation module is used to parse the inquiry baseband signal sent by the response signal transmission module, compose the relevant information obtained from the analysis into a response information packet, and generate a response baseband signal in conjunction with the synchronization header pulse and send it to the response signal transmission module. Alternatively, based on the known transmission mode and information, the module performs RS coding and CRC check calculation to obtain the information pulse code, combines the inquiry pulse synchronization header spread spectrum code, and uses DPSK modulation to obtain the baseband signal and send it to the response signal transmission module. The relevant information includes a random ID number and a random response delay.

[0052] The response signal transmission module is used to receive the second intermediate frequency signal after frequency conversion processing by the second RF transceiver component, and perform low-pass filtering and down-sampling on it to generate an inquiry baseband signal transmitted by the vehicle-mounted radar terminal and send it to the baseband signal generation module; it is also used to transmit the baseband signal generated by the baseband signal generation module to the second RF component for transmission.

[0053] Optionally, the first radio frequency transceiver component and the second radio frequency transceiver component both include a frequency conversion module, a first mixer, and a second mixer;

[0054] The frequency conversion module is used to receive the interrogation baseband signal, filter and amplify it, and then send it to the first mixer and the second mixer in sequence, or process the down-converted signals output by the first mixer and the second mixer, and output them to the first digital signal processing module;

[0055] The first mixer is used to generate a local oscillator signal and mix it with the information output by the frequency conversion module to output a fixed second intermediate frequency signal. If the mixing is up-conversion, it is output to the second mixer; otherwise, it is output to the digital signal processing module;

[0056] The second mixer is used to mix the signal amplified by the response signal transmission module to output a radio frequency signal of a specified frequency band, or receive the response radio frequency signal and down-mix it to output a fixed first intermediate frequency signal to the first mixer for further down-conversion processing.

[0057] Optionally, the first digital signal processing module further includes a ranging module;

[0058] The ranging module is used to receive the ranging instructions sent by the train control system and forward them to the baseband signal generation module. At the same time, it receives the data sent by the response signal receiving module, obtains the propagation delay by generating a pseudocode sequence and calculating the cross-correlation, and calculates the distance between the on-board radar terminal and the trackside radar terminal.

[0059] Optionally, the ranging module is specifically configured to:

[0060] When the vehicle-mounted radar terminal transmits a radio frequency signal, a timing pulse is triggered to start timing. When the response signal returned by the trackside radar terminal is received, the peak value is solved according to relevant calculations, and the timing pulse stops timing. The timing pulse can be used to measure the propagation delay from the vehicle-mounted radar terminal to the trackside radar terminal, thereby measuring the distance between the vehicle-mounted radar terminal and the trackside radar terminal. The radio frequency signal transmitted by the vehicle-mounted radar terminal is a signal modulated by a pseudo-random code with a known code.

[0061] Optionally, the first digital signal processing module further includes a data transmission module;

[0062] The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the train control system into multiple basic packets, and send them to the first digital signal processing module to generate baseband signals for transmission to the trackside radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the trackside radar terminal, and report them to the train control system.

[0063] Optionally, the second digital signal processing module further includes a data transmission module;

[0064] The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the ground train control system into multiple basic packets, and send them to the second digital signal processing module to generate baseband signals, which are transmitted to the on-board radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the on-board radar terminal, and report them to the ground train control system.

[0065] This application also provides an embodiment of a ranging method for a secondary radar device for rail transit applications, which is applicable to the secondary radar for rail transit applications described in the above embodiment, and includes:

[0066] After receiving the control command from the train control system, the first digital signal processing module of the on-board radar terminal generates a baseband interrogation signal modulated by a known pseudo-random code and sends it to the first RF transceiver component. The first RF transceiver component performs digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted RF signal. At the same time, it receives the response RF signal from the trackside radar terminal, performs down-conversion processing, obtains a second intermediate frequency signal, and sends it to the first digital signal processing module.

[0067] The second digital signal processing module performs baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively responds, and exchanges information with the ground train control system; the second RF component down-converts the interrogation RF signal transmitted by the vehicle-mounted radar terminal to obtain an intermediate frequency signal and sends it to the second digital signal processing module. At the same time, the baseband digital signal generated by the second digital signal processing module is subjected to digital-to-analog conversion, filtering, amplification, and mixing to generate the final transmitted RF signal; the baseband digital signal includes a ranging response signal and a digital transmission signal;

[0068] The first digital signal processing module receives the response signal sent by the trackside radar terminal. After frequency conversion processing by the first RF transceiver component, the first digital signal processing module parses and generates a pseudo code sequence, calculates the cross-correlation, calculates the distance between the vehicle-mounted radar terminal and the trackside radar terminal, or parses the digital data frame and reports it.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A secondary radar for rail transit applications, characterized in that: It includes an on-board radar terminal installed on the train and a trackside radar terminal installed beside the track; the on-board radar terminal communicates with the train operation control system and has three basic working modes: inquiry, response and data transmission; the trackside radar terminal communicates with the ground control system and has two basic working modes: response and data transmission; The vehicle-mounted radar terminal includes a first digital signal processing module and a first radio frequency transceiver component. The first digital signal processing module is used to generate a baseband interrogation signal modulated by a known pseudo-random code after receiving a control instruction from the train control system and send it to the first radio frequency transceiver component. The first radio frequency transceiver component is used to perform digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted radio frequency signal. It is also used to receive the response radio frequency signal from the trackside radar terminal, perform down-conversion processing, obtain a second intermediate frequency signal, and send it to the first digital signal processing module. The trackside radar terminal includes a second digital signal processing module and a second radio frequency transceiver component; the second digital signal processing module is used to perform baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively respond, and exchange information with the ground train control system; the second radio frequency component is used to down-convert the interrogation radio frequency signal transmitted by the vehicle-mounted radar terminal to obtain a second intermediate frequency signal and send it to the second digital signal processing module, and is also used to perform digital-to-analog conversion, filtering, amplification, and mixing on the baseband digital signal generated by the second digital signal processing module to generate the final transmitted radio frequency signal; the baseband digital signal includes a ranging response signal and a digital transmission signal; The first digital signal processing module is also used to receive the response signal sent by the trackside radar terminal. After the response signal is frequency-converted by the first RF transceiver component, it is parsed and a pseudo-code sequence is generated in the first digital signal processing module, the cross-correlation is calculated, the distance between the vehicle-mounted radar terminal and the trackside radar terminal is calculated, or the digital transmission data frame is parsed and reported.

2. The secondary radar for rail transit applications according to claim 1, characterized in that: The on-board radar terminal has a built-in operating system, which communicates with the train control system through the operating system, obtains and processes the response information sent by the trackside radar terminal, uploads the processing results to the train control system, and generates a digital transmission signal according to the digital transmission instructions of the train control system; the trackside radar terminal has a built-in operating system, which communicates with the ground train control system through the operating system, obtains and processes the query information sent by the on-board radar terminal, uploads the processing results to the ground train control system, and generates a digital transmission signal according to the digital transmission instructions of the ground train control system; The train control system is used to send control instructions to the first signal processing module in the vehicle-mounted radar terminal; The first signal processing module is used to forward the received control instruction to the physical layer through the processor, and perform corresponding calculation and processing on the signal to be transmitted according to the control instruction.

3. The secondary radar for rail transit applications according to claim 2, characterized in that: The first signal processing module includes a baseband signal generating module and a response signal receiving module; The baseband signal generation module is used to receive instructions from the ranging module or the data transmission module, and based on the known transmission mode and information, perform RS coding calculation and CRC check calculation to obtain the information pulse code, combine it with the interrogation pulse synchronization header spread spectrum code, use DPSK modulation to obtain the pseudo-random code with the known code to modulate the interrogation baseband signal and send it to the first RF transceiver component; The response signal receiving module is used to receive the second intermediate frequency signal after frequency conversion processing by the first RF transceiver component, and perform low-pass filtering and down-sampling on it to generate a response baseband signal. It uses the template matching method to identify the response signal, detect the positioning data pulse, demodulate and interpret the data pulse, obtain a random ID number and random transmission delay, and send the relevant data to the ranging module.

4. The secondary radar for rail transit applications according to claim 1, characterized in that: The second digital signal processing module includes a baseband signal generating module and a response signal transmitting module; The baseband signal generation module is used to parse the inquiry baseband signal sent by the response signal transmission module, compose the relevant information obtained from the analysis into a response information packet, and generate a response baseband signal in conjunction with the synchronization header pulse and send it to the response signal transmission module. Alternatively, based on the known transmission mode and information, the module performs RS coding and CRC check calculation to obtain the information pulse code, combines the inquiry pulse synchronization header spread spectrum code, and uses DPSK modulation to obtain the baseband signal and send it to the response signal transmission module. The relevant information includes a random ID number and a random response delay. The response signal transmission module is used to receive the second intermediate frequency signal after the frequency conversion processing by the second radio frequency transceiver component, and perform low-pass filtering and down-sampling on it to generate an inquiry baseband signal transmitted by the vehicle-mounted radar terminal and send it to the baseband signal generation module; It is also used to transmit the baseband signal generated by the baseband signal generating module to the second radio frequency component for transmission.

5. The secondary radar for rail transit applications according to claim 1, characterized in that: The first radio frequency transceiver component and the second radio frequency transceiver component each include a frequency conversion module, a first mixer, and a second mixer; The frequency conversion module is used to receive the interrogation baseband signal, filter and amplify it, and then send it to the first mixer and the second mixer in sequence, or process the down-converted signals output by the first mixer and the second mixer, and output them to the first digital signal processing module; The first mixer is used to generate a local oscillator signal and mix it with the information output by the frequency conversion module to output a fixed second intermediate frequency signal. If the mixing is up-conversion, it is output to the second mixer; otherwise, it is output to the digital signal processing module; The second mixer is used to mix the signal amplified by the response signal transmission module to output a radio frequency signal of a specified frequency band, or receive the response radio frequency signal and down-mix it to output a fixed first intermediate frequency signal to the first mixer for further down-conversion processing.

6. The secondary radar for rail transit applications according to claim 1, characterized in that: The first digital signal processing module further includes a ranging module; The ranging module is used to receive the ranging instructions sent by the train control system and forward them to the baseband signal generation module. At the same time, it receives the data sent by the response signal receiving module, obtains the propagation delay by generating a pseudocode sequence and calculating the cross-correlation, and calculates the distance between the on-board radar terminal and the trackside radar terminal.

7. The secondary radar for rail transit applications according to claim 6, characterized in that: The ranging module is specifically used for: When the vehicle-mounted radar terminal transmits a radio frequency signal, a timing pulse is triggered to start timing. When the response signal returned by the trackside radar terminal is received, the peak value is solved according to relevant calculations, and the timing pulse stops timing. The timing pulse can be used to measure the propagation delay from the vehicle-mounted radar terminal to the trackside radar terminal, thereby measuring the distance between the vehicle-mounted radar terminal and the trackside radar terminal. The radio frequency signal transmitted by the vehicle-mounted radar terminal is a signal modulated by a pseudo-random code with a known code.

8. The secondary radar for rail transit applications according to claim 5, characterized in that: The first digital signal processing module also includes a data transmission module; The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the train control system into multiple basic packets, and send them to the first digital signal processing module to generate baseband signals for transmission to the trackside radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the trackside radar terminal, and report them to the train control system.

9. The secondary radar for rail transit applications according to claim 5, characterized in that: The second digital signal processing module also includes a data transmission module; The data transmission module is used to disassemble the data transmission instructions and transmission data packets of the ground train control system into multiple basic packets, and send them to the second digital signal processing module to generate baseband signals, which are transmitted to the on-board radar terminal; at the same time, the received basic data packets are packaged according to the device ID to obtain the correct data frames sent by the on-board radar terminal, and report them to the ground train control system.

10. A secondary radar device ranging method for rail transit applications, applicable to the secondary radar for rail transit applications according to any one of claims 1 to 9, characterized in that: include: After receiving the control command from the train control system, the first digital signal processing module of the on-board radar terminal generates a baseband interrogation signal modulated by a known pseudo-random code and sends it to the first RF transceiver component. The first RF transceiver component performs digital-to-analog conversion, filtering, amplification, and mixing on the transmitted baseband digital signal to generate a final transmitted RF signal. At the same time, it receives the response RF signal from the trackside radar terminal, performs down-conversion processing, obtains a second intermediate frequency signal, and sends it to the first digital signal processing module. The second digital signal processing module performs baseband signal processing on the interrogation signal from the vehicle-mounted radar terminal and actively responds, and exchanges information with the ground train control system; the second RF component down-converts the interrogation RF signal transmitted by the vehicle-mounted radar terminal to obtain an intermediate frequency signal and sends it to the second digital signal processing module. At the same time, the baseband digital signal generated by the second digital signal processing module is subjected to digital-to-analog conversion, filtering, amplification, and mixing to generate the final transmitted RF signal; the baseband digital signal includes a ranging response signal and a digital transmission signal; The first digital signal processing module receives the response signal sent by the trackside radar terminal. After frequency conversion processing by the first RF transceiver component, the first digital signal processing module parses and generates a pseudo code sequence, calculates the cross-correlation, calculates the distance between the vehicle-mounted radar terminal and the trackside radar terminal, or parses the digital data frame and reports it.

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