Train anti-collision device and method based on secondary radar

Abstract

The invention discloses a train anti-collision device and method based on a secondary radar. The train anti-collision device is characterized in that an inquiry device of a vehicle-mounted secondary radar on an adjacent train is used for receiving a response signal transmitted by a response device of a trackside secondary radar, estimating first distance measurement and speed measurement information and reporting the first distance measurement and speed measurement information to a train control system; the inquiry device of the vehicle-mounted secondary radar on the tail of the front vehicle is used for receiving a response signal transmitted by the response device of the vehicle-mounted secondary radar on the rear vehicle, estimating second distance measurement and speed measurement information and reporting the second distance measurement and speed measurement information to the train control system; the inquiry device of the vehicle-mounted secondary radar on the head of the rear vehicle is used for receiving a response signal transmitted by the response device of the vehicle-mounted secondary radar on the tail of the front vehicle, estimating second distance measurement and speed measurement information and reporting the second distance measurement and speed measurement information to the train control system; and the train control system is used for performing anti-collision evaluation between adjacent trains according to the received first distance measurement and speed measurement information and the received second distance measurement and speed measurement information so as to realize train collision prevention. The technology is easy to implement, and the safety guarantee of the train is improved.

Description

Technical Field

[0001] The present application relates to the field of secondary radar technology, and in particular to a train collision avoidance device and method based on secondary radar. Background Art

[0002] Train collision avoidance radar is an effective means of ensuring railway operation safety and preventing train collisions. Existing literature 1 (Gao Feng. Framework of a Real-Time Positioning and Collision Avoidance Warning System for EMUs Based on EPLRS [J]. Mechatronics, 2016, June) uses GPS to obtain vehicle positioning information, determine the relative positions of vehicles, and thus achieve collision avoidance. Because GPS information acquisition requires high geographic location and terrain, this method is ineffective in complex interchange environments such as mountainous areas and tunnels. Literature 2 (Liu Feng; Zhou Yuxiang; Liu Haibo; Yang Xiaoqian, A Vehicle-Mounted Millimeter-Wave Train Collision Avoidance Radar System, CN201310099787.7) uses echo detection and parameter estimation from a primary radar system to obtain information such as target speed and distance. This method is easily affected by environmental clutter and has poor reliability. Literature 3 (Duan Zhiwen; Zheng Xiaokai, A Train Collision Warning Device, CN201920540223.5) uses a combination of collision avoidance radar and cameras for monitoring. This method is complex, costly, and difficult to calibrate and maintain. Summary of the Invention

[0003] In view of this, the present application provides a train collision avoidance device and method based on secondary radar, in which the secondary radar is installed on the trackside, at the head and tail of the train, and the purpose of train collision avoidance is achieved by query and response distance measurement and speed measurement, and then by fusing information of multiple speeds and distances.

[0004] The present application discloses a train collision avoidance device based on secondary radar, which includes a secondary radar system and a train control system; the secondary radar system includes an on-board secondary radar installed at the front of each train and an on-board secondary radar installed at the rear of each train, and a trackside secondary radar installed next to the track on which each train travels; the on-board secondary radar, the on-board secondary radar, the trackside secondary radar and the train control system communicate via a communication network;

[0005] The interrogation devices of the onboard secondary radars on adjacent trains are each configured to send an interrogation signal to the trackside secondary radar; the response devices of the trackside secondary radars are configured to receive the interrogation signal and generate a response signal therefrom and transmit the response signal to the interrogation devices of the onboard secondary radars on adjacent trains; the interrogation devices of the onboard secondary radars on adjacent trains are each configured to receive the response signal transmitted by the response devices of the trackside secondary radars and estimate first distance and speed measurement information and report the information to the train control system, the first distance and speed measurement information including the distance between the adjacent trains and the trackside secondary radars, and the speed of each of the adjacent trains;

[0006] the interrogation device of the on-board secondary radar on the rear of the leading vehicle in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the front of the following vehicle; the transponder of the on-board secondary radar on the front of the following vehicle is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the leading vehicle; the interrogation device of the on-board secondary radar on the rear of the leading vehicle is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the following vehicle and estimate second ranging and speed information and report the information to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each of the adjacent trains; or Alternatively, the interrogation device of the on-board secondary radar on the front of the rear car in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the rear of the front car; the transponder of the on-board secondary radar on the front of the rear car is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the front car; the interrogation device of the on-board secondary radar on the rear of the front car is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the rear car and estimate the second ranging and speed information and report it to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each train in the adjacent trains;

[0007] The train control system is used to perform collision avoidance assessment between adjacent trains based on the received first distance measurement and speed measurement information and the second distance measurement and speed measurement information to achieve train collision avoidance.

[0008] Furthermore, the vehicle-mounted secondary radar includes an interrogation device and a response device; the trackside secondary radar includes a response device; the response device of the vehicle-mounted secondary radar is the same as the response device of the trackside secondary radar.

[0009] Furthermore, the trackside secondary radar uses an omnidirectional antenna or a directional antenna whose radiation direction covers the direction of each train to adapt to vehicles coming from all directions;

[0010] Both the onboard secondary radar and the vehicle-mounted secondary radar use directional antennas, with the radiation direction being towards the outside of the train;

[0011] Trackside secondary radar only responds, while vehicle-mounted secondary radar and vehicle-mounted secondary radar both have inquiry and response functions.

[0012] Furthermore, the interrogation device includes an interrogation waveform generation module, a frequency synthesizer, an up-conversion module, a down-conversion module, an interrogation pulse detection and parameter estimation module, and a signal estimation module:

[0013] An interrogation waveform generating module, configured to generate an interrogation waveform consisting of a coherent pulse train;

[0014] A frequency synthesizer, configured to obtain a reference signal from an interrogation frequency source and generate a coherent interrogation frequency signal and a response frequency signal;

[0015] An up-conversion module, configured to up-convert the interrogation waveform generated by the interrogation waveform generation module into an interrogation signal using an interrogation frequency signal and transmit the interrogation signal;

[0016] After receiving the response signal, the down-conversion module is used to receive the response signal and down-convert the response signal into a response waveform using the response frequency signal; the interrogation pulse detection and parameter estimation module is used to estimate the phase and delay of each pulse in the response waveform one by one; the signal estimation module is used to estimate the distance based on the relative delay of the pulse in the response waveform relative to the pulse in the interrogation waveform, and estimate the speed based on the relative phase between the pulses in the response waveform, that is, to obtain a distance estimate at the moment of receiving each response pulse; and to obtain a speed estimate at the moment of receiving each response pulse starting from the second response pulse; the response pulse is the pulse in the response signal.

[0017] Furthermore, the response device includes:

[0018] A frequency synthesizer, configured to obtain a reference signal from a response frequency source and generate a coherent interrogation frequency signal and a response frequency signal;

[0019] A down-conversion module, configured to down-convert the interrogation signal sent by the interrogation device into an interrogation waveform using the interrogation frequency signal;

[0020] An interrogation pulse detection and parameter estimation module, used to estimate the pulse phase and delay in each interrogation waveform;

[0021] The response waveform generation module is used to calculate and set the response pulse phase and delay parameters according to the estimated phase and delay each time a set of phase and delay is received, and generate a response waveform; the response pulse is the pulse in the response signal;

[0022] The up-conversion module is used to use the response frequency signal to up-convert the response waveform into a response signal for transmission.

[0023] Furthermore, the response waveform generation module is used to calculate and generate the phase of the corresponding pulse of the response waveform based on the pulse phase of the interrogation waveform, and realize coherent response under the condition that the interrogation frequency source and the response frequency source are incoherent. At the same time, the response pulse corresponds to the interrogation pulse one-to-one, and the transmission is completed before the next interrogation pulse is received to ensure the real-time performance of the ranging and speed measurement functions.

[0024] Furthermore, during the train's movement, the interrogation device transmits an interrogation signal in a pseudo-periodic manner with randomness, measures distance and speed, and reports the result to the train control system. When the trackside secondary radar and the on-board secondary radar on the following vehicle transmit response signals, a random delay is added to reduce the probability of conflict in the response signals.

[0025] The present application also discloses a train collision avoidance method based on secondary radar, which is applicable to the above-mentioned train collision avoidance device based on secondary radar, and includes:

[0026] The interrogation device generates an interrogation waveform, and uses the interrogation frequency signal to up-convert the interrogation waveform into an interrogation signal and transmits the interrogation signal;

[0027] The answering device uses the interrogation frequency signal to down-convert the received interrogation signal into an interrogation waveform;

[0028] The interrogation pulse detection and parameter estimation module of the transponder estimates the phase and delay of the pulse in each interrogation waveform. Once a set of phase and delay parameters is obtained, the transponder waveform generation module calculates and sets the phase and delay of the reply pulse based on the estimated phase and delay, generates a reply waveform, and uses the reply frequency signal to up-convert the reply waveform into a reply signal for transmission. The reply pulse is the pulse in the reply signal.

[0029] The down-conversion module of the interrogation device down-converts the received response signal into a response waveform using the response frequency signal;

[0030] The interrogation pulse detection and parameter estimation module of the interrogation device estimates the phase and delay of the pulses one by one from the interrogation waveform;

[0031] The response pulse detection and parameter estimation module of the interrogation device estimates the distance based on the relative delay of the pulses in the response waveform relative to the pulses in the interrogation waveform, and estimates the speed based on the relative phase between the pulses in the response waveform. That is, the interrogation device obtains a distance estimate at the time of receiving each response pulse; and obtains a speed estimate at the time of receiving each response pulse starting from the second response pulse.

[0032] After each inquiry, the inquiry device reports the distance measurement information to the train control system; the train control system performs collision avoidance assessment between adjacent trains based on the distance measurement information, and uploads the collision avoidance assessment information to the train control system to achieve train collision avoidance; the distance measurement information includes the first distance measurement and speed measurement information and the second distance measurement and speed measurement information.

[0033] Furthermore, the response waveform generation module calculates and generates the phase of the corresponding pulse of the response waveform based on the pulse phase of the interrogation waveform, which can achieve a coherent response under the condition that the interrogation frequency source and the response frequency source are irrelevant. At the same time, the response pulse corresponds to the interrogation pulse one-to-one and can be transmitted before the next interrogation pulse is received, thereby ensuring the real-time performance of the ranging and speed measurement functions.

[0034] Furthermore, the phase calculation method of the response pulse includes:

[0035] Perform differential calculation on the phase of each interrogation pulse in the interrogation waveform, and assume that the estimated value of the current interrogation pulse phase is φ i, the estimated value of the previous interrogation pulse phase is φ i-1 , then the phase difference is Δφ=φ i -φ i-1 ;

[0036] Adjust the phase difference Δφ to the ±π main value range, expressed as

[0037] Adjust according to forwarding ratio Get the phase difference of the response signal The forwarding ratio k = f T / f I , f I is the interrogation frequency, f T is the response frequency;

[0038] Will Perform integral accumulation operation to obtain the phase of the current response pulse is the phase of the previous response pulse.

[0039] Due to the adoption of the above-mentioned technical solution, the present application has the following advantages: The present application proposes a train collision avoidance device and method based on secondary radar, which has simple technical implementation and obvious effect, improves train safety, can automatically adapt to all-weather and all-day needs, and provide train crews with reliable target information, effectively ensuring traffic safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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.

[0041] Figure 1 A schematic diagram of a train collision avoidance device based on secondary radar according to an embodiment of the present application;

[0042] Figure 2 A schematic diagram of the ranging principle of an embodiment of the present application;

[0043] Figure 3 Schematic diagram of the processing flow of the speed measurement response device according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] 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.

[0045] See also Figure 1 The present application provides an embodiment of a train collision avoidance device based on secondary radar, which includes a secondary radar system and a train control system; the secondary radar system includes an on-board secondary radar installed at the front of each train and an on-board secondary radar installed at the rear of each train, and a trackside secondary radar installed next to the track on which each train travels; the on-board secondary radar, the on-board secondary radar, the trackside secondary radar, and the train control system communicate via a communication network;

[0046] The interrogation devices of the onboard secondary radars on adjacent trains are each configured to send an interrogation signal to the trackside secondary radar; the response devices of the trackside secondary radars are configured to receive the interrogation signal and generate a response signal therefrom and transmit the response signal to the interrogation devices of the onboard secondary radars on adjacent trains; the interrogation devices of the onboard secondary radars on adjacent trains are each configured to receive the response signal transmitted by the response devices of the trackside secondary radars and estimate first distance and speed measurement information and report the information to the train control system, the first distance and speed measurement information including the distance between the adjacent trains and the trackside secondary radars, and the speed of each of the adjacent trains;

[0047] the interrogation device of the on-board secondary radar on the rear of the leading vehicle in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the front of the following vehicle; the transponder of the on-board secondary radar on the front of the following vehicle is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the leading vehicle; the interrogation device of the on-board secondary radar on the rear of the leading vehicle is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the following vehicle and estimate second ranging and speed information and report the information to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each of the adjacent trains; or Alternatively, the interrogation device of the on-board secondary radar on the front of the rear car in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the rear of the front car; the transponder of the on-board secondary radar on the front of the rear car is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the front car; the interrogation device of the on-board secondary radar on the rear of the front car is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the rear car and estimate the second ranging and speed information and report it to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each train in the adjacent trains;

[0048] The train control system is used to perform collision avoidance assessment between adjacent trains based on the received first distance measurement and speed measurement information and the second distance measurement and speed measurement information to achieve train collision avoidance.

[0049] Optionally, the structure of the vehicle-mounted secondary radar is the same as that of the vehicle-mounted secondary radar, and both include an interrogation device and a response device; the trackside secondary radar includes a response device; the response device of the vehicle-mounted secondary radar and the response device of the vehicle-mounted secondary radar are the same as the response device of the trackside secondary radar; the interrogation device of the vehicle-mounted secondary radar is the same as the interrogation device of the vehicle-mounted secondary radar.

[0050] Optionally, the trackside secondary radar uses an omnidirectional antenna or a directional antenna whose radiation direction covers the direction of each train, so as to adapt to oncoming trains from all directions;

[0051] Both the onboard secondary radar and the vehicle-mounted secondary radar use directional antennas, with the radiation direction being towards the outside of the train;

[0052] Trackside secondary radar only responds, while vehicle-mounted secondary radar and vehicle-mounted secondary radar both have inquiry and response functions.

[0053] Optionally, the interrogation device includes an interrogation waveform generation module, a frequency synthesizer, an up-conversion module, a down-conversion module, an interrogation pulse detection and parameter estimation module, and a signal estimation module:

[0054] An interrogation waveform generating module, configured to generate an interrogation waveform consisting of a coherent pulse train;

[0055] A frequency synthesizer, configured to obtain a reference signal from an interrogation frequency source and generate a coherent interrogation frequency signal and a response frequency signal;

[0056] An up-conversion module, configured to up-convert the interrogation waveform generated by the interrogation waveform generation module into an interrogation signal using an interrogation frequency signal and transmit the interrogation signal;

[0057] After receiving the response signal, the down-conversion module is used to receive the response signal and down-convert the response signal into a response waveform using the response frequency signal; the interrogation pulse detection and parameter estimation module is used to estimate the phase and delay of each pulse from the response waveform; the signal estimation module is used to estimate the distance based on the relative delay of the pulses in the response waveform relative to the pulses in the interrogation waveform, and to estimate the speed based on the relative phase between the pulses in the response waveform, that is, to obtain a distance estimate at the time of receiving each response pulse; and to obtain a speed estimate at the time of receiving each response pulse starting from the second response pulse; the response pulse is the pulse in the response signal. Figure 2Ranging Principle: This uses interrogation-response ranging. Specifically, the interrogator transmits a pseudo-randomly modulated signal with a known code, simultaneously triggering a timing pulse to start timing. The responder generates a local pseudo-random code sequence identical to the pseudo-random code transmitted by the interrogator. At the responder receiver, the correlation peak is calculated by cross-correlating the local code with the received code, triggering the responder to transmit a response signal. The interrogator then generates a pseudo-random code sequence identical to the pseudo-random code of the reply signal transmitted by the responder. The cross-correlation between the two is calculated, and the timing pulse is stopped when the cross-correlation peaks. The timing pulses are used to measure the propagation time ΔT from the interrogator to the responder, thereby measuring the distance between the interrogator and the responder.

[0058] Optionally, the response device includes:

[0059] A frequency synthesizer, configured to obtain a reference signal from a response frequency source and generate a coherent interrogation frequency signal and a response frequency signal;

[0060] A down-conversion module, configured to down-convert the interrogation signal sent by the interrogation device into an interrogation waveform using the interrogation frequency signal;

[0061] An interrogation pulse detection and parameter estimation module, used to estimate the pulse phase and delay in each interrogation waveform;

[0062] The response waveform generation module is used to calculate and set the response pulse phase and delay parameters according to the estimated phase and delay each time a set of phase and delay is received, and generate a response waveform; the response pulse is the pulse in the response signal;

[0063] The up-conversion module is used to use the response frequency signal to up-convert the response waveform into a response signal for transmission.

[0064] Optionally, the response waveform generation module is used to calculate and generate the phase of the corresponding pulse of the response waveform based on the pulse phase of the inquiry waveform, and realize coherent response under the condition that the inquiry frequency source and the response frequency source are incoherent. At the same time, the response pulse corresponds to the inquiry pulse one-to-one, and the transmission is completed before the next inquiry pulse is received to ensure the real-time performance of the ranging and speed measurement functions.

[0065] Optionally, during the movement of the train, the interrogation device transmits an interrogation signal in a pseudo-periodic manner with randomness, measures the distance and speed, and reports the result to the train control system; when the trackside secondary radar and the on-board secondary radar on the following vehicle transmit the response signal, a random delay is added to reduce the probability of conflict in the response signal.

[0066] The present application also discloses an embodiment of a train collision avoidance method based on secondary radar, which is applicable to the train collision avoidance device based on secondary radar described in the above embodiment, and includes:

[0067] The interrogation device generates an interrogation waveform, and uses the interrogation frequency signal to up-convert the interrogation waveform into an interrogation signal and transmits the interrogation signal;

[0068] The answering device uses the interrogation frequency signal to down-convert the received interrogation signal into an interrogation waveform;

[0069] The interrogation pulse detection and parameter estimation module of the transponder estimates the phase and delay of the pulse in each interrogation waveform. Once a set of phase and delay parameters is obtained, the transponder waveform generation module calculates and sets the phase and delay of the reply pulse based on the estimated phase and delay, generates a reply waveform, and uses the reply frequency signal to up-convert the reply waveform into a reply signal for transmission. The reply pulse is the pulse in the reply signal.

[0070] The down-conversion module of the interrogation device down-converts the received response signal into a response waveform using the response frequency signal;

[0071] The interrogation pulse detection and parameter estimation module of the interrogation device estimates the phase and delay of the pulses one by one from the interrogation waveform;

[0072] The response pulse detection and parameter estimation module of the interrogation device estimates the distance based on the relative delay of the pulses in the response waveform relative to the pulses in the interrogation waveform, and estimates the speed based on the relative phase between the pulses in the response waveform. That is, the interrogation device obtains a distance estimate at the time of receiving each response pulse; and obtains a speed estimate at the time of receiving each response pulse starting from the second response pulse.

[0073] After each inquiry, the inquiry device reports the distance measurement information to the train control system; the train control system performs collision avoidance assessment between adjacent trains based on the distance measurement information, and uploads the collision avoidance assessment information to the train control system to achieve train collision avoidance; the distance measurement information includes the first distance measurement and speed measurement information and the second distance measurement and speed measurement information.

[0074] Optionally, the response waveform generation module calculates and generates the phase of the corresponding pulse of the response waveform based on the pulse phase of the inquiry waveform, and can achieve coherent response under the condition that the inquiry frequency source and the response frequency source are irrelevant. At the same time, the response pulse corresponds to the inquiry pulse one-to-one, and the transmission can be completed before the next inquiry pulse is received, so as to ensure the real-time performance of the ranging and speed measurement functions.

[0075] Alternatively, see Figure 3 , the phase calculation method of the response pulse includes:

[0076] Perform differential calculation on the phase of each interrogation pulse in the interrogation waveform, and assume that the estimated value of the current interrogation pulse phase is φ i , the estimated value of the previous interrogation pulse phase is φ i-1 , then the phase difference is Δφ=φ i -φi-1 ;

[0077] Adjust the phase difference Δφ to the ±π main value range, expressed as

[0078] Adjust according to forwarding ratio Get the phase difference of the response signal The forwarding ratio k = f T / f I , f I is the interrogation frequency, f T is the response frequency;

[0079] Will Perform integral accumulation operation to obtain the phase of the current response pulse is the phase of the previous response pulse.

[0080] 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 train collision avoidance device based on secondary radar, characterized in that: It includes a secondary radar system and a train control system; the secondary radar system includes an on-board secondary radar installed at the front of each train, an on-board secondary radar installed at the rear of each train, and a trackside secondary radar installed next to the track on which each train travels; The vehicle-mounted secondary radar, vehicle-mounted secondary radar, trackside secondary radar and train control system communicate through the communication network; The interrogation devices of the onboard secondary radars on adjacent trains are each configured to send an interrogation signal to the trackside secondary radar; the response devices of the trackside secondary radars are configured to receive the interrogation signal and generate a response signal therefrom and transmit the response signal to the interrogation devices of the onboard secondary radars on adjacent trains; the interrogation devices of the onboard secondary radars on adjacent trains are each configured to receive the response signal transmitted by the response devices of the trackside secondary radars and estimate first distance and speed measurement information and report the information to the train control system, the first distance and speed measurement information including the distance between the adjacent trains and the trackside secondary radars, and the speed of each of the adjacent trains; the interrogation device of the on-board secondary radar on the rear of the leading vehicle in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the front of the following vehicle; the transponder of the on-board secondary radar on the front of the following vehicle is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the leading vehicle; the interrogation device of the on-board secondary radar on the rear of the leading vehicle is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the following vehicle and estimate second ranging and speed information and report the information to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each of the adjacent trains; or Alternatively, the interrogation device of the on-board secondary radar on the front of the rear car in the adjacent trains is used to send an interrogation signal to the transponder of the on-board secondary radar on the rear of the front car; the transponder of the on-board secondary radar on the front of the rear car is used to receive the interrogation signal and generate a reply signal therefrom and transmit the reply signal to the interrogation device of the on-board secondary radar on the rear of the front car; the interrogation device of the on-board secondary radar on the rear of the front car is used to receive the reply signal transmitted by the transponder of the on-board secondary radar on the front of the rear car and estimate the second ranging and speed information and report it to the train control system, the second ranging and speed information including the distance between the adjacent trains and the speed of each train in the adjacent trains; The train control system is used to perform collision avoidance assessment between adjacent trains based on the received first distance measurement and speed measurement information and the second distance measurement and speed measurement information to achieve train collision avoidance.

2. The train collision avoidance device based on secondary radar according to claim 1, characterized in that: The vehicle-mounted secondary radar includes an interrogation device and a response device; the trackside secondary radar includes a response device; the response device of the vehicle-mounted secondary radar is the same as the response device of the trackside secondary radar.

3. The train collision avoidance device based on secondary radar according to claim 1, characterized in that: Trackside secondary radar uses omnidirectional antennas or directional antennas whose radiation direction covers the direction of all trains to adapt to vehicles coming from all directions; Both the onboard secondary radar and the vehicle-mounted secondary radar use directional antennas, with the radiation direction being towards the outside of the train; Trackside secondary radar only responds, while vehicle-mounted secondary radar and vehicle-mounted secondary radar both have inquiry and response functions.

4. The train collision avoidance device based on secondary radar according to claim 1, characterized in that: The interrogation device includes an interrogation waveform generation module, a frequency synthesizer, an up-conversion module, a down-conversion module, an interrogation pulse detection and parameter estimation module, and a signal estimation module. An interrogation waveform generating module, configured to generate an interrogation waveform consisting of a coherent pulse train; A frequency synthesizer, configured to obtain a reference signal from an interrogation frequency source and generate a coherent interrogation frequency signal and a response frequency signal; An up-conversion module, configured to up-convert the interrogation waveform generated by the interrogation waveform generation module into an interrogation signal using an interrogation frequency signal and transmit the interrogation signal; After receiving the response signal, the down-conversion module is used to receive the response signal and down-convert the response signal into a response waveform using the response frequency signal; An inquiry pulse detection and parameter estimation module is used to estimate the phase and delay of each pulse from the response waveform; a signal estimation module for estimating distance based on the relative time delay of pulses in the reply waveform relative to the pulses in the interrogation waveform, and estimating velocity based on the relative phase between pulses in the reply waveform, i.e., obtaining a distance estimate at the moment each reply pulse is received; obtaining a velocity estimate at the time of each reply pulse starting with the receipt of the second reply pulse; The acknowledge pulse is a pulse in the acknowledge signal.

5. The train collision avoidance device based on secondary radar according to claim 1, characterized in that: The response device comprises: A frequency synthesizer, configured to obtain a reference signal from a response frequency source and generate a coherent interrogation frequency signal and a response frequency signal; A down-conversion module, configured to down-convert the interrogation signal sent by the interrogation device into an interrogation waveform using the interrogation frequency signal; An interrogation pulse detection and parameter estimation module, used to estimate the pulse phase and delay in each interrogation waveform; The response waveform generation module is used to calculate and set the response pulse phase and delay parameters according to the estimated phase and delay each time a set of phase and delay is received, and generate a response waveform; the response pulse is the pulse in the response signal; The up-conversion module is used to use the response frequency signal to up-convert the response waveform into a response signal for transmission.

6. The train collision avoidance device based on secondary radar according to claim 5, characterized in that: The response waveform generation module is used to calculate and generate the phase of the corresponding pulse of the response waveform based on the pulse phase of the interrogation waveform, and realize a coherent response under the condition that the interrogation frequency source and the response frequency source are irrelevant. At the same time, the response pulse corresponds to the interrogation pulse one-to-one and is completed before the next interrogation pulse is received to ensure the real-time performance of the ranging and speed measurement functions.

7. The train collision avoidance device based on secondary radar according to claim 1, characterized in that: During the train's movement, the interrogation device transmits interrogation signals at a pseudo-periodic interval with randomness, measures distance and speed, and reports the results to the train control system. When the trackside secondary radar and the onboard secondary radar on the following train transmit reply signals, a random delay is added to reduce the probability of conflict between reply signals.

8. A train collision avoidance method based on secondary radar, applicable to the train collision avoidance device based on secondary radar according to any one of claims 1 to 7, characterized in that: include: The interrogation device generates an interrogation waveform, and uses the interrogation frequency signal to up-convert the interrogation waveform into an interrogation signal and transmits the interrogation signal; The answering device uses the interrogation frequency signal to down-convert the received interrogation signal into an interrogation waveform; The interrogation pulse detection and parameter estimation module of the transponder estimates the phase and delay of the pulses in each interrogation waveform. Once a set of phase and delay parameters is obtained, the transponder's response waveform generation module calculates and sets the phase and delay of the response pulse based on the estimated phase and delay, generates a response waveform, and uses the response frequency signal to up-convert the response waveform into a response signal for transmission. The response pulse is the pulse in the response signal; The down-conversion module of the interrogation device down-converts the received response signal into a response waveform using the response frequency signal; The interrogation pulse detection and parameter estimation module of the interrogation device estimates the phase and delay of the pulses one by one from the interrogation waveform; The response pulse detection and parameter estimation module of the interrogation device estimates the distance based on the relative delay of the pulses in the response waveform relative to the pulses in the interrogation waveform, and estimates the speed based on the relative phase between the pulses in the response waveform. That is, the interrogation device obtains a distance estimate at the moment of receiving each response pulse; obtaining a velocity estimate at the time of each reply pulse starting with the receipt of the second reply pulse; After each inquiry, the inquiry device reports the distance measurement information to the train control system; the train control system performs collision avoidance assessment between adjacent trains based on the distance measurement information, and uploads the collision avoidance assessment information to the train control system to achieve train collision avoidance; the distance measurement information includes the first distance measurement and speed measurement information and the second distance measurement and speed measurement information.

9. The train collision avoidance method based on secondary radar according to claim 8, characterized in that: The response waveform generation module calculates and generates the phase of the corresponding pulse of the response waveform based on the pulse phase of the interrogation waveform. It can achieve coherent response under the condition that the interrogation frequency source and the response frequency source are irrelevant. At the same time, the response pulse corresponds to the interrogation pulse one-to-one and can be completed before the next interrogation pulse is received, thereby ensuring the real-time performance of the ranging and speed measurement functions.

10. The train collision avoidance method based on secondary radar according to claim 8 or 9, characterized in that: The phase calculation method of the response pulse includes: Perform differential calculation on the phase of each interrogation pulse in the interrogation waveform, and assume that the estimated value of the current interrogation pulse phase is φ i , the estimated value of the previous interrogation pulse phase is φ i-1 , then the phase difference is Δφ=φ i -φ i-1 ; Adjust the phase difference Δφ to the ±π main value range, expressed as Adjust according to forwarding ratio Get the phase difference of the response signal The forwarding ratio k = f T / f I , f I is the interrogation frequency, f T is the response frequency; Will Perform integral accumulation operation to obtain the phase of the current response pulse is the phase of the previous response pulse.

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