Metro vehicle-to-ground communication detection device

Abstract

This subway vehicle-to-ground communication detection device, belonging to the field of communications, includes a microcontroller unit; a pilot signal generator connected to the microcontroller unit; a signal modulation and transmission circuit connected to the pilot signal generator; a demodulation and filtering circuit connected to the signal modulation and transmission circuit; a signal strength detection circuit and a pulse conversion detection circuit connected to the demodulation and filtering circuit, respectively; a logic decision circuit connected to the signal strength detection circuit and the pulse conversion detection circuit; and a drive circuit connected to the logic decision circuit. The core idea of ​​this invention is to detect the link quality of the main service channel through an independent, dedicated pilot channel, thereby achieving fast and reliable fault diagnosis and channel switching. It features high reliability and independence, high real-time performance, rapid response, comprehensive diagnostic functions, strong anti-interference capability, ingenious design, and low cost.

Description

Technical Field

[0001] This utility model belongs to the field of communication technology, specifically relating to a detection device for subway vehicle-to-ground communication. Background Technology

[0002] The detection device for subway vehicle-to-ground communication is crucial for ensuring the safe and efficient operation of the subway. Currently, existing subway vehicle-to-ground communication detection devices mainly suffer from the following technical problems:

[0003] 1. Traditional detection methods may rely on parsing business data packets (such as heartbeat packets), which can be affected by factors such as network congestion, data priority, and processor load, resulting in false alarms and low reliability.

[0004] 2. Traditional detection methods mostly rely on software, and their response speed is limited by network parameters, resulting in weak real-time performance and slow response, making them unsuitable for high-speed moving subway scenarios.

[0005] 3. Traditional detection methods are limited by factors such as link noise, which prevents them from effectively extracting the backbone signal, resulting in poor detection performance and a need to improve anti-interference capabilities.

[0006] In summary, providing a detection device for subway vehicle-to-ground communication that features high reliability and independence, high real-time performance, rapid response, comprehensive diagnostic functions, strong anti-interference ability, ingenious design, and low cost is of great practical significance for the safe and efficient operation of subways. Utility Model Content

[0007] In order to solve the problems existing in the prior art, this utility model provides a detection device for subway vehicle-to-ground communication.

[0008] The technical solution adopted by this utility model to solve the technical problem is as follows:

[0009] The present invention provides a detection device for subway vehicle-to-ground communication, comprising: a microcontroller unit;

[0010] Pilot signal generator connected to the microcontroller unit;

[0011] A signal modulation and transmission circuit connected to a pilot signal generator;

[0012] Demodulation and filtering circuit connected to the signal modulation and transmission circuit;

[0013] The signal strength detection circuit and pulse conversion detection circuit are respectively connected to the demodulation and filtering circuit;

[0014] A logic decision circuit connected to the signal strength detection circuit and the pulse conversion detection circuit;

[0015] A drive circuit connected to a logic decision circuit.

[0016] Furthermore, the pilot signal generator includes: a quartz crystal, an inverter, a first resistor, and a first capacitor; the two ends of the quartz crystal are respectively connected to the input and output terminals of the inverter, the first capacitor is connected to the input terminal of the inverter, and the first resistor is connected to the output terminal of the inverter.

[0017] Furthermore, the signal modulation and transmission circuit includes: a directional coupler, a second resistor, a second capacitor, a third capacitor, and a fourth capacitor; the two ends of the directional coupler are respectively connected to the two ends of the quartz crystal through the second capacitor and the third capacitor, the output end of the directional coupler is connected to the second resistor, and the fourth capacitor is connected in parallel across the two ends of the second resistor.

[0018] Furthermore, the demodulation filtering circuit includes: an LC bandpass filter, a third resistor, a fourth resistor, a fifth resistor, and a fifth capacitor; the LC bandpass filter is connected to the signal modulation and transmission circuit through the third resistor, and the output terminal of the LC bandpass filter is connected to the signal strength detection circuit through the fifth capacitor and the fifth resistor; one end of the fourth resistor is connected to the LC bandpass filter, and the other end is connected to the connection point of the fifth capacitor and the fifth resistor.

[0019] Furthermore, the signal strength detection circuit includes: a first operational amplifier, a first voltage comparator, a sliding rheostat, a diode, a second operational amplifier, and a sixth capacitor; the first operational amplifier is connected to the demodulation filter circuit, the input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier, the output terminal of the second operational amplifier is connected to the diode, the sixth capacitor is connected in parallel across the diode, the input terminal of the first voltage comparator is connected to the diode, and the output terminal of the first voltage comparator is connected to the sliding rheostat.

[0020] Furthermore, the pulse conversion detection circuit includes: a second voltage comparator, a 555 timer, a sixth resistor, a seventh resistor, a seventh capacitor, an eighth capacitor, and a ninth capacitor; the input terminal of the second voltage comparator is connected to the demodulation filter circuit, the input terminal of the 555 timer is connected to the output terminal of the second voltage comparator, the second voltage comparator is also connected to the sixth resistor and the seventh resistor respectively, the eighth capacitor is connected in parallel across the sixth resistor, the ninth capacitor is connected in parallel across the seventh resistor, and the seventh capacitor is connected in parallel across the 555 timer.

[0021] Furthermore, the logic decision circuit includes an AND gate circuit.

[0022] Furthermore, the driving circuit includes: a transistor, a relay, a fault indicator light, an eighth resistor, a ninth resistor, a tenth capacitor, and an eleventh capacitor; the input terminal of the transistor is connected to the output terminal of the logic decision circuit, the input terminal of the relay is connected to the output terminal of the transistor, the output terminal of the relay is connected to the fault indicator light, the eighth resistor and the tenth capacitor are connected in parallel to the two ends of the transistor, the eleventh capacitor is connected in parallel to the two ends of the relay, and the ninth resistor is connected in parallel to the two ends of the fault indicator light.

[0023] Furthermore, the fault indicator light uses a red LED.

[0024] Furthermore, the microcontroller unit, pilot signal generator, and signal modulation and transmission circuit are all located at the ground end; the demodulation and filtering circuit, signal strength detection circuit, pulse conversion and detection circuit, logic decision circuit, and drive circuit are all located at the vehicle end.

[0025] The beneficial effects of this utility model are:

[0026] This utility model provides a detection device for subway vehicle-to-ground communication. Its core idea is to detect the link quality of the main service channel through an independent, dedicated pilot channel, thereby achieving fast and reliable fault diagnosis and channel switching. Its advantages are mainly reflected in the following aspects:

[0027] 1. High reliability and independence;

[0028] This invention employs a dedicated pilot signal at a fixed frequency, completely independent of upper-layer service data. As long as the physical link is unobstructed, the pilot signal can pass through, thus providing the most direct and accurate monitoring of the physical layer and the underlying RF link, resulting in extremely high reliability.

[0029] 2. High real-time performance and rapid response;

[0030] In this invention, signal strength detection (voltage comparator), signal presence detection (monostable circuit), and logic decision (AND gate) are all performed by dedicated hardware circuits. From fault detection to switching, no software intervention is required; the entire process is implemented in hardware, with a response speed in the range of microseconds (μs) to milliseconds (ms). This avoids processing delays and operating system scheduling overhead, enabling instantaneous detection and response to link interruptions, which is crucial for high-speed subway scenarios.

[0031] 3. Comprehensive diagnostic functions (capable of judging both "presence / absence" and "strength / weakness");

[0032] This invention not only detects link interruption (signal presence or absence) but also determines link quality degradation (signal strength). Specifically, the pulse conversion detection circuit determines "presence or absence." It considers any pilot signal of any strength as "present," but cannot distinguish between very strong and very weak signals. The signal strength detection circuit determines "strength or weakness." By comparing with an adjustable reference voltage, it ensures the signal strength is above the system's minimum threshold. The logic decision circuit (AND gate) combines the two, determining the link is normal only when the signal is both "present" and "sufficiently strong." This effectively avoids communication quality degradation caused by excessive signal attenuation (not completely interrupted but unable to communicate reliably), achieving deep diagnostics from "connectivity" to "availability."

[0033] 4. Strong anti-interference ability;

[0034] This invention can accurately extract weak pilot signals from complex radio frequency environments. Pilot signal selection: A low-frequency signal of 1MHz is used as the pilot, which is easy to generate and filter, and has high frequency separation from the service radio frequency signal (usually in the GHz band); the narrow bandwidth characteristics of the high-Q bandpass filter can effectively suppress out-of-band noise and the strong service signal itself, allowing only the 1MHz pilot signal to pass through, resulting in a high signal-to-noise ratio; Modulation and coupling design: The pilot signal is coupled to the main radio frequency path through a directional coupler, with minimal impact on the main signal.

[0035] 5. Ingenious design and controllable cost;

[0036] This invention uses mature, universal, low-cost analog and digital integrated circuit components (such as operational amplifiers, voltage comparators, 555 timers, basic logic gates, and crystal oscillators) instead of expensive dedicated chips or high-performance processors.

[0037] The core of this invention lies in its circuit design concept rather than expensive components. For example, a high-Q LC filter is used to accurately extract the pilot signal, a peak detector is used to convert the signal strength, and a 555 monostable circuit is used to determine the presence of the signal. This design effectively controls hardware costs and BOM (Bill of Materials) complexity while ensuring high performance. Attached Figure Description

[0038] Figure 1 This utility model provides a structural block diagram of a detection device for subway vehicle-to-ground communication.

[0039] Figure 2 The present invention provides a circuit diagram of a detection device for subway vehicle-to-ground communication.

[0040] In the diagram, there is a pilot signal generator (1), a signal modulation and transmission circuit (2), a demodulation and filtering circuit (3), a signal strength detection circuit (4), a pulse conversion and detection circuit (5), a logic decision circuit (6), a drive circuit (7), and a microcontroller unit (8). Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings.

[0042] This utility model provides a detection device for subway vehicle-to-ground communication. As a subsystem of the vehicle-to-ground communication system, it can be integrated into the on-board unit (OBU), ground access point (AP), or base station. It is mainly divided into a ground end and an on-board end, which work together. Its core function is to send a pilot signal of a fixed frequency through the ground end, and the on-board end receives the pilot signal and outputs a feedback signal. The ground end determines the link status by judging the presence and strength of the feedback signal.

[0043] like Figure 1 and Figure 2 As shown, the detection device for subway vehicle-to-ground communication provided by this utility model mainly includes: a pilot signal generator 1, a signal modulation and transmission circuit 2, a demodulation and filtering circuit 3, a signal strength detection circuit 4, a pulse conversion and detection circuit 5, a logic decision circuit 6, a driving circuit 7, and a microcontroller unit 8.

[0044] Among them, the microcontroller unit 8, pilot signal generator 1, and signal modulation and transmission circuit 2 are all located at the ground end, while the demodulation and filtering circuit 3, signal strength detection circuit 4, pulse conversion and detection circuit 5, logic decision circuit 6, and drive circuit 7 are all located at the vehicle end.

[0045] According to this utility model, the microcontroller unit 8 is connected to the pilot signal generator 1, and the microcontroller unit (MCU) 8 sends control signals to the pilot signal generator 1 to control the pilot signal generator 1 to work.

[0046] Specifically, the pilot signal generator 1 is located at the ground end and is used to generate a stable sine wave or square wave signal (pure, unmodulated continuous wave (CW) signal) with a fixed frequency (e.g., 1MHz) and constant amplitude as a pilot signal.

[0047] Preferably, the pilot signal generator 1 can be implemented using a crystal oscillator, specifically consisting of a quartz crystal 101, an inverter 102, a first resistor R1, and a first capacitor C1. The two ends of the quartz crystal 101 are respectively connected to the input and output terminals of the inverter 102, the first capacitor C1 is connected to the input terminal of the inverter 102, and the first resistor R1 is connected to the output terminal of the inverter 102. The pilot signal generator 1 can make the frequency of the output pilot signal most stable.

[0048] Specifically, the signal modulation and transmission circuit 2 is located at the ground end and is connected to the pilot signal generator 1 to couple the pilot signal output by the pilot signal generator 1 into the main radio frequency path.

[0049] Preferably, the signal modulation transmitting circuit 2 mainly comprises: a directional coupler 201, a second resistor R2, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The two ends of the directional coupler 201 are connected to the two ends of the quartz crystal 101 through the second capacitor C2 and the third capacitor C3, respectively. The output end of the directional coupler 201 is connected to the second resistor R2, and the fourth capacitor C4 is connected in parallel across the second resistor R2.

[0050] Specifically, the demodulation filter circuit 3 is located at the vehicle-mounted end and is connected to the signal modulation and transmission circuit 2. It is used to extract the pilot signal from the complex radio frequency signal with extremely high efficiency and filter out the service signal and other noise.

[0051] Preferably, the demodulation filter circuit 3 mainly includes: a high-Q LC bandpass filter 301, whose center frequency precisely matches the pilot frequency (1MHz), and also includes: a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a fifth capacitor C5. The LC bandpass filter 301 is connected to the signal modulation and transmission circuit 2 through the third resistor R3, and the output terminal of the LC bandpass filter 301 is connected to the signal strength detection circuit 4 through the fifth capacitor C5 and the fifth resistor R5. One end of the fourth resistor R4 is connected to the LC bandpass filter 301, and the other end is connected to the connection point of the fifth capacitor C5 and the fifth resistor R5.

[0052] Specifically, the signal strength detection circuit 4 is located on the vehicle side and is connected to the demodulation and filtering circuit 3. It is used to detect whether the amplitude of the extracted pilot signal meets the system setting requirements.

[0053] Preferably, the signal strength detection circuit 4 mainly includes: a first operational amplifier 401, a peak detector, a first voltage comparator 403, and a sliding rheostat PR1; the peak detector mainly consists of a diode Q1, a second operational amplifier 402, and a sixth capacitor C6; the first operational amplifier 401 is connected to the demodulation filter circuit 3, the input terminal of the second operational amplifier 402 is connected to the output terminal of the first operational amplifier 401, the output terminal of the second operational amplifier 402 is connected to the diode Q1, the sixth capacitor C6 is connected in parallel across the diode Q1, the input terminal of the first voltage comparator 403 is connected to the diode Q1, and the output terminal of the first voltage comparator 403 is connected to the sliding rheostat PR1. First, the filtered pilot signal is amplified by the fixed-gain first operational amplifier 401, then the AC signal is converted into a stable DC voltage (its value equal to the AC peak value) by the precision peak detector, and finally, the DC voltage output by the peak detector is sent to the non-inverting input terminal of the first voltage comparator 403, while a reference voltage V is set at the inverting input terminal of the first voltage comparator 403. ref The reference voltage V ref Adjusted by the sliding rheostat PR1, this represents the minimum threshold at which the pilot signal strength voltage meets the system's set requirements; when the pilot signal strength voltage is greater than the reference voltage V... ref When the pilot signal amplitude meets the system setting requirements, the first voltage comparator 403 outputs a high level; conversely, when the pilot signal amplitude does not meet the system setting requirements, the first voltage comparator 403 outputs a low level.

[0054] Specifically, the pulse conversion detection circuit 5 is located on the vehicle side and is connected to the demodulation filter circuit 3. It is used to detect whether the extracted pilot signal exists, regardless of its strength.

[0055] Preferably, the pulse conversion detection circuit 5 mainly includes: a second voltage comparator 501 and a monostable circuit; the monostable circuit mainly consists of a 555 timer 502, a sixth resistor R6, a seventh resistor R7, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9; the input terminal of the second voltage comparator 501 is connected to the demodulation filter circuit 3, the input terminal of the 555 timer 502 is connected to the output terminal of the second voltage comparator 501, the second voltage comparator 501 is also connected to the sixth resistor R6 and the seventh resistor R7 respectively, the eighth capacitor C8 is connected in parallel across the sixth resistor R6, the ninth capacitor C9 is connected in parallel across the seventh resistor R7, and the seventh capacitor C7 is connected in parallel across the 555 timer 502. The second voltage comparator 501 is mainly used for zero-crossing comparison / shaping. First, the filtered pilot signal is converted into a square wave pulse of the same frequency by the second voltage comparator 501. The reference voltage is set to 0V or a very small value. The trigger terminal of the 555 timer 502 is connected to the square wave pulse. As long as the square wave pulse exists, the monostable circuit will be continuously triggered to maintain a high output level, indicating that the pilot signal exists. Once the square wave pulse disappears, the monostable circuit will output a low level after timeout, indicating that the pilot signal is lost.

[0056] Specifically, the logic decision circuit 6 is located at the vehicle end. The logic decision circuit 6 is connected to the signal strength detection circuit 4 and the pulse conversion detection circuit 5 respectively. It is used to analyze and judge the pilot signal strength and the presence of the pilot signal, and make a final decision (whether the vehicle-to-ground communication link is normal or faulty).

[0057] Preferably, the logic decision circuit 6 mainly includes an AND gate circuit 601. First, the output of the signal strength detection circuit 4 (high level indicates the pilot signal amplitude meets the system setting requirements; low level indicates the pilot signal amplitude does not meet the system setting requirements) and the output of the pulse conversion detection circuit 5 (high level indicates the pilot signal exists; low level indicates the pilot signal is lost) are simultaneously connected to the AND gate circuit 601. Only when both conditions (the pilot signal exists and the pilot signal amplitude meets the system setting requirements) are met will the output of the AND gate circuit 601 be high, indicating that the vehicle-to-ground communication link is normal. If either condition is not met (e.g., the pilot signal does not exist, the pilot signal exists but the pilot signal amplitude does not meet the system setting requirements, or the pilot signal does not exist and the pilot signal amplitude does not meet the system setting requirements), the output of the AND gate circuit 601 will become low, indicating a vehicle-to-ground communication link fault.

[0058] Specifically, the drive circuit 7 is located on the vehicle side and is connected to the logic decision circuit 6. At the same time, the drive circuit 7 is also connected to the main communication channel and the backup communication channel in the vehicle-to-ground communication system, respectively, for driving alarms and switching communication channels.

[0059] Preferably, the driving circuit 7 mainly includes: a transistor 701, a relay 702, a fault indicator light 703, an eighth resistor R8, a ninth resistor R9, a tenth capacitor C10, and an eleventh capacitor C11; the input terminal of transistor 701 is connected to the output terminal of AND gate circuit 601, the input terminal of relay 702 is connected to the output terminal of transistor 701, the output terminal of relay 702 is connected to fault indicator light 703, the eighth resistor R8 and the tenth capacitor C10 are connected in parallel to the two ends of transistor 701, the eleventh capacitor C11 is connected in parallel to the two ends of relay 702, and the ninth resistor R9 is connected in parallel to the two ends of fault indicator light 703. Transistor 701 drives relay 702. When AND gate 601 outputs a high level, it indicates that the vehicle-to-ground communication link is normal. Transistor 701 conducts and drives relay 702 to engage, enabling the primary communication channel in the vehicle-to-ground communication system. When AND gate 601 outputs a low level, it indicates that the vehicle-to-ground communication link is faulty. Transistor 701 does not conduct, relay 702 is released, and the system automatically switches to the backup communication channel in the vehicle-to-ground communication system. At the same time, it drives fault indicator 703 to light up. Fault indicator 703 can be implemented using a red LED.

[0060] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this utility model and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this utility model.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A detection device for metro train-ground communication, comprising: The microcontroller unit is characterized by further comprising: Pilot signal generator connected to the microcontroller unit; A signal modulation and transmission circuit connected to a pilot signal generator; Demodulation and filtering circuit connected to the signal modulation and transmission circuit; The signal strength detection circuit and pulse conversion detection circuit are respectively connected to the demodulation and filtering circuit; A logic decision circuit connected to the signal strength detection circuit and the pulse conversion detection circuit; A drive circuit connected to a logic decision circuit.

2. The detection device for subway train-ground communication according to claim 1, characterized by The pilot signal generator includes: a quartz crystal, an inverter, a first resistor, and a first capacitor; the two ends of the quartz crystal are respectively connected to the input and output terminals of the inverter, the first capacitor is connected to the input terminal of the inverter, and the first resistor is connected to the output terminal of the inverter.

3. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The signal modulation and transmission circuit includes: a directional coupler, a second resistor, a second capacitor, a third capacitor, and a fourth capacitor; the two ends of the directional coupler are respectively connected to the two ends of the quartz crystal through the second capacitor and the third capacitor, the output end of the directional coupler is connected to the second resistor, and the fourth capacitor is connected in parallel across the two ends of the second resistor.

4. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The demodulation and filtering circuit includes: an LC bandpass filter, a third resistor, a fourth resistor, a fifth resistor, and a fifth capacitor; the LC bandpass filter is connected to the signal modulation and transmission circuit through the third resistor, and the output terminal of the LC bandpass filter is connected to the signal strength detection circuit through the fifth capacitor and the fifth resistor; one end of the fourth resistor is connected to the LC bandpass filter, and the other end is connected to the connection point of the fifth capacitor and the fifth resistor.

5. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The signal strength detection circuit includes: a first operational amplifier, a first voltage comparator, a sliding rheostat, a diode, a second operational amplifier, and a sixth capacitor; the first operational amplifier is connected to the demodulation filter circuit, the input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier, the output terminal of the second operational amplifier is connected to the diode, the sixth capacitor is connected in parallel across the diode, the input terminal of the first voltage comparator is connected to the diode, and the output terminal of the first voltage comparator is connected to the sliding rheostat.

6. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The pulse conversion detection circuit includes: a second voltage comparator, a 555 timer, a sixth resistor, a seventh resistor, a seventh capacitor, an eighth capacitor, and a ninth capacitor; the input terminal of the second voltage comparator is connected to the demodulation filter circuit, the input terminal of the 555 timer is connected to the output terminal of the second voltage comparator, the second voltage comparator is also connected to the sixth resistor and the seventh resistor respectively, the eighth capacitor is connected in parallel across the sixth resistor, the ninth capacitor is connected in parallel across the seventh resistor, and the seventh capacitor is connected in parallel across the 555 timer.

7. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The logic decision circuit includes an AND gate circuit.

8. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The driving circuit includes: a transistor, a relay, a fault indicator light, an eighth resistor, a ninth resistor, a tenth capacitor, and an eleventh capacitor; the input terminal of the transistor is connected to the output terminal of the logic decision circuit, the input terminal of the relay is connected to the output terminal of the transistor, the output terminal of the relay is connected to the fault indicator light, the eighth resistor and the tenth capacitor are connected in parallel to the two ends of the transistor, the eleventh capacitor is connected in parallel to the two ends of the relay, and the ninth resistor is connected in parallel to the two ends of the fault indicator light.

9. The detection device for subway vehicle-to-ground communication according to claim 8, characterized in that, The fault indicator light uses a red LED.

10. The detection device for subway vehicle-to-ground communication according to claim 1, characterized in that, The microcontroller unit, pilot signal generator, and signal modulation and transmission circuit are all located on the ground; the demodulation and filtering circuit, signal strength detection circuit, pulse conversion and detection circuit, logic decision circuit, and drive circuit are all located on the vehicle.

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