Track section occupancy detection system and method

Abstract

The present invention belongs to the field of track detection technology, and specifically relates to a track section occupancy detection system and method, the system includes a vehicle-mounted device and a ground device; the vehicle-mounted device includes a vehicle-mounted host unit and a vehicle-mounted antenna unit; the vehicle-mounted host unit communicates with the vehicle-mounted computer to obtain the vehicle number information and sends it to the ground device, and at the same time sends the station name information sent by the ground device to the vehicle-mounted computer; the ground device includes a ground signal receiving unit and a ground signal processing unit; the ground signal receiving unit receives the vehicle number information sent by the vehicle-mounted device, and at the same time sends the station name information to the vehicle-mounted device; when the ground signal receiving unit detects that a tram has passed, the ground signal processing unit outputs a 24V switch quantity to a turnout control center, and the 24V switch quantity outputs a low level indicating that a vehicle has passed. The present invention can ensure driving safety and effectively avoid the loss of life and property caused by track train collision and rear-end collision accidents.

Description

Technical Field

[0001] The present invention belongs to the technical field of track detection, and in particular relates to a track section occupancy detection system and method. Background Art

[0002] In the railway signal system, real-time detection of train occupancy in a certain section of track is very important and directly related to the safe operation of driving and dispatching. The detection of train track occupancy status is the information guarantee for train crossing, crossing the line, shunting operations, etc. in the station, and also provides a technical basis for avoiding safety accidents such as train collisions and rear-end collisions. In order to realize the modernization of railway operation management and control, ensure the safety of train operation and improve transportation efficiency, an automated track occupancy detection system is urgently needed. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention proposes a track section occupancy detection system and method. The system has novel design and is easy to operate. The switch control center can obtain the occupancy status of the track section in real time, providing reliable data support for controlling train operation and scheduling, and ensuring driving safety.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a track section occupancy detection system, including a vehicle-mounted device and a ground device;

[0006] The vehicle-mounted equipment includes a vehicle-mounted host unit and a vehicle-mounted antenna unit; the vehicle-mounted host unit is installed in the vehicle compartment, and the vehicle-mounted antenna unit is installed at the lower part of the vehicle body; the vehicle-mounted host unit communicates with the vehicle-mounted computer to obtain the vehicle number information and sends it to the ground equipment, and at the same time sends the station name information sent by the ground equipment to the vehicle-mounted computer;

[0007] The ground equipment includes a ground signal receiving unit and a ground signal processing unit; the ground signal receiving unit is redundantly installed in the middle of the track line, and the ground signal processing unit is installed in a trackside cabinet; the ground signal receiving unit receives the vehicle number information sent by the on-board equipment, and sends the station name information to the on-board equipment at the same time; when the ground signal receiving unit detects that a tram has passed, the ground signal processing unit outputs a 24V switch quantity to the turnout control center, and the 24V switch quantity outputs a low level to indicate that a vehicle has passed.

[0008] Furthermore, the vehicle-mounted host unit is connected to the vehicle-mounted antenna unit via a coaxial line, the vehicle-mounted host unit performs data communication with the vehicle-mounted computer via RS422, and the vehicle-mounted host unit obtains DC24V power from the locomotive power supply.

[0009] Furthermore, the vehicle-mounted host unit includes a vehicle-mounted signal processing circuit and a vehicle-mounted power supply circuit; the vehicle-mounted power supply circuit provides a DC15V working power supply for the vehicle-mounted signal processing circuit; the vehicle-mounted signal processing circuit completes communication with the ground signal receiving unit through the connected vehicle-mounted antenna unit, sends the vehicle-mounted 27MHz signal to the ground signal receiving unit, and at the same time, receives and decodes the 4.2MHz signal sent by the ground signal receiving unit, and sends the decoded signal to the vehicle-mounted computer.

[0010] Furthermore, the on-board power supply circuit converts the DC24V power obtained from the locomotive power supply into a DC15V power output;

[0011] The vehicle-mounted signal processing circuit includes a power supply circuit, an antenna interface and receiving circuit, a detection circuit, a power amplifier circuit, an FPGA circuit, an MCU circuit and a communication circuit; the power supply circuit converts the DC15V input power supply voltage into 5.25V, 5V, 3.3V and 1.2V power supply voltages to provide the vehicle-mounted signal processing circuit with the required power supply voltages DC15V, DC5V, DC3.3V and DC1.2V; the power amplifier circuit is used to perform two-stage power amplification on the vehicle-mounted 27MHz signal; the FPGA circuit is used for encoding and outputting the vehicle-mounted signal and decoding the ground transponder message information; the detection circuit is used for the power amplifier circuit. Control, vehicle-mounted antenna unit self-test, antenna detection detection, MCU temperature detection, power amplifier power detection and power amplifier current detection; the MCU circuit serves as the control core of the vehicle-mounted host unit, and completes communication with the outside world and control and monitoring of internal circuits; the antenna interface and receiving circuit include a transceiver interface circuit and a receiving circuit. The transceiver interface circuit adopts a radio frequency interface to connect to the vehicle-mounted antenna unit, and a filter is used for isolation between the transceiver channels. The receiving circuit processes the received ground signal; the communication circuit includes one isolated RS422 and one isolated CAN to realize communication between the MCU circuit and the vehicle-mounted computer.

[0012] Furthermore, the ground signal receiving unit communicates data with the vehicle-mounted antenna unit via wireless radio frequency, the ground signal receiving unit communicates data with the ground signal processing unit via RS422, and the ground signal receiving unit obtains DC5V power from the ground signal processing unit.

[0013] Furthermore, the ground signal receiving unit includes an analog circuit, a digital circuit, a message receiving circuit, a wireless writing circuit and an RS422 interface circuit; the analog circuit includes a modulation and amplification circuit, which performs FSK modulation and amplification on the transponder message information to be sent; the digital circuit includes a power supply circuit, an MCU circuit, a message storage circuit and a voltage acquisition circuit, and the power supply circuit converts the DC5V power supply obtained from the ground signal processing unit into a power supply voltage of 3.3V and 1.5V, and provides power supply voltages of DC5V, DC3.3V and DC1.5V; the MCU circuit communicates with the ground signal processing unit to process The received on-board information controls the sending of 4.2MHz message information, and completes the message writing together with the wireless writing circuit; the message storage circuit is used to store the fixed message written inside; the voltage acquisition circuit is used to acquire the voltage provided by the power supply circuit; the wireless writing circuit writes the fixed message to the ground signal receiving unit; the message receiving circuit is used to receive the downlink on-board 27MHz signal transmitted by the on-board host unit, and send the processed signal to the MCU circuit, which is processed by the MCU circuit and transmitted to the ground signal processing unit; the RS422 interface circuit uses an RS422 chip to communicate with the ground signal processing unit.

[0014] Furthermore, the ground signal processing unit is connected to the turnout control center through a network communication interface, the ground signal processing unit obtains 220V AC power from the ground power supply, the ground processing unit communicates data with two ground signal receiving units through RS422, and provides DC5V power for the two ground signal receiving units.

[0015] Furthermore, the ground signal processing unit includes a power supply circuit, a control circuit, a ground signal receiving unit interface circuit and a turnout control center interface circuit; the power supply circuit converts 220V AC voltage into 12V and 3.3V DC voltages, and provides power supply voltages DC12V and DC3.3V; the control circuit converts the signal sent by the ground signal receiving unit into a network signal and a level signal and sends it to the turnout control center; the ground signal receiving unit interface circuit is used to connect the ground signal receiving unit and the control circuit; the turnout control center interface circuit is used to connect the turnout control center and the control circuit.

[0016] The present invention also provides a track section occupancy detection method, comprising:

[0017] When the vehicle-mounted host unit is working, it continuously sends radio frequency signals to the ground through the vehicle-mounted antenna unit;

[0018] When there is a ground signal receiving unit within the RF signal radiation range, the ground signal receiving unit will be activated to start internal transmission of 4.2MHz signal, and at the same time, the ground signal receiving unit will receive the vehicle-mounted 27MHz signal sent by the vehicle-mounted antenna unit;

[0019] The ground signal processing unit obtains the section occupancy information output by the ground signal receiving unit, converts it into level signal and network signal and outputs it to the switch control center, which controls it according to the section occupancy status.

[0020] Furthermore, the section occupancy information includes ground transponder message information, vehicle number information and vehicle passing signal; the level signal is a 24V switch quantity, and the 24V switch quantity outputs a low level to indicate that a vehicle has passed.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The track section occupancy detection system of the present invention includes two parts: a vehicle-mounted device and a ground device, wherein the vehicle-mounted device includes a vehicle-mounted host unit and a vehicle-mounted antenna unit, and the ground device includes a ground signal receiving unit and a ground signal processing unit; the vehicle-mounted host unit communicates with the vehicle-mounted computer to obtain information such as the vehicle number and sends it to the ground device, and at the same time sends information such as the station name sent by the ground device to the vehicle-mounted computer; the ground signal receiving unit receives information such as the vehicle number sent by the vehicle-mounted device, and at the same time sends information such as the station name to the vehicle-mounted device; when the ground signal receiving unit detects that a tram has passed, the ground signal processing unit outputs a 24V switch quantity (low level) to the turnout control center to indicate that a tram has passed. The turnout control center of the present invention can analyze the occupancy status of a certain section in real time according to the interval occupancy information provided by the ground signal processing unit, provide reliable data support for train driving and dispatching, ensure the safety of driving, and effectively avoid the loss of life and property caused by track train collision and rear-end collision accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic diagram of the deployment of a track section occupancy detection system according to an embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of a track section occupancy detection system according to an embodiment of the present invention;

[0026] Figure 3is a principle block diagram of a vehicle-mounted host unit according to an embodiment of the present invention;

[0027] Figure 4 is a principle block diagram of a ground signal receiving unit according to an embodiment of the present invention;

[0028] Figure 5 is a principle block diagram of a power supply circuit of a ground signal receiving unit according to an embodiment of the present invention;

[0029] Figure 6 It is a voltage acquisition circuit of a ground signal receiving unit in an embodiment of the present invention;

[0030] Figure 7 It is a principle block diagram of a ground signal processing unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The track section occupancy detection system of this embodiment is as follows: Figure 1 As shown, it includes two parts: on-board equipment and ground equipment; the on-board equipment includes an on-board host unit and an on-board antenna unit; the on-board host unit is installed in the car, and the on-board antenna unit is installed at the bottom of the car body; the on-board host unit communicates with the on-board computer to obtain information such as the car number and sends it to the ground equipment, and at the same time sends information such as the station name sent by the ground equipment to the on-board computer. The ground equipment includes a ground signal receiving unit and a ground signal processing unit; the ground signal receiving unit is installed in the middle of the track line in a redundant manner, and the ground signal processing unit is installed in the trackside cabinet; the ground signal receiving unit receives information such as the car number sent by the on-board equipment, and at the same time sends information such as the station name to the on-board equipment; when the ground signal receiving unit detects that a tram has passed, the ground signal processing unit outputs a 24V switch quantity to the turnout control center, and the 24V switch quantity outputs a low level to indicate that a tram has passed.

[0033] Among them, the ground signal receiving unit adopts a dual set of redundant settings. When the signal receiving circuit, cable, connector, etc. of one ground signal receiving unit fails, the other ground signal receiving unit can still maintain the system operation, thereby improving system reliability.

[0034] In addition, when any device in the ground signal receiving unit or the ground signal processing unit fails, the 24V switch quantity output by the ground signal processing unit is at a low level, indicating that there is a vehicle occupying the current section.

[0035] Specifically, Figure 2 As shown, the vehicle-mounted host unit is connected to the vehicle-mounted antenna unit through a coaxial line, the vehicle-mounted host unit communicates data with the vehicle-mounted computer through RS422, and the vehicle-mounted host unit obtains DC24V power from the locomotive power supply.

[0036] like Figure 3 As shown, the vehicle-mounted host unit includes a vehicle-mounted signal processing circuit and a vehicle-mounted power supply circuit. The vehicle-mounted power supply circuit provides a DC15V working power supply for the vehicle-mounted signal processing circuit; the vehicle-mounted signal processing circuit completes the communication with the ground signal receiving unit through the connected vehicle-mounted antenna unit, sends the vehicle-mounted 27MHz signal to the ground signal receiving unit, and at the same time, receives and decodes the 4.2MHz signal sent by the ground signal receiving unit, and sends the decoded signal to the vehicle-mounted computer.

[0037] The vehicle power supply circuit converts the DC24V power obtained from the locomotive power supply into a DC15V power output. The input power from the vehicle is DC24V, which is sent to the vehicle power supply circuit through the power interface, passes through a self-recovery fuse, and then is sent to the 24V to 15V power module VRB2415LD-40WR3 after filtering. The DC15V output by the power module is sent to the vehicle signal processing circuit through the power output interface. The EMC filter uses FC-D03D from Goldensun.

[0038] The vehicle-mounted signal processing circuit includes a power supply circuit, an antenna interface and receiving circuit, a detection circuit, a power amplifier circuit, an FPGA circuit, an MCU circuit and a communication circuit. These seven parts together complete the functions of the vehicle-mounted host unit. The following is a detailed explanation of these seven parts:

[0039] The main function of the power supply circuit is to convert the DC15V input power supply voltage into 5.25V, 5V, 3.3V and 1.2V power supply voltages, and provide the required power supply voltages DC15V, DC5V, DC3.3V and DC1.2V for the vehicle-mounted signal processing circuit. First, the power conversion chip LMR14020SDDA is used to convert the input 15V voltage into 5.25V; secondly, 5.25V is converted into 3.3V, and 3.3V is converted into 1.2V; finally, the power conversion chip TPS73250DBV is used to convert 5.25V into 5V to power the crystal oscillator, buffer circuit, bias circuit and detection circuit in the power amplifier circuit.

[0040] The power amplifier circuit is mainly used for two-stage power amplification of the vehicle-mounted 27MHz signal. The signal source of the power amplifier part uses a crystal oscillator with a small package (7mm*5mm) to generate a 27MHz signal. The signal is a CMOS level signal, and the driving ability of the oscillator is weak. Therefore, it is buffered by a NAND gate (SN74LVC2G00W-EP) to improve the driving ability. The power supply voltage of the NAND gate is 5V, and the output of the NAND gate is a square wave signal. A low-pass filter is required to filter out harmonics and finally obtain a pure sine wave. In order to match the input impedance of the driver amplifier, a 50-ohm resistor is connected in series to the output of the NAND gate. After filtering, a pi-type attenuator is connected in series, and the peak-to-peak value of the signal delivered to the driver amplifier is between 1.3V and 2.5V. Due to the poor consistency of the static bias current and gain of different power amplifier tubes, it is necessary to adjust the attenuation value of the π-type attenuator to adjust the power value fed into the driver amplifier so that the final output power meets the specified requirements. The driving amplifier uses MACOM's MRF158, which has a gain of 20dB and can output a maximum RF power of 2W; the last-stage power amplifier tube uses MRF171A, which has a maximum small signal gain of 20dB and a maximum output power of 45W. The two-stage amplifier circuit is powered by DC15V, and the crystal oscillator and ASK modulation part are powered by DC5V. In addition, by inputting the vehicle number information sent by FPGA at the buffer and NAND gate in the power amplifier circuit, the 27MHz carrier is modulated by ASK and sent to the ground equipment. In order to ensure that the ground equipment can reliably receive the 27MHz signal sent by the vehicle antenna unit, the ASK modulated vehicle number information uses Manchester encoding.

[0041] The FPGA circuit is mainly used for encoding and outputting vehicle-mounted signals and decoding ground transponder message information. The hardware includes the FPGA core, memory, and 24MHz active crystal oscillator. The FPGA core peripheral interface, memory, and 24MHz active crystal oscillator are powered by DC3.3V, the FPGA core is powered by DC1.2V, and the 24MHz crystal oscillator provides a clock for the FPGA core. The FPGA core provides vehicle-mounted signals for the power amplifier circuit, and the FPGA core receives the ground FSK demodulation signal sent by the antenna interface and the receiving circuit.

[0042] The detection circuit is mainly used for power amplifier control, vehicle antenna unit self-test, antenna detection, MCU temperature detection, power amplifier power detection and power amplifier current detection.

[0043] (1) Power amplifier control

[0044] The power amplifier control is achieved by controlling the bias power supply of the two-stage power amplifier tube. The specific implementation is: the MCU sends a high and low level (PA_DIS) to control whether the two transistors are turned on or not. When PA_DIS is set low, the two transistors are in the cut-off area, and the 5V power supply provides a bias voltage to the gate of the driver tube and the final power amplifier through resistor voltage division. The final bias voltage is provided to the two amplifier tubes after resistor voltage division; when PA_DIS is set high, the transistor is in the saturated conduction area, the gate voltage of the driver tube and the final power amplifier is about 0V, and the power amplifier tube is in the off state.

[0045] (2) Vehicle antenna unit self-test

[0046] When the vehicle host is powered on, the MCU outputs a control signal (ANT_CHECK_EN) of a fixed time length through the IO port, and the self-check circuit provides a maximum DC signal of 14.2mA (the resonance state of the antenna built-in transponder circuit will affect the size of the power supply current), which is transmitted to the vehicle antenna through the coaxial cable. Its working principle is as follows: ANT_CHECK_EN is set high, U404A outputs a low level, Q401 is turned on, Q402 is turned on and works in the amplification state, and the maximum output current can be adjusted by adjusting the resistor R443. The self-check DC is connected to the output end of the receiving low-pass filter, so there is no need to worry about the circuit affecting the transmission channel.

[0047] (3) Antenna detection

[0048] The antenna detection circuit is used to monitor the magnetic field energy emitted from the antenna unit. When the vehicle-mounted power amplifier is working normally, the built-in printed small loop antenna in the antenna unit is used to collect part of the downlink magnetic field energy and rectify it into a DC voltage through the detection circuit. This DC voltage is negative voltage. This DC voltage is transmitted to the power amplifier board through the coaxial line, and is sent to the signal conditioning circuit for reverse through the receiving low-pass filter, converted to positive voltage, and finally sent to the ADC of the MCU for acquisition. The signal conditioning circuit adopts the form of reverse amplification to convert the negative polarity antenna detection voltage into a positive polarity signal with an amplification factor of -1. When the absolute value of the antenna detection voltage collected is very small, it means that the magnetic field energy is weakened or there is a problem with the downlink. The fault point may be in the antenna unit, antenna feeder cable, or power amplifier circuit. When the absolute value of the antenna detection voltage collected is greater than a certain threshold, it means that the emitted magnetic field energy is getting stronger.

[0049] (4) MCU temperature detection

[0050] The vehicle-mounted signal processing circuit uses a temperature sensor to detect the ambient temperature around the MCU on the PCB in real time. When the ambient temperature exceeds the upper limit of the operating temperature allowed by the MCU, the MCU will send an alarm signal to the detection software. The temperature detection uses MAXIM's MAX31723 industrial-grade temperature sensor, which can detect temperatures within the range of -20℃ to 125℃.

[0051] (5) Power amplifier power detection

[0052] The power detection circuit uses capacitor coupling to output a small amount of power and sends it to the detector tube for detection. The detector tube is terminated with a 100-ohm redundant load. The detection output is filtered and amplified before being sent to the ADC in the MCU for collection. At the same time, the amplified detection voltage signal is compared with the reference level (initial setting is 1.24V). When it exceeds the reference level, the output is high, thereby controlling the power amplifier logic control circuit and shutting down the power amplifier.

[0053] (6) Power amplifier current detection

[0054] A 30mΩ precision resistor is connected in series to the 15V power line of the power amplifier. The voltage difference across the precision resistor is detected and amplified using TI's INA240 current detection amplifier with enhanced PWM suppression function. The power supply current of the power amplifier can be calculated according to Ohm's law. The output voltage of INA240 is connected to the ADC pin of the MCU. The MCU collects the voltage value and converts it to the power supply current of the power amplifier.

[0055] The MCU circuit serves as the control core of the vehicle host unit, completing the communication with the outside world and the control and monitoring of the internal circuit. The MCU communicates with the vehicle computer through the RS422 interface to obtain the vehicle number information, and decodes the transponder message information decoded by the FPGA circuit and sends it to the vehicle computer. The MCU and FPGA use serial port communication, which supports the MCU to reset the FPGA. The MCU also implements AD sampling of all power supplies of the vehicle signal processing circuit, uses resistor voltage division, and sends the system power supply to the ADC pin of the control chip to realize power supply voltage detection. The temperature detection uses the MAX31723 industrial-grade temperature sensor with an SPI interface. The antenna detection detection value, power amplifier power detection value, and power amplifier current detection value sent by the detection circuit are also connected through the ADC pin of the control chip to realize circuit parameter detection.

[0056] The antenna interface and receiving circuit include a transceiver interface circuit and a receiving circuit; the transceiver interface circuit is connected to the vehicle-mounted antenna unit using a radio frequency interface, and filters are used to isolate the transceiver channels. Different filter circuits separate the downlink transmission signal (27MHz signal from vehicle to ground) and the uplink signal (4.2MHz signal from ground to vehicle), effectively suppressing the mutual interference between the transmission channel and the receiving channel. The filter circuit includes a transmission bandpass filter, a receiving low-pass filter circuit and a receiving bandpass filter. Among them, the receiving low-pass filter circuit adopts a 9th-order LC Chebyshev low-pass filter, and the attenuation at the stop band 27.095MHz is more than 50dB. The receiving bandpass filter is realized by connecting a high-pass filter and a low-pass filter in series. The high-pass filter adopts a Butterworth high-pass filter for filtering, and the low-pass filter adopts a Butterworth and Chebyshev combination for filtering. The transmission bandpass filter includes two LC series resonances and two LC parallel resonances. The receiving circuit processes the received ground signal, including the signal demodulation circuit, the demodulated signal amplification and shaping circuit and the threshold signal judgment circuit; the signal demodulation circuit uses the NXP chip SA636 to complete the FSK signal demodulation. The amplification and shaping circuit mainly amplifies and shapes the signal output by the signal demodulation circuit, and amplifies the weak FSK message signal into an FSK message signal that can be recognized by the FPGA. The signal output by the SK636 chip passes through the low-pass filter, signal amplification circuit, signal voltage follower circuit, peak detection and voltage comparison circuit, and finally outputs a digital level signal to the FPGA chip. The threshold signal judgment circuit shapes the RSSI analog signal output by the signal demodulation circuit into a digital high and low level through the threshold signal shaping circuit and sends it to the FPGA chip. The threshold signal reflects the strength of the received ground signal, which is convenient for the system program to filter the reported data to prevent false alarms or misreporting.

[0057] The communication circuit includes one isolated RS422 and one isolated CAN to realize the communication between the MCU circuit and the vehicle-mounted computer. The RS422 communication interface isolation and conversion circuit uses ADI's ADM2587, which is a UART to RS-485 chip. The CAN communication interface isolation and conversion circuit uses ADI's ADM3053BRWZ, which is a reserved interface. The RS-422 and CAN communication interface connectors use DB9 female connectors for easy fixation, and communicate with the vehicle-mounted computer through this interface.

[0058] Specifically, Figure 2 As shown, the ground signal receiving unit communicates data with the vehicle-mounted antenna unit via wireless radio frequency, the ground signal receiving unit communicates data with the ground signal processing unit via RS422, and the ground signal receiving unit obtains DC5V power from the ground signal processing unit.

[0059] like Figure 4 As shown, the ground signal receiving unit includes an analog circuit, a digital circuit, a message receiving circuit, a wireless writing circuit and an RS422 interface circuit. The analog circuit includes a modulation and amplification circuit and a wireless power supply circuit; the modulation and amplification circuit performs FSK modulation and amplification on the transponder message information to be sent. FSK (Frequency-shift keying) frequency shift keying uses the discrete value characteristics of baseband digital signals to key the carrier frequency to transmit information. A digital modulation technology, its main advantages are: easy to implement, good anti-noise and anti-attenuation performance. The most common dual-frequency FSK modulation using two frequencies to carry binary 1 and 0 is used here. Wireless power supply circuit: The power supply of the ground signal receiving unit when wirelessly writing messages is obtained by the induced voltage, and the implementation method is bridge rectification. The so-called bridge rectifier circuit is to use diodes to form a rectifier bridge. The digital circuit includes a power supply circuit, an MCU circuit, a message storage circuit and a voltage acquisition circuit, such as Figure 5 As shown, the power supply circuit converts the DC5V power supply obtained from the ground signal processing unit into power supply voltages of 3.3V and 1.5V; due to the wireless message writing function, the energy obtained through the 27M resonant antenna is bridge rectified, and the converted DC level first passes through a 6.2V voltage regulator tube, and then directly supplies the power supply chip to generate 5V, 3.3V, and 1.5V. The MCU circuit is implemented by the main control chip FPGA (A3PN250-VQG100I) and peripheral circuits. The main functions are: one is to communicate with the ground signal processing unit, two is to process the received vehicle information, three is to control the sending of 4.2MHz message information, and four is to complete message writing together with the wireless writing circuit. The message storage circuit is used to store fixed messages written into the internal, and uses MICROCHIP's 4K-bit serial EEPROM memory device 93AA66CT-E / SN. As shown Figure 6As shown, the voltage acquisition circuit is used to collect the voltage provided by the power supply circuit. Specifically, two ADC chips ADC082S021 with SPI interfaces are used to collect the DC5V provided by the ground signal processing unit, and VCC3V3_1, VCC3V3_2, and VCC1V5 converted by the LDO chip. The wireless writing circuit writes fixed messages to the ground signal receiving unit, and uses wireless communication to process the wireless received signal and directly send it to the FPGA. After processing by the FPGA, the message is written into the message storage chip. The message receiving circuit receives the downlink vehicle-mounted 27MHz ASK signal transmitted by the vehicle-mounted host unit, and uses wireless communication to process the wireless received signal and directly send it to the FPGA. After processing by the FPGA, it is transmitted to the ground signal processing unit. When the downlink 27MHz signal is detected, the FPGA starts to send the uplink 4.2MHz. The RS422 interface circuit uses an RS422 chip to communicate with the ground signal processing unit. RS422 uses ADM2587E, a magnetically isolated full-duplex RS-422 transceiver. ADM2587E is an isolated RS-422 transceiver chip launched by ADI based on its iCoupler magnetic isolation technology.

[0060] Specifically, Figure 2 As shown, the ground signal processing unit is connected to the turnout control center through a network communication interface, the ground signal processing unit obtains 220V AC power from the ground power supply, the ground processing unit communicates data with two ground signal receiving units through RS422, and provides DC5V power for the two ground signal receiving units.

[0061] like Figure 7As shown, the ground signal processing unit includes a power supply circuit, a control circuit, a ground signal receiving unit interface circuit and a switch control center interface circuit; the power supply circuit converts 220V AC voltage into 12V and 3.3V DC voltages, provides power supply voltages DC12V and DC3.3V, and the 220V to 12V conversion uses the power module LD10-23B12R2 of Goldensun Company, and the 12V to 3.3V conversion uses the DC / DC chip TPS54202DDCR of TI Company. The control circuit converts the signal sent by the ground signal receiving unit into a network signal and a level signal and sends it to the turnout control center. The GD32F107VT chip is selected as the control chip. Two serial ports are used to communicate with the two ground signal receiving units respectively to obtain the section occupancy information. The communication output is controlled by a pulse signal. The MII interface of the control chip is used to convert it into a network signal through the PHY chip DP83848I, and the section occupancy information is sent to the turnout control center. The pulse control signal is used to control the output +24V level, and the section occupancy information is sent to the turnout control center through the level signal. The ground signal receiving unit interface circuit is used to connect the ground signal receiving unit and the control circuit. The interface isolation and conversion circuit uses ADI's ADM2587, which is a UART to RS-485 chip. The interface protection part uses TVS tubes and parallel-connected self-recovery fuses. The connector uses a cage spring connector. The power output conversion part uses the WRB1205SD-3WR2 power module of Goldensun. One power module is used to power the two ground signal receiving units. The interface circuit of the turnout control center is used to connect the turnout control center and the control circuit. The network part uses the MII interface of the CPU, and TI's DP83848I is selected as the PHY chip. The interface protection uses a network transformer and ESD protection. The network connector uses a shielded RJ45 socket. The 24V level output uses the Golden Sun B1224XT-1WR2 power module with an output voltage of 24V. To control the output level, the optocoupler relay AQY211R2S is used as the output control. The control signal is a pulse signal. When there is a pulse signal, the +24V level is output, indicating that there is no car. When there is no pulse signal or the equipment fails, the +24V output interface outputs a low level, indicating that there is a car.

[0062] A detection method based on the above-mentioned track section occupancy detection system includes:

[0063] When the vehicle-mounted host unit is working, it continuously sends radio frequency signals to the ground through the vehicle-mounted antenna unit;

[0064] When there is a ground signal receiving unit within the RF signal radiation range, the ground signal receiving unit will be activated to start internal transmission of 4.2MHz signal, and at the same time, the ground signal receiving unit will receive the vehicle-mounted 27MHz signal sent by the vehicle-mounted antenna unit;

[0065] The ground signal processing unit obtains the section occupancy information output by the ground signal receiving unit, converts it into level signal and network signal and outputs it to the switch control center, which controls it according to the section occupancy status.

[0066] The section occupancy information includes ground transponder message information, vehicle number information and vehicle passing signal. The ground transponder message information includes kilometer mark, slope, direction, etc. The switch control center can locate the position information of the tram according to the ground transponder message information and determine the specific vehicle according to the vehicle number information; the level signal is a 24V switch quantity, and the 24V switch quantity outputs a low level to indicate that a vehicle has passed.

[0067] The track section occupancy detection system has a single set of ground equipment at each station. After the tram passes through the system, the ground signal processing unit of the system outputs a 24V switch quantity (low level) to the switch control center. For example: the tram passes through the exit track occupancy detection equipment of station 1 and the entrance track occupancy detection equipment of station 2 in sequence, indicating that a vehicle has passed through the section and the occupancy status has been released.

[0068] It should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0069] Finally, it should be noted that the above is only a preferred embodiment of the present invention, which is only used to illustrate the technical solution of the present invention, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A track section occupancy detection system, characterized in that: Including vehicle-mounted equipment and ground equipment; The vehicle-mounted equipment includes a vehicle-mounted host unit and a vehicle-mounted antenna unit; the vehicle-mounted host unit is installed in the vehicle compartment, and the vehicle-mounted antenna unit is installed at the lower part of the vehicle body; the vehicle-mounted host unit communicates with the vehicle-mounted computer to obtain the vehicle number information and sends it to the ground equipment, and at the same time sends the station name information sent by the ground equipment to the vehicle-mounted computer; The on-board host unit is connected to the on-board antenna unit through a coaxial line, the on-board host unit communicates data with the on-board computer through RS422, and the on-board host unit obtains DC24V power from the locomotive power supply; the on-board host unit includes an on-board signal processing circuit and an on-board power supply circuit; the on-board power supply circuit provides a DC15V working power supply for the on-board signal processing circuit; the on-board signal processing circuit completes communication with the ground signal receiving unit through the connected on-board antenna unit, sends the on-board 27MHz signal to the ground signal receiving unit, and at the same time, receives and decodes the 4.2MHz signal sent by the ground signal receiving unit, and sends the decoded signal to the on-board computer; the on-board power supply circuit converts the DC24V power obtained from the locomotive power supply into a DC15V power output; the on-board signal processing circuit includes a power supply circuit, an antenna interface and a receiving circuit, a detection circuit, a power amplifier circuit, an FPGA circuit, an MCU circuit and a communication circuit; the power supply circuit converts the DC15V input power voltage into a 5 .25V, 5V, 3.3V and 1.2V power supply voltages provide the required power supply voltages DC15V, DC5V, DC3.3V and DC1.2V for the vehicle-mounted signal processing circuit; the power amplifier circuit is used to perform two-stage power amplification on the vehicle-mounted 27MHz signal; the FPGA circuit is used for encoding and outputting vehicle-mounted signals and decoding ground transponder message information; the detection circuit is used for power amplifier control, vehicle-mounted antenna unit self-test, antenna detection detection, MCU temperature detection, power amplifier power detection and power amplifier current detection; the MCU circuit serves as the control core of the vehicle-mounted host unit to complete communication with the outside world and control and monitoring of internal circuits; the antenna interface and receiving circuit includes a transceiver interface circuit and a receiving circuit. The transceiver interface circuit uses a radio frequency interface to connect to the vehicle-mounted antenna unit, and a filter is used to isolate the transceiver channels. The receiving circuit processes the received ground signal; the communication circuit includes one isolated RS422 and one isolated CAN to realize communication between the MCU circuit and the vehicle-mounted computer; The ground equipment includes a ground signal receiving unit and a ground signal processing unit; the ground signal receiving unit is redundantly installed in the middle of the track line, and the ground signal processing unit is installed in a trackside cabinet; the ground signal receiving unit receives the vehicle number information sent by the on-board equipment, and sends the station name information to the on-board equipment; when the ground signal receiving unit detects that a tram has passed, the ground signal processing unit outputs a 24V switch value to the turnout control center, and the 24V switch value outputs a low level to indicate that a tram has passed; The ground signal receiving unit performs data communication with the vehicle-mounted antenna unit via wireless radio frequency, and performs data communication with the ground signal processing unit via RS422, and obtains DC5V power from the ground signal processing unit; the ground signal receiving unit includes an analog circuit, a digital circuit, a message receiving circuit, a wireless writing circuit and an RS422 interface circuit; the analog circuit includes a modulation and amplification circuit, which performs FSK modulation and amplification on the transponder message information to be sent; the digital circuit includes a power supply circuit, an MCU circuit, a message storage circuit and a voltage acquisition circuit, and the power supply circuit converts the DC5V power obtained from the ground signal processing unit into a power supply voltage of 3.3V and 1.5V to provide power Voltage DC5V, DC3.3V and DC1.5V; the MCU circuit communicates with the ground signal processing unit, processes the received vehicle-mounted information, controls the sending of 4.2MHz message information, and completes the message writing together with the wireless writing circuit; the message storage circuit is used to store the fixed message written inside; the voltage acquisition circuit is used to acquire the voltage provided by the power supply circuit; the wireless writing circuit writes a fixed message to the ground signal receiving unit; the message receiving circuit is used to receive the downlink vehicle-mounted 27MHz signal transmitted by the vehicle-mounted host unit, and sends the processed signal to the MCU circuit, which is processed by the MCU circuit and transmitted to the ground signal processing unit; the RS422 interface circuit adopts an RS422 chip to communicate with the ground signal processing unit.

2. The track section occupancy detection system according to claim 1, characterized in that: The ground signal processing unit is connected to the turnout control center through a network communication interface, the ground signal processing unit obtains 220V AC power from the ground power supply, the ground signal processing unit communicates data with two ground signal receiving units through RS422, and provides DC5V power for the two ground signal receiving units.

3. The track section occupancy detection system according to claim 2, characterized in that: The ground signal processing unit includes a power supply circuit, a control circuit, a ground signal receiving unit interface circuit and a switch control center interface circuit; the power supply circuit converts 220V AC voltage into 12V and 3.3V DC voltages, and provides power supply voltages DC12V and DC3.3V; the control circuit converts the signal sent by the ground signal receiving unit into a network signal and a level signal and sends it to the switch control center; the ground signal receiving unit interface circuit is used to connect the ground signal receiving unit and the control circuit; the switch control center interface circuit is used to connect the switch control center and the control circuit.

4. A method for detecting track section occupancy, characterized in that: Using the track section occupancy detection system according to any one of claims 1 to 3 to perform track section occupancy detection specifically includes: When the vehicle-mounted host unit is working, it continuously sends radio frequency signals to the ground through the vehicle-mounted antenna unit; When there is a ground signal receiving unit within the RF signal radiation range, the ground signal receiving unit will be activated to start internal transmission of 4.2MHz signal, and at the same time, the ground signal receiving unit will receive the vehicle-mounted 27MHz signal sent by the vehicle-mounted antenna unit; The ground signal processing unit obtains the section occupancy information output by the ground signal receiving unit, converts it into level signal and network signal and outputs it to the switch control center, which controls it according to the section occupancy status.

5. The track section occupancy detection method according to claim 4, characterized in that: The section occupancy information includes ground transponder message information, vehicle number information and vehicle passing signal; the level signal is a 24V switch quantity, and the 24V switch quantity outputs a low level to indicate that a vehicle has passed.

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