Vehicle-mounted broadband satellite communication modulation and demodulation unit

Abstract

The utility model discloses a vehicle-mounted broadband satellite communication modulation and demodulation unit, which comprises a power supply circuit, a clock circuit, an SoC (System on Chip) integrated with an ARM (Advanced RISC Machines) and an FPGA (Field Programmable Gate Array), a starting storage chip, a flash memory chip, a memory chip, a debugging serial port, two vehicle-mounted Ethernet interfaces, a Wi-Fi (Wireless Fidelity) module, an RS422 chipset and a radio frequency input and output unit. According to the vehicle-mounted broadband satellite communication modulation and demodulation unit provided by the utility model, functions of analog-to-digital / digital-to-analog conversion of satellite signals, satellite baseband service processing, Wi-Fi communication, vehicle-mounted Ethernet communication and the like can be integrated into one circuit board, so that the space occupancy rate of a whole vehicle is reduced, and the product cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of satellite communication of vehicle, especially a kind of satellite communication modulation and demodulation unit of broadband of vehicle. BACKGROUND

[0002] The rapid development of emerging fields such as intelligent connected vehicles, autonomous driving and mobile Internet of Things has put forward higher requirements for mobile communication. However, more than 80% of the land area in the world lacks ground network coverage, especially in remote and rural areas, which makes it difficult for traditional ground communication systems to meet the needs of these emerging applications. Satellite communication can better compensate for the situation that ground communication systems are difficult to cover due to topographic limitations, providing extensive communication coverage.

[0003] Current vehicle-mounted satellite communication usually only supports narrowband communication, such as voice and short messages. This narrowband communication method has obvious limitations in data transmission rate and bandwidth, and cannot meet the needs of intelligent connected vehicles and autonomous driving for high bandwidth, low latency and high reliability. For example, autonomous vehicles need to transmit a large amount of sensor data and high-definition map data in real time to ensure the safety and efficient operation of the vehicle. In addition, intelligent connected vehicles need to exchange data frequently with other vehicles and infrastructure to realize the function of Internet of Vehicles.

[0004] The existing technology has the following disadvantages: narrowband communication cannot provide sufficient bandwidth to support high data rate applications, limiting the efficiency and quality of data transmission; the high latency characteristic of narrowband communication cannot meet the needs of real-time applications, affecting the performance of autonomous driving and Internet of Vehicles; the communication stability and reliability of existing vehicle-mounted satellite communication systems in complex environments are poor, and are easily affected by interference and signal attenuation. UTILITY MODEL CONTENT

[0005] The utility model aims to provide a kind of satellite communication modulation and demodulation unit of broadband of vehicle to solve the above problems existing in prior art.

[0006] Technical scheme, a kind of satellite communication modulation and demodulation unit of broadband of vehicle, comprising:

[0007] SoC integrated with ARM and FPGA is used to realize the modulation and demodulation function of satellite signal, including processing system module and programmable logic module;

[0008] Boot storage chip is connected with processing system module through Quad SPI, and is used to store the boot program of SoC integrated with ARM and FPGA;

[0009] Flash chip is connected with processing system module through SDIO, and is used to store operating system, application program and log;

[0010] Memory chip, connected with the processing system module through DDR, used for storing cache information in system running process;

[0011] Clock circuit, connected with the SoC integrated with ARM and FPGA, used for generating clock used by each chip;

[0012] Debugging serial port, connected with the UART interface of the processing system module through the RS232 chip, used for debugging the single board;

[0013] First vehicle Ethernet interface, connected with the processing system module through the RGMII interface, used for communicating with the vehicle machine Ethernet system and realizing satellite communication data communication;

[0014] Second vehicle Ethernet interface, connected with the programmable logic module through the RGMII interface, used for communicating with the antenna;

[0015] Wi-Fi module, connected with the programmable logic module through the SDIO, and connected with external equipment through the antenna, used for emitting hot spot to the outside;

[0016] RS422 chip set, connected with the programmable logic module through the GPIO, and connected with the second automobile connector through the RS422 interface, used for controlling the antenna radio frequency switch;

[0017] Radio frequency input and output unit, interconnected with the SoC integrated with ARM and FPGA through corresponding interfaces, used for transmitting and receiving processing of wideband satellite signals;

[0018] Power circuit, connected with the first automobile connector, used for realizing conversion from input 12V power supply to board-level power supply used by each chip.

[0019] Beneficial effects, the vehicle wideband satellite communication modulation and demodulation unit provided by the utility model can realize functions such as analog / digital conversion of satellite signals, satellite baseband service processing, Wi-Fi communication, vehicle Ethernet communication and the like integrated into one circuit board, realizes satellite signal modulation and demodulation functions, provides high bandwidth, low delay and high reliability communication services, simultaneously reduces the space occupancy of the whole vehicle, and reduces the cost of products. DRAWINGS

[0020] Figure 1 It is the principle block diagram of the utility model.

[0021] Figure 2 It is the clock circuit diagram of the utility model embodiment.

[0022] Figure 3 It is the CAN bus circuit diagram of the utility model embodiment.

[0023] Figure 4 The first receiver circuit diagram of the RS422 chip set in the embodiment of the utility model.

[0024] Figure 5 The first transmitter circuit diagram of the RS422 chip set in the embodiment of the utility model.

[0025] Figure 6 The second receiver circuit diagram of the RS422 chip set in the embodiment of the utility model.

[0026] Figure 7 The second transmitter circuit diagram of the RS422 chip set in the embodiment of the utility model. DETAILED DESCRIPTION

[0027] As Figure 1 shown, the application provides a kind of vehicle-mounted broadband satellite communication modulation and demodulation unit, including power supply circuit, clock circuit, integrated ARM and FPGA SoC, start-up memory chip, flash memory chip, memory chip, debugging serial port, two-way vehicle-mounted Ethernet interface, Wi-Fi module, RS422 chip set, radio frequency input and output unit, connector and the like part.

[0028] According to an aspect of the application, the power supply circuit is connected with the first automobile connector, for realizing the conversion of input 12V power supply to the board-level power supply of 5V, 3.3V, 2.5V, 2.0V, 1.8V, 1.35V, 1.3V and the like used by chip.The power supply circuit also contains the timing control circuit of the above-mentioned board-level small power supply.

[0029] According to an aspect of the application, the clock circuit is connected with the integrated ARM and FPGA SoC, and contains TCXO (temperature compensated crystal oscillator), ordinary crystal oscillator, crystal resonator and clock buffer and the like device, and the clock circuit generates multiple clock and provides for each chip of single board.

[0030] According to an aspect of the application, the integrated ARM and FPGA SoC, SoC can select ZYNQ-7045, mainly for realizing the modulation and demodulation function of satellite signal.In the receiving end of chip, the programmable logic module (PL) module of integrated ARM and FPGA SoC receives data from radio frequency input and output unit, carries out demodulation and decoding, then the data handled is sent to network interface or Wi-Fi via processing system module (PS) module;Sending end, PS module pushes the service data from network interface to PL module, and PL module is handled according to specified carrier mode, and the digital signal generated is sent to radio frequency input and output unit.

[0031] According to an aspect of the present application, the start-up memory chip is connected to the processing system module through Quad SPI, and is mainly used for storing the start-up program of the SoC integrated with ARM and FPGA, and is a serial flash memory (SERIAL FLASH MEMORY) for the QSPI (Quad Serial Peripheral Interface) interface.

[0032] According to an aspect of the present application, the flash memory chip is connected to the processing system module through SDIO, and is mainly used for storing the operating system, application program, log and the like, and is an embedded multi media card (Embedded Multi Media Card, eMMC) for the SDIO (Secure Digital Input and Output) interface.

[0033] According to an aspect of the present application, the memory chip is connected to the processing system module through DDR, and is mainly used for storing the cache information in the system running process. The memory chip is a 1GB DDR3 memory, and 2 pieces of 512MB 16-bit wide DDR3 are used to realize the 32-bit system data interface through the bit width extension.

[0034] According to an aspect of the present application, the debugging serial port is mainly used for debugging the single board. The debugging serial port connector is connected to the UART of the PS of the SoC integrated with ARM and FPGA through the RS232 chip.

[0035] According to an aspect of the present application, the two-way vehicle-mounted Ethernet interface, wherein the first vehicle-mounted Ethernet interface is used for communicating with the vehicle machine Ethernet system, and realizes the communication of satellite communication data. The second vehicle-mounted Ethernet interface communicates with the antenna. The first vehicle-mounted Ethernet interface is connected to the PS of the SoC integrated with ARM and FPGA through the vehicle-mounted Ethernet chip PHY1, and the interface is RGMII. The second vehicle-mounted Ethernet interface is connected to the PL of the SoC integrated with ARM and FPGA through the vehicle-mounted Ethernet chip PHY2, and the interface is RGMII.

[0036] According to an aspect of the present application, the Wi-Fi module is connected to the programmable logic module through SDIO, and simultaneously performs Wi-Fi connection with the external wireless electronic device, and is used for emitting a hotspot outward. The board card makes the external electronic device with Wi-Fi function connect to the hotspot through emitting the hotspot outward.

[0037] According to an aspect of the present application, the RS422 chip set is connected to the programmable logic module through GPIO, and is connected to the second automobile connector through the RS422 interface, and is used for controlling the antenna radio frequency switch.

[0038] According to an aspect of the present application, the radio frequency input and output unit is interconnected with the integrated ARM and FPGA SoC through the LVDS interface, and is used for transmitting and receiving processing of wideband satellite signals. The radio frequency input and output unit contains devices such as frequency agile device AD9363, radio frequency amplifier, low pass filter, radio frequency switch, etc.

[0039] As shown in Figure 2 According to an aspect of the present application, the clock circuit includes digital-to-analog converter U20, resistor R82, resistor R87, resistor R88, resistor R108, capacitor C196, capacitor C512, capacitor C529, capacitor C530, capacitor C107, capacitor C108, capacitor C109, capacitor C113, crystal oscillator U18 and magnetic bead L17, wherein pin 1 and pin 4 of the digital-to-analog converter U20 are grounded, pin 2 of the digital-to-analog converter U20 is connected to the power supply, pin 3 of the digital-to-analog converter U20 and pin 1 of the crystal oscillator U18 are connected, pin 7 of the crystal oscillator U18 is grounded, pin 14 of the crystal oscillator U18 is connected to one end of the capacitor C107, the capacitor C108 and the capacitor C109 and the magnetic bead L17, the other end of the capacitor C107, the capacitor C108 and the capacitor C109 is grounded, the other end of the magnetic bead L17 is connected to the power supply, pin 8 of the crystal oscillator U18 and one end of the capacitor C113 are connected, pin 5 of the digital-to-analog converter U20 is grounded, pin 6 of the digital-to-analog converter U20 and one end of the resistor R87 are connected, the other end of the resistor R87 is grounded, pin 7, pin 8, pin 9 and pin 10 of the digital-to-analog converter U20 are connected to one end of the capacitor C196, the capacitor C512, the capacitor C529 and the capacitor C530, the other end of the capacitor C196, the capacitor C512, the capacitor C529 and the capacitor C530 is grounded, one end of the capacitor C196 is connected to the power supply, pin 11 of the digital-to-analog converter U20 is connected to one end of the resistor R108, the other end of the resistor R108 is connected to one end of the resistor R88 and the power supply, the other end of the resistor R88 is connected to pin 12 of the digital-to-analog converter U20, pin 13, pin 15 and pin 16 of the digital-to-analog converter U20 are connected to pin 10 of the digital-to-analog converter U20, pin 14 of the digital-to-analog converter U20 is connected to one end of the resistor R82, the other end of the resistor R82 is connected to pin 13 of the digital-to-analog converter U20, pin 17 of the digital-to-analog converter U20 is connected to pin 1 of the digital-to-analog converter U20.

[0040] As shown in Figure 3As shown, according to one aspect of this application, an in-vehicle broadband satellite communication modem unit further includes a CAN bus circuit, comprising a CAN transceiver U118, a common-mode choke L6018, a protection diode D21, capacitors C964, C965, C970, and C971, resistors R860, R843, and R842. Pin 2 of the CAN transceiver U118 is grounded; pin 3 of the CAN transceiver U118 is simultaneously connected to one end of capacitor C964 and a power supply, with the other end of capacitor C964 grounded; pin 4 of the CAN transceiver U118 is connected to one end of resistor R860; pin 5 of the CAN transceiver U118 is simultaneously connected to one end of capacitor C965 and a power supply, with the other end of capacitor C965 grounded. Pin 6 of transceiver U118 is simultaneously connected to pin 1 of common mode choke L6018 and one end of resistor R843. The other end of resistor R843 is simultaneously connected to pin 2 of common mode choke L6018 and pin 7 of CAN transceiver U118. Pin 8 of CAN transceiver U118 is connected to one end of resistor R842, and the other end of resistor R842 is grounded. Pin 3 of common mode choke L6018 is simultaneously connected to one end of capacitor C970 and pin 1 of protection diode D21. The other end of capacitor C970 is simultaneously connected to one end of capacitor C971 and pin 3 of common mode choke L6018. The other end of capacitor C971 is simultaneously connected to pin 4 of common mode choke L6018 and pin 2 of protection diode D21, and pin 3 of protection diode D21 is grounded.

[0041] like Figures 4 to 7 As shown, according to one aspect of this application, the RS422 chipset includes a first receiver circuit, a first transmitter circuit, a second receiver circuit, and a second transmitter circuit. The first receiver circuit includes a chip U119, protection diodes D32 and D33, resistors R844, R845, R846, R847, and R848, and a capacitor C966. Pin 1 of chip U119 is connected to one end of resistors R845, C966, and R848 simultaneously. The other end of capacitor C966 is connected to pin 2 of chip U119 and ground simultaneously. One end of capacitor C966 is connected to the power supply. Resistor R848... The other end is connected to pin 3 of chip U119 and one end of resistor R847. The other end of resistor R845 is connected to pin 5 of chip U119, one end of resistor R844 and pin 1 of protection diode D33. The other end of resistor R844 is connected to pin 4 of chip U119, one end of resistor R846 and pin 1 of protection diode D32. The other end of resistor R846 is grounded. Pins 2 of protection diode D32 and pins 2 of protection diode D33 are grounded.

[0042] The first transmitter circuit comprises a chip U120, a protection diode D34, a protection diode D36, a resistor R849, a resistor R850, a resistor R851 and a capacitor C967, wherein pin 2 of the chip U120 is connected to one end of the resistor R851, one end of the capacitor C967 and a power supply, the other end of the resistor R851 is connected to pin 3 of the chip U120, the other end of the capacitor C967 is grounded, pin 4 of the chip U120 is connected to one end of the resistor R850, the other end of the resistor R850 is connected to pin 1 of the protection diode D36, pin 5 of the chip U120 is grounded, pin 6 of the chip U120 is connected to one end of the resistor R849, the other end of the resistor R849 is connected to pin 1 of the protection diode D34, and pins 2 of the protection diode D34 and the protection diode D36 are grounded.

[0043] The second receiver circuit comprises a chip U121, a protection diode D35, a protection diode D37, a resistor R852, a resistor R853, a resistor R854, a resistor R855, a resistor R856 and a capacitor C968, wherein pin 1 of the chip U121 is connected to one end of the resistor R853, the capacitor C968 and the resistor R856, the other end of the capacitor C968 is connected to pin 2 of the chip U121 and a ground at the same time, one end of the capacitor C968 is connected to a power supply, the other end of the resistor R856 is connected to pin 3 of the chip U121 and one end of the resistor R855 at the same time, the other end of the resistor R853 is connected to pin 5 of the chip U121, one end of the resistor R852 and pin 1 of the protection diode D35 at the same time, the other end of the resistor R852 is connected to pin 4 of the chip U121, one end of the resistor R854 and pin 1 of the protection diode D37 at the same time, the other end of the resistor R854 is grounded, and pins 2 of the protection diode D35 and the protection diode D37 are grounded.

[0044] The second transmitter circuit comprises a chip U122, a protection diode D38, a protection diode D39, a resistor R857, a resistor R858, a resistor R859 and a capacitor C969, wherein pin 2 of the chip U122 is connected to one end of the resistor R858, one end of the capacitor C969 and a power supply at the same time, the other end of the resistor R858 is connected to pin 3 of the chip U122, the other end of the capacitor C969 is grounded, pin 4 of the chip U122 is connected to one end of the resistor R859, the other end of the resistor R859 is connected to pin 1 of the protection diode D38, pin 5 of the chip U122 is grounded, pin 6 of the chip U122 is connected to one end of the resistor R857, the other end of the resistor R857 is connected to pin 1 of the protection diode D39, and pins 2 of the protection diode D39 and the protection diode D38 are grounded.

[0045] It should be noted that each specific technical feature described in the foregoing detailed description can be combined in any suitable manner without departing from the scope of the present application. To avoid unnecessary repetition, the present application does not describe each and every possible combination of the features.

Claims

1. A vehicle-mounted broadband satellite communication modem unit, characterized by The application relates to a satellite communication system, which comprises the following parts: An SoC integrated with ARM and FPGA, which is used for realizing the modulation and demodulation functions of satellite signals and comprises a processing system module and a programmable logic module; A starting storage chip connected with the processing system module through a Quad SPI, which is used for storing the starting program of the SoC integrated with ARM and FPGA; A flash memory chip connected with the processing system module through an SDIO, which is used for storing an operating system, application programs and logs; A memory chip connected with the processing system module through a DDR, which is used for storing cache information in a system running process; A clock circuit connected with the SoC integrated with ARM and FPGA, which is used for generating clocks used by the chips; A debugging serial port connected with a UART interface of the processing system module through an RS232 chip, which is used for debugging the single board; A first vehicle-mounted Ethernet interface connected with the processing system module through an RGMII interface, which is used for communicating with a vehicle machine Ethernet system and realizing the communication of satellite communication data; A second vehicle-mounted Ethernet interface connected with the programmable logic module through an RGMII interface, which is used for communicating with an antenna; A Wi-Fi module connected with the programmable logic module through an SDIO and connected with external equipment through an antenna, which is used for emitting a hotspot to the outside; An RS422 chip set connected with the programmable logic module through a GPIO and connected with a second automobile connector through an RS422 interface, which is used for controlling an antenna radio frequency switch; A radio frequency input and output unit interconnected with the SoC integrated with ARM and FPGA through corresponding interfaces, which is used for transmitting and receiving processing of wideband satellite signals; A power supply circuit connected with a first automobile connector, which is used for realizing the conversion of an input 12V power supply into a board-level power supply used by the chips.

2. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, In a receiving end, the programmable logic module of the SoC integrated with ARM and FPGA receives data from the radio frequency input and output unit, carries out demodulation and decoding, and obtains processing data; the processing data is sent to the first vehicle-mounted Ethernet interface or the Wi-Fi module through the processing system module; In a sending end, the processing system module pushes service data from the first vehicle-mounted Ethernet interface to the programmable logic module; the programmable logic module processes the data according to a pre-specified carrier mode, generates digital signals; and the digital signals are sent to the radio frequency input and output unit.

3. The vehicle-mounted broadband satellite communication modem unit according to claim 2, wherein, The clock circuit comprises a temperature compensation crystal oscillator, a common crystal oscillator, a crystal resonator and a clock buffer.

4. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, The radio frequency input and output unit comprises a frequency agile unit, a radio frequency amplifier, a low-pass filter and a radio frequency switch; and the unit is interconnected with the SoC integrated with ARM and FPGA through an LVDS interface.

5. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, The starting storage chip is a QSPI interface serial flash memory; the flash memory chip is an SDIO interface embedded multimedia card; and the memory chip is a 1024MB DDR3 memory, which realizes a 32-bit system data interface through bit width expansion of two pieces of 512MB 16-bit width DDR3.

6. The vehicle-mounted broadband satellite communication modem unit of claim 1, wherein, The first vehicle-mounted Ethernet interface is connected with the RGMII interface of the processing system module through a vehicle-mounted Ethernet chip PHY1; and the second vehicle-mounted Ethernet interface is connected with the RGMII interface of the programmable logic module through a vehicle-mounted Ethernet chip PHY2.

7. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, The board card of the Wi-Fi module can make the external electronic equipment with Wi-Fi function connect to the hotspot by emitting the hotspot outward.

8. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, The clock circuit comprises a digital-to-analog converter U20, a resistor R82, a resistor R87, a resistor R88, a resistor R108, a capacitor C196, a capacitor C512, a capacitor C529, a capacitor C530, a capacitor C107, a capacitor C108, a capacitor C109, a capacitor C113, a crystal oscillator U18 and a magnetic bead L17, wherein a pin 1 and a pin 4 of the digital-to-analog converter U20 are grounded, a pin 2 of the digital-to-analog converter U20 is connected with a power supply, a pin 3 of the digital-to-analog converter U20 and a pin 1 of the crystal oscillator U18 are connected, a pin 7 of the crystal oscillator U18 is grounded, a pin 14 of the crystal oscillator U18 is connected with one end of the capacitor C107, the capacitor C108, the capacitor C109 and the magnetic bead L17, the other end of the capacitor C107, the capacitor C108 and the capacitor C109 is grounded, the other end of the magnetic bead L17 is connected with the power supply, a pin 8 of the crystal oscillator U18 is connected with one end of the capacitor C113, a pin 5 of the digital-to-analog converter U20 is grounded, a pin 6 of the digital-to-analog converter U20 is connected with one end of the resistor R87, the other end of the resistor R87 is grounded, a pin 7, a pin 8, a pin 9 and a pin 10 of the digital-to-analog converter U20 are connected with one end of the capacitor C196, the capacitor C512, the capacitor C529 and the capacitor C530, the other end of the capacitor C196, the capacitor C512, the capacitor C529 and the capacitor C530 is grounded, one end of the capacitor C196 is connected with the power supply, a pin 11 of the digital-to-analog converter U20 is connected with one end of the resistor R108, the other end of the resistor R108 is connected with one end of the resistor R88 and the power supply, the other end of the resistor R88 is connected with a pin 12 of the digital-to-analog converter U20, a pin 13, a pin 15 and a pin 16 of the digital-to-analog converter U20 are connected with the pin 10 of the digital-to-analog converter U20, a pin 14 of the digital-to-analog converter U20 is connected with one end of the resistor R82, the other end of the resistor R82 is connected with a pin 13 of the digital-to-analog converter U20, a pin 17 of the digital-to-analog converter U20 is connected with the pin 1 of the digital-to-analog converter U20.

9. The vehicle-mounted broadband satellite communication modem unit according to claim 1, wherein, The CAN bus circuit includes CAN transceiver U118, common mode choke L6018, protection diode D21, capacitor C964, capacitor C965, capacitor C970, capacitor C971, resistor R860, resistor R843 and resistor R842, wherein pin 2 of CAN transceiver U118 is grounded, pin 3 of CAN transceiver U118 is connected to one end of capacitor C964 and power supply, the other end of capacitor C964 is grounded, pin 4 of CAN transceiver U118 is connected to one end of resistor R860, pin 5 of CAN transceiver U118 is connected to one end of capacitor C965 and power supply, the other end of capacitor C965 is grounded, pin 6 of CAN transceiver U118 is connected to pin 1 of common mode choke L6018 and one end of resistor R843, the other end of resistor R843 is connected to pin 2 of common mode choke L6018 and pin 7 of CAN transceiver U118, pin 8 of CAN transceiver U118 is connected to one end of resistor R842, the other end of resistor R842 is grounded, pin 3 of common mode choke L6018 is connected to one end of capacitor C970 and pin 1 of protection diode D21, the other end of capacitor C970 is connected to one end of capacitor C971 and pin 3 of common mode choke L6018, the other end of capacitor C971 is connected to pin 4 of common mode choke L6018 and pin 2 of protection diode D21, pin 3 of protection diode D21 is grounded.

10. The vehicle-mounted broadband satellite communication modem unit of claim 1, wherein, The RS422 chip set includes at least two groups of receiver circuit and transmitter circuit, wherein the receiver circuit includes chip U119, protection diode D32, protection diode D33, resistor R844, resistor R845, resistor R846, resistor R847, resistor R848 and capacitor C966, wherein pin 1 of chip U119 is connected to one end of resistor R845, capacitor C966 and resistor R848, the other end of capacitor C966 is connected to pin 2 of chip U119 and ground, one end of capacitor C966 is connected to power supply, the other end of resistor R848 is connected to pin 3 of chip U119 and one end of resistor R847, the other end of resistor R845 is connected to pin 5 of chip U119, one end of resistor R844 and pin 1 of protection diode D33, the other end of resistor R844 is connected to pin 4 of chip U119, one end of resistor R846 and pin 1 of protection diode D32, the other end of resistor R846 is grounded, pin 2 of protection diode D32 and pin 2 of protection diode D33 are grounded; The transmitter circuit comprises a chip U120, a protection diode D34, a protection diode D36, a resistor R849, a resistor R850, a resistor R851 and a capacitor C967, wherein pin 2 of the chip U120 is connected with one end of the resistor R851, one end of the capacitor C967 and a power supply, the other end of the resistor R851 is connected with pin 3 of the chip U120, the other end of the capacitor C967 is grounded, pin 4 of the chip U120 is connected with one end of the resistor R850, the other end of the resistor R850 is connected with pin 1 of the protection diode D36, pin 5 of the chip U120 is grounded, pin 6 of the chip U120 is connected with one end of the resistor R849, the other end of the resistor R849 is connected with pin 1 of the protection diode D34, pin 2 of the protection diode D34 and pin 2 of the protection diode D36 are grounded.

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