Method for implementing a ground station of broadcast automatic dependent surveillance applied to a civil defense command vehicle

Abstract

The application discloses a broadcast automatic dependent surveillance ground station implementation method applied to a civil air defense command vehicle, and relates to the field of civil air defense command vehicles.The broadcast automatic dependent surveillance ground station comprises a civil air defense ADS-B ground station host, an ADS-B omnidirectional antenna and a civil air defense terminal display and control system; wherein the civil air defense ADS-B ground station host comprises a processing module and a receiving module; the implementation method comprises the following steps: the ADS-B omnidirectional antenna receives data link messages from the air, the civil air defense ADS-B ground station host decodes the data link messages to obtain original messages, the original messages are parsed and recombined, a flight path report is output according to user requirements and is output to the civil air defense terminal display and control system.The application can effectively monitor aircrafts in a target airspace.

Description

Technical Field

[0001] This invention relates to the field of automatic dependent surveillance technology, and in particular to a method for implementing automatic dependent surveillance ground stations for civil defense command vehicles. Background Technology

[0002] Currently, air situation monitoring systems suffer from problems such as limited intelligence sources, poor intelligence channels, and difficulties in training support. Civil defense command vehicles are unable to effectively monitor aircraft within the target airspace. Furthermore, existing ADS-B ground station equipment on the market cannot meet the daily usage requirements of civil defense command vehicles due to its large size, heavy weight, high power consumption, and incompatible output data formats. Summary of the Invention

[0003] In view of this, the present invention provides a method for implementing a broadcast-type automatic dependent surveillance ground station applied to a civil defense command vehicle.

[0004] This invention discloses a method for implementing a broadcast-type automatic dependent surveillance ground station applied to a civil defense command vehicle. The broadcast-type automatic dependent surveillance ground station includes a civil defense ADS-B ground station host, an ADS-B omnidirectional antenna, and a civil defense terminal display and control system. The civil defense ADS-B ground station host includes a processing module and a receiving module. The implementation method includes: The ADS-B omnidirectional antenna receives data link messages from the air. The ADS-B ground station host decodes the data link messages to obtain the original messages, parses and reassembles the original messages, and outputs track reports according to user requirements to the civil defense terminal display and control system.

[0005] Furthermore, the ADS-B ground station host of the civil defense can perform real-time self-checks, determine the status of the host based on the self-check results, and generate a status report; through the civil defense terminal display and control system, the flight track can be displayed intuitively, airspace situation information can be obtained, and the status of the ground station can be remotely monitored and configuration parameters can be modified. The broadcast automatic dependent surveillance ground station also includes an antenna amplifier and a GNSS antenna; the antenna amplifier amplifies the data link messages received by the ADS-B omnidirectional antenna; the GNSS antenna receives GPS and BeiDou signals.

[0006] Furthermore, the processing module mainly performs ADS-B raw message decoding, track processing, GNSS time synchronization and self-detection, and outputs the track report to the civil defense terminal display and control system; The processing module adopts an architecture of a decoding module and processing module software; the decoding module is implemented using an FPGA, and the processing module software is implemented using a CPU; the FPGA completes decoding and HDLC synchronous serial port interface expansion; the CPU completes track processing, self-testing, and system control; the processing module software includes a message receiving module, a message parsing and distribution module, a track tracking module, a user service management module, a system monitoring module, a periodic service module, a track report data generation module, a GNSS servo module, and a time synchronization module; The implementation method of the decoding module includes: The FPGA receives the sampled signal from the receiving module, completes pulse generation, amplitude correlation, leader detection, and deinterleaving decoding to obtain a valid ADS-B message after error correction. The ADS-B message is then output to the CPU for decoding processing via the data bus.

[0007] Furthermore, the signal processing procedure of the decoding module is as follows: The received baseband digital signal undergoes pulse detection to generate a reference level. Simultaneously, it performs three verifications: Mode S validity verification, power consistency verification, and DF validity verification. If all three verifications fail, the preamble of the baseband digital signal is discarded. If all three verifications pass, it is retried, generating a bit and a confidence bit. Error detection is performed on the bit and confidence bit. If an error is found, conservative error correction is performed. If conservative error correction also fails, brute-force error correction is performed. If brute-force error correction fails, the message is discarded. If all three conditions are met—error detection, conservative error correction, and brute-force error correction—the message is sent.

[0008] Furthermore, the implementation method of the message receiving module includes: The ADS-B ground station receiving module receives and decodes ADS-B messages via an RF antenna, performs CRC verification and correctness checks, detects erroneous data, and sets the corresponding alarm status flag in the module; data that passes the correctness check provides correct messages for the message distribution function; the ADS-B ground station can correctly receive and process message types DF17 and DF18. The implementation method of the message parsing and distribution module includes: After receiving ADS-B mode extended discontinuous oscillation messages in DF17 and DF18 formats, the ADS-B ground station first distinguishes the message version and, according to the format specified in RTCA DO-260B, parses each data item into a data format that can be intuitively accessed by the user. For S mode messages, the S mode address and A code are parsed out. After completing the data item parsing, a corresponding timestamp is appended to the data according to the different data types, providing different data information for the implementation of the track tracking function.

[0009] Furthermore, the implementation method of the trajectory tracking module includes: After the message distribution module converts ADS-B messages of different formats into data format information of the same format, the track tracking function uses these messages to establish the track status of the target aircraft and form a complete track file. The content of the track file is based on the integration of RTCA DO-260B and ED-129, and the content is detailed to meet the user's data requirements. After the track tracking is completed, a track update event is actively generated. The implementation method of the user service management module includes: Users of civil defense ADS-B ground station data can use civil defense display and control terminals to establish a network connection with the civil defense ADS-B ground station, obtain surrounding airspace traffic situation information, and remotely maintain the ground station; the civil defense ADS-B ground station provides users with corresponding data according to their needs.

[0010] Furthermore, the implementation method of the system monitoring module includes: The system monitoring module monitors the status of the internal software and hardware of the civil defense ADS-B ground station equipment in real time, detects faults in a timely manner, provides information to network management and maintenance, and then provides warning information to users through the civil defense display and control terminal. The implementation method of the periodic service module includes: The periodic service module provides precise periodic time services, generating periodic messages at the smallest granularity to provide millisecond-level precision for the implementation of other system functions.

[0011] Furthermore, the implementation method of the track report data generation module includes: The track report data generation module selects the correct data from the track file according to the user service list, combines them to generate track reports required by different users, and sends them to the civil defense display and control terminal via UDP for users to obtain relevant information; among which, the relevant information includes the airspace traffic situation around the civil defense ADS-B ground station; the track report is output externally according to the period set by the user; The implementation method of the GNSS servo module includes: The GNSS servo module receives RS232 serial port messages, organizes and saves GNSS information, and obtains precise second pulse signals; the GNSS information includes UTC time, position, and geometric altitude. The implementation method of the time synchronization module includes: The time synchronization module receives the second pulse to obtain the precise timestamp. When the time information provided by the GNSS message exceeds the minimum time error tolerance value of the local system time, it calibrates the local system time.

[0012] Furthermore, the implementation method of the receiving module includes: The receiving module demodulates the radio frequency signal and sends the amplitude sampling signal and synchronization clock of the baseband signal to the decoding board for subsequent processing; at the same time, it sends the baseband video signal to the detection port for detection. The signal received by the antenna is sent to the receiving module via a coupler. First, it passes through an isolator and a limiter, and then is amplified by a low-noise amplifier. The amplified signal enters a filter to remove noise. The filtered high-frequency signal is then mixed with the local oscillator signal and filtered after passing through an RF attenuator to obtain an intermediate frequency (IF) signal. After amplification and filtering, the IF signal is detected and driven to obtain a baseband video signal. This signal is then converted to an analog-to-digital (AD) converter to obtain a digitized baseband signal, which is output to the decoding module.

[0013] Furthermore, the main unit of the civil defense ADS-B ground station also includes a power supply module; the method for implementing the power supply module includes: The power module outputs multiple stable DC voltages through electromagnetic compatibility filtering, voltage surge protection, overvoltage protection, relay remote control AC, rectification filtering, two-stage DC / DC conversion, and low-pass filtering. The power module uses AC power as input. It rectifies and filters the input AC voltage to obtain DC voltage, and then performs DC / DC conversion on the DC voltage to obtain a DC 28V voltage. It can also use a negative DC voltage as input and obtain a positive DC voltage through DC / DC conversion. After external AC-DC conversion, the comparison circuit prioritizes the use of AC, while ensuring seamless switching to another input when one input is open.

[0014] Because of the adoption of the above technical solution, the present invention has the following advantages: 1. Receive target-related information and GNSS positioning information broadcast by airborne vehicles via a 1090MHz data link, and display the ADS-B target's point and track information on a two-dimensional geographic information platform. Simultaneously, effectively monitor key areas / targets of interest in civil defense projects; 2. To generate a universal intelligence format for ADS-B target information (targets that broadcast their own information via the 1090ES data link), and to output GJB5779, 826, 40 and CAT021 format messages, and to be compatible with air defense surveillance systems; 3. Achieve miniaturization and low power consumption design for ADS-B ground stations. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 This is a block diagram of the civil defense ADS-B ground station host system according to an embodiment of the present invention; Figure 2 This is a block diagram illustrating the processing module principle of an embodiment of the present invention; Figure 3 This is a schematic diagram of the decoding module processing flow according to an embodiment of the present invention; Figure 4 This is a functional block diagram of the processing module in an embodiment of the present invention; Figure 5 This is a schematic diagram of the message receiving module processing flow according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the message parsing and distribution module processing flow according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the processing flow of the trajectory tracking module in an embodiment of the present invention; Figure 8 This is a schematic diagram of the user service module function processing flow according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the system monitoring module processing flow according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the processing flow of the periodic service module in an embodiment of the present invention; Figure 11 This is a schematic diagram of the processing flow of the track report data generation module in an embodiment of the present invention; Figure 12 This is a schematic diagram of the GNSS servo module processing flow according to an embodiment of the present invention; Figure 13 This is a schematic diagram of the time synchronization module processing flow according to an embodiment of the present invention; Figure 14 This is a block diagram of the power module according to an embodiment of the present invention. Detailed Implementation

[0017] The present invention will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0018] See Figure 1This invention provides an embodiment of a method for implementing a broadcast-type automatic dependent surveillance ground station applied to a civil defense command vehicle. In this embodiment, the broadcast-type automatic dependent surveillance ground station of the civil defense command vehicle consists of a civil defense ADS-B ground station host, an ADS-B omnidirectional antenna, an antenna amplifier, a GNSS antenna (GPS + Beidou), a civil defense terminal display and control system, cables and accessories, as detailed in Table 1.

[0019] Table 1. Equipment Composition of Civil Defense ADS-B Ground Station

[0020] This embodiment illustrates the working principle and composition of the ADS-B ground station host for civil defense, the implementation methods of the processing module, the receiving module, and the power supply module, as detailed below: 1. Working principle and composition of the ADS-B ground station main unit for civil defense: The ADS-B ground station host, in conjunction with the omnidirectional antenna, receives 1090ES data link messages from the air, decodes them to obtain 112-bit raw messages, parses and reassembles the raw messages, and outputs track reports according to user requirements. These reports are then transmitted to the civil defense terminal display and control system via Ethernet or fiber optic cable. The ADS-B ground station host performs real-time self-tests, determines its own status based on the self-test results, and generates a CAT023 status report. Users can visually display the track, obtain airspace situation information, and remotely monitor the ground station status and modify configuration parameters through the display and control terminal.

[0021] The ADS-B ground station main unit for civil defense consists of four parts: a processing module, a GNSS module, a receiving module, and a power supply module. Figure 1 As shown.

[0022] 2. Implementation method of the processing module: The processing module mainly performs functions such as ADS-B raw message decoding, track processing, GNSS time synchronization, and self-detection. It also outputs track reports to the civil defense terminal display and control system via optical / electrical / serial network.

[0023] The core of the processing module adopts an architecture of a decoding module (FPGA) + processing module software (CPU). The FPGA handles decoding and HDLC synchronous serial port interface expansion; the CPU handles trajectory processing, self-testing, and system control functions. The block diagram of the processing module is shown below. Figure 2 As shown.

[0024] 2.1 Implementation method of the decoding module: The decoding module is implemented using an FPGA. The FPGA receives the sampled signal from the receiving module, performs pulse generation, amplitude correlation, leader detection, deinterleaving decoding, and obtains a valid ADS-B message after error correction. The ADS-B message is then output to the CPU for decoding via the data bus. The signal processing flow of the decoding module is as follows: Figure 3 As shown.

[0025] 2.2 Software Implementation Method of Processing Module: The processing module software is implemented using a CPU. The CPU performs track processing, self-testing, and system control functions. Its functional module diagram is shown below. Figure 4 As shown. The processing module software includes a message receiving module, a message parsing and distribution module, a track tracking module, a user service management module, a system monitoring module, a periodic service module, a track report data generation module, a GNSS servo module, and a time synchronization module, the implementation methods of which are as follows: Message receiving module implementation method: The ADS-B ground station receiving module receives and decodes ADS-B messages via its RF antenna, performs CRC checks and correctness checks, and sets corresponding alarm status flags for erroneous data. Data that passes the correctness check provides the correct messages for the message distribution function. The ADS-B ground station can correctly receive and process DF17 and DF18 message types. The system supports a maximum of 300 ADS-B targets. Simultaneously, the system supports receiving and forwarding messages of types DF00 to DF24 for extracting information such as 3A codes. The message receiving module's processing flow is as follows: Figure 5 As shown.

[0026] Message parsing and distribution module implementation method: After receiving ADS-B 1090MHz S-mode extended discontinuous oscillation messages in DF17 and DF18 formats, the ADS-B ground station first distinguishes the message version and, according to the format specified in RTCA DO-260B, parses each data item into a user-accessible data format. For S-mode messages, the S-mode address and A code are parsed out. After data item parsing, a corresponding timestamp is appended to the data based on its data type, providing different data information for the implementation of the track tracking function. The processing flow of the message parsing and distribution module is as follows: Figure 6 As shown.

[0027] Implementation method of track tracking module: After the message distribution module converts ADS-B messages of different formats into a unified data format, the track tracking function uses these messages to establish the target aircraft's track status, forming a complete track file. The track file content is based on the integrated RTCA DO-260B and ED-129 standards, providing detailed information to meet user data requirements. Furthermore, it proactively generates track update events after completing specific track tracking. The processing flow of the track tracking module is as follows: Figure 7 As shown.

[0028] Implementation method of user service management module: Users are the recipients of data from the Civil Defense ADS-B ground station. They utilize the Civil Defense display and control terminal to establish a network connection with the Civil Defense ADS-B ground station, obtain surrounding airspace traffic situation information, and remotely maintain the ground station. The Civil Defense ADS-B ground station provides users with data tailored to their specific report types and other requirements. The processing flow of the user service management module is as follows: Figure 8 As shown.

[0029] System monitoring module implementation method: The system monitoring module monitors the internal software and hardware status of the civil defense ADS-B ground station equipment in real time, promptly detects faults, provides information to network management and maintenance, and then displays warning messages to users through the civil defense display and control terminal. The processing flow of the system monitoring module is as follows: Figure 9 As shown.

[0030] Implementation method of periodic service module: The periodic service module provides precise periodic timing services, generating periodic messages with the smallest granularity, providing millisecond-level precision for the implementation of other system functions. The processing flow of the periodic service module is as follows: Figure 10 As shown.

[0031] Implementation method of track report data generation module: The track report data generation module selects the correct data from the track files according to the user service list, combines them to generate track reports needed by different users, and sends them to the civil defense display and control terminal via UDP, allowing users to obtain information such as airspace traffic conditions around the civil defense ADS-B ground station. In addition to the standard CAT021 format, the track report data generation module can also generate track reports in various traditional radar intelligence data formats such as GJB5779, 826, and Document No. 40. Track reports are output according to the user-defined cycle. The processing flow of the track report data generation module is as follows: Figure 11 As shown.

[0032] GNSS servo module implementation method: The GNSS servo module receives RS232 serial port messages, organizes and saves GNSS information, including UTC time, position, geometric altitude, and other data, while also obtaining precise second pulse signals. The processing flow of the GNSS servo module is as follows: Figure 12 As shown.

[0033] Time synchronization module implementation method: The time synchronization module receives the second pulse to obtain a precise timestamp. When the time information provided by the GNSS message differs from the local system time by more than the minimum time error tolerance value, the local system time is calibrated. The time synchronization function's processing flow is as follows: Figure 13 As shown.

[0034] Implementation method of the receiving module: The receiving module demodulates the 1090MHz radio frequency signal and sends the amplitude sampling signal of the baseband signal and the synchronization clock to the decoding board for subsequent processing; at the same time, it sends the baseband video signal to the detection port for detection.

[0035] The signal received by the antenna is sent to the receiving module via a coupler. It first passes through an isolator and a limiter before being amplified by a low-noise amplifier. The limiter protects the low-noise amplifier, while the isolator isolates reflections from the limiter. The amplified signal then enters a filter to remove noise. The filtered high-frequency signal is then mixed with the local oscillator signal and filtered again after passing through an RF attenuator to obtain the intermediate frequency (IF) signal. After amplification and filtering, the IF signal is detected and driven to obtain the baseband video signal. This signal is then converted to an analog-to-digital converter (AD) to obtain the digitized baseband signal, which is output to the decoding module.

[0036] The receiving module mainly consists of a coupler, a low-noise amplifier, a filter, a local oscillator, an intermediate frequency filter, digital processing, a self-test signal generator, and video processing components.

[0037] Figure 1 Implementation method of the power module in the document: The power module outputs multiple stable DC voltages through electromagnetic compatibility filtering, voltage surge protection, overvoltage protection, relay remote control AC, rectification filtering, two-stage DC / DC conversion, and low-pass filtering.

[0038] The power module uses 220V / 50Hz AC power as input. It rectifies and filters the input 220V AC to obtain 300V DC, then performs a DC / DC conversion to obtain 28V DC. Alternatively, it uses -48V DC as input, which is converted to 24V DC. After external AC / DC conversion, a comparator circuit prioritizes AC input while ensuring seamless switching between inputs. Figure 14 As shown.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for implementing a broadcast-type automatic dependent surveillance ground station applied to a civil defense command vehicle, characterized in that, The broadcast-type automatic dependent surveillance ground station includes a civil defense ADS-B ground station host, an ADS-B omnidirectional antenna, and a civil defense terminal display and control system; wherein, the civil defense ADS-B ground station host includes a processing module and a receiving module; The implementation method includes: The ADS-B omnidirectional antenna receives data link messages from the air. The civil defense ADS-B ground station host decodes the data link messages to obtain the original messages, parses and reassembles the original messages, and outputs a trajectory report according to the user's requirements and outputs it to the civil defense terminal display and control system. The processing module completes ADS-B raw message decoding, track processing, GNSS time synchronization and self-detection, and outputs the track report to the civil defense terminal display and control system. The processing module adopts an architecture of a decoding module and processing module software; the decoding module is implemented using an FPGA, and the processing module software is implemented using a CPU; the FPGA completes decoding and HDLC synchronous serial port interface expansion; the CPU completes track processing, self-testing, and system control; the processing module software includes a message receiving module, a message parsing and distribution module, a track tracking module, a user service management module, a system monitoring module, a periodic service module, a track report data generation module, a GNSS servo module, and a time synchronization module; The implementation method of the decoding module includes: The FPGA receives the sampled signal from the receiving module, completes pulse generation, amplitude correlation, leader detection and deinterleaving decoding, and obtains a valid ADS-B message after error correction. The ADS-B message is then output to the CPU for decoding processing via the data bus. The signal processing procedure of the decoding module is as follows: The received baseband digital signal undergoes pulse detection to generate a reference level. Simultaneously, it performs three verifications: Mode S validity verification, power consistency verification, and DF validity verification. If all three verifications fail, the preamble of the baseband digital signal is discarded. If all three verifications pass, it is retried, generating a bit and a confidence bit. Error detection is performed on the bit and confidence bit. If an error is found, conservative error correction is performed. If conservative error correction also fails, brute-force error correction is performed. If brute-force error correction fails, the message is discarded. If all three conditions are met—error detection, conservative error correction, and brute-force error correction—the message is sent. The implementation method of the message receiving module includes: The ADS-B ground station receiving module receives and decodes ADS-B messages via an RF antenna, performs CRC verification and correctness checks, detects erroneous data, and sets the corresponding alarm status flag in the module; data that passes the correctness check provides correct messages for the message distribution function; the ADS-B ground station can correctly receive and process message types DF17 and DF18. The implementation method of the message parsing and distribution module includes: After receiving ADS-B mode extended intermittent oscillation messages in DF17 and DF18 formats, the ADS-B ground station first distinguishes the message version and, according to the format specified in RTCA DO-260B, parses each data item into a data format that can be intuitively accessed by the user. For S mode messages, the S mode address and A code are parsed out. After completing the data item parsing, a corresponding timestamp is appended to the data according to the different data types, providing different data information for the implementation of the track tracking function. The implementation method of the trajectory tracking module includes: After the message distribution module converts ADS-B messages of different formats into data format information of the same format, the track tracking function uses these messages to establish the track status of the target aircraft and form a complete track file. The content of the track file is based on the integration of RTCA DO-260B and ED-129, and the content is detailed to meet the user's data requirements. After the track tracking is completed, a track update event is actively generated. The implementation method of the user service management module includes: Users of civil defense ADS-B ground station data can use civil defense display and control terminals to establish a network connection with the civil defense ADS-B ground station, obtain surrounding airspace traffic situation information, and remotely maintain the ground station; the civil defense ADS-B ground station provides users with corresponding data according to their needs; The implementation method of the system monitoring module includes: The system monitoring module monitors the status of the internal software and hardware of the civil defense ADS-B ground station equipment in real time, detects faults in a timely manner, provides information to network management and maintenance, and then provides warning information to users through the civil defense display and control terminal. The implementation method of the periodic service module includes: The periodic service module provides precise periodic time services, generating periodic messages at the smallest granularity to provide millisecond-level precision for the implementation of other system functions; The implementation method of the trajectory report data generation module includes: The track report data generation module selects the correct data from the track file according to the user service list, combines them to generate track reports required by different users, and sends them to the civil defense display and control terminal via UDP for users to obtain relevant information; among which, the relevant information includes the airspace traffic situation around the civil defense ADS-B ground station; the track report is output externally according to the period set by the user; The implementation method of the GNSS servo module includes: The GNSS servo module receives RS232 serial port messages, organizes and saves GNSS information, and obtains precise second pulse signals; the GNSS information includes UTC time, position, and geometric altitude. The implementation method of the time synchronization module includes: The time synchronization module receives the second pulse to obtain the precise timestamp. When the time information provided by the GNSS message exceeds the minimum time error tolerance value of the local system time, it calibrates the local system time.

2. The method according to claim 1, characterized in that, The ADS-B ground station host of the civil defense can perform real-time self-test, determine the status of the unit based on the self-test results, and generate a status report; the flight track can be displayed intuitively through the civil defense terminal display and control system, airspace situation information can be obtained, and the status of the ground station can be remotely monitored and configuration parameters can be modified. The broadcast automatic dependent surveillance ground station also includes an antenna amplifier and a GNSS antenna; the antenna amplifier amplifies the data link messages received by the ADS-B omnidirectional antenna; the GNSS antenna receives GPS and BeiDou signals.

3. The method according to claim 1, characterized in that, The implementation method of the receiving module includes: The receiving module demodulates the radio frequency signal and sends the amplitude sampling signal and synchronization clock of the baseband signal to the decoding board for subsequent processing; at the same time, it sends the baseband video signal to the detection port for detection. The signal received by the antenna is sent to the receiving module via a coupler. First, it passes through an isolator and a limiter, and then is amplified by a low-noise amplifier. The amplified signal enters a filter to remove noise. The filtered high-frequency signal is then mixed with the local oscillator signal and filtered after passing through an RF attenuator to obtain an intermediate frequency (IF) signal. After amplification and filtering, the IF signal is detected and driven to obtain a baseband video signal. This signal is then converted to an analog-to-digital (AD) converter to obtain a digitized baseband signal, which is output to the decoding module.

4. The method according to claim 1, characterized in that, The civil defense ADS-B ground station host also includes a power supply module; the implementation method of the power supply module includes: The power module outputs multiple stable DC voltages through electromagnetic compatibility filtering, voltage surge protection, overvoltage protection, relay remote control AC, rectification filtering, two-stage DC / DC conversion, and low-pass filtering. The power module uses AC power as input. It rectifies and filters the input AC voltage to obtain DC voltage, and then performs DC / DC conversion on the DC voltage to obtain a DC 28V voltage. It can also use a negative DC voltage as input and obtain a positive DC voltage through DC / DC conversion. After external AC-DC conversion, the comparison circuit prioritizes the use of AC and ensures seamless switching to another input when one input terminal is open.

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