A method for constructing a distributed DME ranging system

Abstract

This application discloses a method for constructing a distributed DME ranging system, relating to the fields of navigation technology and network communication technology. The method involves mounting a ground-based DME antenna, a first remote radio frequency unit, a second remote radio frequency unit, and a radio frequency switch assembly on the top of a tower; placing a first response control unit, a second response control unit, and a status control unit in an equipment rack within a computer room, and installing a remote control unit in a monitoring room; designing a dual-backup architecture with three operating modes, selecting the backup mode according to different scenarios; after the interrogation pulse emitted by the aircraft's onboard interrogator is received by the ground-based DME antenna, it is forwarded to the currently operating transponder via the radio frequency switch assembly for processing and generation of a response pulse, which is then forwarded back to the ground-based DME antenna via the radio frequency switch assembly for response, thus achieving aircraft positioning. This method solves the problems of insufficient scenario adaptability and generalization capability of existing DME systems and reduces radio frequency cable loss.

Description

Technical Field

[0001] This application relates to the fields of navigation technology and network communication technology, and in particular to a method for constructing a distributed DME ranging system. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) have made significant progress in the aviation field, but because GNSS signals are highly susceptible to interference and spoofing, ground-based navigation remains one of the most widely used navigation technologies in civil aviation. Distance measuring systems (DMEs) are an indispensable component of ground-based navigation.

[0003] The DME system provides the slant range of the aircraft relative to the ground-based DME station. When used in conjunction with a VHF omnidirectional beacon (VOR), the DME forms a range-azimuth polar coordinate positioning system; when used in conjunction with an Instrument Landing System (ILS), the DME provides distance information for aircraft approach and landing; the DME system can also be used independently to determine the aircraft's position using at least two DME stations, providing operational support for PBN (Performance-Based Navigation).

[0004] In addition to traditional ground-based navigation ground-based distance measuring (DME) systems, in recent years, to adapt to the development of the low-altitude economy and general aviation market, the research and development of DME ground equipment has been moving towards miniaturization, portability, and low cost. Some DME equipment needs to be installed on telecommunications towers, co-located with communication equipment to achieve resource savings and cost reduction.

[0005] However, existing DME systems are designed for specific scenarios, have fixed operating modes, and are limited by the signal attenuation problem of radio frequency cables, resulting in reduced transmission power of DME systems and aircraft being unable to obtain accurate positioning information. Summary of the Invention

[0006] In this embodiment of the application, a method for constructing a distributed DME ranging system is provided, which solves the problem of insufficient scenario adaptability and generalization ability of existing DME systems and reduces the line loss of radio frequency cables.

[0007] In a first aspect, embodiments of this application provide a method for constructing a distributed DME ranging system. This method includes: mounting a ground-based DME antenna, a first remote radio frequency unit, a second remote radio frequency unit, and a radio frequency switch assembly on the top of a tower; placing a first response control unit, a second response control unit, and a status control unit in an equipment rack within a computer room, and installing a remote control unit in a monitoring room; designing a dual-backup architecture with three working modes: cold backup, hot backup, and regular backup, selecting the backup mode according to different scenarios; wherein the first remote radio frequency unit and the first response control unit constitute a first transponder, the second remote radio frequency unit and the second response control unit constitute a second transponder, and the first and second transponders implement the dual-backup architecture; the aircraft's onboard interrogator transmits... After the interrogation pulse is received by the ground-based DME antenna, it is forwarded to the currently operating transponder via the radio frequency switching assembly for processing and generation of a response pulse. The response pulse is then forwarded to the ground-based DME antenna via the radio frequency switching assembly for response, thus achieving aircraft positioning. The first transponder and the second transponder serve as the operating transponder and backup transponder, respectively. The monitors in the first and second transponder control units monitor the operating status of the currently operating transponder through couplers inside the first and second remote radio frequency units. The status control unit and the remote control unit realize the system status display and control functions. The ground-based DME antenna type is selected according to actual needs, and the internal structure and parameters of the radio frequency switching assembly, remote radio frequency unit, and transponder control unit are configured.

[0008] In one possible implementation, the ground-based DME antenna is connected to an RF switch assembly via two RF cables. The two RF cables are used to transmit interrogation pulse signals received from the aircraft from the ground-based DME antenna, and to transmit response pulse signals returned from the RF switch assembly back to the ground-based DME antenna for transmission. The RF switch assembly is connected to a first remote RF unit and a second remote RF unit via two sets of RF cables. The first remote RF unit is connected to a first response control unit via a set of data buses and a set of control buses. The second remote RF unit is connected to a second response control unit via a set of data buses and a set of control buses. The first and second response control units are connected to a status control unit via control buses. A remote control unit is connected to the first and second response control units via network cables. Couplers inside the first and second remote RF units couple RF pulse signals to monitors inside the first and second remote RF units, respectively.

[0009] In one possible implementation, the selection of backup modes according to different scenarios includes: In cold backup mode, the backup transponder is completely inactive, the system operates at low power, and the time to switch from the active transponder to the backup transponder is greater than 10 seconds, suitable for scenarios with low switching time requirements and energy conservation needs; In hot backup mode, the backup transponder operates normally, and the output radio frequency response signal is sent to the load, with the time to switch from the active transponder to the backup transponder less than 1 second, suitable for scenarios with high real-time requirements; In conventional backup mode, the power amplifier module of the backup transponder is inactive, all other components operate normally, the system power consumption is low, and the time to switch from the active transponder to the backup transponder is less than 10 seconds, suitable for scenarios such as air routes where a balance between power consumption and switching time is required.

[0010] In one possible implementation, the interrogation pulse emitted by the aircraft's onboard interrogator is received by the ground-based DME antenna and forwarded to the currently operating transponder via a radio frequency switching assembly for processing and generation of a response pulse. The response pulse is then forwarded to the ground-based DME antenna via the radio frequency switching assembly for response, thus achieving aircraft positioning. This includes: the aircraft's onboard interrogator sending an interrogation pulse to the ground-based DME antenna via its onboard antenna; the ground-based DME antenna receiving the pulse; and the radio frequency selection switch in the radio frequency switching assembly forwarding the received interrogation pulse to the operating transponder. In the operating transponder, the receiving channel in the remote radio frequency unit amplifies and mixes the interrogation pulse signal to generate an intermediate frequency (IF) signal. The response processing board in the response control unit decodes and delays the IF signal and, together with other pulses generated by the response processing board, follows the system's specified priority order. The system first generates a trigger pulse signal. The 1kW / 100W power amplifier module modulates and amplifies the trigger pulse signal into an RF pulse signal that meets the system requirements. The response pulse is forwarded to the ground DME antenna via an RF selection switch for response. The aircraft receives the response pulse and uses it for positioning. The monitor obtains one response pulse through a coupler, selects any transponder to send an interrogation pulse signal, and generates a status monitoring pulse signal based on the coupled response pulse. The main control board controls the monitor and response processing board through the control bus and communicates with the status control unit and remote control unit to monitor the transponder's operating status. The response pulse signal generated by the operating transponder is coupled out through the coupler to the receiving channel. After being frequency-converted by 63MHz, it forms a pilot pulse signal, which is then corrected for the transponder's own channel delay in the response processing board.

[0011] In one possible implementation, the selection of the ground DME antenna type according to actual needs includes: the ground DME antenna type includes a single omnidirectional antenna and a multi-element antenna array; a single omnidirectional antenna is suitable for situations where installation time is tight; when extensive and uniform signal coverage is required, a multi-element antenna array is selected.

[0012] In one possible implementation, the internal structure and parameters of the configured radio frequency switch assembly, remote radio frequency unit, and response control unit include: the radio frequency switch assembly includes a load, a radio frequency selection switch, and two duplexers, which are respectively connected to the ground DME antenna to achieve mutual backup; in hot backup mode, the response pulse signal output by the backup transponder is output to the load by the radio frequency selection switch for absorption and impedance matching; both the first and second remote radio frequency units include a receiving channel, a 1kW / 100W power amplifier module, and a coupler, the receiving channel being responsible for amplifying and mixing the interrogation pulse signal to generate an intermediate frequency signal; the equipment with the optional 1kW power amplifier module can be used alone or in conjunction with a VOR station for route guidance, and the equipment with the optional 100W power amplifier module can be used in conjunction with ILS / MLS for terminal area and approach guidance; the coupler couples the radio frequency pulse signal to the monitor and the corresponding receiving channel respectively; both the first and second response control units include a response processing board, a monitor, and a main control board.

[0013] One or more technical solutions provided in the embodiments of this application have at least the following technical effects: This application provides a method for constructing a distributed DME ranging system. The ground DME antenna, first remote radio frequency unit, second remote radio frequency unit, and radio frequency switch assembly are mounted on the top of a tower. The first response control unit, second response control unit, and status control unit are housed in an equipment rack within a computer room, and the remote control unit is installed in a monitoring room. A dual-backup architecture with three operating modes—cold backup, hot backup, and regular backup—is designed, with the backup mode selected according to different scenarios. Interrogation pulses emitted by the aircraft's onboard interrogator are received by the ground DME antenna and forwarded to the currently operating transponder via the radio frequency switch assembly for processing and generation of response pulses. The response pulses are then forwarded back to the ground DME antenna via the radio frequency switch assembly for response, achieving aircraft positioning. Monitors in the first and second response control units monitor the operating status of the currently operating transponder through couplers within the first and second remote radio frequency units. The status control unit and remote control unit provide system status display and control functions. The ground DME antenna type is selected according to actual needs, and the internal structure and parameters of the radio frequency switch assembly, remote radio frequency unit, and response control unit are configured. This application addresses the shortcomings of existing DME systems in terms of scenario adaptability and generalization capabilities. It features multiple DME system operating modes to adapt to diverse scenarios, enabling aircraft to obtain accurate positioning information and reducing RF cable loss. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A flowchart illustrating a method for constructing a distributed DME ranging system, as provided in this application embodiment; Figure 2 This is a schematic diagram of a distributed DME ranging system provided in an embodiment of this application. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0017] The following description of some technologies involved in the embodiments of this application is provided to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, some descriptions of well-known functions and structures are omitted in the following description.

[0018] This application provides a method for constructing a distributed DME ranging system, such as... Figure 1 As shown, the method includes steps S101 to S105. Wherein, Figure 1 This is merely one execution order shown in the embodiments of this application and does not represent the only execution order for a method of constructing a distributed DME ranging system. Where the final result can be achieved, Figure 1 The steps shown can be performed in parallel or in reverse order.

[0019] S101: The ground-based DME antenna, the first remote radio frequency unit, the second remote radio frequency unit, and the radio frequency switch assembly are installed on the top of the tower. The first response control unit, the second response control unit, and the status control unit are placed in the equipment cabinet inside the equipment room, and the remote control unit is installed in the monitoring room.

[0020] Specifically, the ground-based DME antenna, as a key interface for communication with the aircraft, is responsible for receiving interrogation pulse signals from the aircraft's onboard interrogator and transmitting the system-generated response pulse signals back to the aircraft to achieve positioning functionality. The aircraft consists of an onboard interrogator and an onboard antenna.

[0021] The remote control unit provides operators with a convenient way to remotely control the system. Operators can fully control the system and view the system status in real time from the monitoring room through the remote control unit, achieving similar functions to the status control unit, but with the flexibility of remote operation.

[0022] The ground-based DME antenna is connected to the radio frequency switching assembly via two radio frequency cables. The two radio frequency cables are used to transmit interrogation pulse signals received from the aircraft from the ground-based DME antenna, and to transmit response pulse signals returned from the radio frequency switching assembly to the ground-based DME antenna for transmission.

[0023] The radio frequency switch assembly is connected to the first remote radio frequency unit and the second remote radio frequency unit via two sets of radio frequency cables, respectively.

[0024] Specifically, this connection method enables the RF switch assembly to flexibly control the switching of signals between different remote RF units, accurately forwarding the interrogation pulse signal to the corresponding transponder according to the system's operating mode and actual needs, ensuring the efficient operation of the system.

[0025] The first remote radio frequency unit is connected to the first response control unit via a set of data buses and a set of control buses. The second remote radio frequency unit is connected to the second response control unit via a set of data buses and a set of control buses.

[0026] Specifically, the data bus is responsible for transmitting various data information, such as processed intermediate frequency signals, between the remote radio frequency unit and the response control unit; the control bus is used to transmit control commands, enabling the response control unit to accurately control and monitor the working status of the remote radio frequency unit, and realize the collaborative work between the two.

[0027] The first response control unit and the second response control unit are respectively connected to the status control unit via a control bus.

[0028] The remote control unit is connected to the first response control unit and the second response control unit via network cables.

[0029] Couplers inside the first and second remote RF units couple RF pulse signals to monitors inside the first and second remote RF units, respectively.

[0030] Specifically, the monitor can acquire relevant information about the radio frequency pulse signal in real time, monitor and analyze the working status of the remote radio frequency unit in real time, and promptly detect and report any possible faults or abnormalities, thus providing a strong guarantee for the stable operation of the system.

[0031] S102: Designed with a dual-backup architecture featuring three working modes: cold backup, hot backup, and regular backup, allowing selection of the backup mode based on different scenarios. Specifically, the first remote radio frequency unit and the first response control unit constitute the first transponder, while the second remote radio frequency unit and the second response control unit constitute the second transponder. The first and second transponders implement the dual-backup architecture.

[0032] Choose the backup mode according to different application scenarios, including the following:

[0033] In cold backup mode, the backup transponder is completely inactive, and the system operates at low power. The time to switch from the active transponder to the backup transponder is greater than 10 seconds, making it suitable for scenarios with low switching time requirements and energy-saving needs.

[0034] In hot backup mode, the backup transponder works normally and sends the output radio frequency response signal to the load. The time to switch from the working transponder to the backup transponder is less than 1 second, which is suitable for scenarios with high real-time requirements.

[0035] In the normal backup working mode, the power amplifier module of the backup transponder does not work, while the other components work normally. The system power consumption is low, and the time to switch from the working transponder to the backup transponder is less than 10 seconds. It is suitable for scenarios such as air routes where there are requirements for balancing power consumption and switching time.

[0036] S103: The interrogation pulse emitted by the aircraft's onboard interrogator is received by the ground-based DME antenna and forwarded to the currently operating transponder via an RF switching assembly for processing and generation of a response pulse. The response pulse is then forwarded to the ground-based DME antenna via the RF switching assembly for response, thus achieving aircraft positioning. The first transponder and the second transponder serve as the operating transponder and backup transponder, respectively.

[0037] For example, when the first transponder is a working transponder, the second transponder is a backup transponder; when the first transponder is a backup transponder, the second transponder is a working transponder.

[0038] The interrogation pulses emitted by the aircraft's onboard interrogator are received by the ground-based DME antenna and then forwarded to the currently operating transponder via the radio frequency switching assembly for processing and generation of a response pulse. The response pulses are then forwarded to the ground-based DME antenna via the radio frequency switching assembly for response, thereby achieving aircraft positioning, including the following:

[0039] The aircraft's onboard interrogator sends an interrogation pulse to the ground-based DME antenna via the onboard antenna. After the ground-based DME antenna receives the pulse, the radio frequency selection switch in the radio frequency switching assembly forwards the received interrogation pulse to the working transponder.

[0040] For example, if the first transponder is currently active, the radio frequency selection switch will direct the interrogation pulse to the first transponder.

[0041] In the working transponder, the receiving channel in the remote radio frequency unit amplifies and mixes the interrogation pulse signal to generate an intermediate frequency signal. The response processing board in the response control unit decodes and delays the intermediate frequency signal and generates a trigger pulse signal together with other pulses generated by the response processing board according to the priority level specified by the system. The 1kW / 100W power amplifier module modulates and amplifies the trigger pulse signal into a radio frequency pulse signal that meets the requirements of the system.

[0042] The response pulse is forwarded to the ground DME antenna via a radio frequency selection switch for response, and the aircraft uses the response pulse to locate itself.

[0043] The monitor obtains one response pulse through the coupler, selects any transponder to send an interrogation pulse signal, and generates a status monitoring pulse signal based on the coupled response pulse. The main control board controls the monitor and response processing board through the control bus, and communicates with the status control unit and remote control unit to monitor the working status of the transponders.

[0044] The response pulse signal generated by the working transponder is coupled out to the receiving channel through the coupler. After being frequency-converted by 63MHz, it is transformed into a pilot pulse signal, which is used in the response processing board to correct the channel delay of the working transponder.

[0045] Specifically, the correction process is crucial to ensuring the accuracy and consistency of the response pulse signal output by the transponder. It can effectively eliminate delay errors caused by signal transmission and processing, and improve the accuracy and reliability of the entire DME ranging system.

[0046] S104: The monitors in the first and second response control units monitor the working status of the currently working transponder through the couplers inside the first and second remote radio frequency units. The status control unit and the remote control unit realize the system status display and control functions.

[0047] Specifically, both the first and second response control units are equipped with monitors. When the system is operational, the currently operating transponder generates a response pulse signal. During transmission, these response pulse signals pass through couplers located within the first and second remote radio frequency (RF) units. The coupler's function is to couple a portion of the signal from the main signal path at a certain ratio, creating a separate response pulse signal that is transmitted to the monitors in both units. For example, if the first transponder, composed of the first RF unit and the first response control unit, is operational, the coupler within the first RF unit will couple a portion of the response pulse signal generated by the first transponder and transmit it to the monitor in the first response control unit. Similarly, if the second transponder, composed of the second RF unit and the second response control unit, is operational, the coupler within the second RF unit will transmit the signal to the monitor in the second response control unit. Upon receiving the response pulse signal transmitted through the coupler, the monitor performs a series of processes under program control. It can select any transponder to receive a monitoring and interrogation pulse signal according to a preset program. This monitoring and interrogation pulse signal is then transmitted to the corresponding transponder via the RF switch assembly transmission path.

[0048] Upon receiving a monitoring interrogation pulse signal, the transponder generates a response pulse signal according to the normal procedure. Simultaneously, the monitor generates a status monitoring pulse signal based on the coupled response pulse signals (including the response pulses from the active transponder and the response pulse signals from its own monitoring interrogation). By comparing and analyzing the characteristics of these signals, such as signal strength, frequency, and time interval, the monitor can determine whether the currently active transponder is operating normally. For example, if the strength of the response pulse signal is abnormally weakened or the time interval changes irregularly, the monitor can determine that the active transponder may be malfunctioning or unstable.

[0049] S105: Select the ground DME antenna type according to actual needs, and configure the internal structure and parameters of the RF switch assembly, remote RF unit and response control unit.

[0050] Select the type of terrestrial DME antenna based on actual needs, including the following: Ground-based DME antenna types include single omnidirectional antennas and multi-element antenna arrays.

[0051] A single omnidirectional antenna is suitable for situations where installation time is tight.

[0052] Specifically, when faced with tight installation deadlines, a single omnidirectional antenna is a more ideal choice. Its installation process is relatively simple, requiring no complex debugging and calibration work, enabling rapid deployment and putting the DME ranging system into use as quickly as possible. For example, in temporary navigation points or emergency rescue scenarios where navigation services need to be established quickly, a single omnidirectional antenna can meet the need for rapid deployment due to its convenient installation characteristics. However, single omnidirectional antennas also have certain limitations. Because towers can obstruct the antenna to some extent, radiation blind spots may form in certain directions. In cases where the tower structure is complex or the surrounding environment has many obstacles, radiation blind spots may affect the signal coverage and quality, thereby affecting the aircraft's positioning accuracy.

[0053] When a wide and uniform signal coverage is required, choose a multi-element antenna array.

[0054] Specifically, multi-element antenna arrays are a superior choice when wide and uniform signal coverage is required. Multi-element antenna arrays can be arranged around a tower, and by rationally designing the number, spacing, and arrangement of antenna elements, they can effectively extend the signal coverage area and make the signal strength more uniform in all directions. For example, in large airports or areas with frequent air traffic, where stable and reliable navigation services are needed for a large number of aircraft, multi-element antenna arrays can ensure that aircraft in different positions and flight attitudes can accurately receive DME signals, achieving precise positioning. Multi-element antenna arrays not only improve signal coverage and quality, but also allow for flexible control of the signal propagation direction and shape through beamforming and other technologies, further optimizing navigation performance. For example, the beam direction of the antenna array can be adjusted according to the airport runway layout and the aircraft's flight trajectory, making the signal more concentrated in key areas, improving navigation accuracy and safety.

[0055] Configure the internal structure and parameters of the RF switch assembly, remote RF unit, and response control unit, including the following:

[0056] Figure 2This is a schematic diagram of a distributed DME ranging system provided in an embodiment of this application. The radio frequency switch assembly (RRU3) includes a load, a radio frequency selection switch, and two duplexers. The two duplexers are connected to the ground-based DME antenna, providing mutual backup. In hot backup mode, the response pulse signal output by the backup transponder is output to the load via the radio frequency selection switch for absorption and impedance matching. Both the first remote radio frequency unit (RRU1) and the second remote radio frequency unit (RRU2) include a receiving channel, a 1kW / 100W power amplifier module, and a coupler. The receiving channel amplifies and mixes the interrogation pulse signal to generate an intermediate frequency signal. The device equipped with the 1kW power amplifier module can be used independently or in conjunction with a VOR station for en-route guidance. The device equipped with the 100W power amplifier module can be used in conjunction with an ILS / MLS (Instrument Landing System / Microwave Landing System) for terminal area and approach guidance. The coupler couples the radio frequency pulse signal to the monitor and the corresponding receiving channel, respectively. Both the first and second response control units (BBU1 and BBU2) include a response processing board, a monitor, and a main control board. The status control unit is BBU3.

[0057] Specifically, under normal operating conditions, the two duplexers work together to ensure stable signal transmission. When one duplexer fails, the other duplexer can quickly take over, ensuring continuous system operation and improving system reliability and stability.

[0058] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for constructing a distributed DME ranging system, characterized in that, include: The ground-based DME antenna, the first remote radio frequency unit, the second remote radio frequency unit, and the radio frequency switch assembly are installed on the top of the tower; the first response control unit, the second response control unit, and the status control unit are installed in the equipment cabinet in the computer room, and the remote control unit is installed in the monitoring room. The design features a dual-backup architecture with three working modes: cold backup, hot backup, and regular backup. The backup mode is selected according to different scenarios. The first remote radio frequency unit and the first response control unit constitute the first transponder, and the second remote radio frequency unit and the second response control unit constitute the second transponder. The first transponder and the second transponder realize the dual-backup architecture. The interrogation pulse sent by the aircraft's onboard interrogator is received by the ground DME antenna and forwarded to the currently working transponder via the radio frequency switching assembly for processing and generation of a response pulse. The response pulse is then forwarded to the ground DME antenna via the radio frequency switching assembly for response, thereby achieving aircraft positioning. The first transponder and the second transponder serve as the working transponder and the backup transponder, respectively. The monitors in the first and second response control units monitor the working status of the currently working transponders through the couplers inside the first and second remote radio frequency units. The status control unit and remote control unit realize the system status display and control functions. Select the ground-based DME antenna type according to actual needs, and configure the internal structure and parameters of the RF switch assembly, remote RF unit, and response control unit. In cold backup mode, the backup transponder is completely inactive, and the system operates at low power. The time to switch from the active transponder to the backup transponder is greater than 10 seconds, which is suitable for scenarios with low switching time requirements and energy saving. In hot backup mode, the backup transponder works normally and the output radio frequency response signal is sent to the load. The time to switch from the working transponder to the backup transponder is less than 1 second, which is suitable for scenarios with high real-time requirements. In the normal backup working mode, the power amplifier module of the backup transponder does not work, while the other components work normally. The system power consumption is low, and the time to switch from the working transponder to the backup transponder is less than 10 seconds. It is suitable for scenarios where the route has requirements for balancing power consumption and switching time.

2. The method for constructing a distributed DME ranging system according to claim 1, characterized in that, The ground-based DME antenna is connected to the radio frequency switch assembly via two radio frequency cables. The two radio frequency cables are used to transmit the interrogation pulse signal received from the aircraft from the ground-based DME antenna, and to transmit the response pulse signal returned from the radio frequency switch assembly to the ground-based DME antenna for transmission. The radio frequency switch assembly is connected to the first remote radio frequency unit and the second remote radio frequency unit via two sets of radio frequency cables, respectively. The first remote radio frequency unit is connected to the first response control unit through a set of data buses and a set of control buses; The second remote radio frequency unit is connected to the second response control unit via a set of data buses and a set of control buses; The first and second response control units are respectively connected to the status control unit via a control bus; The remote control unit is connected to the first response control unit and the second response control unit via network cables; Couplers inside the first and second remote RF units couple RF pulse signals to monitors inside the first and second remote RF units, respectively.

3. The method for constructing a distributed DME ranging system according to claim 1, characterized in that, The interrogation pulse emitted by the aircraft's onboard interrogator is received by the ground-based DME antenna, and then forwarded to the currently operating transponder via a radio frequency switching assembly for processing and generation of a response pulse. The response pulse is then forwarded to the ground-based DME antenna via the radio frequency switching assembly for response, thereby achieving aircraft positioning, including: The aircraft's onboard interrogator sends an interrogation pulse to the ground-based DME antenna via the onboard antenna. After the ground-based DME antenna receives the pulse, the radio frequency selection switch in the radio frequency switching assembly forwards the received interrogation pulse to the working transponder. In the working transponder, the receiving channel in the remote radio frequency unit amplifies and mixes the interrogation pulse signal to generate an intermediate frequency signal. The response processing board in the response control unit decodes and delays the intermediate frequency signal and generates a trigger pulse signal together with other pulses generated by the response processing board according to the priority level specified by the system. The 1kW / 100W power amplifier module modulates and amplifies the trigger pulse signal into a radio frequency pulse signal that meets the requirements of the system. The response pulse is forwarded to the ground DME antenna via a radio frequency selective switch for response, and the aircraft receives the response pulse to locate itself. The monitor obtains one response pulse through the coupler, selects any transponder to send an interrogation pulse signal, and generates a status monitoring pulse signal based on the coupled response pulse. The main control board controls the monitor and response processing board through the control bus, and communicates with the status control unit and remote control unit to monitor the working status of the transponders. The response pulse signal generated by the working transponder is coupled out to the receiving channel through the coupler. After being frequency-converted by 63MHz, it is transformed into a pilot pulse signal, which is used in the response processing board to correct the channel delay of the working transponder.

4. The method for constructing a distributed DME ranging system according to claim 1, characterized in that, The selection of the ground-based DME antenna type according to actual needs includes: Ground-based DME antenna types include single omnidirectional antennas and multi-element antenna arrays; A single omnidirectional antenna is suitable for situations where installation time is tight. When a wide and uniform signal coverage is required, choose a multi-element antenna array.

5. The method for constructing a distributed DME ranging system according to claim 1, characterized in that, The internal structure and parameters of the configured radio frequency switch assembly, remote radio frequency unit, and response control unit include: The radio frequency switching assembly includes a load, a radio frequency selection switch, and two duplexers. The two duplexers are connected to the ground DME antenna respectively to achieve mutual backup. In hot backup mode, the response pulse signal output by the backup transponder during normal operation is output to the load via an RF selection switch for absorption and impedance matching. Both the first and second remote radio frequency units include a receiving channel, a 1kW / 100W power amplifier module, and a coupler. The receiving channel is responsible for amplifying and mixing the interrogation pulse signal to generate an intermediate frequency signal. The equipment with the optional 1kW power amplifier module can be used alone or in conjunction with the VOR station for en-route guidance; the equipment with the optional 100W power amplifier module can be used in conjunction with the ILS / MLS for terminal area and approach guidance. The coupler couples the radio frequency pulse signal to the monitor and the corresponding receiving channel, respectively; Both the first and second response control units include a response processing board, a monitor, and a main control board.

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