Foldable coaxial rotor electromagnetic signal interference troubleshooting system and method

Abstract

The present application belongs to the technical field of electromagnetic signal interference troubleshooting, and particularly relates to a coaxial rotor electromagnetic signal interference troubleshooting system and method with a foldable launching cylinder. The electromagnetic signal interference troubleshooting system adopts a coaxial rotor unmanned aerial vehicle carrying a foldable direction-finding antenna array. The aerial part is foldable as a whole and can be accommodated in a launching cylinder after folding. The system can be launched by the launching cylinder, facilitating portability and rapid deployment, and meeting the application requirements of special occasions such as in-vehicle launching or airborne dropping. The coaxial rotor unmanned aerial vehicle carries a multi-antenna monitoring and direction-finding load. The coaxial rotor unmanned aerial vehicle flies in a tilted rotor disc mode. Compared with a multi-rotor unmanned aerial vehicle, the attitude changes little during flight, and the influence on the antenna array attitude is small. The unmanned aerial vehicle can continuously direction-find electromagnetic targets during flight. The system is provided with an antenna control mechanism, which can adaptively adjust the antenna array spacing in the air according to the required frequency range, expand the direction-finding frequency range of the system, avoid ambiguity, and improve the working efficiency of the system.

Description

Electromagnetic signal interference troubleshooting system and method for foldable coaxial rotor Technical Field

[0001] This invention belongs to the field of electromagnetic signal interference investigation technology, specifically relating to a coaxial rotor electromagnetic signal interference investigation system and interference investigation method that can be folded and fired from a tube. Background Technology

[0002] Emergency monitoring, direction finding, and interference investigation of electromagnetic signals are crucial aspects of electromagnetic control. Traditional methods for electromagnetic signal monitoring and positioning primarily rely on manual investigation, fixed monitoring stations, and mobile monitoring vehicles. These methods are not only time-consuming and labor-intensive, but also fail to quickly and accurately identify concealed signal sources. Furthermore, direction finding accuracy drops significantly when encountering building obstructions or complex geographical environments, and at low monitoring points, radio signals may not even be received. Therefore, in recent years, aerial monitoring and positioning systems based on unmanned aerial vehicle (UAV) platforms have become a research hotspot.

[0003] Using drones equipped with relevant equipment for aerial detection and location of abnormal electromagnetic signals offers advantages over traditional methods such as manual inspection, fixed monitoring stations, and mobile monitoring vehicles. These advantages include improved visibility, avoidance of signal obstruction, and high mobility. Combined with image recognition technology, the location and type of interference sources can be determined more accurately and quickly, significantly compensating for the shortcomings of traditional electromagnetic interference signal detection and location methods. Therefore, aerial electromagnetic signal monitoring and location systems based on drone platforms have become a research hotspot in recent years.

[0004] Typical products currently available include the German OBSERVERAMU series drones, Jiuhua Yuantong drone monitoring and direction finding equipment, Huari HR-62X aerial monitoring and direction finding system, DJI Sky Cells interference detection system, and the illegal broadcast search and location system based on a drone platform developed by Nanjing University of Aeronautics and Astronautics. These systems, as a supplement to traditional electromagnetic signal monitoring methods, can significantly improve the mobility of monitoring and direction finding equipment, effectively avoid signal obstruction by buildings and mountains, improve the efficiency of electromagnetic signal monitoring and location, effectively reduce system usage and maintenance costs, and expand the scope of applications.

[0005] Currently, most electromagnetic signal direction finding and positioning systems based on single UAV platforms simply use multi-rotor UAV platforms to mount monitoring and direction finding equipment. This results in large and bulky systems, which are not conducive to carrying, transportation, and rapid deployment. Furthermore, the antenna array is fixed to the multi-rotor UAV, and to avoid the influence of UAV attitude changes on antenna direction finding, hovering direction finding is often used, limiting system performance. For multi-antenna array direction finding methods, the antenna spacing is usually fixed and manually adjusted or replaced, which can easily lead to phase ambiguity issues, limiting the direction finding frequency range and affecting system performance.

[0006] Currently, there are various implementation schemes for UAV-borne monitoring and direction finding systems. For example, the invention patent "A Monitoring and Direction Finding System Based on Aircraft-borne Ascending Interferometer" (application publication number: CN105182282A) discloses a monitoring and direction finding system that includes a rotorcraft, a flight remote controller, monitoring and direction finding equipment, and a monitoring and direction finding terminal. The monitoring and direction finding equipment is mounted on the rotorcraft and includes an electronic compass, a GPS antenna, a GPS module, a direction finding antenna, a receiver, an x86 processor, a WIFI module, and a WIFI omnidirectional antenna.

[0007] This invention achieves a fixed connection between the antenna and the UAV through a mounting device. Although the direction-finding antenna array can be folded, it still needs to be disassembled, making storage, transportation, and deployment inconvenient. To avoid phase ambiguity under different signal frequency conditions, two different antenna distance installation methods are used. Depending on different mission requirements, the direction-finding antenna array may need to be replaced, which is also inconvenient.

[0008] The invention patent "An Unmanned Aerial Vehicle (UAV) Monitoring and Direction Finding System and Its Working Method" (application publication number: CN106353715A) discloses an UAV-borne monitoring and direction finding system and its working method. According to the description of the invention, the antenna diameter adjustment in this invention is achieved by adjusting the relative position between the first carbon fiber tube and the second carbon fiber tube by aligning a clip with a hole set on the second carbon fiber tube. The adjustment is done manually and cannot be continuously adjusted.

[0009] An invention patent (application publication number: CN113044209A) discloses a drone and a direction-finding system, providing a compact drone that simultaneously ensures flight and direction-finding functions. Typically, rotor units are distributed externally to the drone to ensure flight stability. Since the antenna units are positioned close to the rotor units, they are appropriately spaced relative to each other, thus generating direction-finding functionality. However, this invention has certain shortcomings, primarily due to the use of a multi-rotor and fixed direction-finding antenna array. When the drone is in continuous flight, attitude changes can affect the direction-finding accuracy of the antenna array. Furthermore, the antenna array diameter cannot be changed, suggesting a limited operating frequency range.

[0010] In summary, the existing technical solutions have the following technical problems:

[0011] (1) Existing technical solutions mostly use rotor platforms to mount monitoring and direction finding loads, without considering overall folding, and do not have tube-type launch function, which limits their application in some special applications (such as vehicle-mounted launch, aircraft airdrop, etc.).

[0012] (2) The monitoring and direction finding antenna arrays used in the existing technical solutions are mostly fixed to the multi-rotor platform. Based on the flight principle of multi-rotor UAVs, the large attitude changes of the UAV during flight will affect the attitude of the antenna array relative to the ground. If the pitch direction of the antenna array is not calibrated, it will lead to the direction finding association error. Therefore, most UAV-borne monitoring and direction finding systems currently adopt the hovering direction finding method and do not have the ability to find direction while moving.

[0013] (3) In the antenna array direction finding scheme, in order to avoid direction finding ambiguity, the horizontal and vertical distance between each antenna is less than λ / 2, where λ / 2 is half the wavelength of the highest operating frequency. In existing technical solutions, the horizontal spacing between each antenna is usually fixed or can only be adjusted manually. For monitoring and direction finding tasks with a wide frequency band, it is necessary to replace or adjust the antenna spacing on the ground, which is inefficient. Summary of the Invention

[0014] To address the aforementioned technical problems, this invention provides a foldable coaxial rotor electromagnetic signal interference troubleshooting system and method. This electromagnetic signal interference troubleshooting system uses a coaxial rotor UAV equipped with a foldable direction-finding antenna array, which can be folded and housed in a launch tube for easy carrying and rapid deployment. The coaxial rotor UAV flies using a tilting propeller disk, resulting in more stable flight attitude compared to multi-rotor UAVs, enabling continuous direction finding during flight. Furthermore, the use of a continuously adjustable direction-finding antenna array allows for adaptive adjustment of the antenna array spacing in flight according to the required frequency range, expanding the system's direction-finding frequency range.

[0015] This invention is achieved through the following technical solution:

[0016] A foldable coaxial rotor electromagnetic signal interference detection system is disclosed. The system includes an airborne section and a ground-based transmission and control section. The airborne section is foldable and is launched from a launch tube after being folded.

[0017] The aerial component includes a coaxial rotor unmanned aerial vehicle (UAV) platform and a monitoring and direction-finding payload with an antenna control mechanism mounted on the coaxial rotor UAV platform.

[0018] The coaxial rotor UAV platform includes a rotor and power module, a flight control module, an onboard power supply, flight control and navigation sensors, a mission computer, an airborne link terminal, and a gimbal camera; the monitoring and direction finding payload includes a multi-channel monitoring and direction finding receiver, an antenna control mechanism, and several antennas. The antenna control mechanism is used to adaptively adjust the antenna array spacing in the air to expand the direction finding frequency range.

[0019] The mission computer, the antenna control mechanism, the multi-channel monitoring and direction finding receiver, the flight control and navigation sensor, and the air link terminal are connected via a communication interface. The flight control and navigation sensor, the rotor and power module, and the flight control module are connected via a control interface. The gimbal camera and the air link terminal are connected via a communication interface.

[0020] Furthermore, the airborne portion and the ground-based transmission and control portion are wirelessly connected via a data link. The data link is used to transmit video captured by the gimbal camera, spectrum information sent by the multi-channel monitoring and direction-finding receiver, UAV status information sent by the mission computer, and command information sent by the ground-based transmission and control portion.

[0021] Furthermore, the monitoring and direction-finding payload is used to monitor and determine the direction of electromagnetic signals in space; the antenna is used to receive electromagnetic signals in space, and the antenna is an omnidirectional broadband antenna with a receiving frequency band of 30MHz to 20GHz; several antennas are arranged in a uniform circle around the fuselage of the UAV, and all antennas are always parallel to the axis of the central section of the UAV in both unfolded and folded states.

[0022] The multi-channel monitoring and direction-finding receiver is located in the middle section of the UAV and is used to process, analyze, and calculate the direction-finding signals received by the antenna.

[0023] Furthermore, the antenna control mechanism is located outside the middle section of the UAV and is used to adjust the deployment angle of the antenna array and control the antenna array to retract and fold, so that the radius of the antenna array is adjusted according to the frequency of the direction to be measured signal, ensuring that the distance between two adjacent antennas is less than λ / 2, so as to avoid direction ambiguity; where λ is the maximum frequency of the direction to be measured signal.

[0024] Furthermore, the antenna control mechanism includes several sets of antenna control units, with each antenna corresponding to a set of antenna control units. Each set of antenna control units includes a servo motor disposed outside the middle section of the UAV, a first pivot seat disposed outside the middle section of the UAV and located directly below the servo motor, a second pivot seat and a third pivot seat disposed on the antenna, and a first link and a second link of the same length. The distance between the servo motor and the first pivot seat is equal to the distance between the second pivot seat and the third pivot seat.

[0025] One end of the first connecting rod is connected to the servo motor, and the other end is connected to the second pivot seat located on the upper part of the antenna. One end of the second connecting rod is connected to the first pivot seat, and the other end is connected to the third pivot seat located on the lower part of the antenna.

[0026] Furthermore, the antenna control mechanism, driven by the rotation of the servo motor, causes the antenna to extend or retract, thereby adjusting the spacing between the antennas; the maximum distance D between two adjacent antennas in the antenna array is calculated using the following formula:

[0027] D=(Lsin(α)+0.5*S)×sin(π / n);

[0028] In the formula, L is the length of the first or second link, α is the link deployment angle, S is the fuselage diameter, and n is the number of antenna array elements (i.e., the number of antennas installed outside the middle section of the UAV).

[0029] Furthermore, the ground transmission and control section includes a transmitter tube, a ground link terminal, ground telemetry and control equipment, and an RTK base station;

[0030] The ground-based link is used for two-way wireless communication with the airborne link on the UAV, and the ground-based link transmits data to the ground-based telemetry and control equipment and receives instruction information uploaded by the ground-based telemetry and control equipment; the ground-based telemetry and control equipment and the ground-based link are connected through a communication interface.

[0031] Furthermore, RTK base stations are used to provide differential positioning for UAVs, improving the UAV's own navigation and positioning accuracy, and thus improving direction finding and positioning accuracy.

[0032] Furthermore, the launch tube includes a launch tube cap, a launch tube body, a launch tube base, and several deployment supports; the launch tube cap and the base are square structures with rounded corners;

[0033] The launch tube base is equipped with a gas generator to provide launch thrust and launch the air portion; the launch tube body serves as a guide.

[0034] The deployment brackets are located at the bottom of the launch tube base, and there are at least three of them; the deployment brackets are foldable and stackable.

[0035] An electromagnetic signal interference troubleshooting method, employing the aforementioned coaxial rotor electromagnetic signal interference troubleshooting system, the method comprising:

[0036] The operator carries the launch tube to the designated location, opens the launch tube cap, unfolds the launch tube unfolding bracket, stands the launch tube vertically on the ground, and launches the drone in a folded state;

[0037] After the drone leaves the tube, its rotors unfold and work under the drive of the power module, and the drone enters flight mode to conduct reconnaissance and search.

[0038] The antenna control mechanism controls the deployment of the antenna array and controls the horizontal spacing between adjacent antennas to be D. The monitoring and direction-finding load starts to monitor and determine the electromagnetic signals in space. The spacing D is adaptively adjusted according to the frequency of the received signal so that the spacing D satisfies the condition: D≤λ / 2, in order to avoid direction-finding ambiguity.

[0039] Once the target is detected and locked, the airborne unit performs direction finding and positioning trajectory planning, and locates the target based on continuous direction finding information. Then, the gimbal camera is used to capture images of the target and transmit them back to the operator.

[0040] Beneficial technical effects of the present invention:

[0041] The electromagnetic signal interference investigation system provided by this invention uses a coaxial rotor UAV equipped with a foldable direction-finding antenna array. The entire aerial part is foldable and can be housed in a launch tube after folding. It can be launched from the launch tube, making it convenient to carry and quickly deploy, and meeting the needs of special occasions such as vehicle-mounted launch or airdrop from a carrier aircraft.

[0042] The electromagnetic interference investigation system provided by this invention uses a coaxial rotor UAV equipped with a multi-antenna monitoring and direction-finding payload. The coaxial rotor UAV flies by tilting its propeller disk. Compared with multi-rotor UAVs, it has less attitude change during flight and less impact on the attitude of the antenna array, enabling the UAV to continuously determine the direction of electromagnetic targets during flight.

[0043] The electromagnetic signal interference investigation system provided by this invention has an antenna control mechanism that can adaptively adjust the antenna array spacing in the air according to the required frequency range, expand the system's direction finding frequency range, avoid ambiguity problems, and improve system efficiency. Attached Figure Description

[0044] Figure 1 is a structural diagram of a coaxial rotor electromagnetic signal interference detection system that can be folded by a cannon in an embodiment of the present invention;

[0045] Figure 2 is a schematic diagram of the overall layout of the aerial portion in an embodiment of the present invention;

[0046] Figure 3 is a schematic diagram of the antenna retraction and folding process in an embodiment of the present invention;

[0047] Figure 4 is a schematic diagram of antenna spacing calculation in an embodiment of the present invention;

[0048] Figure 5 is a schematic diagram of the launching tube structure in an embodiment of the present invention;

[0049] Figure 6 is a schematic diagram of the folded state of the aerial platform in an embodiment of the present invention.

[0050] Figure 7 is a top view of the folded aerial platform in an embodiment of the present invention.

[0051] Figure 8 is a schematic diagram of the operation of the electromagnetic signal interference investigation system in an embodiment of the present invention;

[0052] The attached diagram is labeled as follows: 1-1. Top section of the UAV; 1-2. Middle section of the UAV; 1-3. Antenna; 1-4. Servo motor; 1-5. Linkage rod; 1-6. Gimbal camera; 2-1. Launch tube cap; 2-2. Launch tube body; 2-3. Launch tube base; 2-4. Deployment support. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0054] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0055] Currently, most common UAV-borne monitoring and direction-finding systems directly mount monitoring and direction-finding payloads on multi-rotor UAVs. The influence of the UAV's attitude on the payload's direction-finding performance limits this to hovering direction finding followed by cross-positioning, resulting in low efficiency. To address these issues, this invention provides an embodiment of a foldable, canister-launched coaxial rotor electromagnetic interference detection system. The aim is to provide an electromagnetic interference detection system capable of efficient and continuous direction finding of electromagnetic radiation targets in flight, applicable to special environments such as canister-launched and airborne deployment, and with a wide direction-finding frequency range.

[0056] Example 1: A foldable coaxial rotor electromagnetic signal interference detection system, as shown in Figure 1, the electromagnetic signal interference detection system includes an airborne part and a ground-based transmission and control part; the airborne part has a foldable structure, and the folded airborne part is launched from a launch tube;

[0057] The aerial component includes a foldable coaxial rotor unmanned aerial vehicle platform and a monitoring and direction-finding payload with an antenna control mechanism mounted on the coaxial rotor unmanned aerial vehicle platform.

[0058] The coaxial rotor UAV platform includes a rotor and power module, a flight control module, an onboard power supply, flight control and navigation sensors, a mission computer, an airborne link terminal, and a gimbal camera. The monitoring and direction-finding payload includes a multi-channel monitoring and direction-finding receiver, an antenna control mechanism, and several antennas. The antenna control mechanism is used to adaptively adjust the antenna array spacing in the air to expand the direction-finding frequency range. Specifically, the number of antennas is 3 to 5, corresponding to the number of channels in the multi-channel monitoring and direction-finding receiver; that is, 3 channels correspond to 3 antennas, and 4 channels correspond to 4 antennas.

[0059] The mission computer, the antenna control mechanism, the multi-channel monitoring and direction finding receiver, the flight control and navigation sensor, and the air link terminal are connected via a communication interface. The flight control and navigation sensor, the rotor and power module, and the flight control module are connected via a control interface. The gimbal camera and the air link terminal are connected via a communication interface.

[0060] In this embodiment, the airborne portion and the ground-based transmission and control portion are wirelessly connected via a data link. This data link is used to transmit video captured by the gimbal camera, spectrum information transmitted by the multi-channel monitoring and direction-finding receiver, UAV status information transmitted by the mission computer, and command information transmitted by the ground-based transmission and control portion. Specifically, the data link includes an airborne end and a ground-based end, both of which include network interfaces and serial ports, used to realize wireless data transmission between the airborne portion and the ground control portion of the foldable coaxial rotor electromagnetic signal interference investigation system.

[0061] In this embodiment, as shown in Figure 2, the rotor and power module includes a rotor and a power submodule. The power submodule is located in the top section 1-1 of the UAV and is used to control the rotor to rotate according to flight control commands, generate thrust, and enable the UAV to take off and fly. The rotor has a foldable structure. After folding, the rotor is close to the fuselage and can be placed in the launch tube.

[0062] The flight control module is located in the middle section 1-2 of the UAV and is used to control the tilt of the propeller disk, generate lateral force, and control the UAV's maneuvering flight.

[0063] The onboard power supply is located in the middle section 1-2 of the UAV and is used to power various electrical devices of the UAV.

[0064] The flight control and navigation sensors (including flight control and navigation sensors) are located in the middle section 1-2 of the UAV. The flight control is used to control the stable flight of the UAV and can receive and execute waypoints and instructions sent by the mission computer. The navigation sensors are used to measure the attitude, position, speed and other information of the UAV as input for UAV control.

[0065] The mission computer is located in the middle section 1-2 of the UAV. The mission computer uses an embedded computer platform and includes various interfaces such as USB, serial port, and GPIO, enabling communication with the monitoring and orientation-finding payload, flight control and navigation sensors, and the air link (airborne terminal). The mission computer receives, parses, and forwards spectrum data and orientation-finding data from the multi-channel monitoring and orientation-finding receiver; reads UAV navigation and status information from the flight control system; controls the UAV; performs time synchronization processing on signal angle measurement information, UAV navigation, and status information and sends it to the airborne terminal; and receives ground control commands, including control over the UAV flight mode and the monitoring and orientation-finding payload.

[0066] The gimbal cameras 1-6 are mounted on the bottom of the drone and are capable of pitch (0 degrees to -90 degrees) and azimuth rotation (0-360 degrees), and can capture images in a specified direction for target identification.

[0067] In this embodiment, the monitoring and direction-finding payload is used to monitor and determine the direction of electromagnetic signals in space; the antennas 1-3 in the monitoring and direction-finding payload are used to receive electromagnetic signals in space, and the antennas are omnidirectional broadband antennas with a receiving frequency band of 30MHz to 20GHz; several antennas are arranged in a uniform circle around the fuselage of the UAV, and all antennas are always parallel to the axis of the middle section 1-2 of the UAV in both unfolded and folded states.

[0068] The multi-channel monitoring and direction-finding receiver is located in the middle section 1-2 of the UAV and is used to process, analyze, and calculate the direction-finding signal received by the antenna; the multi-channel monitoring and direction-finding receiver contains at least 3 channels;

[0069] The antenna control mechanism is located outside the middle section 1-2 of the UAV and is used to adjust the deployment angle of the antenna array and control the antenna array to retract and fold, so that the antenna array radius is adjusted according to the frequency of the signal to be measured, ensuring that the distance between two adjacent antennas is less than λ / 2, so as to avoid direction ambiguity; where λ is the maximum frequency of the signal to be measured; as shown in Figure 3, the antenna control mechanism can make the antenna retract and fold, close to the fuselage.

[0070] In this embodiment, the antenna control mechanism includes several sets of antenna control units, with each antenna corresponding to a set of antenna control units. Each set of antenna control units includes a servo motor 1-4 disposed outside the middle section of the UAV, a first pivot seat disposed outside the middle section of the UAV and located directly below the servo motor, a second pivot seat and a third pivot seat disposed on the antenna, and two connecting rods 1-5 of the same length (including the first connecting rod and the second connecting rod). The distance between the servo motor and the first pivot seat is equal to the distance between the second pivot seat and the third pivot seat.

[0071] One end of the first link is connected to the servo motor, and the other end is connected to the second pivot seat located on the upper part of the antenna (forming a rotating joint). One end of the second link is connected to the first pivot seat (forming a rotating joint), and the other end is connected to the third pivot seat located on the lower part of the antenna (forming a rotating joint). The antenna, the first link, the second link, and the portion between the external servo motor and the first pivot seat in the middle section of the UAV are defined as a parallelogram structure. The first link and the second link are parallel to each other, and the angle between the first link or the second link and the middle section of the UAV is α, which is the link deployment angle.

[0072] In this embodiment, the antenna control mechanism, driven by the rotation of the servo motor, causes the antenna to extend or retract, thereby adjusting the spacing between the antennas; as shown in Figure 4, the distance D between two adjacent antennas in the antenna array is calculated using the following formula:

[0073] D=(Lsin(α)+0.5*S)×sin(π / n);

[0074] In the formula, L is the length of the first or second link, α is the link deployment angle, S is the fuselage diameter, and n is the number of antenna array elements (i.e., the number of antennas installed outside the middle section of the UAV).

[0075] In this embodiment, the ground transmission and control section includes a transmitter tube, a ground link terminal, ground telemetry and control equipment, and an RTK base station;

[0076] The ground link terminal is used for two-way wireless communication with the airborne link terminal of the UAV, and the ground link terminal transmits data to the ground measurement and control equipment and receives instruction information uploaded by the ground measurement and control equipment; the ground measurement and control equipment and the ground link terminal are connected through a communication interface;

[0077] The ground-based telemetry and control equipment is used to communicate with the data link. The main functions of the ground-based telemetry and control equipment include: displaying spectrum data; having a control interface for the multi-channel monitoring direction-finding receiver; having the basic functions of a UAV ground station, capable of displaying maps, UAV status (including but not limited to UAV battery level, flight attitude, UAV position, heading, status, etc.), and track information; and embedding a direction-finding and positioning algorithm and a track generation program, wherein the direction-finding and positioning algorithm adopts a two-dimensional direction-finding and positioning method based on extended Kalman filtering, which can calculate the target position based on the accumulated UAV position and direction-finding information.

[0078] RTK base stations are used to provide differential positioning for drones, improving the drone's own navigation and positioning accuracy, and thus improving direction finding and positioning accuracy.

[0079] In this embodiment, the launch tube is an integrated storage and transportation launch tube, used to launch drones (specifically, vertically upward launch), enabling rapid system deployment; and the launch tube also serves as packaging for storage and transportation.

[0080] As shown in Figure 5, the launch tube includes a launch tube cap 2-1, a launch tube body 2-2, a launch tube base 2-3, and several unfolding supports 2-4; the launch tube cap and base are square structures with rounded corners; this square structure can prevent the launch tube from rolling during transportation.

[0081] The launch tube base is equipped with a gas generator to provide launch thrust; once ignited, it can generate sufficient thrust to launch the air portion; the launch tube body serves as a guide.

[0082] The deployment brackets are located at the bottom of the launch tube base, and there are at least three of them. The deployment brackets are foldable for easy transportation and can be locked after being deployed to increase the stability of the launch tube when launching the drone.

[0083] The electromagnetic interference troubleshooting system provided by this invention organically combines a coaxial rotor platform and a multi-channel monitoring and direction-finding system, greatly mitigating the impact of UAV attitude on the direction-finding of the monitoring and direction-finding payload. It enables on-the-move direction finding for the UAV and improves the overall system efficiency. Its main principle is as follows: the coaxial rotor UAV controls the deflection of its rotor disk through the flight control system, generating a direction-finding component force, thereby controlling the UAV's horizontal maneuvering. Since the UAV's overall center is below the rotor, only a small deflection is needed to generate sufficient torque to balance the direction-finding component force. In contrast, multi-rotor UAVs cannot deflect their rotor disks relative to the fuselage; they can only adjust the rotational speed of each propeller to generate different lift, thus changing the fuselage attitude and achieving lateral flight. Therefore, the attitude changes of multi-rotor UAVs during flight are much greater than those of coaxial rotor UAVs.

[0084] Based on the electromagnetic interference detection system proposed in this invention, the aerial portion can be folded (as shown in Figures 6-7) for launch via a launch tube. The folding scheme is as follows: First, adjust the gimbal camera to -90 degrees, vertically downwards. Then, control the linkage extension angle α to 0 degrees using the antenna control mechanism, so that each antenna is close to the middle section 1-2 of the UAV. Finally, fold each rotor along the fuselage. The folded flight platform can then be placed inside the circular launch tube.

[0085] Example 2: An electromagnetic signal interference troubleshooting method, employing the coaxial rotor electromagnetic signal interference troubleshooting system described in the above examples, as shown in Figure 8. The method includes:

[0086] The operator carries the launch tube to the designated location, opens the launch tube cap, unfolds the launch tube unfolding bracket, stands the launch tube vertically on the ground, and launches the drone in a folded state;

[0087] After the drone leaves the tube, its rotors unfold and work under the drive of the power module, and the drone enters flight mode to conduct reconnaissance and search.

[0088] The antenna control mechanism controls the deployment of the antenna array and controls the horizontal spacing between adjacent antennas to be D. The monitoring and direction-finding load starts to monitor and determine the electromagnetic signals in space. The spacing D is adaptively adjusted according to the frequency of the received signal so that the spacing D satisfies the condition: D≤λ / 2, in order to avoid direction-finding ambiguity.

[0089] Once the target is detected and locked, the airborne unit performs direction finding and positioning trajectory planning, and locates the target based on continuous direction finding information. Then, the gimbal camera is used to capture images of the target and transmit them back to the operator.

[0090] The electromagnetic signal interference investigation system provided by this invention adopts an antenna control mechanism combined with a foldable coaxial rotor UAV layout. The aerial part can be folded as a whole and launched through a launch tube, which can meet special application occasions such as in-vehicle launch and airdrop from carrier aircraft.

[0091] The electromagnetic signal interference investigation system provided by this invention adopts a coaxial rotor drone platform. Compared with multi-rotor drones, the coaxial rotor drone generates lateral force by tilting the rotor disk during flight, and the tilt angle of the body is small, which has little impact on the attitude of the monitoring and direction-finding load, thus enabling the system to have the ability to locate and position in flight.

[0092] The electromagnetic signal interference investigation system provided by this invention has an antenna control mechanism that can adjust the antenna spacing in the air according to the frequency, thereby expanding the system's direction finding frequency range and improving the system's application efficiency.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability, characterized in that, The electromagnetic interference detection system includes an airborne component and a ground-based transmission and control component. The airborne component has a foldable structure, and when folded, it is launched from a launch tube. The airborne component includes a coaxial rotor UAV platform and a monitoring and direction-finding payload with an antenna control mechanism mounted on the coaxial rotor UAV platform. The coaxial rotor UAV platform includes a rotor and power module, a flight control module, an onboard power supply, flight control and navigation sensors, a mission computer, an airborne link terminal, and a gimbal camera. The monitoring and direction-finding payload includes a multi-channel monitoring and direction-finding receiver, an antenna control mechanism, and several antennas. The antenna array spacing is adaptively adjusted in mid-air to extend the direction-finding frequency range. The mission computer, antenna control mechanism, multi-channel monitoring and direction-finding receiver, flight control and navigation sensors, and air-to-air link are connected via a communication interface. The flight control and navigation sensors, rotor and power module, and flight control module are connected via a control interface. The gimbal camera and air-to-air link are connected via a communication interface. The antenna control mechanism is located outside the central section of the UAV and is used to adjust the deployment angle of the antenna array and control its retraction and folding, so that the antenna array radius is adjusted according to the frequency of the direction-finding signal. To avoid direction-finding ambiguity, the distance between two adjacent antennas must be less than λ / 2; where λ is the maximum frequency of the signal to be detected. The antenna control mechanism includes several sets of antenna control units, with each antenna corresponding to one set of antenna control units. Each set of antenna control units includes a servo motor located outside the middle section of the UAV, a first pivot seat located outside the middle section of the UAV and directly below the servo motor, a second pivot seat and a third pivot seat located on the antenna, and a first and second connecting rod of the same length. The distance between the servo motor and the first pivot seat is equal to the distance between the second pivot seat and the third pivot seat. The first connecting rod is connected at one end to the servo motor and at the other end to the second pivot seat located on the upper part of the antenna. The second connecting rod is connected at one end to the first pivot seat and at the other end to the third pivot seat located on the lower part of the antenna. The antenna control mechanism, driven by the rotation of the servo motor, causes the antenna to unfold or retract, thereby adjusting the spacing between each antenna. The maximum distance D between two adjacent antennas in the antenna array is calculated by the following formula: D = (Lsin(α) + 0.5*S) × sin(π / n); where L is the length of the first or second connecting rod, α is the unfolding angle of the connecting rod, S is the diameter of the fuselage, and n is the number of antenna array elements.

2. The coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability according to claim 1, characterized in that, The airborne segment and the ground-based transmission and control segment are wirelessly connected via a data link. The data link is used to transmit video captured by the gimbal camera, spectrum information sent by the multi-channel monitoring and direction-finding receiver, UAV status information sent by the mission computer, and command information sent by the ground-based transmission and control segment.

3. The coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability according to claim 1, characterized in that, The monitoring and direction-finding payload is used to monitor and determine the direction of electromagnetic signals in space; the antenna is used to receive electromagnetic signals in space, and the antenna is an omnidirectional broadband antenna with a receiving frequency band of 30MHz to 20GHz. Several antennas are arranged in a uniform circle around the fuselage of the UAV, and all antennas are always parallel to the axis of the central section of the UAV in both unfolded and folded states; the multi-channel monitoring and direction-finding receiver is located in the central section of the UAV and is used to process, analyze and calculate the direction-finding signals received by the antennas.

4. The coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability according to claim 1, characterized in that, The ground launch and control unit includes a launch tube, a ground link terminal, ground telemetry and control equipment, and an RTK base station; the ground link terminal is used for two-way wireless communication with the airborne link terminal of the UAV, and the ground link terminal transmits data to the ground telemetry and control equipment and receives instruction information uploaded by the ground telemetry and control equipment; the ground telemetry and control equipment and the ground link terminal are connected through a communication interface.

5. The coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability according to claim 4, characterized in that, RTK base stations are used to provide differential positioning for drones, improving the drone's own navigation and positioning accuracy, and thus improving direction finding and positioning accuracy.

6. The coaxial rotor electromagnetic signal interference detection system with foldable barrel firing capability according to claim 5, characterized in that, The launch tube includes a launch tube cap, a launch tube body, a launch tube base, and several deployment supports; the launch tube cap and base are square structures with rounded corners; the launch tube base is equipped with a gas generator to provide launch thrust to launch the air portion; the launch tube body serves as a guide; the deployment supports are located at the bottom of the launch tube base, and there are at least 3 of them; the deployment supports are foldable and stackable.

7. A method for investigating electromagnetic signal interference, employing the coaxial rotor electromagnetic signal interference investigation system according to any one of claims 1-6, characterized in that, The method includes: an operator carrying a launch tube to a predetermined location, opening the launch tube cap, unfolding the launch tube unfolding bracket, and vertically placing the launch tube on the ground to launch the folded UAV; after the UAV exits the tube, the rotor unfolds and operates under the drive of the power module, and the UAV enters flight mode to conduct reconnaissance and search; the antenna control mechanism controls the antenna array to unfold and controls the horizontal distance between adjacent antennas to be D; the monitoring and direction-finding load begins to monitor and determine the electromagnetic signals in space, and adaptively adjusts the distance D according to the received signal frequency so that the distance D satisfies the condition: D≤λ / 2, in order to avoid direction-finding ambiguity; when the target is detected and locked, the aerial part performs direction-finding and positioning trajectory planning, and locates the target based on continuous direction-finding information, and then uses a gimbal camera to capture the target image and transmit it back to the operator.

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