Unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing

Abstract

The invention belongs to the technical field of distributed optical fiber sensing and low-altitude security and protection, and particularly relates to an unmanned aerial vehicle long-distance tracking method based on distributed optical fiber vibration sensing. The invention relates to an unmanned aerial vehicle vibration / electromagnetic fusion multi-mode identification method, a special installation formation design, a dispersion compensation and amplitude phase error compensation design, an unmanned aerial vehicle target vibration / electromagnetic fusion multi-mode identification design, a detection capability calculation method of an unmanned aerial vehicle vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability coupling model, a long-distance sensing optical cable and an electromagnetic monitoring node. According to the tracking method, a special optical fiber installation mode, dispersion compensation and phase error compensation of an original phase signal, a vibration / electromagnetic fusion multi-mode identification method, an unmanned aerial vehicle vibration sound pressure-space attenuation model-distributed optical fiber processing equipment detection capability corresponding method and other innovative work are adopted; a mature distributed optical fiber vibration sensing system is utilized to realize long-distance passive detection and target tracking of the low-slow-small unmanned aerial vehicle.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of distributed optical fiber sensing and low-altitude security and defense, and particularly relates to a UAV long-distance tracking system based on distributed optical fiber vibration sensing. BACKGROUND

[0002] The distributed optical fiber vibration sensing system has become a relatively mature technical means in perimeter security systems for important targets, and has advantages such as simple structure, long detection distance, immunity to electromagnetic interference, and easy construction. At present, it is mainly used for detection of abnormal events such as people, vehicles, and construction through vibration signal recognition. Due to factors such as sensing accuracy and signal processing methods, it currently has no detection and recognition capability for UAV targets. Using the distributed optical fiber vibration sensing system to detect and recognize "low, slow, and small" UAVs has advantages such as passive concealed sensing, long detection distance (with the extension of the optical fiber), and no need for additional hardware investment. With the development of technology, it will gradually become a natural choice. Some research units have focused on the above-mentioned fusion application problems, such as the CN109991569B patent, which points out that the existing optical fiber DAS system lacks height information and multi-rotor feature confusion when detecting aircraft; the US20230123456A1 patent points out that this method relies on a pre-set UAV feature library and cannot identify new variable-pitch models; the EP3783356B1 patent has a maximum optical fiber monitoring distance of 30 km and does not solve the problem of multi-target aliasing; CN110926533A only uses FFT spectrum analysis and cannot distinguish between UAV and bird vibrations, with a false positive rate of >40%; WO202318456A1 and the "Fiber-optic UAV detection using CNN, Optics Express 30, 2022" paper have weak UAV positioning capabilities, only distance information, and weak signal processing and three-dimensional target detection capabilities. Therefore, there is currently no mature application scheme for UAV detection and long-distance tracking based on distributed optical fiber vibration sensing. SUMMARY

[0003] The purpose of the present application is to provide a UAV long-distance tracking system based on distributed optical fiber vibration sensing. The tracking system uses innovative methods such as special optical fiber installation, dispersion compensation and phase error compensation of raw phase signals, vibration / electromagnetic fusion multi-modal recognition, UAV vibration sound pressure-space attenuation model-distributed optical fiber processing device detection capability correspondence, and realizes long-distance passive detection and target tracking of "low, slow, and small" UAVs using a mature distributed optical fiber vibration sensing system.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: The application discloses a long-distance tracking system for an unmanned aerial vehicle (UAV) based on distributed optical fiber vibration sensing, which comprises a special installation array design, dispersion compensation and amplitude-phase error compensation design, multi-modal recognition design of vibration / electromagnetic fusion of the UAV target, a detection capability calculation method of a "UAV vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model, a distributed optical fiber vibration sensing device, a long-distance sensing optical cable and an electromagnetic monitoring node. The special installation array design is used for realizing sensing and obtaining of three-dimensional information of the UAV target, including height, azimuth and pitch; the dispersion compensation and amplitude-phase error compensation design is used for improving sensing distance and target positioning accuracy of the distributed optical fiber; the multi-modal recognition design of vibration / electromagnetic fusion of the UAV target is used for reducing false alarm rate of the system to the UAV target; the detection capability calculation method of the "UAV vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model is used for overall system design; and the distributed optical fiber vibration sensing device, the long-distance sensing optical cable and the electromagnetic monitoring node are essential hardware for realizing system functions.

[0005] Further, the special installation array design comprises the following: In combination with the requirement of accurate positioning of height information in a classical positioning algorithm, the sensing optical cable for height calculation is obtained by spiral laying of the optical cable, and the spiral segment parameters are a radius of 2 m±10% and a pitch of 1.8 m±5%; in combination with the requirement of accurate positioning of azimuth and pitch information in the classical positioning algorithm, the sensing optical cable for azimuth and pitch calculation is obtained by L-shaped laying of the optical cable, and the L-shaped segment parameters are a long side of 70 m±5% and a short side of 40 m±5%. The above two modes are alternately used in adjacent positions, and finally, the optical cable for UAV positioning is the sensing optical cable containing alternately arranged spiral segments and L-shaped segments.

[0006] Further, the dispersion compensation and amplitude-phase error compensation design comprises the following: The original phase signals obtained by the DAS device are subjected to dispersion compensation and amplitude-phase error compensation; the dispersion compensation is used for further improving sensing distance and signal quality of the distributed optical fiber; after the compensation, the effective sensing distance of the single-channel DAS device reaches 50 km; since the optical pulses in the DAS device do not reach different positions at the same time, in order to unify the time reference in the UAV positioning area and obtain more accurate amplitude-phase information, the amplitude-phase error compensation needs to be combined with three elements of optical pulse frequency, optical cable laying condition and optical speed; the original phase signals after the compensation are time-aligned array receiving signals, and high-precision azimuth and pitch estimation information is obtained by using a spatial spectrum positioning algorithm.

[0007] Further, the vibration / electromagnetic fusion multi-modal recognition design of the unmanned aerial vehicle target includes the following: firstly, wavelet decomposition is carried out on the vibration signal of the suspected unmanned aerial vehicle, db8 wavelet is used for 5-layer decomposition, and all node energy normalization values of the 5th layer are extracted as vibration wavelet packet energy moments E; then, the electromagnetic monitoring node closest to the position of the suspected unmanned aerial vehicle is called, and the normalized cross-correlation coefficient R of vibration and electromagnetic is calculated combined with the received radio electromagnetic signal; when 0.55E+0.45R>0.68 is met, it is determined that it is a "low, slow and small" unmanned aerial vehicle.

[0008] Further, the detection capability calculation method of the "unmanned aerial vehicle vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model includes the following: in order to ensure that the unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing can effectively track and identify the unmanned aerial vehicle target, the detection capability calculation method of the "unmanned aerial vehicle vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model is established. According to the coupling model, after the minimum noise level index of the distributed optical fiber processing equipment is known, combined with the sound wave attenuation law of air / ground, the corresponding minimum vibration sound pressure value of the system detecting the unmanned aerial vehicle is calculated inversely, and then a mapping relationship is established with the sound wave attenuation distance under the condition of fixed sound pressure value, that is, the detection distance of the system to the unmanned aerial vehicle target, wherein the sound wave attenuation law in the air corresponds to the optical cable hanging network, overhead or ground laying, and the sound wave attenuation law on the ground corresponds to the buried laying of the optical cable, so as to determine the detection distance index of the unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing.

[0009] The specific working process of the unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing is as follows: S1, the distributed optical fiber vibration sensing system is designed in the important target area where the "low, slow and small" unmanned aerial vehicle needs to be detected, the vibration sound pressure value or sound pressure value range of the possible unmanned aerial vehicle is determined, the running mode of the optical cable is determined combined with the minimum noise level of the distributed optical fiber processing equipment, the specific positions of the spiral segment and the L-shaped segment are determined, and the electromagnetic monitoring node is installed in part of the area; S2, construction and on-site debugging are carried out according to the system design, and after debugging, the system passively receives the vibration signal of the position of the optical cable and processes it in real time; S3, the vibration / electromagnetic fusion multi-modal recognition design of the unmanned aerial vehicle target is completed at the position where the suspected unmanned aerial vehicle vibration signal is received, and the specific process is as follows: the original phase signal is subjected to dispersion compensation, then wavelet decomposition and feature vector generation are combined, the data of the nearest electromagnetic monitoring node are fused, and it is judged whether it is an unmanned aerial vehicle or not, if it is an unmanned aerial vehicle target, lateral positioning and trajectory prediction are carried out, and if it is not an unmanned aerial vehicle target, the event is recorded to the environmental event library; S4, the original signal of the unmanned aerial vehicle target is combined with the light pulse frequency, the optical cable laying condition and the light speed in the optical cable to compensate amplitude phase error, the original phase signal after compensation is an array received signal aligned in time, high-precision azimuth and pitch angle information can be obtained by using a spatial spectrum positioning algorithm, target positioning information at multiple time points is obtained to form a track of the unmanned aerial vehicle target, and the unmanned aerial vehicle is detected, identified and tracked at a long distance.

[0010] The unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing provided by the application has the following advantages: firstly, the unmanned aerial vehicle detection process is passive, and the range is effectively expanded by using the advantages of distributed optical fiber vibration sensing, so that unmanned aerial vehicle detection and identification within tens of kilometers are realized; secondly, combined with a special optical cable laying method, a signal compensation algorithm and a high-precision positioning and identification algorithm, three-dimensional positioning information of the height, azimuth and pitch of the unmanned aerial vehicle target can be realized, and the correct identification rate of the unmanned aerial vehicle target is higher than that of traditional methods; a mature distributed optical fiber vibration sensing system is formed to realize the overall design scheme of long-distance passive detection and target tracking of "low, slow and small" unmanned aerial vehicles, which is very suitable for deployment in application fields with distributed optical fiber sensing technology and low-altitude security technology; in general, the application effectively solves the problems of high false alarm rate and lack of three-dimensional positioning information in the detection, identification and tracking of unmanned aerial vehicles by the existing distributed optical fiber vibration sensing system, and forms an unmanned aerial vehicle long-distance tracking system and method based on distributed optical fiber vibration sensing. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Fig. 1 is a structural schematic diagram of the unmanned aerial vehicle long-distance tracking system of the application; Figure 2 Fig. 2 is a flowchart of the multi-modal identification method of the vibration / electromagnetic fusion of the unmanned aerial vehicle target of the application; Figure 3 Fig. 3 is a flowchart of the multi-modal identification process of the vibration / electromagnetic fusion of the application; Figure 4 Fig. 4 is a flowchart of the detection distance of the unmanned aerial vehicle target by the coupling model system of "unmanned aerial vehicle vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability". DETAILED DESCRIPTION

[0012] Specific embodiments 1: the technical solutions of the present application will be described below in conjunction with examples, obviously, the described examples are part of the embodiments of the present application, rather than all the embodiments. Based on the examples in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application. It should be noted that: in the present application, if there is no special description, all the embodiments and preferred implementation methods mentioned in this paper can be combined to form new technical solutions. In the present application, if there is no special description, all the technical features and preferred features mentioned in this paper can be combined to form new technical solutions. It should be pointed out that the classical positioning algorithm appearing in this application is TDOA, AOA, etc., and the spatial spectrum positioning algorithm is MUSIC, which are well-known algorithms and processing steps in the industry. The construction principle of the "drone vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection ability" coupling model in this application is: the vibration sound pressure is the original signal V0 of the target to be detected. The sound pressure decays with the distance, and the law is the exponential decay of the distance to the second or third power. After reaching the distributed optical fiber processing equipment end, it will combine the attenuation law to be a specific sound pressure value V1. The deformation amount that the distributed optical fiber processing equipment can detect has a one-to-one correspondence with the sound pressure value. If the minimum sound pressure value Vmin that the distributed optical fiber processing equipment can detect is greater than V1, the optical fiber processing equipment cannot detect and identify the drone vibration. Only when Vmin is less than V1, the optical fiber processing equipment can detect and identify the drone vibration.

[0013] As shown in the specification Figure 1 As shown in the specification Figure 4 The embodiment of the present application provides a long-distance tracking system for unmanned aerial vehicles based on distributed optical fiber vibration sensing, which mainly includes special installation array design, dispersion compensation and amplitude phase error compensation design, multi-modal recognition design of vibration / electromagnetic fusion of unmanned aerial vehicle targets, detection ability calculation method of "drone vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection ability" coupling model, distributed optical fiber vibration sensing equipment, long-distance sensing optical cable and electromagnetic monitoring node.

[0014] In order to use the original vibration signal obtained by the distributed optical fiber to locate the UAV target in three dimensions, the sensing optical cable itself is specially installed in an array pattern. In combination with the requirement for accurate positioning of the height information in the classical positioning algorithm, the sensing optical cable used for height calculation is obtained by spirally laying the optical cable, and the parameters of the spiral section are a radius of 2 m±10% and a pitch of 1.8 m±5%. In combination with the requirement for accurate positioning of the azimuth and pitch information in the classical positioning algorithm, the sensing optical cable used for azimuth and pitch calculation is obtained by laying the optical cable in an L shape, and the parameters of the L-shaped section are a long side of 70 m±5% and a short side of 40 m±5%. The above two modes are used alternately in close proximity, and the optical cable used for UAV positioning finally is the sensing optical cable containing the alternately arranged spiral section and L-shaped section.

[0015] The original phase signal obtained by the DAS device is compensated for dispersion and amplitude-phase error. The dispersion compensation is to further improve the sensing distance and signal quality of the distributed optical fiber. After compensation, the effective sensing distance of the single-channel DAS device can reach 50 km. Since the optical pulses in the DAS device do not arrive at different positions at the same time, in order to unify the time reference in the UAV positioning area and obtain more accurate amplitude-phase information, it is necessary to combine the optical pulse frequency, optical cable laying conditions and optical speed in the optical cable to compensate for the amplitude-phase error. The compensated original phase signal is an array of received signals aligned in time, and the spatial spectrum positioning algorithm can obtain high-precision azimuth and pitch estimation information.

[0016] In the design, only the acoustic vibration signal is used for UAV detection, which is easy to produce a large false alarm rate. In order to improve the recognition accuracy of the UAV target, part of the electromagnetic monitoring nodes are added to the system, and a multi-modal recognition design of vibration / electromagnetic fusion is adopted. The specific steps are as follows: first, the vibration signal of the suspected UAV is wavelet decomposed, db8 wavelet is used for 5-layer decomposition, and the normalized value of all node energies in the 5th layer is extracted as the vibration wavelet packet energy moment E; Then, the electromagnetic monitoring node closest to the position of the suspected UAV is called, and the normalized cross-correlation coefficient R of vibration and electromagnetic is calculated combined with the received radio electromagnetic signal; when 0.55E+0.45R>0.68 is satisfied, it is determined as a "low and slow" UAV.

[0017] To ensure that the unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing can effectively track and identify unmanned aerial vehicle targets, a detection capability calculation method of the coupling model of "unmanned aerial vehicle vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" is established. According to the coupling model, after the minimum noise level index of the distributed optical fiber processing equipment is known, combined with the sound wave attenuation law of the air / ground, the corresponding minimum vibration sound pressure value of the system that can detect the unmanned aerial vehicle is calculated inversely, and then a mapping relationship is established with the sound wave attenuation distance under the condition of a fixed sound pressure value, that is, the detection distance of the system to the unmanned aerial vehicle target. The sound wave attenuation law in the air corresponds to the optical cable hanging network, overhead or ground laying, and the sound wave attenuation law on the ground corresponds to the buried laying of the optical cable. The detection distance index of the unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing can be determined.

[0018] The unmanned aerial vehicle long-distance tracking system based on distributed optical fiber vibration sensing of the application has the following characteristics when applied: the distributed optical fiber vibration sensing equipment based on the principle of Φ-OTDR and the special layout of the spiral / L-shaped alternating sensing optical cable are used as the core, combined with the selective deployment of electromagnetic monitoring nodes and data processing platform, the whole process monitoring function of "vibration signal collection-> signal compensation-> target identification-> three-dimensional positioning-> track tracking" is realized; the sensing optical cable adopts the composite layout scheme of spiral structure and L-shaped alternation: the radius is 2m±10%, the pitch is 1.8m±5%, and each segment contains ≥5 complete spiral segments for height sensing; the long side is 70m±5%, the short side is 40m±5%, and the L-shaped segment with an interval of ≤200m is responsible for azimuth / elevation sensing, and a three-dimensional detection network is constructed through the cooperative layout of the above two geometric structures. The dispersion compensation of the DAS original phase signal is carried out through the frequency domain equalization algorithm, so that the effective sensing distance of a single channel is extended to 50km; at the same time, based on the optical pulse propagation time model, combined with the optical pulse frequency, the optical cable layout condition and the speed of light parameter, the time delay of each sensing point is calculated and the phase alignment processing is implemented, and the high-precision amplitude and phase error compensation is realized. The target identification method adopts a multi-modal fusion strategy: first, the vibration signal is decomposed by db8 wavelet for 5 layers, and the normalized value E of the node energy of the 5th layer is extracted; at the same time, the data of the adjacent electromagnetic monitoring nodes are called, and the normalized cross-correlation coefficient R of the vibration and electromagnetic signals is calculated; finally, the reliable identification of the unmanned aerial vehicle target is realized through the weighted fusion criterion 0.55E+0.45R>0.68. The three-dimensional positioning and track tracking are based on the aligned signals after compensation, the azimuth / elevation angle is obtained through the spatial spectrum function construction and peak value search, and the height is calculated combined with the spiral segment data; the complete unmanned aerial vehicle track containing height, azimuth and speed is generated in real time by fusing multi-time positioning information through Kalman filtering. By establishing the coupling model of "unmanned aerial vehicle vibration sound pressure-space attenuation law-equipment detection ability", first, the minimum noise level of the system is determined, then the minimum sound pressure value that can be detected is calculated according to the optical cable layout method, the air sound wave attenuation model for overhead / ground and the ground sound wave attenuation model for buried ground, and finally the quantitative mapping relationship between sound pressure and detection distance is established. Three-stage standardized operation process is adopted: before deployment, the protection area is determined through site investigation, the optical cable path and electromagnetic node position are planned; in the construction stage, the special structure optical cable is laid according to the design and the equipment installation and debugging are completed; in the operation, the signals are collected and processed in real time, the target is automatically identified and the three-dimensional track alarm is generated, the data archiving and analysis are completed synchronously, and the complete security closed loop is formed. In terms of detection capability, the effective detection distance of a single channel reaches 50 kilometers; in terms of positioning accuracy, the horizontal positioning error is not more than ±1.5 meters, and the height direction positioning error is not more than ±2 meters; in terms of target identification, the accuracy is more than 85%, and the false alarm rate is controlled below 15%; in terms of response speed, the whole process from target detection to complete track generation can be completed within 3 seconds.

[0019] The present embodiment makes full use of the existing distributed optical fiber vibration sensing system, and realizes effective detection and tracking of "low, slow and small" unmanned planes through an innovative optical cable laying method, a signal processing algorithm and a multi-modal recognition technology, and is particularly suitable for low-altitude security applications of important infrastructure.It should be noted that in the present application, the specific meaning of the above-mentioned terms in the present application can be understood by those skilled in the art according to specific circumstances.In addition, it should be understood that although the present application is described in the form of embodiments, each embodiment does not contain only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A long-range tracking system for unmanned aerial vehicles based on distributed fiber optic vibration sensing, characterized by, The application relates to a special installation array design, dispersion compensation and amplitude-phase error compensation design, multi-modal recognition design of vibration / electromagnetic fusion of a UAV target, a detection capability calculation method of a "UAV vibration sound pressure-spatial attenuation law-distributed optical fiber processing equipment detection capability" coupling model, a distributed optical fiber vibration sensing device, a long-distance sensing optical cable and an electromagnetic monitoring node. The special installation array design is used for sensing and obtaining three-dimensional information of the height, azimuth and pitch of a UAV target; the dispersion compensation and amplitude-phase error compensation design is used for improving the sensing distance and target positioning accuracy of the distributed optical fiber; the multi-modal recognition design of vibration / electromagnetic fusion of the UAV target is used for reducing the false alarm rate of the system to the UAV target; the detection capability calculation method of the "UAV vibration sound pressure-spatial attenuation law-distributed optical fiber processing equipment detection capability" coupling model is used for the design of the overall system; and the distributed optical fiber vibration sensing device, the long-distance sensing optical cable and the electromagnetic monitoring node are essential hardware for completing the system function. The special installation array design comprises the following: In combination with the requirement of accurate positioning of the height information in a classical positioning algorithm, the sensing optical cable for height calculation is obtained through spiral laying of the optical cable, the spiral segment parameters are a radius of 2m+ / -10% and a pitch of 1.8m+ / -5%; in combination with the requirement of accurate positioning of the azimuth and pitch information in the classical positioning algorithm, the sensing optical cable for azimuth and pitch calculation is obtained through L-shaped laying of the optical cable, the L-shaped segment parameters are a long side of 70m+ / -5% and a short side of 40m+ / -5%; the above two modes are alternately used in the vicinity of the position, and finally the optical cable for UAV positioning is the sensing optical cable containing alternately arranged spiral segments and L-shaped segments.

2. The unmanned aerial vehicle long-range tracking system based on distributed optical fiber vibration sensing of claim 1, wherein, The dispersion compensation and amplitude-phase error compensation design comprises the following: The original phase signals obtained by the DAS equipment are subjected to dispersion compensation and amplitude-phase error compensation; the dispersion compensation is used for improving the sensing distance and signal quality of the distributed optical fiber; after the compensation, the effective sensing distance of the single-channel DAS equipment reaches 50km; because the optical pulses in the DAS equipment do not reach different positions at the same time, in order to unify the time reference in the UAV positioning area and obtain more accurate amplitude-phase information, amplitude-phase error compensation needs to be conducted in combination with the optical pulse frequency, the optical cable laying condition and the optical speed in the optical cable; after the compensation, the original phase signals are received signals in an aligned array in the time domain, and high-precision azimuth and pitch information can be obtained by using a spatial spectrum positioning algorithm.

3. The long-range tracking system for unmanned aerial vehicles based on distributed fiber optic vibration sensing according to claim 2, characterized in that, The multi-modal recognition design of vibration / electromagnetic fusion of the UAV target comprises the following: firstly, the vibration signals of the suspected UAV are subjected to wavelet decomposition, db8 wavelet is adopted for 5-layer decomposition, and all the node energy normalization values in the 5th layer are extracted as vibration wavelet packet energy moments E; then the electromagnetic monitoring node closest to the position of the UAV is called, and the normalized cross-correlation coefficient R of vibration and electromagnetic is calculated in combination with the received radio electromagnetic signals; when 0.55E+0.45R>0.68 is met, the UAV is determined as a "low, slow and small" UAV.

4. The long-range tracking system for unmanned aerial vehicles based on distributed fiber optic vibration sensing according to claim 3, characterized in that, The detection capability calculation method of the "drone vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model includes the following: in order to ensure that the long-distance tracking system of the unmanned aerial vehicle based on distributed optical fiber vibration sensing can effectively track and identify the unmanned aerial vehicle target, the detection capability calculation method of the "drone vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model is established; according to the coupling model, after knowing the minimum noise level index of the distributed optical fiber processing equipment, the system's corresponding minimum vibration sound pressure value that can be detected is calculated by combining the air / ground sound wave attenuation law, and then a mapping relationship with the sound wave attenuation distance under the condition of fixed sound pressure value, that is, the detection distance of the system to the unmanned aerial vehicle target is established, wherein the air sound wave attenuation law corresponds to the optical cable hanging network, overhead or ground layout, and the ground sound wave attenuation law corresponds to the optical cable buried layout, so as to determine the detection distance index of the long-distance tracking system of the unmanned aerial vehicle based on distributed optical fiber vibration sensing.

5. The long-range tracking system for unmanned aerial vehicles based on distributed fiber optic vibration sensing according to claim 4, characterized in that, The construction principle of the "drone vibration sound pressure-space attenuation law-distributed optical fiber processing equipment detection capability" coupling model is that the vibration sound pressure is the original signal V0 of the target to be detected, the vibration sound pressure continuously attenuates with the distance, and the law is exponential attenuation with the distance to the power of 2 or 3, and reaches the distributed optical fiber processing equipment end with a specific sound pressure value V1. The deformation amount that can be detected by the distributed optical fiber processing equipment has a one-to-one correspondence with the sound pressure value. If the minimum sound pressure value Vmin that can be detected by the distributed optical fiber processing equipment is greater than V1, the optical fiber processing equipment cannot detect and identify the unmanned aerial vehicle vibration. Only when Vmin is less than V1, the optical fiber processing equipment can detect and identify the unmanned aerial vehicle vibration.

6. The unmanned aerial vehicle long-range tracking system based on distributed optical fiber vibration sensing of claim 1, wherein, The sensing optical cable adopts a composite layout scheme of alternating spiral structure and L-shaped structure: radius 2m±10%, pitch 1.8m±5%, each segment containing ≥5 complete spiral segments for height perception; long side 70m±5%, short side 40m±5%, L-shaped segment with interval ≤200m responsible for azimuth / pitch perception, and a three-dimensional detection network is constructed through the cooperative layout of the above two geometric structures.

7. The long-range tracking system for unmanned aerial vehicles based on distributed fiber optic vibration sensing according to claim 1, wherein, Three-stage standardized operation process is adopted: before deployment, the protection area is determined through site survey, the optical cable path and electromagnetic node position are planned; in the construction stage, the special structure optical cable is laid according to the design and the equipment installation and debugging are completed; in the operation, the signals are collected and processed in real time, the target is automatically identified and the three-dimensional track alarm is generated, the data archiving and analysis are completed synchronously, and the complete security closed loop is formed.

8. The long-range tracking system based on distributed optical fiber vibration sensing for unmanned aerial vehicles according to any of claims 1-7, characterized in that, The working process is as follows: S1, design the distributed optical fiber vibration sensing system in the important target area where the "low, slow and small" unmanned aerial vehicle needs to be detected, determine the vibration sound pressure value or sound pressure value range of the unmanned aerial vehicle, determine the layout mode of the optical cable in combination with the minimum noise level of the distributed optical fiber processing equipment, determine the specific position of the spiral segment and the L-shaped segment, and install electromagnetic monitoring nodes in some areas; S2, construction and on-site debugging are carried out according to the system design, and after debugging, the system passively receives the vibration signals of the position of the optical cable and processes them in real time. S3, complete the multi-modal recognition design of the unmanned aerial vehicle target vibration / electromagnetic fusion at the position where the suspected unmanned aerial vehicle vibration signal is received, the specific process is to perform dispersion compensation on the original phase signal, then combine wavelet decomposition and feature vector generation, judge whether it is an unmanned aerial vehicle after fusing the data of the nearest electromagnetic monitoring node, if it is an unmanned aerial vehicle target, perform lateral positioning and trajectory prediction, if it is not an unmanned aerial vehicle target, record the event to the environmental event library; S4, combine the light pulse frequency, the optical cable laying condition and the light speed in the optical cable to compensate the amplitude and phase error of the original signal of the unmanned aerial vehicle target, the original phase signal after compensation is an array received signal aligned in time, use the spatial spectrum positioning algorithm to obtain high-precision azimuth and elevation angle information, obtain the target positioning information at the moment to form the track of the unmanned aerial vehicle target, realize the detection, recognition and long-distance tracking of the unmanned aerial vehicle.

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