Method and related apparatus for determining the location of ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout.

Abstract

This disclosure provides a method and related apparatus for determining the location of ultrashort baseline lightning strikes using a multi-antenna monostatic three-dimensional layout. The method utilizes a multi-antenna three-dimensional layout to construct one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error by different combinations of antennas. The time difference between each VHF antenna of the same pulse signal is obtained by different antenna combinations. Two-dimensional observations without system error are performed using the regular pentagonal interferometer arrays. The two-dimensional observation results with system error obtained from the equilateral triangular arrays are corrected. Then, the two-dimensional information obtained from the regular pentagonal interferometer arrays is used as a reference, and the corrected two-dimensional information obtained from the multiple equilateral triangular interferometer arrays is intersected in three-dimensional space to obtain three-dimensional information. This disclosure can achieve ultra-high-resolution three-dimensional location determination for lightning discharges, and can achieve nanosecond time resolution and digital-meter order spatial resolution of the lightning discharge process.

Description

[Technical Field]

[0001] This disclosure belongs to the technical field of lightning strike location, and more specifically relates to a method and related apparatus for ultrashort baseline lightning strike location in a multi-antenna monostatic three-dimensional layout.

[0002] (Cross-reference of related applications) This disclosure claims priority based on a Chinese patent application filed with the China Patent Administration on 26 February 2024, application number 2024102087018, titled "Method and related apparatus for determining the location of ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout," the entirety of which is incorporated herein by reference. [Background technology]

[0003] In the field of lightning detection technology, conventional methods mainly include magnetic direction finding, time-of-arrival (TOA) detection, and interferometry, each of which uses electromagnetic signals to locate lightning strikes. TOA and interferometry have attracted attention due to their unique detection methods. TOA utilizes the measurement of the time difference at which electromagnetic signals arrive at different receivers, while interferometry utilizes the detection of broadband very high frequency signals. However, these conventional methods have limitations in practical use. For example, TOA can provide three-dimensional information, but has limitations in temporal resolution and spatial accuracy. Interferometry has high temporal resolution, but can only provide two-dimensional information of lightning strikes.

[0004] To obtain highly accurate positional information on the discharge and development process of lightning strikes, three-dimensional lightning observation based on interferometer arrays is becoming an increasingly important research direction in the field of lightning observation. Currently, observation methods using two-station interferometer arrays, based on installing two sets of interferometer arrays far apart, can achieve three-dimensional observation of the lightning discharge process. However, when the two sets of interferometer arrays are installed 10 km apart, the high-precision three-dimensional lightning positioning capability of the two-station interferometer array is greatly limited due to the influence of factors such as the electromagnetic environment of the stations, electromagnetic signal attenuation, positioning result matching, and system errors. Attempts have also been made to use multi-antenna monostatic configurations based on ultrashort baseline interferometer arrays. However, in actual observations, this observation method can achieve some degree of three-dimensional positioning of some signals, but due to electromagnetic signal interference and the baseline length being much shorter than the distance at which the lightning signal originates, many errors in the three-dimensional positioning results spread radially, leading to problems such as variability in positioning results. [Overview of the Initiative]

[0005] One objective of this disclosure is to provide a method and related apparatus for ultrashort baseline lightning strike localization of a multi-antenna monostatic three-dimensional layout, which enables ultra-high-resolution three-dimensional localization of lightning discharge processes, with a temporal resolution for localizing lightning discharge events reaching the order of nanoseconds and a theoretical resolution of spatial error increasing to the order of digital meters. Embodiments of this disclosure can be realized as follows.

[0006] In the first part, the present disclosure provides a method for locating ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout. The multi-antenna monostatic three-dimensional layout includes an interferometer array composed of a combination of different numbers of very short frequency (VHF) antennas, the interferometer array including one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error, the method comprising: collecting a very short frequency (VHF) radiation signal received by each of the VHF antennas; determining the time difference between identical pulse signals between different VHF antennas based on the VHF radiation signal; and using the regular pentagonal interferometer array and the equilateral triangular interferometer array, respectively, to locate a radiation source emitting the VHF radiation signal, obtaining one set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles. The method includes the steps of: making corrections to multiple sets of the second azimuth angle and second elevation angle to obtain multiple sets of target azimuth angle and target elevation angle; using the direction in which the first azimuth angle and first elevation angle are located as a reference direction, determining one target position point in the reference direction, minimizing the distance from the radiation passing through the target position point in the reference direction to the center of the radiation with the multiple sets of target azimuth angle and target elevation angle as the reference direction, determining the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle and the second azimuth angle; and determining the generation time of the ultrashort wave radiation signal based on the three-dimensional coordinates and the time it takes for the ultrashort wave radiation signal to propagate to the central VHF antenna at the speed of light, wherein there is no system error in the first azimuth angle and the first elevation angle, and there is a system error in the second azimuth angle and the second elevation angle.

[0007] In a second aspect, the present disclosure provides a multi-antenna monostatic three-dimensional layout ultrashort baseline lightning location device. The multi-antenna monostatic three-dimensional layout includes an interferometer array composed of different combinations of the VHF antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error, the multi-antenna monostatic three-dimensional layout ultrashort baseline lightning location device includes an acquisition module, a pre-processing module, a two-dimensional location module, a correction module, and a three-dimensional location module, the acquisition module is configured to acquire ultrashort frequency radiation signals received by each of the VHF antennas, the pre-processing module is configured to determine the time difference of identical pulse signals between different VHF antennas based on the ultrashort frequency radiation signals, and the two-dimensional location module performs interferometric location using the regular pentagonal interferometer array and the equilateral triangular interferometer array, respectively, based on the time difference of identical pulse signals between different VHF antennas, thereby acquiring the ultrashort frequency radiation signals The system is configured to obtain one set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles of a radiation source that emits radiation, wherein there is no system error in the first azimuth and first elevation angles, and there is a system error in the second azimuth and second elevation angles, and the correction module is configured to perform corrections on multiple sets of second azimuth and second elevation angles to obtain multiple sets of target azimuth and target elevation angles, and the three-dimensional positioning module uses the direction in which the first azimuth and first elevation angles are located as the reference direction, and the reference direction The three-dimensional positioning module is configured to determine a single target position point in a given direction, minimize the distance from the radiation to the center of multiple sets of radiation with the target azimuth and elevation angles as reference directions in the given reference direction, and determine the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle, and the second azimuth angle. The three-dimensional positioning module is further configured to determine the generation time of the ultrashort wave radiation signal based on the three-dimensional coordinates and the time it takes for the ultrashort wave radiation signal to propagate to the central VHF antenna at the speed of light.

[0008] In a third aspect, the Disclosure provides a three-dimensional positioning system for ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout. The system comprises a plurality of ultrashort frequency (VHF) antennas and a computer device, wherein the multi-antenna monostatic three-dimensional layout includes an interferometer array composed of different combinations of the VHF antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and a plurality of sets of equilateral triangular interferometer arrays with angular error, the plurality of VHF antennas are configured to receive and transmit ultrashort frequency (VHF) radiated signals to the computer device, and the computer device is configured to perform a method for positioning ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout according to any one of the embodiments described above.

[0009] The ultrashort baseline lightning strike positioning method and related apparatus for a multi-antenna monostatic three-dimensional layout according to the embodiments of this disclosure achieves ultra-high-precision monostatic three-dimensional positioning for lightning discharge events. Utilizing a multi-antenna three-dimensional layout, a set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error are constructed using combinations of different numbers of antennas. Radiation information from each VHF antenna is collected, analyzed, and processed to obtain the time difference between identical pulse signals from different VHF antennas. Using these time differences, two-dimensional observations are performed using the regular pentagonal interferometer array and the multiple equilateral triangular interferometer arrays. Furthermore, based on the spatial relationship between the equilateral triangular interferometer arrays and the regular pentagonal interferometer arrays, corrections are made to the two-dimensional directional information obtained by the multiple equilateral triangular interferometer arrays. Finally, using the two-dimensional information without system error obtained by the equilateral triangular interferometer arrays as a reference, the two-dimensional information obtained by the multiple equilateral triangular interferometer arrays intersects in three-dimensional space to obtain three-dimensional information. This disclosure enables ultra-high-resolution three-dimensional positioning of lightning discharge processes, achieving a time resolution on the nanosecond order for positioning lightning discharge events, and increasing the theoretical resolution of spatial errors to the digital-meter order. [Brief explanation of the drawing]

[0010] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings used in the embodiments will be briefly described below. The drawings to be described only show some embodiments of the present disclosure and do not limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using their inventive abilities.

[0011] [Figure 1] It is a schematic diagram of a multi-antenna monostatic three-dimensional layout according to an embodiment of the present disclosure. [Figure 2] It is a schematic flowchart of an ultra-short baseline lightning strike location calibration method based on a multi-antenna monostatic three-dimensional layout according to an embodiment of the present disclosure. [Figure 3] It is a schematic diagram showing the comparison between raw data and upsampled data according to an embodiment of the present disclosure. [Figure 4] It is a schematic diagram of a generalized cross-correlation waveform matching method using a main window and a variable auxiliary window according to an embodiment of the present disclosure. [Figure 5] It is a schematic diagram of a VHF waveform that can be matched by a generalized cross-correlation technique according to an embodiment of the present disclosure. [Figure 6a] It is a schematic diagram of determining source two-dimensional information. [Figure 6b] It is a schematic diagram of a location calibration error evaluation method taking a 3-antenna array as an example. [Figure 7a] It is a schematic diagram of the principle of three-dimensional location calibration according to an embodiment of the present disclosure. [Figure 7b] It is a schematic diagram showing that the target azimuth angles obtained by a set of 5 three-antenna interferometer arrays centered on antenna G are evenly distributed around the true azimuth angle of radiation source Q according to an embodiment of the present disclosure. [Figure 7c] It is a schematic diagram showing that the target elevation angles obtained by a set of 5 three-antenna interferometer arrays centered on antenna G are evenly distributed around the true elevation angle of radiation source Q according to an embodiment of the present disclosure. [Figure 8]This is a block diagram showing a functional module of a multi-antenna monostatic three-dimensional layout ultrashort baseline lightning strike positioning device 300 according to an embodiment of the present disclosure. [Figure 9] This is a block diagram of the configuration of computer equipment 400 according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] To clarify the purpose, technical proposals, and advantages of the embodiments of this disclosure, the technical proposals in the embodiments of this disclosure will be described clearly and completely below with reference to the drawings used in the embodiments of this disclosure. It should be noted that the embodiments described are only a selection of embodiments of this disclosure, and not all embodiments. The components in the embodiments of this disclosure shown herein with reference to the drawings can be arranged and designed in various configurations.

[0013] Therefore, the detailed descriptions of the embodiments of the Disclosure shown in the drawings are merely illustrative of selected embodiments of the Disclosure and do not limit the scope of the Disclosure to be protected. All other embodiments that a person skilled in the art could obtain without using their inventive ability based on the embodiments of the Disclosure also fall within the scope of the Disclosure.

[0014] Similar symbols indicate similar things in drawings, so if they are defined in one drawing, it is unnecessary to define or interpret them further in other drawings.

[0015] In the description of this disclosure, any directions or positional relationships expressed using terms such as “up,” “down,” “inside,” and “outside” are based on the drawings or represent the typical orientation or positional relationship of the product relating to the disclosure, and are merely for the purpose of providing a brief and simplified explanation of the disclosure. They do not expressly or implicitly imply that the device or element in question necessarily has a particular orientation or is configured or operated in a particular orientation, and therefore do not limit the disclosure.

[0016] Furthermore, terms such as "first," "second," etc., are merely used for distinction and explanation, and do not explicitly or implicitly indicate relative importance.

[0017] Features in the embodiments of this disclosure can be combined with each other, as long as they do not contradict each other.

[0018] In the embodiments of this disclosure, the very high frequency (VHF) radiation detection antennas used in a lightning broadband interferometer (INTF) array are arranged in the layout shown in Figure 1, which is a schematic diagram of a multi-antenna monostatic three-dimensional layout according to the embodiments of this disclosure, showing seven VHF antennas A to G.

[0019] Antenna A is positioned as the central VHF antenna, spaced above the coordinate origin O, and antennas B through F are positioned around the coordinate origin O. The distance between any two adjacent antennas B through F is L, and the five antennas B through F form a highly symmetrical regular pentagon. The distance between each of antennas B through F and antenna A is L1 (short baseline length). In this way, antenna A and two adjacent antennas from B through F form an equilateral triangle, and therefore antennas A through F constitute a set of six antennas forming a regular pentagonal interferometer array (ABCDEF) with no angular error. Antenna G is located directly above Antenna A, and due to the height of Antenna G relative to the coordinate origin O, Antenna G and two non-adjacent antennas from Antennas B to F form an equilateral triangle, with a baseline length of L2. Therefore, Antennas B to G constitute five sets of equilateral triangular interferometer arrays (let's call them GBD, GCE, GDF, GEB, and GFC), each containing three antennas, and the zenith direction of the cosine plane of the five sets of equilateral triangular interferometer arrays is uniformly distributed around the axis where the coordinate origin O and Antenna G are located.

[0020] To ensure the accuracy of signal matching and the feasibility of antenna placement, the short baseline length L1 is set to approximately 10 meters (e.g., L1 = 11.76 meters), which is an ultrashort baseline observation system, where the short baseline length L1 is much smaller than that of conventional three-dimensional lightning strike positioning systems. Furthermore, the baseline length L2 of the equilateral triangle, as shown in the example layout in Figure 1, can be set to 19.02 meters.

[0021] To utilize the basic positioning principle of the interferometer array, for the sake of explanation, the antenna array consisting of antennas A to G will be referred to as the INTF array. The seven VHF antennas of the INTF array have the same performance specifications and all employ very high frequency (50-180 MHz) RF receiving antennas. The time-series waveform of each receiver is synchronously recorded at a sampling rate of 400 MHz / s and a sampling accuracy of 14 bits, with an initial time resolution of 2.5 ns, and performance can be improved with the capabilities of future acquisition cards. On the other hand, it is ensured that ABCDEF still constitute a regular hexagonal structure, while on the other hand, vertical observation margin can be provided to the antenna array.

[0022] In the embodiments of this disclosure, Antenna A, positioned as the central antenna at a distance from the ground, has a relatively short baseline length when configured with any other antenna, significantly improving the accuracy of matching different antenna signals. Depending on the placement of Antenna G, on the one hand, it can provide five sets of equilateral triangular interferometer arrays and provide vertical observation margin to the antenna arrays. On the other hand, when Antenna G is the central antenna of five sets of interferometer arrays (GBD, GCE, GDF, GEB, GFC), the zenith direction of the cosine plane of these five sets of interferometer arrays is uniformly distributed around the axis OG, and the system error distribution curves of each of these five sets of interferometer arrays are distributed circularly at equal angles according to the actual incident direction of the radiated signal. The embodiments of this disclosure can obtain accurate three-dimensional positioning information by making full use of the unique error distribution characteristics of these five sets of equilateral triangular interferometer arrays to eliminate the influence of system errors.

[0023] In the embodiments of this disclosure, a high-speed field change instrument (abbreviated as a high-speed antenna, FA) is a dedicated instrument that participates in coordinated network observations with the INTF and measures changes in the ground-vertical electric field, and has an attenuation constant of 100 μs. The high-speed antenna has high sensitivity in the frequency range from 3 kHz to over 20 MHz. This observation method greatly improves the accurate matching of VHF radiated signals generated during the lightning discharge process with low-frequency electric field waveforms and is particularly important for the analysis of the development of microsecond-order discharge events. The high-speed field change instrument is mainly used for identifying the physical processes of lightning discharges and is not used for lightning strike location.

[0024] Based on the multi-antenna monostatic three-dimensional layout shown in Figure 1, embodiments of the present disclosure provide a three-dimensional location method for ultrashort baseline lightning strikes. Referring to Figure 2, Figure 2 is a schematic flowchart of a method for location of ultrashort baseline lightning strikes based on a multi-antenna monostatic three-dimensional layout according to embodiments of the present disclosure. The method is implemented by a high-performance computer device and includes the following steps.

[0025] In S201, the very high frequency (VHF) radiation signals received by each VHF antenna are collected, and the time difference between identical pulse signals between different VHF antennas is determined based on the VHF radiation signals.

[0026] In S202, positioning is performed using a regular pentagonal interferometer array and a regular triangular interferometer array, respectively, based on the time difference of identical pulse signals between different VHF antennas, to obtain one set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles of a radiation source emitting an ultrashort wave radiation signal. The first azimuth and first elevation angles have no system error, while the second azimuth and second elevation angles have a system error.

[0027] In S203, multiple sets of second azimuth angles and second elevation angles are modified to obtain multiple sets of target azimuth angles and target elevation angles.

[0028] In S204, the direction in which the first azimuth angle and the first elevation angle are located is used as the reference direction, one target position point is determined in the reference direction, the distance from the radiation passing through the target position point in the reference direction to the center of multiple sets of radiation with target azimuth angles and target elevation angles as the reference direction is minimized, and the three-dimensional coordinates of the radiation source are determined based on the target position point, the first azimuth angle and the second azimuth angle.

[0029] In S205, the generation time of the ultrashort wave radiation signal is determined based on the three-dimensional coordinates and the time it takes for the ultrashort wave radiation signal to propagate to the central VHF antenna at the speed of light.

[0030] In steps S201 to S205 described above, a multi-antenna three-dimensional layout is used to construct one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error by combining different numbers of antennas. Then, ultra-short wave radiation information is collected, analyzed, and processed from each VHF antenna and high-speed field change measuring instrument to obtain the time difference of the same pulse signal between different VHF antennas. Using each time difference, two-dimensional observations are performed using the regular pentagonal interferometer array and the multiple equilateral triangular interferometer arrays. Furthermore, based on the spatial relationship between the equilateral triangular interferometer array and the regular pentagonal interferometer array, corrections are made to the two-dimensional directional information obtained by the multiple equilateral triangular interferometer arrays. Finally, using the two-dimensional information without system error obtained from the regular pentagonal interferometer array as a reference, the two-dimensional information obtained from the multiple equilateral triangular interferometer arrays intersects in three-dimensional space to obtain three-dimensional information. This disclosure enables ultra-high-resolution three-dimensional localization of lightning discharge processes, with a time resolution of nanoseconds for localizing lightning discharge events and a theoretical resolution of spatial error on the order of digital meters.

[0031] The following explains each of the above steps in detail. In the embodiment shown in Figure 1, the following is an example of an embodiment of step S201 as a selectable embodiment.

[0032] Step a1: The collection card collects the very high frequency (VHF) radiation signals received by each VHF antenna, and the VHF radiation signals are pre-processed.

[0033] In the embodiments of this disclosure, a single high-speed data acquisition card with a sampling frequency of 400 MHz is used to collect VHF radiated signals from each VHF antenna.

[0034] As can be seen from the above, the high-speed field change meter also participates in coordinated network observation with the INTF, and, like the INTF array antenna, the field change signal of the high-speed field change meter may be synchronously recorded by other acquisition cards with the same sampling frequency and precision. Therefore, in the actual implementation process, the computer equipment can integrate two high-speed data acquisition cards, each with a sampling frequency of 400 MHz and a total of eight channels, to perform high-speed acquisition of the VHF radiated signals from each VHF antenna and the field change signals from one high-speed field meter, each with 14-bit precision.

[0035] Furthermore, to ensure the time synchronization accuracy of the two acquisition cards, high-precision GPS clock synchronization technology is utilized. This method, which combines hardware triggers and software algorithms, can further reduce time errors. In addition, because the amount of data generated by the 400MHz high-speed acquisition card is enormous and places high demands on the data processing and storage system, a high-performance computing platform, large-capacity storage devices, and parallel processing technology may be used to improve data processing speed.

[0036] In actual implementation, since the length of the baseline combination formed by any antenna of the antenna array is less than 20m, the computer equipment can be equipped with an air-conditioned case located in the open space at the center of the multi-antenna array to reduce the impact of data cables on signal acquisition.

[0037] In the embodiments of this disclosure, the preprocessing operations include signal feature analysis, signal high-magnification upsampling, signal high-frequency cutoff, and noise reduction.

[0038] Signal feature analysis uses the DBM_EEMD method to analyze the VHF radiated signal generated by a lightning strike. It measures the ambient background noise and the principal components of the lightning strike VHF radiated signal containing the noise, preparing for subsequent signal matching to determine the time difference at which the same pulse signal reaches each VHF antenna. The DBM_EEMD algorithm is a further development of the ensemble empirical mode decomposition (EEMD) algorithm, and by applying a double-sided bidirectional mirror (DBM) extension to the signal awaiting decomposition, it optimizes the signal features, improves the algorithm's noise reduction performance, and particularly enhances the accuracy of extracting weak pulse signals.

[0039] Before performing high-magnification upsampling of the signal, considering the work of the INTF antenna in the VHF band, the acquisition card used with a sampling frequency of 400 MHz has a sampling frequency ratio of slightly more than 2(400 / 180) than the cutoff frequency. Even if an acquisition card with a higher sampling frequency is used in the future, it is difficult for this ratio to exceed 10 in a short time, and as a result the detected VHF radiated signal will look like the raw data shown in Figure 3, which is a schematic diagram showing a comparison between raw data and upsampled data according to an embodiment of this disclosure, and the raw data exhibits a piecewise linear form consisting of points at 2.5 nanosecond intervals. This piecewise linear waveform is not differentiable and cannot be directly optimized and filtered using DBM_EEMD. Furthermore, due to the discreteness of the VHF radiated signal, the number of measurements within a narrow window is limited, and when calculating the correlation coefficient of the window waveform at different antennas using the cross-correlation method, the error is relatively large, making it difficult to obtain the expected signal matching effect. Although the temporal resolution of the waveform has reached 2.5 nanoseconds, this temporal resolution is still insufficient to achieve three-dimensional positioning with a digital-meter order, and even higher spatial resolution. To solve the above problem, embodiments of this disclosure provide a method for performing high-magnification upsampling on the original VHF radiated signal using multiphase filter technology, thereby achieving high-magnification sampling (e.g., 100 to 500 times) of the original VHF radiated signal, greatly improving the temporal resolution of the signal, greatly improving the differentiability of the original signal, improving the accuracy of decomposition and reconstruction by DBM_EEMD for VHF radiated signals, and improving the effectiveness of cross-correlation analysis for different antenna signals.

[0040] After determining the main features of the VHF radiated signal through signal feature analysis, the embodiments of this disclosure perform quality control and reconstruction on the VHF radiated signal using a bandpass filter constructed based on DBM_EEMD to preserve the high-frequency signal components in the VHF radiated signal. This effectively improves the accuracy of waveform matching and allows for more accurate capture of pulse peak times, which is important for determining the time difference between identical pulse signals between different antennas and achieving precise localization of the radiation source.

[0041] Although some true signal components are lost after processing a VHF radiated signal containing noise using the bandpass filter described above, this sacrifice of some signal components is very valuable for accurately localizing lightning discharge events. This is because a very small amount of noise component remains in the signal, significantly reducing the impact of noise. The signal component after bandpass filtering is relatively simple, the bandwidth is relatively narrow, effectively improving the accuracy of signal matching and contributing to the richness and accuracy of extracting pulse information in the waveform.

[0042] Step a2: After preprocessing, signal matching is performed on the very high frequency (VHF) radiated signals received by all VHF antennas to determine the peak time at which the same pulse signal reaches each VHF antenna, and the time difference is determined based on the peak times corresponding to two different VHF antennas.

[0043] Step a2 described above includes the following steps as an embodiment according to the embodiments of the present disclosure.

[0044] Step a2-1: Matching is performed for the very high frequency (VHF) radiated signals of different VHF antennas using generalized cross-correlation techniques. In the matching process, the matching wait signal for each VHF antenna consists of one main window and two auxiliary windows. For the central antenna, the values ​​of its two auxiliary windows are set to 0, while for the other VHF antennas, the scale of the auxiliary windows is determined by the baseline length configured with the central antenna.

[0045] In the embodiments of this disclosure, after performing quality control and reconstruction of the signal using a bandpass filter based on DBM_EEMD, following the feature analysis of the original VHF radiated signal in step a2 above, the signal is matched to signals on different antennas using generalized cross-correlation techniques to prepare for further identification and matching of pulse signals. Thus, embodiments of this disclosure first provide a signal matching method based on a variable-scale window. For ease of understanding, refer to Figure 4, which is a schematic diagram of a generalized cross-correlation waveform matching method using a main window and a variable auxiliary window according to embodiments of this disclosure.

[0046] As shown in Figure 4, the embodiment of this disclosure divides the VHF radiated signal of 48 sampling points into three parts. The Main Mindow is located in the middle and has a length of 16 sampling points, with auxiliary windows of the same length on each side. Using the multi-antenna monostatic three-dimensional layout shown in Figure 1, in the specific implementation process, antenna A (chA) is the central antenna, 16 sampling points are extracted in the Main Mindow, and the auxiliary windows are set to 0. For antennas B to G (chX, X=B...G), the Main Mindow extracts the true signal for the same time period as chA, but their auxiliary windows are extended to the true signal of N sampling points, and the length of the auxiliary windows is calculated based on the optical path difference of the baseline currently configured between the antenna and the central antenna.

[0047] For example, if the short baseline length L1 in Figure 1 is 11.76 meters, the time difference that occurs when a VHF radiated signal struck by lightning is received by the INTF antenna does not exceed 39 nanoseconds, which is the time it takes for light to propagate 11.76 meters at the speed of light. At a sampling frequency of 400 MHz (time resolution: 2.5 nanoseconds), this corresponds to a deviation of approximately 16 sampling points (applied to antennas BCDEF). For antenna G, if the distance between A and G is 10 meters, 14 sampling points is the upper limit of its auxiliary window. Although the difference from other antennas is only two sampling points, for a VHF signal at a sampling frequency of 400 MHz in the ultrashort baseline layout shown in Figure 1, even a single incorrect matching of sampling points can have a serious impact on localization. For this reason, the length of the auxiliary window is set to 16 or 14 sampling points. To maintain similar weighting between the main window and the auxiliary window, the length of the main window is also set to 16 sampling points.

[0048] The combination of a main window and a variable auxiliary window offers several advantages. First, it prevents the repeated use of pulse signals in positioning. This is because, when scanning the signal at 16 sampling points (40 nanoseconds) on the time axis of channel A, the signals from other antennas (main window and two auxiliary windows) are matched with the main window signal morphology of channel A using a generalized cross-correlation method, preventing duplication of positioning information. Furthermore, this combination method actually overcomes the limitation of the minimum window width of window matching algorithms limited by the INTF antenna baseline length. In particular, with only a main window and no auxiliary windows in channel A, the accuracy of window matching by generalized cross-correlation is significantly improved, and the accuracy of matching and information extraction for pulse signals on smaller time scales can be enhanced.

[0049] Step a2-2: The matching results are scanned using a microscale window with a predetermined width. If the number of pulse peaks within the microscale window matches the number of VHF antennas, it is determined that pulses have been detected at all VHF antennas.

[0050] To perform matching and information extraction on pulse signals on smaller time scales, embodiments of the present disclosure further provide pulse extraction in microscale windows. Specifically, after signal matching based on a variable-scale window, a microscale window with a width of only a predetermined nanosecond (the specific value of the predetermined nanosecond can be determined based on the signal characteristics, e.g., 5 nanoseconds) is scanned, and a specific combination in which the number of pulse peaks within the microscale window is 7 is searched, with the goal of accurately extracting the matching time of the pulse peaks.

[0051] As shown in Figure 4, the signals from antennas B to G (chX, X=B...G) are Δt relative to the signal from antenna chA. AX After the shift, window matching is achieved, and the result is shown in Figure 5. Figure 5 is a schematic diagram of the VHF waveform that was matched by the generalized cross-correlation technique according to an embodiment of this disclosure. In conventional interferometer-based positioning techniques and the long-baseline three-dimensional lightning strike positioning system LMA, this time difference Δt AX This is used to obtain directional or positional information of a radiation source. However, in window-based positioning techniques, the time-series correlation within the window between two antennas is primarily affected by one or more strong pulse signals. Due to interference from other signals within the window, the time delay between antennas calculated by the generalized cross-correlation method generally shifts from the peak time of the strongest pulse within the window.

[0052] As shown in Figure 5, in the specific implementation process, the timestamps of all pulse peaks whose peak value exceeds a set threshold are identified within the main window of central station chA. For example, the strongest pulse in chA in Figure 5 has a peak time of Tp. Then, a microscale window with a width of 5 nanoseconds is constructed, centered on Tp, covering chA and chX (X=B...G). The presence or absence of a pulse peak within the window in chX (X=B...G) is detected, and if a pulse is detected in any of the seven antenna signals within the 5 nanosecond microscale window, the next step is performed.

[0053] Steps a2-3: Similarity is determined for the pulse waveforms of all detected VHF antennas. If the correlation coefficient of pulses between two VHF antennas exceeds a predetermined threshold, the peak times of pulses from all VHF antennas are extracted, and the time difference is determined based on the peak times corresponding to the two different VHF antennas.

[0054] In the embodiments of this disclosure, first, a similarity determination is made to all pulse waveforms for which preliminary matching has been achieved in the above step. Specifically, waveforms with a width of 10 nanoseconds are extracted around each pulse peak time (TpA, TpB, ..., TpG) where pairing was successful, and their correlation coefficients are calculated. Of these pulse waveforms, only if the correlation coefficients of two pairs of them both exceed 0.8 are these pulse signals considered to originate from the same "lightning" event. The peak times of the pulses determined to have been successfully paired are TpA, TpB, ..., TpG, and therefore, based on these peak times, the time difference in which the same pulse information reaches two different antennas can be determined. For example, using chA and chB as an example, the time difference Δt for the same pulse signal to reach antennas A and B is Δt. AB Δt AB =T pA -T pB Therefore, C is used in an antenna array composed of n antennas. n m = n! / m!(nm)! time difference τ of pairsij is generated. Here, τ ij is the time difference for the same radiation source to reach the i-th and j-th antennas, n is the number of antennas, and m = 2.

[0055] Referring to the embodiment shown in FIG. 2, in step S202, position calibration by an interferometer for each group is performed using the arrival times of the pulses matched at 7 stations. As shown in FIG. 1, a six-antenna regular pentagon interferometer array (ABCDEF) is used to obtain a two-dimensional direction (Az_0, El_0) without angular error of the pulse signal, and five sets of equilateral triangle interferometer arrays (GBD, GCE, GDF, GEB, GFC) with angular error, each including three antennas, are used to obtain a two-dimensional direction (Az i , El i ; i = 1, 2... 5) with angular error of the pulse signal.

[0056] For easy understanding, first, a general solution for position calibration by a basic interferometer is described.

[0057] In an array with at least three antennas arranged, the number of baseline combinations is n(n - 1) / 2n. As shown in FIG. 6a, FIG. 6a is a geometric schematic diagram for determining the source two-dimensional position. The source with the baseline direction and time delay τ is shown in FIG. 6a respectively. The arrival time difference τ d between two antennas defines a straight line perpendicular to the baseline in the cosine projection, and the mathematical expression is shown in Equation (1).

[0058]

Equation

[0059] Here, cos(α) and cos(β) are the direction cosines of the baseline formed by the i-th and j-th antennas, which are unknown parameters. θ ij is the included angle between the baseline formed by the i-th and j-th antennas and the true north direction, and d ijτ is the baseline length formed by the i-th and j-th antennas, and ij This is the time difference between the arrival of the same radiation source at the i-th and j-th antennas. If the time delay is accurate, equation (1) can be solved.

[0060] In the specific implementation process, equation (1) can be solved using the nonlinear least squares method, which is widely used in three-dimensional lightning location systems. In an interferometer array detection system, an antenna array of n antennas can constitute n(n-1) / 2 sets of equations of the form of equation (1). Since equation (1) has two unknown parameters cos(α) and cos(β), when three antennas constitute three baselines, equation (1) is an overdetermined system. The result obtained by the nonlinear least squares method is a projection of the radiation source in the cosine plane, which satisfies equation (2).

[0061]

number

[0062] Here, Δt rms This represents the error level of pulse peak time extraction, and the estimated time error at an INTF sampling frequency of 400M does not exceed 2.5 nanoseconds (per sampling point). ij fit This represents the difference in arrival time of the same radiation source at the i-th and j-th antennas obtained by nonlinear least-squares iterative calculation, and τ ij obsThis represents the observed time difference in arrival of the same radiation source at the i-th and j-th antennas. The cos(α) and cos(β) that minimize the value of equation (2) are found using the nonlinear least squares method. As shown in Figure 6b, Figure 6b is a schematic diagram of a positioning error evaluation method using a 3-antenna array as an example. This error is a calculation error caused by a minute time error, and unlike the system error in the embodiments of this disclosure, its cause is that the basic principle of positioning by interferometers is based on the assumption that the radiated signal propagates as a plane wave, but in reality the radiated signal propagates as a spherical wave, so the plane wave assumption leads to the system error. The distribution characteristics of the system error are related to the number of antennas and the antenna layout, and the stronger the symmetry of the antenna layout, the smaller the system error becomes. The system error of an equilateral triangle (3 antennas) interferometer is distributed periodically, and when the number of antennas increases to 5 or more and the antenna layout has a highly symmetrical structure with central symmetry or axial symmetry, the system error is completely eliminated.

[0063] As shown in Figure 6b, the points where the pulse arrival time differences of two baselines intersect in the projection plane, along with the determined azimuthal coordinates (cos(α), cos(β)), are indicated. Based on the two-dimensional coordinates Sp(cos(α), cos(β)) in the cosine projection plane, the spatial two-dimensional coordinates of the pulse radiation source can be calculated. See equation (3).

[0064]

number

[0065] Based on the basic general solution described above, the embodiments of this disclosure first use a 6-antenna (ABCDEF) interferometer array to determine the first azimuth and first elevation angles (Az_0, El_0) of the radiation source with respect to antenna A. When the interferometer array has 5 or more sets of antennas and the antenna layout is symmetrically distributed, the system error in the two-dimensional positioning result is completely eliminated, and therefore the first azimuth and first elevation angles are free from system error. Then, using a 3-antenna interferometer array (GBD, GCE, GDF, GEB, GFC), the second azimuth and second elevation angles of the radiation source are determined with respect to antenna G, respectively, and (Az i ',El i Let i = 1, 2…5). If there are fewer than 5 interferometer array antennas, a periodic system error exists in the two-dimensional positioning result, and the periodic distribution characteristics of the system error are related to the antenna layout. Therefore, the second azimuth angle and the second azimuth angle have system errors.

[0066] After obtaining a first azimuth angle and first elevation angle (Az_0, El_0) without system error and a second azimuth angle and second elevation angle with multiple sets of system error, the correction method for step S203 includes, but is not limited to, the following: A correction formula for the azimuth angle and elevation angle is constructed based on known parameters; for example, a correction function is constructed considering factors such as system deviation and environmental influences; the second azimuth angle and second elevation angle are substituted into the function for correction and the target value is calculated; or, the second azimuth angle and second elevation angle for multiple sets of known parameters are collected, compared, and statistically analyzed to obtain the system error of the azimuth angle and elevation angle relative to the true value. Then, the subsequent second azimuth angle and second elevation angle are corrected based on these calibration parameters. Therefore, in the embodiment of this disclosure, referring to the observation layout shown in Figure 1, the cosine plane of the position determination result by the 3-antenna interferometer array (GBD, GCE, GDF, GEB, GFC) is parallel to the plane formed by the 3 antennas and forms an angle with the cosine plane formed by antennas BCDEF. For this reason, using the polar coordinates of the plane formed by the 3 antennas and the cosine plane formed by the 5 antennas BCDEF, the cosine plane formed by GBD, GCE, GDF, GEB, GFC is rotated so that it is parallel to the cosine plane formed by ABCDEF (i.e., the BCDEF plane), and the corrected target azimuth angle and target elevation angle (Az) are obtained. i ',El i We obtain ';i=1, 2...5).

[0067] Corrected target azimuth and elevation (Az) i ',El i Based on ';i=1, 2…5), three-dimensional positioning is performed relative to the radiation source. Referring to the embodiment shown in Figure 2, in an optional embodiment, step S204 according to the embodiment of the present disclosure is as follows.

[0068] Step b1: Starting from the coordinate origin, determine the first radiation expression awaiting resolution using the first azimuth angle and first elevation angle as direction vectors. Starting from antenna G, determine the second radiation expression awaiting resolution using the central azimuth angle and central elevation angle of all target azimuth angles and target elevation angles as direction vectors. Both the first and second radiation expressions awaiting resolution contain parameters awaiting resolution.

[0069] Step b2: Construct a distance function between the first radiation expression awaiting solution and the second radiation expression awaiting solution, and perform nonlinear optimization on the distance function to determine the target parameter that minimizes the function value of the distance function.

[0070] Step b3: Based on the target parameters, obtain the first radiation expression to be solved and acquire the three-dimensional coordinates of the radiation source.

[0071] To facilitate understanding of the above embodiments, refer to Figure 7a, which is a schematic diagram of the principle of three-dimensional positioning according to an embodiment of the present disclosure. The system error of the first and second azimuth angles (Az_0, El_0) formed by the interferometer array composed of ABCEDF is 0, which theoretically indicates that this is the actual direction of the radiation source Q. The target azimuth angle and target elevation angle (Az_0, El_0) obtained by the modified three-antenna interferometer array (GBD, GCE, GDF, GEB, GFC) i ',El i '(i=1, 2…5) has system errors, which are periodically distributed according to the layout of the interferometer array baseline, and as a result, the two-dimensional positioning results for the same radiation source Q from these five sets of 3-antenna interferometer arrays (GBD, GCE, GDF, GEB, GFC) cannot intersect at point Q.

[0072] For example, as shown in Figure 7a, when the central azimuth and elevation angles of the five radiation rays extending from antenna point G all point to Q, the result is expressed by equation (4).

[0073]

number

[0074] Here, N is the number of 3-antenna interferometer arrays. Under ideal conditions, (Az_0,El_0) and (Az',El') intersect at point Q, but due to random positioning errors resulting from a time resolution of 2.5 ns at a sampling frequency of 400 MHz, Q and Q do not overlap, meaning (Az_0,El_0) and (Az',El') do not intersect.

[0075] However, the embodiments of this disclosure, based on the layout shown in Figure 1, obtain the target azimuth and target elevation (Az) angles using five sets of three-antenna interferometer arrays (GBD, GCE, GDF, GEB, GFC). i ',El i The '(i=1, 2...5) is stably distributed around the actual position of the radiation source Q. Referring to Figures 7b and 7c, Figure 7b is a schematic diagram of the target azimuth angles uniformly distributed around the true azimuth angle of the radiation source Q, obtained by a 5-set 3-antenna interferometer array centered on antenna G according to an embodiment of the present disclosure. Figure 7c is a schematic diagram of the target elevation angles uniformly distributed around the true elevation angle of the radiation source Q, obtained by a 5-set 3-antenna interferometer array centered on antenna G according to an embodiment of the present disclosure. Thus, using the two-dimensional direction (Az_0,El_0) obtained by the 6-antenna interferometer array ABCEDF as the reference direction, that is, using direction OQ in Figure 7a as the reference direction, the coordinates of the point at L1 when radiation L2 (Az',El') is closest to radiation L1 (Az_0,El_0) are found, and these are the three-dimensional coordinates (x,y,z) of the radiation source Q to be solved. Therefore, steps b1 to b3 above can be understood as follows.

[0076] Starting from the coordinate origin O, the first azimuth angle and the first elevation angle (Az_0, El_0) are used as the direction vector (d1 → ) and construct the first pending radiation expression L1 as the pending parameter (t), A+t·d1 → This is expressed as follows, where A is the coordinate of the coordinate origin O.

[0077] Starting from antenna G, the central azimuth and central elevation angles (d2) of all target azimuth and elevation angles are defined. → Using ) as the direction vector and the parameter s related to the solution waiting parameter t, we construct the second solution waiting radiation expression L2, and B+s·d2 → This can be expressed as follows, where s is a function of t.

[0078] Then the distance function becomes ||(A+t·d1 → )-(B+s·d2 → This can be expressed as )∥, which is a general nonlinear optimization problem and can be solved using conventional methods, so we will omit the explanation here. If we find the optimal solution parameter t that minimizes the distance function, we can calculate the coordinates of the point corresponding to L1, i.e., A+t·d1 → Thus, we can obtain the true three-dimensional coordinates (x, y, z) of the radiation source Q.

[0079] Optionally, after determining the three-dimensional coordinates of the radiation source, the occurrence time of the lightning strike event (i.e., the emission of the very high frequency radiation signal) of the radiation source can also be determined. Therefore, the embodiment for step S205 is as follows: Using the calculated Q(x, y, z) coordinates and the time it takes for the VHF radiation signal to propagate from the radiation source Q to antenna A at the speed of light, the occurrence time t_0 of the radiation source is calculated to realize the spatiotemporal position of the radiation event, which is represented by Q(t0, x, y, z).

[0080] As can be seen from the embodiments described above, the ultrashort baseline lightning strike location method based on a multi-antenna monostatic three-dimensional layout according to the embodiments of this disclosure has the following advantages.

[0081] First, the embodiments of this disclosure utilize an ultra-wideband (50-180 MHz), highly sensitive radiated signal receiving antenna, and employ two high-speed data acquisition cards with a sampling frequency of 400 MHz and a sampling accuracy of 14 bits. This allows for extremely high temporal resolution of detected lightning discharge events, reaching the nanosecond order. Furthermore, by utilizing signal processing and matching techniques, it is possible to acquire ultra-precise three-dimensional channels and developmental features of the lightning discharge process with nanosecond-order resolution.

[0082] Furthermore, the ultrashort baseline monostatic multi-antenna three-dimensional layout proposal according to the embodiments of this disclosure fully utilizes the system error characteristics of interferometer arrays with different numbers of antennas; that is, the system error of the 6-antenna regular polygonal interferometer array is 0, and the system error of the 3-antenna equilateral triangle interferometer array is periodically distributed. By utilizing the multi-antenna combined interferometer positioning coupling technology according to this disclosure, the three-dimensional spatial position and time at which the lightning VHF radiated signal occurs can be accurately obtained.

[0083] Furthermore, the embodiments of this disclosure process the original observed signal using ultra-high magnification upsampling technology, perform optimization and bandpass filtering on the upsampled signal using DBM_EEMD technology, and utilize cross-correlation matching technology that combines a main window and a variable-scale auxiliary window. This process can improve the temporal resolution of the VHF radiated signal and greatly improve the accuracy of waveform cross-correlation matching.

[0084] Furthermore, compared to the centroid method commonly used in conventional lightning strike location techniques, the novel pulse matching technique according to the embodiments of this disclosure, namely, signal matching based on a variable-scale window and a method of pulse extraction in a microscale window, allows for precise matching and location of each pulse event in the lightning VHF radiation signal, significantly improving the ability to identify and locate lightning discharge events. By acquiring two-dimensional location information of six interferometer arrays using various combinations of different numbers of antennas and performing coordinate correction, and by realizing precise three-dimensional location of the lightning radiation signal using multi-interferometer array coupling technology, it is possible to obtain richer and more accurate lightning discharge information than conventional two-dimensional location methods using interferometer arrays and long-baseline lightning strike location systems.

[0085] Based on a similar concept to that shown in Figure 2, embodiments of the present disclosure further provide a multi-antenna monostatic three-dimensional layout ultrashort baseline lightning location device 300. Referring to Figure 8, Figure 8 is a block diagram showing the functional modules of a multi-antenna monostatic three-dimensional layout ultrashort baseline lightning location device 300 according to embodiments of the present disclosure. The device 300 includes an acquisition module 310, a preprocessing module 320, a two-dimensional location module 330, a correction module 340, and a three-dimensional location module 350.

[0086] The collection module 310 is configured to collect the very high frequency (VHF) radiation signals received by each of the VHF antennas, and the preprocessing module 320 is configured to determine the time difference between identical pulse signals between different VHF antennas based on the VHF radiation signals.

[0087] The two-dimensional positioning module 330 is configured to perform interferometric positioning using a regular pentagonal interferometer array and a regular triangular interferometer array, respectively, based on the time difference of identical pulse signals between different VHF antennas, in order to obtain one set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles of a radiation source emitting a very high frequency (VHF) radiation signal, with no system error in the first azimuth and first elevation angles, and system error in the second azimuth and second elevation angles.

[0088] The correction module 340 is configured to perform corrections on multiple sets of second azimuth angles and second elevation angles to obtain multiple sets of target azimuth angles and target elevation angles.

[0089] The three-dimensional positioning module 350 is configured to use the direction in which the first azimuth angle and the first elevation angle are located as the reference direction, to determine one target position point in the reference direction, to minimize the distance from the radiation in the reference direction to the center of multiple sets of radiation with target azimuth angles and target elevation angles as the reference direction, and to determine the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle, and the second azimuth angle.

[0090] The three-dimensional positioning module 350 is configured to determine the generation time of the very short wave radiation signal based on three-dimensional coordinates and the time it takes for the very short wave radiation signal to propagate to the central VHF antenna at the speed of light.

[0091] The data acquisition module 310, preprocessing module 320, two-dimensional positioning module 330, correction module 340, and three-dimensional positioning module 350 according to the embodiments of this disclosure can work together to perform the steps shown in Figure 2, thereby achieving corresponding technical effects.

[0092] In a selectable embodiment, the VHF antenna includes seven antennas A through G, where antenna A is the central VHF antenna and is located directly above the coordinate origin, and antennas B through F are arranged around the coordinate origin and are equally distanced to it. Antennas B through F form a highly symmetrical regular pentagon, and antennas A through F constitute one set of the regular pentagonal interferometer array, with antenna A and two adjacent antennas from B through F forming an equilateral triangle. Antenna G is located directly above antenna A, and due to the height of antenna G relative to the coordinate origin, antenna G and two non-adjacent antennas from B through F constitute five sets of equilateral triangular interferometer arrays.

[0093] In an optional embodiment, the three-dimensional positioning module 350 is configured to specifically use the direction in which the first azimuth angle and the first elevation angle are located as the reference direction, to determine one target position point in the reference direction, to minimize the distance from the radiation passing through the target position point in the reference direction to the center of multiple sets of radiation with target azimuth angles and target elevation angles as the reference direction, to determine the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle and the second azimuth angle, to determine the first unsolvable radiation expression formula starting from the coordinate origin and using the first azimuth angle and the first elevation angle as direction vectors, and to determine the antenna G The process includes: starting from a point, determining the second radiation expression awaiting resolution using the central azimuth and elevation angles of all target azimuth and elevation angles as direction vectors, ensuring that the first and second radiation expressions awaiting resolution each contain parameters awaiting resolution, constructing a distance function between the first and second radiation expressions awaiting resolution, performing nonlinear optimization on the distance function to determine the target parameters that minimize the function value of the distance function, and obtaining the first radiation expression awaiting resolution based on the target parameters to obtain the three-dimensional coordinates of the radiation source.

[0094] In an optional embodiment, the modification module 340 specifically rotates the second azimuth and second elevation angles of each set using polar coordinates of the cosine plane composed of five sets of equilateral triangular interferometer arrays and the cosine plane composed of regular pentagonal interferometer arrays, so that the modified second azimuth and second elevation angles of each set become the target azimuth and target elevation angles, respectively.

[0095] In an optional embodiment, the acquisition module 310 is specifically configured to acquire very high frequency (VHF) radiation signals received by each VHF antenna using an acquisition card, and the preprocessing module 320 specifically preprocesses the acquired VHF radiation signals, performs signal matching on the VHF radiation signals received by all VHF antennas after preprocessing, determines the peak time at which the same pulse signal reaches each VHF antenna, and determines the time difference based on the peak times corresponding to two different VHF antennas.

[0096] In an optional embodiment, the preprocessing module 320 specifically analyzes the VHF radiated signal to obtain a background noise signal and the main components of the VHF radiated signal including noise, performs high-magnification upsampling on the signal using a multiphase filter to improve the time accuracy of the signal and improve the non-differentiable characteristics of the original signal, and filters the VHF radiated signal using a single bandpass filter to retain the high-frequency signal components.

[0097] In an optional embodiment, the preprocessing module 320 is configured to perform matching for very high frequency (VHF) radiated signals from different VHF antennas using generalized cross-correlation techniques, wherein the matching wait signal for each VHF antenna consists of one main window and two auxiliary windows. The matching wait signal for the central antenna has the values ​​of its two auxiliary windows set to 0. For the other VHF antennas, the matching results are scanned using a microscale window whose auxiliary window scale is determined by the baseline length configured with the central antenna and whose width is a predetermined value. If the number of pulse peaks in the microscale window matches the number of VHF antennas, it is determined that pulses have been detected for all VHF antennas. A similarity judgment is then performed on the waveforms of the pulses from all detected VHF antennas. If the correlation coefficient of pulses between two VHF antennas exceeds a predetermined threshold, the peak times of pulses from all VHF antennas are extracted, and the time difference is determined based on the peak times corresponding to two different VHF antennas.

[0098] In the above embodiments of this application, the module classifications are merely illustrative and represent only logical functional classifications; actual implementations may involve different classifications. Furthermore, each functional unit in each embodiment of this application may be integrated into a single processing unit, function as an independent physical entity, or integrate two or more units into a single unit. The above-mentioned integrated unit may be implemented in hardware form or as a software-based functional unit.

[0099] Based on the schematic diagram of the multi-antenna monostatic three-dimensional layout shown in Figure 1 and the concept shown in Figure 2, embodiments of the present disclosure further provide a three-dimensional positioning system for ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout. The system comprises a plurality of ultrashort frequency (VHF) antennas and computer equipment, wherein the multi-antenna monostatic three-dimensional layout includes an interferometer array composed of different combinations of VHF antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and a plurality of sets of equilateral triangular interferometer arrays with angular error, the plurality of VHF antennas are configured to receive and transmit ultrashort frequency (VHF) radiated signals to the computer equipment, and the computer equipment is configured to perform the ultrashort baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to embodiments of the present disclosure.

[0100] Based on the embodiment shown in Figure 2, the embodiment of the present application further provides a computer device 400, which is configured to perform a very short baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to the embodiment of the present disclosure.

[0101] Referring to Figure 9, which is a block diagram of the configuration of a computer device 400 according to an embodiment of the present disclosure, the computer device 400 includes a memory 401, a processor 402, a communication interface 403, and a bus 404, the memory 401, the processor 402, and the communication interface 403 being electrically connected to each other directly or indirectly to enable data transmission or exchange. For example, these elements are electrically connected to each other via one or more communication buses or signal lines.

[0102] Optionally, bus 404 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. Buses are classified into address buses, data buses, control buses, etc. For simplicity, Figure 9 shows this with only one thick line, but this does not mean that there is only one bus or one type of bus.

[0103] In embodiments of this application, the processor 402 may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, which can implement or execute each method, step, and logic block according to embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in embodiments of this application may be completed directly by a hardware processor or by a combination of hardware and software modules in the processor. The software modules are located in memory 401, and the processor 402 reads program instructions in memory 401 and works with its hardware to implement each step of the method.

[0104] In embodiments of this application, the memory 401 may be non-volatile memory such as a hard disk drive (HDD) or solid-state drive (SSD), or it may be volatile memory such as RAM. The memory may be, but is not limited to, any other medium that has or stores desired program code in the form of instructions or data structures and is accessible by a computer. The memory in embodiments of this application may be any other device capable of implementing a circuit or storage function and is configured to store instructions and / or data.

[0105] Memory 401 stores software programs and modules, for example, the instructions / modules for the multi-antenna monostatic three-dimensional layout ultrashort baseline lightning positioning device 300 according to an embodiment of the present disclosure, which are stored in memory 401 in the form of software or firmware, or incorporated into the operating system (OS) of the computer device 400. The processor 402 performs various functional applications and data processing by executing the software programs or modules stored in memory 401. The communication interface 403 is configured to communicate signals or data with other node devices.

[0106] For the sake of easy and simple explanation, the specific operating processes of the above-described apparatus and units are omitted here, as those skilled in the art can refer to the corresponding processes in embodiments of the above-described method.

[0107] The structure shown in Figure 9 is merely illustrative, and the computer device 400 may contain more or fewer components than those shown in Figure 9, and may have a different configuration from that shown in Figure 9. The components shown in Figure 9 may be implemented by hardware, software, or a combination thereof.

[0108] Computer equipment 400 can be any electronic product capable of interacting with a user, such as a personal computer, tablet, smartphone, personal digital assistant (PDA), game console, Internet Protocol Television (IPTV), or smart wearable device.

[0109] Computer equipment 400 further comprises network equipment and / or user equipment. Network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud consisting of a large number of host computers or network servers based on cloud computing.

[0110] The networks on which the computer equipment 400 is deployed include, but are not limited to, the Internet, wide area networks, metropolitan area networks, local area networks, and virtual private networks (VPNs).

[0111] Based on the above embodiment, this application further provides a storage medium in which a computer program is stored, and when the computer program is executed by a computer, the computer performs the ultrashort baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to the above embodiment.

[0112] Based on the above embodiments, embodiments of this application further provide a computer program. When the computer program is executed on a computer, the computer performs the ultrashort baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to the above embodiments.

[0113] Based on the embodiments described above, embodiments of this application further provide a chip configured to read a computer program stored in memory and to perform the ultrashort baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to the embodiments described above.

[0114] Embodiments of this application further provide a computer program product which, when executed on a computer, includes instructions which the computer performs the ultrashort baseline lightning strike positioning method for a multi-antenna monostatic three-dimensional layout according to the above embodiment.

[0115] Embodiments of this application will be described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of this application. Instructions can be used to realize each process and / or block in the flowcharts and / or block diagrams, and combinations of processes and / or blocks in the flowcharts and / or block diagrams. These instructions can be applied to the processor of a general-purpose computer, a dedicated computer, an embedded processor device, or other programmable data processing equipment to configure the equipment, thereby enabling instructions executed by the processor of the computer or other programmable data processing equipment to realize specific functions in one or more processes in the flowchart and / or one or more blocks in the block diagrams.

[0116] The computer program instructions can also be stored in computer-readable memory that can instruct a computer or other programmable data processing device to function in a particular manner, and the product can be configured to include instruction means that use the instructions stored in the computer-readable memory to implement a particular function in one or more processes of a flowchart and / or one or more blocks of a block diagram.

[0117] These computer program commands can be loaded into a computer or other programmable data processing device to realize processing performed on the computer by having a series of operational steps executed on the computer or other programmable device, and instructions executed on the computer or other programmable terminal device can also provide steps to realize a specific function in one or more processes in a flowchart and / or one or more blocks in a block diagram.

[0118] The foregoing are merely specific embodiments of the present disclosure, and the scope of protection of the present disclosure is not limited thereto. Any modifications or substitutions made by a person skilled in the art within the scope of the present disclosure fall within the scope of protection of the present disclosure. Accordingly, the scope of protection of the present disclosure is equivalent to the claims. [Industrial applicability]

[0119] According to the above proposal, ultra-high-resolution three-dimensional positioning of lightning discharge processes can be achieved, with a temporal resolution of nanoseconds for positioning lightning discharge events, and a theoretical resolution of spatial error that can be increased to the order of digital meters.

[0120] In the specification of this application, some symbols or characters used in the international application are not usable on the Japan Patent Office's electronic filing system for national phase entry, and have therefore been replaced with corresponding strings. The correspondence between the replaced strings and the symbols used in the international application is shown in the <Symbol Correspondence Table> below.

[0121] [Table 1]

Claims

1. A method for determining the location of a lightning strike using an ultrashort baseline in a multi-antenna monostatic three-dimensional layout, The multi-antenna monostatic three-dimensional layout includes an interferometer array composed of a combination of different numbers of very high frequency (VHF) antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error, and the method for determining the position of a very high frequency baseline lightning strike in the multi-antenna monostatic three-dimensional layout is: The steps include: collecting the ultra-short wave radiated signals received by each of the aforementioned VHF antennas, and determining the time difference between identical pulse signals between different VHF antennas based on the ultra-short wave radiated signals; The steps include: determining the position of a radiation source emitting the ultrashort wave radiation signal by using a regular pentagonal interferometer array and a regular triangular interferometer array, respectively, based on the time difference of the same pulse signals between different VHF antennas, thereby obtaining a set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles; The steps include: making adjustments to multiple sets of the aforementioned second azimuth angles and second elevation angles to obtain multiple sets of target azimuth angles and target elevation angles; The steps include: defining the direction in which the first azimuth angle and the first elevation angle are located as the reference direction, determining one target position point in the reference direction, minimizing the distance from the radiation passing through the target position point in the reference direction to the center of multiple sets of radiation with the target azimuth angle and target elevation angle as the reference direction, and determining the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle, and the second azimuth angle; The process includes determining the generation time of the ultrashort wave radiation signal based on the three-dimensional coordinates and the time it takes for the ultrashort wave radiation signal to propagate to the central VHF antenna at the speed of light, There is no system error in the first azimuth angle and the first elevation angle, but there is a system error in multiple second azimuth angles and second elevation angles. A method for determining the location of ultrashort baseline lightning strikes in a multi-antenna monostatic three-dimensional layout, characterized by the features described above.

2. The VHF antenna includes seven antennas, A to G. Antenna A is the central VHF antenna and is located directly above the coordinate origin. Antennas B to F are arranged around the coordinate origin and are equally far from the coordinate origin. Antennas B to F form a highly symmetrical regular pentagon, and antennas A to F constitute one set of the regular pentagonal interferometer array. Antenna A and two adjacent antennas from antennas B to F form an equilateral triangle. Antenna G is located directly above antenna A. Depending on the height of antenna G relative to the coordinate origin, antenna G and non-adjacent antennas from antennas B to F constitute five sets of the equilateral triangular interferometer array. A method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout as described in feature 1.

3. The steps of determining the three-dimensional coordinates of the radiation source are as follows: the direction in which the first azimuth angle and the first elevation angle are located is used as the reference direction, a target position point is determined in the reference direction, the distance from the radiation passing through the target position point in the reference direction to the center of multiple sets of radiation with the target azimuth angle and target elevation angle as the reference direction is minimized, and the three-dimensional coordinates of the radiation source are determined based on the target position point, the first azimuth angle and the second azimuth angle. The steps include: determining a first radiation expression awaiting resolution using the coordinate origin as the starting point and the first azimuth angle and the first elevation angle as direction vectors; determining a second radiation expression awaiting resolution using the antenna G as the starting point and the central azimuth angle and central elevation angle of all the target azimuth angles and target elevation angles as direction vectors; and including the parameters awaiting resolution in each of the first and second radiation expressions awaiting resolution; The steps include constructing a distance function between the first radiation expression awaiting resolution and the second radiation expression awaiting resolution, performing nonlinear optimization on the distance function to determine the target parameter that minimizes the function value of the distance function, The step includes solving the first radiation expression to be solved based on the target parameters to obtain the three-dimensional coordinates of the radiation source. The method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout according to feature 2.

4. The step of making adjustments to multiple sets of the aforementioned second azimuth angles and second elevation angles to obtain multiple sets of target azimuth angles and target elevation angles is: The process includes a step of rotating the second azimuth angle and second elevation angle of each set using the polar coordinates of the cosine plane formed by the five sets of equilateral triangular interferometer arrays and the cosine plane formed by the regular pentagonal interferometer array, so that the modified second azimuth angle and second elevation angle of each set become the target azimuth angle and target elevation angle, respectively. A method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout according to feature 2 or 3.

5. The step of collecting the very high frequency (VHF) radiation signals received by each of the VHF antennas and determining the time difference between identical pulse signals between different VHF antennas based on the VHF radiation signals is: The steps include collecting the ultra-short wave radiated signals received by each of the aforementioned VHF antennas using a collection card, and performing preprocessing on the ultra-short wave radiated signals, The process includes, after preprocessing, performing signal matching on the ultrashort wave radiated signals received by all of the VHF antennas, determining the peak time at which the same pulse signal reaches each of the VHF antennas, and determining the time difference based on the peak times corresponding to two different VHF antennas. A method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout according to any one of claims 1 to 4.

6. Preprocessing the aforementioned ultrashort wave radiated signal is performed as follows: The steps include: performing an analysis on the aforementioned ultra-high frequency radiation signal to obtain a background noise signal and the main components of the ultra-high frequency radiation signal including noise; The process involves using a multiphase filter to perform high-magnification upsampling on the signal, thereby improving the time accuracy of the signal and altering the non-differentiable characteristics of the original signal. The process includes the step of configuring a bandpass filter to filter the ultra-short wave radiated signal and leave the high-frequency signal components. A method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout according to feature 5.

7. After preprocessing, the step of performing signal matching on the ultrashort wave radiated signals received by all the VHF antennas, determining the peak time at which the same pulse signal reaches each of the VHF antennas, and determining the time difference based on the peak times corresponding to two different VHF antennas is as follows: A generalized cross-correlation technique is used to match the ultra-short wave radiated signals of different VHF antennas, wherein the matching waiting signal for each VHF antenna consists of one main window and two auxiliary windows, the values ​​of the two auxiliary windows for the matching waiting signal of the central antenna are set to 0, and for the other VHF antennas besides the central antenna, the scale of the auxiliary windows is determined by the baseline length configured with the central antenna, in a step, The steps include scanning the matching results using a microscale window with a predetermined width, and determining that pulses have been detected in all VHF antennas if the number of pulse peaks in the microscale window matches the number of VHF antennas, The process includes the steps of: performing a similarity determination on the pulse waveforms of all detected VHF antennas; if the correlation coefficient of pulses between two VHF antennas exceeds a predetermined threshold, extracting the peak times of pulses from all VHF antennas; and determining the time difference based on the peak times corresponding to two different VHF antennas. A method for determining the location of an ultrashort baseline lightning strike in a multi-antenna monostatic three-dimensional layout, as described in 5 or 6.

8. A multi-antenna monostatic three-dimensional layout ultrashort baseline lightning strike positioning device, The multi-antenna monostatic three-dimensional layout includes an interferometer array composed of a combination of different numbers of VHF antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and multiple sets of equilateral triangular interferometer arrays with angular error, and the ultrashort baseline lightning location device of the multi-antenna monostatic three-dimensional layout includes an acquisition module, a pre-processing module, a two-dimensional location module, a correction module, and a three-dimensional location module. The acquisition module is configured to acquire the very high frequency (VHF) radiation signals received by each of the VHF antennas, and the preprocessing module is configured to determine the time difference between identical pulse signals between different VHF antennas based on the VHF radiation signals. The two-dimensional positioning module is configured to perform interferometric positioning using a regular pentagonal interferometer array and a regular triangular interferometer array, respectively, based on the time difference of identical pulse signals between different VHF antennas, in order to obtain one set of first azimuth and first elevation angles and multiple sets of second azimuth and second elevation angles of the radiation source emitting the ultrashort wave radiation signal, wherein the first azimuth and first elevation angles have no system error, and the multiple second azimuth and second elevation angles have system error. The correction module is configured to perform corrections on multiple sets of the second azimuth angle and second elevation angle to obtain multiple sets of target azimuth angle and target elevation angle. The three-dimensional positioning module is configured to use the direction in which the first azimuth angle and the first elevation angle are located as the reference direction, to determine one target position point in the reference direction, to minimize the distance from the radiation to the center of multiple sets of radiation with the target azimuth angle and target elevation angle as the reference direction in the reference direction, and to determine the three-dimensional coordinates of the radiation source based on the target position point, the first azimuth angle, and the second azimuth angle. The three-dimensional positioning module is further configured to determine the generation time of the very high frequency radiation signal based on the three-dimensional coordinates and the time it takes for the very high frequency radiation signal to propagate to the central VHF antenna at the speed of light. A multi-antenna monostatic three-dimensional layout ultrashort baseline lightning strike positioning device characterized by this feature.

9. The VHF antenna includes seven antennas, A to G. Antenna A is the central VHF antenna and is located directly above the coordinate origin. Antennas B to F are arranged around the coordinate origin and are equally far from the coordinate origin. Antennas B to F form a highly symmetrical regular pentagon, and antennas A to F constitute one set of the regular pentagonal interferometer array. Antenna A and two adjacent antennas from antennas B to F form an equilateral triangle. Antenna G is located directly above antenna A. Depending on the height of antenna G relative to the coordinate origin, antenna G and non-adjacent antennas from antennas B to F constitute five sets of the equilateral triangular interferometer array. The ultrashort baseline lightning strike positioning device for a multi-antenna monostatic three-dimensional layout as described in feature 8.

10. A three-dimensional positioning system for ultrashort baseline lightning strikes using a multi-antenna monostatic three-dimensional layout, The multi-antenna monostatic three-dimensional layout ultrashort baseline lightning three-dimensional positioning system comprises a plurality of ultrashort wave (VHF) antennas and computer equipment, wherein the multi-antenna monostatic three-dimensional layout includes an interferometer array composed of different combinations of the VHF antennas, the interferometer array includes one set of regular pentagonal interferometer arrays without angular error and a plurality of sets of equilateral triangular interferometer arrays with angular error, the plurality of VHF antennas are configured to receive and transmit ultrashort wave radiated signals to the computer equipment, and the computer equipment is configured to perform the multi-antenna monostatic three-dimensional layout ultrashort baseline lightning positioning method described in any one of claims 1 to 7. A three-dimensional positioning system for ultrashort baseline lightning strikes, characterized by a multi-antenna monostatic three-dimensional layout.

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