Ultra-long-range lightning location method and system based on very low frequency electromagnetic pulse signals

Abstract

The present invention belongs to the field of lightning detection, and specifically relates to an ultra-long-range lightning location method and system based on very low frequency electromagnetic pulse signals, aiming to solve the problem that existing three-dimensional lightning location methods cannot meet the needs of long-range lightning monitoring. The present invention includes: real-time acquisition of lightning electromagnetic pulse data from each detection station and time window screening; secondary matching through signal cross-correlation method; calculation of the initial position of lightning based on the data of secondary matching; iterative optimization through nonlinear least squares algorithm with the initial position of lightning as the center to obtain the lightning position after error optimization; if the distance between the two positions is less than the set error, the optimized lightning position is used as the located lightning position. The present invention can achieve real-time and high-precision detection of lightning activities within a range of thousands of kilometers, with a positioning accuracy of 2-10km within the detection network and positioning accuracy outside the detection network that can be better than 1% of the signal propagation distance. The detection efficiency of lightning within the detection network is higher than 60%, and the maximum detection distance can reach more than 8,000km.

Description

Technical Field

[0001] The present invention belongs to the field of lightning detection, and in particular relates to an ultra-long-range lightning positioning method and system based on very low frequency electromagnetic pulse signals. Background Art

[0002] Lightning is closely related to human production and daily life. Monitoring lightning and its location is crucial for understanding thunderstorm activity and revealing lightning discharge mechanisms. This is typically achieved through the use of very low frequency (VLF) / low frequency (LF), very high frequency (VHF), and optical radiation signals generated during lightning discharges. Global lightning monitoring and location technology has evolved significantly from single-station to multi-station monitoring, from cloud-to-ground return strokes to full lightning flashes, from full lightning flashes to lightning discharge channels, and from ground-based lightning observations to satellite-based lightning observations.

[0003] Research on three-dimensional lightning location technology began in the early 21st century. This technology monitors very low frequency (VLF) and low frequency (LF) electromagnetic pulse (EMP) signals emitted by lightning and uses the time difference of arrival of these signals combined with direction-finding techniques to locate the lightning source. The maximum distance between stations is approximately 150 km, with an average location error of approximately 300 meters. Due to the attenuation of LEP signals in air, a single detection station is only efficient at detecting LEP ground-wave signals within a range of 300-500 km, significantly limiting the detection range of three-dimensional lightning location systems. Currently, to obtain real-time information on thunderstorm activity over a wider area, one approach is to add more ground-based detection stations to expand the network coverage to areas prone to thunderstorms. However, this approach still lacks effective coverage for thunderstorm activity in distant seas. Alternatively, lightning sensors carried by meteorological satellites can be used for detection, but these methods suffer from suboptimal detection efficiency and accuracy.

[0004] Therefore, this field is in urgent need of developing new long-distance ground-based lightning monitoring technologies to meet the needs of long-distance real-time monitoring of lightning. Summary of the Invention

[0005] In order to solve the above-mentioned problem in the prior art, namely, the problem that the existing three-dimensional lightning location method cannot meet the needs of long-distance lightning monitoring, the present invention provides an ultra-long-distance lightning location method based on very low frequency electromagnetic pulse signals, the location method comprising:

[0006] Step S10: acquiring lightning electromagnetic pulse data from each detection station in real time, and performing time window screening on the collected data in combination with the detection time difference to obtain preliminary screening homologous lightning electromagnetic pulse data;

[0007] Step S20, performing secondary matching by using a signal cross-correlation method, and taking two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold as secondary screening homologous lightning electromagnetic pulse data;

[0008] Step S30, calculating the initial position of the lightning using a spherical triangulation signal arrival time difference positioning method based on the two-screen homologous lightning electromagnetic pulse data;

[0009] Step S40, taking the initial lightning position as the center, iteratively optimizing using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position;

[0010] Step S50: If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is used as the located lightning position.

[0011] In some preferred embodiments, the sliding window step size of the time window is the maximum time difference between the lightning electromagnetic pulse signal and the detection stations in the detection network, which is determined based on the maximum baseline distance of the detection network.

[0012] In some preferred embodiments, step S30 includes:

[0013] Step S31: normalize the propagation distances of lightning L along paths δ1 and δ2 to detection devices P1 and P2, respectively, and construct a relationship between the distance difference and propagation time of the lightning signal.

[0014] Step S32, using the spherical trigonometric cosine theorem to calculate the cosines of both sides of the relationship, and jointly establishing the time difference equation of the detection devices P1 and P2 for the lightning L;

[0015] Step S33: For a set number of detection devices, using the method corresponding to steps S31 and S32, jointly establish the time difference equation for lightning L for any two detection device groups other than the detection device groups P1 and P2;

[0016] Step S34: solving the combination of the time difference equations to obtain the initial position of the lightning.

[0017] In some preferred embodiments, the relationship between the distance difference and propagation time of the lightning signal is:

[0018]

[0019] Where t1 is the time it takes for lightning L to propagate along path δ1 to reach detection device P1, t2 is the time it takes for lightning L to propagate along path δ2 to reach detection device P2, c is the propagation speed of the lightning electromagnetic pulse signal, and R is the radius of the earth.

[0020] In some preferred embodiments, the method of calculating the cosines of both sides of the relationship equation by the spherical trigonometric cosine theorem is as follows:

[0021] cosδ2cosδ1+sinδ2sinδ1=cos K(t2-t1)

[0022] Where K = c / R.

[0023] In some preferred embodiments, the time difference equation of the detection devices P1 and P2 for lightning L is:

[0024]

[0025] Among them, the unknown quantities are the distance δ1 between the lightning and the detection equipment P1 and the azimuth δ 1，2 To detect the distance between devices P1 and P2, is the azimuth of the lightning and the detection device P1 relative to geographic north, is the azimuth of the detection device P2 relative to the detection device P1, is the angle between the side LP1 formed by the lightning L and the detection device P1 and the side P1P2 formed by the detection devices P1 and P2, is the azimuth of the lightning L relative to the detection device P1.

[0026] In some preferred embodiments, step S40 includes:

[0027] Step S41, taking the initial lightning position as the calculation starting point, setting the convergence accuracy ε and the maximum number of iterations N;

[0028] Step S42: Calculate the step length h of the iterative optimization process of the nonlinear least squares algorithm based on the initial lightning location data. lm , and determine the step size;

[0029] Step S43: If the step length h lm <ε, the iteration is completed and the lightning position after error optimization is obtained; otherwise, the lightning location data is updated and the iteration growth rate ρ is calculated;

[0030] Step S44: Update the damping coefficient μ for the search direction and descent speed control based on the iterative speed increase ρ, and jump to step S42.

[0031] In some preferred embodiments, the step length h lm for:

[0032] h lm =-(J(x) T J(x)+μI) -1 J(x) T f(x)

[0033] Where J(x) is the Jacobian matrix of the lightning detection data x, T represents the matrix transpose operation, μ is the damping coefficient, I is the identity matrix, and f(x) is the objective function related to the unknown quantity x.

[0034] In some preferred embodiments, the iterative growth rate ρ is:

[0035]

[0036] Among them, x new =x+h lm For updated lightning location data.

[0037] In some preferred embodiments, the damping coefficient μ for controlling the search direction and the descent speed is updated based on the iterative speed increase ρ, and the method is as follows:

[0038]

[0039] Where ← represents parameter update and v is the gain factor that affects the damping coefficient μ.

[0040] Another aspect of the present invention provides an ultra-long-range lightning location system based on very low frequency electromagnetic pulse signals, the location system comprising:

[0041] Data acquisition module, used to obtain lightning electromagnetic pulse data from each detection station in real time;

[0042] The data initial screening module is used to perform time window screening on the collected data in combination with the detection time difference to obtain the initial screening homologous lightning electromagnetic pulse data;

[0043] A data matching module is used to perform secondary matching by using a signal cross-correlation method, and the primary screening lightning electromagnetic pulse data of two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold are used as the secondary screening homologous lightning electromagnetic pulse data;

[0044] An initial positioning module is used to calculate the initial position of the lightning based on the two-screen homologous lightning electromagnetic pulse data by using the spherical triangulation signal arrival time difference positioning method;

[0045] A positioning optimization module is used to iteratively optimize the lightning position with the initial lightning position as the center using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position;

[0046] The positioning result determination module is used to determine the positioning result. If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is the located lightning position.

[0047] A third aspect of the present invention provides an ultra-long-range lightning location device based on very low frequency electromagnetic pulse signals, the location device comprising:

[0048] Very low frequency lightning electromagnetic pulse signal detection equipment, used for real-time acquisition, processing, data storage, network transmission and high-precision time synchronization of very low frequency electromagnetic pulse signals;

[0049] The data processing center station is used to receive and process data sent back by very low frequency lightning electromagnetic pulse signal detection equipment in real time, and perform real-time analysis and positioning calculation, data transmission, archiving and storage, and backup of the data;

[0050] The display terminal is used to receive and display lightning activity information in real time, as well as to query historical data.

[0051] Beneficial effects of the present invention:

[0052] (1) The present invention uses an ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals. With fewer lightning electromagnetic pulse detection sites and extremely low cost investment, a ground-based lightning electromagnetic pulse detection system is constructed to achieve a large-scale lightning location effect with high positioning accuracy. In particular, a reasonable site layout can further expand the lightning detection efficiency in offshore areas. The positioning accuracy within the detection network can reach 2-10 km, and the positioning accuracy outside the detection network can be better than 1% of the signal propagation distance. The maximum detection distance can reach more than 8,000 km.

[0053] (2) The present invention is based on an ultra-long-distance lightning location method using very low frequency electromagnetic pulse signals. The lightning electromagnetic pulse detection equipment adopts an integrated design with high integration. It has equipment self-test and network data transmission functions, is solar-powered, and is easy to install and maintain, facilitating unmanned operation.

[0054] (3) The present invention is based on an ultra-long-range lightning location method using very low frequency electromagnetic pulse signals. The very low frequency lightning electric field waveform data collected by the lightning electromagnetic pulse detection equipment and the lightning location data calculated by the lightning electromagnetic pulse detection system can constitute a massive lightning database, which is conducive to in-depth research on lightning propagation effects and mechanisms, D ionospheric height, lightning electric field pulse signal feature analysis and identification, thunderstorm activity patterns and characteristics, thunderstorm forecasting technology, etc., and promotes international exchanges and cooperation. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0056] Figure 1 1 is a flow chart of an ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to the present invention;

[0057] Figure 2 Schematic diagram of the propagation of lightning electromagnetic pulse signals in an Earth-ionosphere waveguide according to an embodiment of the ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals of the present invention;

[0058] Figure 3 Schematic diagram of electric field waveforms of lightning very low frequency electromagnetic pulse signals at different distances collected according to an embodiment of the present invention's ultra-long-distance lightning location method based on very low frequency electromagnetic pulse signals;

[0059] Figure 4 This is a schematic diagram of the positioning process of an embodiment of an ultra-long-distance lightning positioning method based on very low frequency electromagnetic pulse signals of the present invention;

[0060] Figure 5 A density map of lightning activity in the Eurasian continent and the western Pacific region within one day detected by a very low frequency lightning monitoring system according to one embodiment of the present invention's ultra-long-distance lightning location method based on very low frequency electromagnetic pulse signals;

[0061] Figure 6 This is a schematic diagram of the composition, signal acquisition, and data transmission of the ultra-long-distance lightning location device based on very low frequency electromagnetic pulse signals of the present invention;

[0062] Figure 7 This is a system composition block diagram of a lightning very low frequency electromagnetic pulse signal acquisition and processing device of an ultra-long-distance lightning location system based on very low frequency electromagnetic pulse signals of the present invention. DETAILED DESCRIPTION

[0063] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0064] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0065] The present invention provides an ultra-long-range lightning location method based on very low frequency (VLF) electromagnetic pulse (EMP) signals. Taking into account the long-range propagation characteristics of VLF electromagnetic radiation signals generated by lightning in Earth-ionosphere waveguides, an ultra-long-range lightning detection system is constructed using a plurality of electromagnetic pulse signal detection devices that are rationally distributed and have a baseline distance of more than 1,000 km. This method solves the problem that existing VLF / low-frequency three-dimensional lightning location systems with a baseline of 10-300 km are unable to detect over long distances, thereby achieving real-time, high-precision, and high-efficiency detection of lightning activity over vast land and oceans.

[0066] The present invention provides an ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals, the location method comprising:

[0067] Step S10: acquiring lightning electromagnetic pulse data from each detection station in real time, and performing time window screening on the collected data in combination with the detection time difference to obtain preliminary screening homologous lightning electromagnetic pulse data;

[0068] Step S20, performing secondary matching by using a signal cross-correlation method, and taking two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold as secondary screening homologous lightning electromagnetic pulse data;

[0069] Step S30, calculating the initial position of the lightning using a spherical triangulation signal arrival time difference positioning method based on the two-screen homologous lightning electromagnetic pulse data;

[0070] Step S40, taking the initial lightning position as the center, iteratively optimizing using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position;

[0071] Step S50: If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is used as the located lightning position.

[0072] In order to more clearly illustrate the ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals of the present invention, the following is combined with Figure 1 Each step in the embodiment of the present invention is described in detail.

[0073] The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to the first embodiment of the present invention includes steps S10 to S50, each of which is described in detail as follows:

[0074] Step S10: acquiring lightning electromagnetic pulse data from each detection station in real time, and performing time window screening on the collected data in combination with the detection time difference to obtain preliminarily screened homologous lightning electromagnetic pulse data.

[0075] The data received in real time can be stored in the server running memory and local storage media in chronological order.

[0076] like Figure 2Figure 2 is a schematic diagram illustrating the propagation of lightning electromagnetic pulse signals in an Earth-ionosphere waveguide according to an embodiment of the present invention's ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals. The very low frequency electromagnetic radiation signals generated by lightning propagate over long distances in the Earth-ionosphere waveguide. An ultra-long-range lightning detection system can be constructed using multiple electromagnetic pulse signal detection devices that are reasonably distributed and have a baseline distance of more than 1000 km. This enables real-time, high-precision, and high-efficiency detection of lightning activity over vast land and ocean areas.

[0077] like Figure 3 As shown, this is a schematic diagram of the electric field waveforms of lightning very low frequency electromagnetic pulse signals collected at different distances according to an embodiment of the present invention's ultra-long-distance lightning location method based on very low frequency electromagnetic pulse signals. As the signal propagation distance increases, the superposition of multi-hop signals becomes more obvious and the low-frequency component becomes stronger.

[0078] Calculate the analytical signal m of a collected very low frequency electromagnetic pulse signal m(t) a (t), m a (t) The calculation expression is as follows:

[0079] m a (t) = F -1 (F(m)2u)=m(t)+in(t) (1)

[0080] Where F represents Fourier transform, F -1 represents the inverse Fourier transform, u represents the unit step function, and n(t) is the Hilbert transform of m(t).

[0081] According to the analytical signal m a (t) Calculate the envelope e(t) of the original signal. The calculation expression of e(t) is as follows:

[0082]

[0083] Find the time corresponding to the maximum value of the envelope e(t), which is the signal arrival time.

[0084] The very low frequency electromagnetic pulse detection equipment of the present invention calculates the signal peak intensity and pulse signal rise time, fall time, signal-to-noise ratio and other parameters of each lightning electromagnetic pulse signal collected as signal characteristics. The original waveform data accompanying the collected signal is packaged according to the defined data transmission format and transmitted in real time via the Internet to the data processing center station for positioning calculation.

[0085] The sliding window step size of the time window is the maximum time difference between the lightning electromagnetic pulse signal and each detection station in the detection network, which is determined based on the maximum baseline distance of the detection network.

[0086] Based on the maximum baseline distance of the detection network, the maximum time difference between the lightning electromagnetic pulse signal reaching each detection station in the detection network can be determined. This time difference is used as a sliding window to match the time when the lightning arrives at each detection station. When the signal arrival times calculated by multiple stations are within the same time window, it can be preliminarily determined that these data are from the same source.

[0087] The sliding window step size of the time window can be obtained by formula (3):

[0088]

[0089] Among them, D i Indicates the baseline distance between adjacent sites, max(D i ) represents the maximum baseline distance, and c is the propagation speed of the lightning electromagnetic pulse signal.

[0090] Step S20, performing secondary matching by signal cross-correlation method, taking the primary screening lightning electromagnetic pulse data of two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold as the secondary screening homologous lightning electromagnetic pulse data.

[0091] The sliding time window method can quickly and preliminarily screen out homologous data from large amounts of data. However, in some special cases, some noise or non-homologous signals may be mixed into the screening results. To more accurately screen homologous data, based on the rapid screening results of the sliding time window, the signal cross-correlation method is used for secondary matching. The correlation coefficient of two lightning electromagnetic pulse waveform data sets adjacent in time is calculated to ensure that the data in the resulting sequence has a high degree of correlation.

[0092] Step S30: Calculate the initial position of the lightning based on the two-screen homologous lightning electromagnetic pulse data by using the spherical triangulation signal arrival time difference positioning method.

[0093] When the distance between detection stations (baseline length) or between the lightning source and the detection station exceeds line of sight, the Earth's curvature causes very low-frequency lightning signals to propagate far in the Earth-ionosphere waveguide. Continuing to assume that the signals propagate in a straight line can lead to significant errors in the results, or even failure to converge. Assuming the Earth is a uniform sphere, when the number of selected homologous data points is four or more, spherical triangulation is used to calculate the initial lightning position.

[0094] like Figure 4 FIG. 1 is a schematic diagram of the positioning process of an embodiment of the ultra-long-distance lightning positioning method based on very low frequency electromagnetic pulse signals of the present invention. Figure 4 The diagram shows the signal propagation along the spherical surface, and the method for calculating the initial position of lightning is detailed.

[0095] In step S31 , the propagation distances of the lightning L along the paths δ1 and δ2 to the detection devices P1 and P2 are normalized, and a relationship between the distance difference and the propagation time of the lightning signal is constructed.

[0096] The normalization process is shown in formula (4):

[0097]

[0098] Among them, δ N is the normalized propagation distance, N represents the number of the detection device, D N It represents the spherical distance between the detection device numbered N and the lightning L, and R is the radius of the earth.

[0099] The distance between detection devices P1 and P2 is denoted as δ 1，2 , are the azimuths of lightning and detection equipment P1 and P2 relative to geographic north, is the azimuth angle of the detection device P1 relative to the detection device P2.

[0100] The relationship between the distance difference and propagation time of lightning signal is shown in formula (5):

[0101]

[0102] Wherein, t1 is the time for the lightning L to propagate along the path δ1 to the detection device P1, t2 is the time for the lightning L to propagate along the path δ2 to the detection device P2, and c is the propagation speed of the lightning electromagnetic pulse signal.

[0103] Using the spherical trigonometric cosine theorem, we can get formula (6):

[0104]

[0105] in, is the angle between the side LP1 formed by the lightning L and the detection device P1 and the side P1P2 formed by the detection devices P1 and P2, is the azimuth of the lightning L relative to the detection equipment P1, is the azimuth angle of the detection device P2 relative to the detection device P1.

[0106] The relationship between the azimuth angles is shown in formula (7):

[0107]

[0108] Step S32 , using the spherical trigonometric cosine theorem to calculate the cosines of both sides of the relationship, and jointly establishing the time difference equation of the detection devices P1 and P2 for the lightning L.

[0109] Let K = c / R and take the cosine of both sides of equation (5) to obtain equation (8):

[0110] cosδ2cosδ1+sinδ2sinδ1=cos K(t2-t1) (8)

[0111] Combining equations (6) and (8), we can obtain the time difference equation of detection devices P1 and P2 for lightning L, as shown in equation (9):

[0112]

[0113] Among them, the unknown quantities are the distance δ1 between the lightning and the detection equipment P1 and the azimuth

[0114] In step S33 , for a set number of detection devices, the time difference equations for lightning L for any two detection device groups other than the detection device groups P1 and P2 are jointly established by the method corresponding to steps S31 and S32 .

[0115] Step S34: solving the combination of the time difference equations to obtain the initial position of the lightning.

[0116] Therefore, using the above method requires at least three detection devices to obtain a location solution. Considering the phase ambiguity problem caused by solving the problem with three stations, data from at least four detection devices are required to obtain a more reliable initial lightning location.

[0117] Step S40 , taking the initial lightning position as the center, iteratively optimizing using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position.

[0118] Step S41 , taking the initial lightning position as the calculation starting point, setting the convergence accuracy ε and the maximum number of iterations N.

[0119] If the initial lightning position cannot be obtained, the calculation ends and the initial position is returned.

[0120] Step S42: Calculate the step length h of the iterative optimization process of the nonlinear least squares algorithm based on the initial lightning location data. lm , and determine the step size.

[0121] Step length h lm The calculation method is shown in formula (10):

[0122] h lm =-(J(x) T J(x)+μI) -1 J(x) T f(x) (10)

[0123] Where J(x) is the Jacobian matrix of the lightning detection data x, T represents the matrix transpose operation, μ is the damping coefficient, I is the identity matrix, and f(x) is the objective function related to the unknown quantity x.

[0124] The distance δ1 and azimuth between the lightning and the detection device P1 These two unknown quantities, One way to express f(x) is as shown in formula (11):

[0125]

[0126] Step S43: If the step length h lm <ε, the iteration is completed and the lightning position after error optimization is obtained; otherwise, the lightning location data is updated and the iterative growth rate ρ is calculated.

[0127] The updated lightning location data is shown in formula (12):

[0128] x new =x+h lm (12)

[0129] At this time, the iterative growth rate ρ is as shown in formula (13):

[0130]

[0131] Step S44: Update the damping coefficient μ for the search direction and descent speed control based on the iterative speed increase ρ, and jump to step S42.

[0132] The update of the damping coefficient for search direction and descent speed control based on the iterative growth rate ρ is shown in formula (14):

[0133]

[0134] Where ← represents parameter update and v is the gain factor that affects the damping coefficient μ.

[0135] After the damping coefficient is updated, step S42 is continued to be executed, and the calculation is iterated in a loop.

[0136] Step S50: If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is used as the located lightning position.

[0137] Calculate the distance D between the two positioning results obtained in step S30 and step S40 i-lm , when the distance D i-lm When the error is less than a certain range, the lightning position information after error optimization by the nonlinear least squares algorithm in step S40 is output as the lightning location result.

[0138] In practical applications, the method, system and device proposed by the present invention have good applicability. Figure 5 Figure 2 shows a density map of lightning activity over Eurasia and the western Pacific region over a single day, as detected by a very low frequency (VLF) lightning monitoring system, according to one embodiment of the present invention's ultra-long-distance lightning location method based on very low frequency (VLF) electromagnetic pulse (EMP) signals. The results, presented as lightning density, are compared with data from the same area detected by a high-precision three-dimensional lightning monitoring system. The VLF lightning detection system's location accuracy is 2-10 km within the detection network, and better than 1% of the signal propagation distance outside the network. Lightning detection efficiency within the detection network exceeds 60%, and the maximum detection distance reaches over 8,000 km.

[0139] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0140] The second embodiment of the present invention provides an ultra-long-range lightning location system based on very low frequency electromagnetic pulse signals, the location system comprising:

[0141] Data acquisition module, used to obtain lightning electromagnetic pulse data from each detection station in real time;

[0142] The data initial screening module is used to perform time window screening on the collected data in combination with the detection time difference to obtain the initial screening homologous lightning electromagnetic pulse data;

[0143] A data matching module is used to perform secondary matching by using a signal cross-correlation method, and the primary screening lightning electromagnetic pulse data of two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold are used as the secondary screening homologous lightning electromagnetic pulse data;

[0144] An initial positioning module is used to calculate the initial position of the lightning based on the two-screen homologous lightning electromagnetic pulse data by using the spherical triangulation signal arrival time difference positioning method;

[0145] A positioning optimization module is used to iteratively optimize the lightning position with the initial lightning position as the center using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position;

[0146] The positioning result determination module is used to determine the positioning result. If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is the located lightning position.

[0147] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the system described above can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0148] The third embodiment of the present invention is an ultra-long-range lightning locating device based on a very low frequency electromagnetic pulse signal, such as Figure 6 Figure 2 shows the composition, signal acquisition, and data transmission of the ultra-long-range lightning location device based on very low frequency (VLF) electromagnetic pulse (EMP) signals of the present invention. The lightning EMP detection equipment distributed at various field observation stations operates in the very low frequency (VLF) band. The VLF LEP location system consists of at least four VLF LEP signal detection devices and a data processing center. The baseline distance of the detection equipment is over 1000 km, and the detection equipment and the data processing center exchange data via the Internet.

[0149] The positioning device includes:

[0150] Very low frequency lightning electromagnetic pulse signal detection equipment is used for real-time collection, processing, data storage, network transmission and high-precision time synchronization of very low frequency electromagnetic pulse signals, and transmits the processing results to the data processing center station via the Internet.

[0151] The data processing center station consists of a high-performance server and its associated storage, network communication, and power supply equipment. It is used to receive and process data sent back by very low frequency lightning electromagnetic pulse signal detection equipment in real time, and perform real-time analysis and positioning calculation, data transmission, archiving and backup of the data. The server runs a special positioning algorithm to achieve ultra-long-distance detection of lightning very low frequency electromagnetic pulses.

[0152] The display terminal is used to receive and display lightning activity information in real time, as well as to query historical data.

[0153] The very low frequency lightning electromagnetic pulse signal detection equipment includes the following modules:

[0154] The signal acquisition module includes a very low frequency signal receiving antenna, a low-noise signal amplification circuit, a filtering circuit, and an analog / digital conversion circuit to quickly acquire very low frequency pulse signals.

[0155] The real-time processing module includes a high-speed processor that completes functions such as signal trigger acquisition, signal time marking, signal arrival time calculation, signal strength calculation, and signal characteristic parameter calculation;

[0156] Precision time stamp module, including GPS / Beidou timing, location information acquisition and signal time stamping functions. The signal time stamp is based on the precise time information output by the GPS / Beidou timing module;

[0157] Communication module, including wired network communication, wireless mobile network communication and serial data transmission functions;

[0158] Data storage module, which stores the collected data in a local large-capacity memory according to a defined data storage format;

[0159] The high-purity power supply module provides stable and pure power to each functional module of the equipment.

[0160] Very low frequency electromagnetic pulse detection equipment uses an electric field whip antenna to obtain high gain far field signal reception capability.

[0161] The very low frequency electromagnetic pulse detection station uses solar power to ensure the purity of the power supply to the greatest extent possible and reduce the impact of power supply line noise on high-sensitivity signal acquisition.

[0162] like Figure 7 The figure shows a block diagram of the system composition of the lightning VLF electromagnetic pulse signal acquisition and processing equipment of the ultra-long-range lightning location system based on VLF electromagnetic pulse signals of the present invention. The lightning radiation electric field signal induced by the VLF signal receiving antenna is converted into a digital signal that can be calculated by the processor after passing through a low-noise signal amplification circuit, a filtering circuit, and an analog / digital conversion circuit. Among them, the signal acquisition channel includes two independently operating channels. The 3dB frequency range of channel A is 3kHz to 15kHz, and the 3dB frequency range of channel B is 3kHz to 30kHz. The dual-channel design can meet the signal reception and gain requirements of different distances. Channel A has a low frequency range and is mainly used for longer-distance detection needs (>8000km). The analog / digital conversion rate is set to 500KSPS.

[0163] Signal acquisition is primarily based on triggered sampling. Based on predefined signal thresholds, the processor autonomously determines whether to acquire and process the current signal. For signals that meet these thresholds, the processor records a discrete time series of 2 milliseconds (milliseconds) before and after the trigger, totaling 1000 sampling points (at a 500 kSPS sampling rate). This includes approximately 120 μS (microseconds) before the trigger, an empirical value used to ensure complete recording of the lightning pulse before and after the trigger.

[0164] Based on the precise time information output by the precise time scale module, the trigger time of the sampling signal is marked. According to the timing accuracy of the GPS / Beidou timing system in open outdoor conditions, the trigger time mark accuracy can be better than 100ns (nanoseconds).

[0165] Compared with lightning electromagnetic pulse ground wave signals, which have obvious peak arrival times, very low frequency electromagnetic pulse signals propagate in the Earth-ionosphere waveguide. On the one hand, the ground wave signals are significantly attenuated and difficult to measure. On the other hand, multi-hop signals superimpose on each other, making it impossible to calculate the exact signal arrival time.

[0166] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the above-described device can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0167] It should be noted that the ultra-long-range lightning location system and device based on very low frequency electromagnetic pulse signals provided in the above embodiments are merely exemplified by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be combined into one module or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are merely for the purpose of distinguishing the modules or steps and are not to be considered as improper limitations of the present invention.

[0168] An electronic device according to a fourth embodiment of the present invention includes:

[0169] at least one processor; and

[0170] a memory communicatively connected to at least one of the processors; wherein,

[0171] The memory stores instructions that can be executed by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals.

[0172] A fifth embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are configured to be executed by the computer to implement the aforementioned ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals.

[0173] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes and related instructions of the storage device and processing device described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0174] Those skilled in the art should be able to appreciate that, in conjunction with the modules and method steps of each example described in the embodiments disclosed herein, it is possible to implement them with electronic hardware, computer software, or a combination of the two, and the programs corresponding to the software modules and method steps can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. In order to clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0175] The terms "first", "second", etc. are used to distinguish similar objects, rather than to describe or indicate a particular order or sequence.

[0176] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0177] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for ultra-long-range lightning location based on very low frequency electromagnetic pulse signals, characterized in that: The positioning method includes: Step S10: acquiring lightning electromagnetic pulse data from each detection station in real time, and performing time window screening on the collected data in combination with the detection time difference to obtain preliminary screening homologous lightning electromagnetic pulse data; Step S20, performing secondary matching by using a signal cross-correlation method, and taking the primary screening lightning electromagnetic pulse data of two temporally adjacent primary screening homologous lightning electromagnetic pulse data whose correlation is higher than a set threshold as the secondary screening homologous lightning electromagnetic pulse data; Step S30, based on the two-screen homologous lightning electromagnetic pulse data, calculates the initial position of the lightning by using the spherical triangulation signal arrival time difference positioning method, including: Step S31: Lightning L along the path and Spread to detection devices respectively and The propagation distance is normalized, and the relationship between the distance difference and propagation time of the lightning signal is constructed: ； in, The lightning L along the path Propagation to detection equipment time, The lightning L along the path Propagation to detection equipment time, c is the propagation speed of lightning electromagnetic pulse signal, is the radius of the Earth; Step S32, calculating the cosines of both sides of the relationship using the spherical trigonometric cosine theorem: ； in, ; Combined detection equipment and Time difference equation for lightning L; the detection device and The time difference equation for lightning L is: ； Among them, the unknown quantities are lightning and detection equipment distance and azimuth , For detection equipment and distance, Lightning and detection equipment Azimuth relative to geographic north, For detection equipment Relative to detection equipment The azimuth of For lightning L and detection equipment The formed edge and detection equipment and The formed edge The angle of is the lightning L relative to the detection device azimuth; Step S33: for a set number of detection devices, respectively, the detection devices are connected by the corresponding method of step S31-step S32. and The time difference equation for lightning L between any two detection equipment groups outside the group; Step S34, solving the combination of the time difference equations to obtain the initial position of the lightning; Step S40, taking the initial lightning position as the center, iteratively optimizing using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position; Step S50: If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is used as the located lightning position.

2. The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to claim 1, characterized in that: The sliding window step size of the time window is the maximum time difference between the lightning electromagnetic pulse signal and each detection station in the detection network, which is determined based on the maximum baseline distance of the detection network.

3. The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to claim 1, characterized in that: Step S40 includes: Step S41: Taking the initial position of the lightning as the calculation starting point, set the convergence accuracy and the maximum number of iterations N; Step S42: Calculate the step size of the iterative optimization process of the nonlinear least squares algorithm based on the initial lightning location data. , and determine the step size; Step S43, if the step length , the iteration is completed and the lightning position after error optimization is obtained; otherwise, the lightning location data is updated and the iteration speed is calculated. ; Step S44, based on the iterative speed increase Damping coefficient for search direction and descent speed control and jump to step S42.

4. The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to claim 3, characterized in that: The step length for: ； in, Lightning detection data x of Jacobian matrix, T represents the matrix transpose operation, is the damping coefficient, I is the unit matrix, For the unknown quantity x Related objective functions.

5. The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to claim 4, characterized in that: The iterative speed increase for: ； in, For updated lightning location data.

6. The ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to claim 5, characterized in that: Based on the iterative speed Damping coefficient for search direction and descent speed control The update method is: ； in, represents parameter update, To affect the damping coefficient The gain factor.

7. An ultra-long-range lightning location system based on very low frequency electromagnetic pulse signals, used to implement the ultra-long-range lightning location method based on very low frequency electromagnetic pulse signals according to any one of claims 1 to 6, characterized in that: The positioning system comprises: Data acquisition module, used to obtain lightning electromagnetic pulse data from each detection station in real time; The data initial screening module is used to perform time window screening on the collected data in combination with the detection time difference to obtain the initial screening homologous lightning electromagnetic pulse data; A data matching module is used to perform secondary matching by using a signal cross-correlation method, and the primary screening lightning electromagnetic pulse data of two temporally adjacent primary screening homologous lightning electromagnetic pulse data with a correlation higher than a set threshold are used as the secondary screening homologous lightning electromagnetic pulse data; An initial positioning module is used to calculate the initial position of the lightning based on the two-screen homologous lightning electromagnetic pulse data by using the spherical triangulation signal arrival time difference positioning method; A positioning optimization module is used to iteratively optimize the lightning position with the initial lightning position as the center using a nonlinear least squares algorithm until the convergence accuracy is lower than a set threshold or the maximum number of iterations is reached, thereby obtaining an error-optimized lightning position; The positioning result determination module is used to determine the positioning result. If the distance between the initial lightning position and the error-optimized lightning position is less than a set error, the error-optimized lightning position is the positioned lightning position.

8. An ultra-long-range lightning locating device based on very low frequency electromagnetic pulse signals, used to implement the ultra-long-range lightning locating method based on very low frequency electromagnetic pulse signals according to any one of claims 1 to 6, characterized in that: The positioning device includes: Very low frequency lightning electromagnetic pulse signal detection equipment, used for real-time acquisition, processing, data storage, network transmission and high-precision time synchronization of very low frequency electromagnetic pulse signals; The data processing center station is used to receive and process data sent back by very low frequency lightning electromagnetic pulse signal detection equipment in real time, and perform real-time analysis and positioning calculation, data transmission, archiving and storage, and backup of the data; The display terminal is used to receive and display lightning activity information in real time, as well as to query historical data.

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