Single-station lightning three-dimensional positioning method and system

Abstract

The invention provides a single-station lightning three-dimensional positioning system and method. The positioning system mainly comprises a direction detection unit, a distance detection unit, a GNSS time service unit, a positioning unit and a three-dimensional image generation unit. A plurality of VHF antennas, an electric field antenna and a magnetic field antenna synchronously collect lightning signals, the lightning signals are converted into digital signals through analog-to-digital conversion, and GNSS time service marks timestamps and stores the timestamps. The direction detection unit detects the time difference from the lightning radiation source to the VHF antenna, performs angle and time difference conversion, and calculates the elevation angle and azimuth angle of the lightning radiation source. And the distance detection unit performs fast Fourier transform on the acquired electric field signal and magnetic field signal, fits a ratio curve constant A and a ratio curve constant B, and calculates the distance between the lightning radiation source and the observation station. And matching the azimuth angle, the elevation angle and the distance information marked with the same timestamp, positioning the position of an instant lightning radiation source, and matching all positioning results of a continuous lightning event one by one according to the same timestamp to obtain a lightning three-dimensional graph in the space model.

Description

Technical Field

[0001] The invention relates to the fields of meteorology, atmospheric electricity and space science and technology, and in particular to a three-dimensional lightning positioning method and system. Background Art

[0002] Lightning is one of the important phenomena in atmospheric electromagnetic activities, and is of great significance to the research in meteorology, atmospheric electricity, and space science. Lightning location is of great scientific significance for detecting the charge structure, charge density distribution, and its evolution with the development of thunderstorm processes in thunderstorm clouds, and for revealing the physical mechanism of lightning occurrence and development. There are many lightning location methods in the prior art, such as: time difference method (TOA) and arrival time difference method (TDOA) are currently commonly used lightning location technologies, and interferometric positioning technology is also a lightning location method in the prior art. Single-station interferometer positioning can only map the elevation and azimuth of lightning, and cannot reflect the distance information of lightning. To obtain the three-dimensional information of lightning, multiple interferometer stations need to be deployed. The three-dimensional position of lightning is calculated by the azimuth and distance difference of multiple stations, which requires complex equipment deployment and site synchronization, increasing the cost of equipment. In actual detection and positioning, it is necessary to go back and forth to debug at various sites separated by tens of kilometers, which greatly increases the workload of manual debugging.

[0003] The existing multi-station lightning positioning methods, whether it is the time difference method (TOA), the arrival time difference method (TDOA), or the interferometer positioning technology, are all based on the time synchronization provided by the global navigation satellite system (GNSS). At the moment of lightning, the lightning signals collected by multiple detection stations are marked with timestamps, and each detection station transmits the data to the central station. The central station synchronizes the lightning signal according to the timestamp. Although the timing clock accuracy of the global navigation satellite system reaches the nanosecond level, for high-speed data collection such as lightning signals, there are still errors in the time synchronization of different observation stations, which affects the accuracy of the central station's lightning positioning. Summary of the invention

[0004] The purpose of the present invention is to provide a single-station lightning three-dimensional positioning system and method. The positioning system mainly includes a direction detection unit, a distance detection unit, a GNSS timing unit, a positioning unit, and a three-dimensional image generation unit. Several VHF antennas of the direction detection unit and the electric field antenna and magnetic field antenna of the distance detection unit synchronously collect lightning signals, are connected to the radio frequency signal acquisition processor and the electric field and magnetic field signal acquisition processor through cables, and are converted into digital signals through high-speed A / D conversion. The GNSS timing unit outputs a high-precision clock frequency as a sampling reference clock for high-speed A / D conversion to ensure the accuracy of the signal conversion time. The output high-precision full-second clock signal 1PPS and NMEA0183 data with time information cooperate with the sampling reference clock to mark the timestamp for the detected lightning signal and store it. The direction detection unit detects the time difference Δt from the lightning radiation source to the VHF antenna and spatially maps it, performs angle and time difference conversion, and calculates the elevation angle of the lightning radiation source. EN and azimuth A-Z The distance detection unit performs fast Fourier transform on the collected electric field signal E and magnetic field signal H, and converts the ratio of the electric field spectrum to the magnetic field spectrum ( E ω / H ω ) and frequency (f) are plotted into a ratio curve, and the ratio curve is filtered using a high-pass filter and a low-pass filter. The ratio curve constant A in the high-frequency band and the ratio curve constant B in the low-frequency band are fitted. Constants A and B are substituted into the distance formula to calculate the distance between the lightning radiation source and the observation station. r . The azimuths of the same timestamps will be marked A-Z , Elevation EN ,distance r Information matching, locate the location of the lightning radiation source in an instant ( x , y , z ), all the location results of a continuous lightning event are matched one by one according to the same timestamp to obtain the three-dimensional graphics of lightning in the spatial relationship model.

[0005] The technical solution adopted by the present invention is: to provide a single-station lightning three-dimensional positioning method, which is a three-dimensional positioning method based on the combination of interference lateral and electromagnetic ranging, and includes the following steps.

[0006] S1. Lightning signal collection. Several VHF antennas of the direction detection unit and the electric field antenna and magnetic field antenna of the distance detection unit synchronously collect lightning signals, which are connected to the RF signal acquisition processor and the electric field and magnetic field signal acquisition processor through cables. The analog signals are converted into digital signals through high-speed A / D conversion. The GNSS timing unit outputs a high-precision clock frequency as a sampling reference clock for high-speed A / D conversion to ensure the accuracy of the signal conversion time. The output high-precision full-second clock signal 1PPS and NMEA0183 data with time information are used in conjunction with the sampling reference clock to mark the timestamp and store the detected lightning signals.

[0007] S2. Extract the stored lightning signal data and establish a spatial relationship model between the measuring station and the lightning radiation source.

[0008] S3, the time difference from the lightning radiation source detected by the direction detection unit to the VHF antenna Δt , calculate the incident angle between the lightning radiation source and the antenna I.

[0009] S4, direction detection unit according to the time difference Δt Spatial mapping, angle and time difference conversion, calculation of the elevation angle of the lightning radiation source EN and azimuth A-Z.

[0010] S5. The distance detection unit collects the electric field signal E and magnetic field signals H Perform fast Fourier transform (FFT) to convert the recorded electric field signal and magnetic field signal into frequency domain to obtain the electric field spectrum ( E ω ) and magnetic field spectrum ( H ω ), and then the ratio of the electric field spectrum to the magnetic field spectrum ( E ω / H ω ) and frequency ( f ) are plotted as a ratio curve.

[0011] S6, the distance detection unit uses a high-pass filter to filter the contrast curve, E ω / H ω ) and frequency ( f ) ratio curve is fitted, and the high-frequency ratio curve tends to a constant A; a low-pass filter is used to filter the ratio curve, and ( E ω / H ω ) and frequency ( f) is fitted, and the ratio curve of the low-frequency band tends to a constant B.

[0012] S7. Substitute constants A and B into the distance formula to calculate the distance between the lightning radiation source and the observation station. r .

[0013] S8, mark the azimuth with the same timestamp A-Z , Elevation EN ,distance r Information matching, locating the lightning radiation source in an instant ( x,y,z ), all the location results of a continuous lightning event are matched one by one according to the same timestamp to obtain the three-dimensional graphics of lightning in the spatial relationship model.

[0014] In step S3, according to the time difference of reaching any two VHF antennas Δt , the incident angle of the lightning radiation source i Calculate according to the following formula: , in: c is the speed of light, d is the baseline length of the two antennas.

[0015] In step S4, the elevation angle of the lightning radiation source is EN and azimuth A-Z , calculated according to the following formula: , , , Where: Elevation EN Observation base point i The angle between the lightning radiation source and the horizontal plane projection, azimuth A-Z is the angle between the Y axis and the horizontal projection line of the lightning radiation source clockwise. α Observation base point i The angle between the lightning radiation source and the X-axis is β Observation base point i The spatial angle between the lightning radiation source and the Y axis is F ij The Y axis is clockwise and ij The angle of the baseline ( ij The azimuth of the baseline), c is the speed of light, Δt ij The radiation source reaches the base point i and base point j The time difference, d ij As the base point i and base point jspacing.

[0016] The frequency band of the high-pass filter in step S6 is f =60 kHz~120 kHz, use the following equation to ( E ω / H ω ) and frequency ( f ) is fitted to determine the constant A: , in: G is a correction factor that takes into account the difference in system gain between the electric and magnetic field measurement systems; m 0 is the magnetic permeability, e 0 is the electrical constant.

[0017] The frequency band of the low-pass filter in step S6 is f =100 Hz~15 kHz, use the following equation to solve ( E ω / H ω ) and frequency ( f ) ratio curve is fitted to determine the constant B: , , in, k is the wave number, which defines the magnitude of the wave vector of the electromagnetic wave; r is the distance between the lightning radiation source and the observation station; f The frequency of the lightning signal to be detected (Hz); c is the propagation speed of electromagnetic waves, taking the speed of light; d Is a value less than 1.

[0018] In step S7, the distance between the lightning radiation source and the observation station r , calculated according to the following formula: , in, c is the propagation speed of electromagnetic waves, taking the speed of light; π is the ratio of pi.

[0019] The position (x, y, z) of a lightning radiation source in step S8 is calculated according to the following formula: , in:( x i , y i, z i ) are the station coordinates.

[0020] Each frame of lightning located in step 8 in a lightning event is matched one by one according to the marked timestamp to draw a continuous three-dimensional image of lightning.

[0021] The present invention provides a single-station lightning three-dimensional positioning system, which mainly includes a direction detection unit 1, a distance detection unit 2, a GNSS timing unit 3, a three-dimensional positioning unit 4, and a three-dimensional image generation unit 5. The hardware of the direction detection unit 1 is composed of a plurality of VHF antennas 101, a radio frequency signal acquisition processor 102, and a radio frequency signal storage 103; the software of the direction detection unit 1 includes a time difference calculation module 104, an angle and time difference conversion module 105, and an azimuth and elevation angle calculation module 106. The hardware of the distance detection unit 2 is composed of an electric field antenna 201, a magnetic field antenna 202, an electric field and magnetic field signal acquisition processor 203, and an electric field and magnetic field signal storage 204; the software of the distance detection unit 2 includes an electric field time domain waveform generation module 205, a magnetic field time domain waveform generation module 206, a fast Fourier transform module 207, an electric field and magnetic field spectrum ratio calculation module 208, a high frequency band constant A fitting module 209, a low frequency band constant B fitting module 210, and a distance calculation module 211.

[0022] There are at least three VHF antennas 101, and the antennas are not collinear, and the antenna spacing is 10-100m, forming a phased antenna array. The magnetic field antenna 202 is composed of two orthogonal magnetic rods, which are respectively aligned in the north-south and east-west directions.

[0023] The GNSS timing unit 3 includes a highly stable oven-controlled crystal oscillator (OCXO). The second pulse signal output by the GNSS timing unit 3 is a sampling reference signal. The frequency offset of the output of the highly stable oven-controlled crystal oscillator (OCXO) is measured, and the frequency loop of the highly stable oven-controlled crystal oscillator (OCXO) is calibrated and compensated. The highly stable oven-controlled crystal oscillator (OCXO) outputs a high-precision clock signal and a second signal. The time in the NMEA0183 protocol of the acquired clock signal plus 1s is used as the reference time t for the start of acquisition. start And wait for the system second pulse signal as the start time of collection.

[0024] The beneficial effects of the present invention are as follows: the positioning system only requires one measuring station to be equipped with multiple antennas to form a phased antenna array, thereby reducing the cost of the positioning system; there is no need for long-distance system debugging between stations, thereby reducing the debugging workload. It overcomes the defects of multi-station positioning systems that require good line-of-sight conditions between stations and are greatly restricted by factors such as terrain and weather. The same clock is used as the sampling reference clock for each antenna, and time synchronization is not required, which ensures the accuracy of the signal conversion time and the accuracy of positioning. Single-station positioning only relies on data collection and processing at the local measuring station, and data transmission is more direct, which can achieve higher real-time performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A lightning location system frame of the present invention; Figure 2 A flowchart of the positioning method of the present invention; Figure 3 This is a schematic diagram of interferometer time difference measurement; Figure 4 It is a three-dimensional schematic diagram of interferometer direction finding; Figure 5 Schematic diagram of the interferometer direction finding plane.

[0026] In the figure: 1-direction detection unit, 2-distance detection unit, 3-GNSS timing unit, 4-positioning unit, 5-three-dimensional image generation unit, 101-VHF antenna, 102-RF signal acquisition processor, 103-RF signal memory, 104-time difference calculation module, 105-angle and time difference conversion module, 106-azimuth elevation calculation module, 201-electric field antenna, 202-magnetic field antenna, 203-electric field and magnetic field signal acquisition processor, 204-electric field and magnetic field signal memory, 205-electric field time domain waveform generation module, 206-magnetic field time domain waveform generation module, 207-fast Fourier transform module, 208-electric field and magnetic field spectrum ratio calculation module, 209-high frequency band constant A fitting module, 210-low frequency band constant B fitting module, 211-distance calculation module. DETAILED DESCRIPTION

[0027] In order for those skilled in the art to better understand the present invention, Figure 1~Figure 5 The present invention is further described, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0028] The single-station lightning three-dimensional positioning system of the present invention mainly includes a direction detection unit 1, a distance detection unit 2, a GNSS timing unit 3, a three-dimensional positioning unit 4, and a three-dimensional image generation unit 5. The lightning positioning system is shown in FIG. Figure 1The hardware of the direction detection unit 1 is composed of several VHF antennas 101, a radio frequency signal acquisition processor 102, and a radio frequency signal storage 103. Two VHF antennas 101 can form a baseline for detecting the time difference between the two antennas. Δt Calculate the incident angle of the lightning radiation source i , but the time difference Δt When spatial mapping is used to convert angles and time differences, one baseline cannot solve two unknown parameters. The time difference of two baselines is required. Δt Calculated incident angle of the lightning radiation source i , solve the equations. Therefore, there are at least 3 VHF antennas 101, and the antennas are not collinear, forming a phased antenna array. 3 non-collinear antennas can form three baselines, and 4 non-collinear antennas can form six baselines. In actual lightning positioning, 4 VHF antennas 101 are preferred. There is no strict restriction on the arrangement of the VHF antenna 101, which can be determined according to the topography, but the angle between the two baselines should not be less than 30°. The antenna spacing is related to the frequency of the lightning electromagnetic wave. The antenna spacing is small at high frequencies and large at low frequencies. Generally, the antenna spacing is preferably 10~100m. The radio frequency signal acquisition processor 102 includes a high-speed A / D converter, a signal conditioner, and a high-speed data acquisition card. The hardware of the distance detection unit 2 is composed of an electric field antenna 201, a magnetic field antenna 202, an electric field and magnetic field signal acquisition processor 203, and an electric field and magnetic field signal memory 204. The electric field antenna 201 and the magnetic field antenna 202 are arranged near the VHF antenna 101. The magnetic field antenna 202 is composed of two orthogonal magnetic bars, which are respectively aligned in the north-south and east-west directions. The electric field and magnetic field signal acquisition processor 203 includes a high-speed A / D converter, a signal conditioner, and a high-speed data acquisition card. The high-speed data acquisition card of the radio frequency signal acquisition processor 102 and the electric field and magnetic field signal acquisition processor 203 can share a multi-channel acquisition card, or the radio frequency signal and the electric field and magnetic field signal can be acquired by two acquisition cards respectively.

[0029] The lightning signals collected by each antenna of the single-station positioning system of the present invention can be completed by lightning positioning and three-dimensional lightning image drawing without relying on the global satellite positioning system GNSS timing, and only relying on the system clock to mark the timestamp. In order to share data with other lightning positioning systems and study the same lightning event, the system adopts the global satellite positioning system GNSS timing to obtain a unified coordinate position and the absolute time of the lightning signal. The GNSS timing unit 3 can adopt China's Beidou satellite navigation system BDS, or the US satellite navigation system GPS, the Russian satellite navigation system GLONASS, and the EU satellite navigation system GALILEO, preferably BDS or GPS, and the GNSS timing unit 3 includes a GNSS antenna and a GNSS receiver. The GNSS timing unit 3 also includes a high-stable constant temperature crystal oscillator (OCXO). The second pulse signal output by the GNSS timing unit 3 is the sampling reference signal. The frequency offset of the high-stable constant temperature crystal oscillator (OCXO) output is measured, and the frequency loop of the high-stable constant temperature crystal oscillator (OCXO) is calibrated and compensated. The high-stable constant temperature crystal oscillator (OCXO) outputs a high-precision clock signal and a second signal. The time in the NMEA0183 protocol of the acquired clock signal plus 1s is used as the reference time t for the start of acquisition. start And wait for the system second pulse signal as the start time of collection.

[0030] The software of the direction detection unit 1 includes a time difference calculation module 104, an angle and time difference conversion module 105, and an azimuth and elevation angle calculation module 106. The software of the distance detection unit 2 includes an electric field time domain waveform generation module 205, a magnetic field time domain waveform generation module 206, a fast Fourier transform module 207, an electric field and magnetic field spectrum ratio calculation module 208, a high frequency band constant A fitting module 209, a low frequency band constant B fitting module 210, and a distance calculation module 211. The software of the direction detection unit 1, the software of the distance detection unit 2, the three-dimensional positioning unit 4, and the three-dimensional image generation unit 5 are programs compiled for calculating lightning positioning parameters.

[0031] The single-station lightning three-dimensional positioning method of the present invention is a three-dimensional positioning method based on the combination of interference lateral and electromagnetic ranging. The flowchart of the positioning method of the present invention is shown in FIG. Figure 2 ; Includes the following steps.

[0032] Step 1, lightning signal collection, several VHF antennas 101 of the direction detection unit 1 and the electric field antenna 201 and magnetic field antenna 202 of the distance detection unit synchronously collect lightning signals, and are connected to the RF signal acquisition processor 102 and the electric field and magnetic field signal acquisition processor 203 through cables. The signals are amplified and filtered, and the analog signals are converted into digital signals through high-speed A / D conversion. The digital signal is phase-adjusted according to the pre-set phase calibration data to eliminate the phase deviation between different antenna units. After phase calibration, the digital signals collected by each antenna are weighted and combined to form a beam. During the beamforming process, different phase weights are applied to the digital signals of each antenna unit to achieve the required beam directivity. The GNSS timing unit 3 outputs a high-precision clock frequency as a sampling reference clock for high-speed A / D conversion to ensure the accuracy of the signal conversion time. The output high-precision full second clock signal 1PPS and NMEA0183 data with time information cooperate with the sampling reference clock to mark the timestamp and store the detected lightning signal. The lightning signal collected by the direction detection unit 1 is stored in the radio frequency signal memory 103, and the electric field and magnetic field signal collected by the distance detection unit 2 is stored in the electric field and magnetic field signal memory 204. The stored lightning signal contains a unified coordinate position and absolute time data of the lightning signal.

[0033] Step 2: Extract the stored lightning signal data and establish a spatial relationship model between the measuring station and the lightning radiation source. This model is the basis for solving the spatial geometric relationship between the measuring station and the lightning radiation source.

[0034] Step 3: The direction detection unit 1 detects the time difference between the lightning radiation source and the VHF antenna 101. Δt , calculate the incident angle between the lightning radiation source and the antenna baseline i Except when the lightning radiation source is located directly above the measuring station, the lightning radiation source and the baseline formed by the two antennas are at a certain tilt angle, which is called the incident angle. i . Angle of incidence i It is a spatial angle, which is neither parallel to the three-dimensional coordinate axis xyz nor perpendicular to the coordinate axis xyz. It is an inclined angle in three-dimensional space. The distance from the lightning radiation source to the two antennas is much greater than the baseline length formed by the two antennas. d When the high-frequency electromagnetic wave from the radiation source reaches the antenna, the electromagnetic wave is approximately a parallel wave, with an incident angle relative to the baseline. i , the time it takes for the electromagnetic waves to reach the two antennas is different, there is a time difference Δt , based on the time difference Δt and baseline length d And the propagation speed c of electromagnetic waves, using the cosine theorem of a right triangle in space, the angle of incidence can be calculated i , the incident angle of the lightning radiation source i and VHF antenna baseline diagram see Figure 3 , angle of incidence i Calculate according to the following formula: ,

[0035] Step 4: Direction detection unit 1 detects the direction of the Δt Spatial mapping, angle and time difference conversion, calculation of the elevation angle of the lightning radiation source EN and azimuth A-Z . A phased array composed of several VHF antennas is an important component of the interferometric positioning system. During the propagation of electromagnetic waves, when two or more waves with the same or similar frequencies meet in space, their respective vibration states will interact with each other, resulting in interference. According to the principle of interferometric lightning positioning, multiple VHF antennas collect high-frequency lightning signals (30MHz-300MHz), and the signals received on each antenna will produce different time differences. D t , by calculating the arrival time difference of the signal between each two antennas Δt , combined with the spatial polyhedron composed of the radiation source and the VHF antenna array, the cosine theorem of the spatial right triangle is used. After the conversion of the angle and time difference, the azimuth of the lightning radiation source relative to the measuring station can be calculated. A-Z and elevation EN Information, the device that uses this method to locate lightning is called an interferometer. See the schematic diagram of interferometer direction finding Figure 4 , Figure 4 It is a spatial stereogram, and the coordinate axes xyz are perpendicular to each other. In the figure, A, B, C, and D are VHF antennas. The four antennas are only an embodiment and are not a limitation of the present invention. Point P is the lightning radiation source, and point Q is the vertical projection of point P. Now, taking antennas A and B as an example, the elevation angle of the radiation source of the lightning interferometry positioning method is explained. EN and azimuth A-Z The solution method is to use antenna A as the observation base point. i , antenna B is the direction base point j , known conditions: base point i and base point j Coordinates; the distance between the two base points is d ij , which is the baseline length; the radiation source P reaches the base point i and base point j Time difference Δt ij ; F ij The Y axis is clockwise and ij The angle of the baseline ( ij The azimuth of the baseline). Unknown condition: Angle α Observation base pointi The angle between the lightning radiation source and the X-axis is β Observation base point i The angle between the lightning radiation source and the Y axis. Need to solve: elevation angle EN , is the observation base point i The angle between the lightning radiation source P and the horizontal plane projection; azimuth A-Z , is the angle between the Y axis and the horizontal projection line (AQ) of the lightning radiation source P in clockwise direction. EN and azimuth A-Z , calculated according to the following formula: , In the above equation, there is an angle α and angle β There are two unknowns and one baseline cannot be solved. Two baselines are needed to solve the equations. Therefore, at least three VHF antennas are needed, and three antennas can form three baselines. Figure 4 There are four VHF antennas A, B, C, and D, which can form six baselines. The spacing between the VHF antennas is much smaller than the distance from the measuring station to the lightning radiation source P. The antenna array composed of the VHF antennas can be regarded as a point. α and angle β The result is solved by the least square method to find the optimal solution, and then substituted into the following formula to calculate the elevation angle of the lightning radiation source. EN and azimuth A-Z : ,

[0036] Step 5: Calculate the elevation angle according to step 4 EN and azimuth A-Z , it is only two-dimensional data mapped to the measuring station. The distance from the measuring station to the lightning radiation source P is missing, and the three-dimensional positioning result of the lightning cannot be obtained. The low-frequency signals (100Hz-15KHz) collected by the electric field antenna 201 and the magnetic field antenna 202 of the distance detection unit 2 are the vertical electric field and horizontal magnetic field of the measuring station relative to the lightning radiation source. These signals are time domain waveforms. According to the conclusion that the amplitude of the lightning electromagnetic wave signal is constantly attenuating with distance, in theory, the distance to the lightning radiation source can be judged by the amplitude of the magnetic field and electric field waveforms, and the approximate distance from the radiation source to the measuring station can be calculated. However, due to the instantaneous change of the lightning current, the electric field and magnetic field waveforms are also constantly changing, so the distance cannot be judged solely by the amplitude of the electric field and magnetic field time domain waveforms. To eliminate the influence of current changes, the distance can be determined by calculating the ratio of the electric field and the magnetic field. This ratio no longer depends on the lightning current, but changes with the change of distance. The distance detection unit 2 collects the electric field signal E and magnetic field signalsH Perform fast Fourier transform (FFT) to convert the recorded electric field signal and magnetic field signal into frequency domain to obtain the electric field spectrum ( E ω ) and magnetic field spectrum ( H ω ), and then the ratio of the electric field spectrum to the magnetic field spectrum ( E ω / H ω ) and frequency ( f ) are plotted as a ratio curve.

[0037] Step 6: Ratio of electric field spectrum to magnetic field spectrum ( E ω / H ω ) In the high frequency band or low frequency band, after calculation by the formula, the ratio will tend to a constant. The distance between the lightning radiation source and the measuring station can be calculated by substituting the two constants into the distance formula. r The distance detection unit 2 uses a high-pass filter to filter the contrast curve. E ω / H ω ) and frequency ( f ) ratio curve is fitted, and the ratio curve of the high frequency band tends to a constant A The frequency band of the high-pass filter is f =60 kHz~120 kHz, use the following equation to ( E ω / H ω ) and frequency ( f ) ratio curve is fitted to determine the constant A : , in: G is a correction factor that takes into account the difference in system gain between the electric and magnetic field measurement systems; m 0 is the magnetic permeability, e 0 is the electrical constant; The distance detection unit 2 uses a low-pass filter to filter the contrast value curve. E ω / H ω ) and frequency ( f ) ratio curve is fitted, and the ratio curve of the low frequency band tends to a constant B The frequency band of the low-pass filter is f =100 Hz~15 kHz, use the following equation to solve ( Eω / H ω ) and frequency ( f ) ratio curve is fitted to determine the constant B : ,, in, k is the wave number, which defines the magnitude of the wave vector of the electromagnetic wave; r is the distance between the lightning radiation source and the observation station; f The frequency of the lightning signal to be detected (Hz); c is the propagation speed of electromagnetic waves, taking the speed of light; d is a value less than 1 and is determined by fitting.

[0038] Step 7. Substitute constants A and B into the distance formula to calculate the distance between the lightning radiation source and the observation station. r . The distance between the lightning radiation source and the observation station r , calculated according to the following formula: , in, c is the propagation speed of electromagnetic waves, taking the speed of light; π is the ratio of pi.

[0039] Step 8: Mark the azimuth with the same timestamp A-Z , Elevation EN ,distance r Information matching, locating the lightning radiation source in an instant ( x,y,z ). See Figure 4 In the embodiment, the vertical projection point Q of the lightning radiation source P is at a distance of i The length of (antenna A) is AQ= r cos EN The lightning radiation source P is relative to the observation base point i The coordinates of x i , y i , z i ), plus the increment Δx、Δ y、Δz , which is the location of the lightning radiation source ( x,y,z ). Increment Δx、Δy ,See Figure 5 Schematic diagram of the direction finding plane of the instrument. Δx =cos EN cos AE , Δy = cos EN sin AE , increment Δzis the vertical distance from the lightning radiation source P to the projection point Q, Δz = r sin EN . A frame of lightning radiation source ( x,y,z ) position, calculated according to the following formula: in:( x i , y i , z i ) are the station coordinates.

[0040] All the lightning location results of each frame of a continuous lightning event are matched one by one according to the same timestamp, and continuous images are drawn to obtain the three-dimensional graphics of lightning in the spatial relationship model.

[0041] The description and drawings of this application are only a specific implementation method and are not restrictive. Under the guidance of this application, technicians in this field can make many forms without departing from the scope of protection of the purpose of this application and the claims, all of which are within the scope of protection of this application.

Claims

1. A single-station lightning three-dimensional positioning method, characterized by: The positioning method is a three-dimensional positioning method based on the combination of interference lateral and electromagnetic ranging, comprising the following steps: S1. Lightning signal acquisition. Several VHF antennas of the direction detection unit and the electric field antenna and magnetic field antenna of the distance detection unit synchronously collect lightning signals, which are connected to the RF signal acquisition processor and the electric field and magnetic field signal acquisition processor through cables. The analog signals are converted into digital signals through high-speed A / D conversion respectively. The GNSS timing unit outputs a high-precision clock frequency as a sampling reference clock for high-speed A / D conversion to ensure the accuracy of the signal conversion time. The output high-precision full-second clock signal 1PPS and NMEA0183 data with time information cooperate with the sampling reference clock to mark the timestamp for the detected lightning signal and store it. S2, extracting the stored lightning signal data and establishing a spatial relationship model between the measuring station and the lightning radiation source; S3, the time difference from the lightning radiation source detected by the direction detection unit to the VHF antenna Δt , calculate the incident angle between the lightning radiation source and the antenna θ ; S4, direction detection unit according to the time difference Δt Spatial mapping, angle and time difference conversion, calculation of the elevation angle of the lightning radiation source EL and azimuth AZ ; S5. The distance detection unit collects the electric field signal E and magnetic field signals H Perform fast Fourier transform (FFT) to convert the recorded electric field signal and magnetic field signal into frequency domain to obtain the electric field spectrum ( E ω ) and magnetic field spectrum ( H ω ), and then the ratio of the electric field spectrum to the magnetic field spectrum ( E ω / H ω ) and frequency ( f ) is plotted as a ratio curve; S6, the distance detection unit uses a high-pass filter to filter the contrast curve, E ω / H ω ) and frequency ( f ) ratio curve is fitted, and the high-frequency ratio curve tends to a constant A; a low-pass filter is used to filter the ratio curve, and ( E ω / H ω ) and frequency ( f ) is fitted, and the ratio curve of the low-frequency band tends to a constant B; S7. Substitute constants A and B into the distance formula to calculate the distance between the lightning radiation source and the observation station. r ; S8, mark the azimuth with the same timestamp AZ , Elevation EL ,distance r Information matching, locating the lightning radiation source in an instant ( x,y,z ), all the location results of a continuous lightning event are matched one by one according to the same timestamp to obtain the three-dimensional graphics of lightning in the spatial relationship model.

2. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: In step S3, according to the time difference of reaching any two VHF antennas Δt , the incident angle of the lightning radiation source θ Calculate according to the following formula: ， in: c is the speed of light, d is the baseline length of the two antennas.

3. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: In step S4, the elevation angle of the lightning radiation source is EL and azimuth AZ , calculated according to the following formula: ， ， ， Where: Elevation EL Observation base point i The angle between the lightning radiation source and the horizontal plane projection, azimuth AZ is the angle between the Y axis and the horizontal projection line of the lightning radiation source clockwise. α Observation base point i The angle between the lightning radiation source and the X-axis is β Observation base point i The spatial angle between the lightning radiation source and the Y axis is Φ ij The Y axis is clockwise and ij The angle of the baseline ( ij The azimuth of the baseline), c is the speed of light, Δt ij The radiation source reaches the base point i and base point j The time difference, d ij As the base point i and base point j spacing.

4. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: The frequency band of the high-pass filter in step S6 is f =60 kHz~120 kHz, use the following equation to ( E ω / H ω ) and frequency ( f ) ratio curve is fitted to determine the constant A : ， in: G is a correction factor that takes into account the difference in system gain between the electric and magnetic field measurement systems; μ 0 is the magnetic permeability, ε 0 is the electrical constant.

5. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: The frequency band of the low-pass filter in step S6 is f =100 Hz~15 kHz, use the following equation to solve ( E ω / H ω ) and frequency ( f ) ratio curve is fitted to determine the constant B : ， in, k is the wave number, which defines the magnitude of the wave vector of the electromagnetic wave; r is the distance between the lightning radiation source and the observation station; f The frequency of the lightning signal to be detected (Hz); c is the propagation speed of electromagnetic waves, taking the speed of light; δ Is a value less than 1.

6. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: In step S7, the distance between the lightning radiation source and the observation station r , calculated according to the following formula: ， in, c is the propagation speed of electromagnetic waves, taking the speed of light; π is the ratio of pi.

7. The single-station lightning three-dimensional positioning method according to claim 1, characterized in that: The position (x, y, z) of a lightning radiation source in step S8 is calculated according to the following formula: ， in:( x i , y i , z i ) are the station coordinates.

8. The single-station lightning three-dimensional positioning method according to claim 7, characterized in that: Each frame of lightning located in step 8 in a lightning event is matched one by one according to the marked timestamp to draw a continuous three-dimensional image of lightning.

9. A single-station lightning three-dimensional positioning system according to claim 1, characterized in that: The invention mainly comprises a direction detection unit (1), a distance detection unit (2), a GNSS timing unit (3), a three-dimensional positioning unit (4), and a three-dimensional image generation unit (5). The hardware of the direction detection unit (1) comprises a plurality of VHF antennas (101), a radio frequency signal acquisition processor (102), and a radio frequency signal storage unit (103); the software of the direction detection unit (1) comprises a time difference calculation module (104), an angle and time difference conversion module (105), and an azimuth and elevation angle calculation module (106); the distance detection unit The hardware of (2) is composed of an electric field antenna (201), a magnetic field antenna (202), an electric field and magnetic field signal acquisition processor (203), and an electric field and magnetic field signal memory (204); the software of the distance detection unit (2) includes an electric field time domain waveform generation module (205), a magnetic field time domain waveform generation module (206), a fast Fourier transform module (207), an electric field and magnetic field spectrum ratio calculation module (208), a high frequency band constant A fitting module (209), a low frequency band constant B fitting module (210), and a distance calculation module (211).

10. The single-station lightning three-dimensional positioning system according to claim 8, characterized in that: The VHF antennas (101) are at least three and the antennas are not collinear. The antenna spacing is 10-100 m, forming a phased antenna array. The magnetic field antenna (202) is composed of two orthogonal magnetic rods, which are respectively aligned in the north-south and east-west directions. The GNSS timing unit (3) includes a high-stable constant temperature crystal oscillator (OCXO). The second pulse signal output by the GNSS timing unit (3) is used as a sampling reference signal. The frequency offset of the output of the high-stable constant temperature crystal oscillator (OCXO) is measured, and the frequency loop of the high-stable constant temperature crystal oscillator (OCXO) is calibrated and compensated. The high-stable constant temperature crystal oscillator (OCXO) outputs a high-precision clock signal and a second signal. The time in the NMEA0183 protocol of the acquired clock signal plus 1 second is used as the collection start reference time t start And wait for the system second pulse signal as the start time of collection.

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