An integrated optical and electromagnetic tropospheric lightning detection system

Abstract

The present invention discloses an integrated optical, electromagnetic, and tropospheric lightning detection system, comprising a detector, a flight platform, and a ground center. The detector is equipped with a three-dimensional electric field detector, a three-dimensional magnetic field detector, an image acquisition device, a spectrophotometer, a GNSS navigation system, and a six-axis sensor. The GNSS receiver uses real-time phase kinematics (RTK) to measure the phase difference between the antennas to obtain the azimuth of the two GNSS receivers relative to true north. The six-axis sensor performs attitude and inclination correction to obtain the detector's ECEF coordinates, which are then converted to an ENU coordinate system with the ground center as the origin. The image acquisition device captures lightning images, the spectrophotometer identifies lightning discharge types, the three-dimensional electric field detector measures vector electric field intensity, and the three-dimensional magnetic field detector measures vector magnetic field intensity. The detection system utilizes multi-dimensional technology to integrate optical, electrical, and magnetic sensors, overcoming the limitations of single sensors to form an integrated optical, electromagnetic, and tropospheric lightning detection system.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric science detection technology, and in particular to a tropospheric lightning detection system based on the integration of optical, electric field, and magnetic field multi-sensors for real-time detection of tropospheric lightning type, location, energy, and charge distribution. Background Art

[0002] Traditional lightning detection mostly relies on ground-based detection stations. Electric field sensors detect changes in the electric field generated by lightning to estimate lightning intensity. Magnetic field antennas detect the transient magnetic field generated by lightning currents and use magnetic orientation to locate lightning. High-speed cameras or photoelectric sensors capture lightning optical signals and analyze the duration and intensity of the flash. Multi-station collaboration achieves wide-area positioning based on the time difference of arrival (TOA) or directional convergence (DF) of lightning electromagnetic waves. In densely overcast thunderstorms, the clouds completely block the visible light of lightning. As a result, systems relying on optical sensors cannot directly capture lightning images or optical signals, making it impossible to determine lightning morphology (such as channel branching and flash intensity). This limits discharge type analysis and energy estimation.

[0003] In traditional ground-based lightning detection systems, the detection of horizontal electric fields (i.e., electric field components parallel to the ground) faces significant technical limitations. This is primarily due to the high surface conductivity of the ground, which, assuming the ground is a good conductor, results in a zero horizontal electric field. Vegetation, buildings, or terrain undulations near the ground can alter the local electric field distribution, causing electric field distortion and masking the true lightning signal. Electromagnetic interference (e.g., 50 / 60 Hz power frequency interference) generated by artificial electromagnetic sources such as power lines and communications equipment is much stronger than the lightning horizontal electric field signal (typically kHz-level transient pulses), resulting in a very low signal-to-noise ratio (SNR). Most lightning electric field models (e.g., the dipole model) assume that the charge center is located perpendicular to the cloud layer and only calculate the impact of the vertical electric field on the ground, without considering horizontal charge separation or lateral discharge processes within the cloud.

[0004] Satellite remote sensing technology, using optical imaging sensors (such as lightning imagers and multispectral cameras) carried by satellites, can capture the optical radiation signals (visible and near-infrared bands) of cloud-top lightning. However, satellites are too far away from lightning bolts to achieve high resolution, and therefore cannot detect changes in the lightning's electric and magnetic field strengths. The high cost of satellite remote sensing makes it difficult to popularize and promote. Summary of the Invention

[0005] The present invention aims to provide an integrated opto-electromagnetic tropospheric lightning detection system, comprising a detector, a flight platform, and a ground-based center. The detector is equipped with a three-dimensional electric field detector, a three-dimensional magnetic field detector, an image acquisition device, a spectrophotometer, a GNSS navigation system, and a six-axis sensor. The GNSS receiver uses real-time phase kinematics (RTK) to measure the phase difference between the antennas to obtain the azimuth of the two GNSS receivers relative to true north. The six-axis sensor performs attitude and inclination correction to obtain the detector's ECEF coordinates. True north direction is determined from the ECEF coordinates, and the coordinates are converted to an ENU coordinate system with the ground center as the origin. The image acquisition device captures lightning images, the spectrophotometer identifies lightning discharge type, the three-dimensional electric field detector measures vector electric field intensity, and the three-dimensional magnetic field detector measures vector magnetic field intensity, forming an integrated opto-electromagnetic tropospheric lightning detection system. The lightning images, electric field strength, magnetic field strength, photoelectric signals, ambient temperature, and coordinate data collected by the detector are calculated by the calculation module and stored in the data storage module. The data is wirelessly transmitted back to the ground center through the data transmission module. The ground center demodulates the data marked with timestamps to obtain the tropospheric lightning detection results.

[0006] The present invention is implemented through the following technical solution: an integrated optical and electromagnetic tropospheric lightning detection system, comprising: a detector 100, a flight platform 200, and a ground center 300. The detector 100 comprises a spherical equipment compartment 101, from which six cantilevers 102 extend. These cantilevers 102 are arranged perpendicularly, with two pairs running horizontally and one pair running vertically. Each cantilever 102 is provided with a spherical probe 103 at its outer end. Strip-shaped electrodes 104 are located within each cantilever 102. One end of each electrode 104 is connected to the probe 103, and the other end is connected to a charge amplifier 105 via a shielded cable. The probe 103 and electrodes 104 form an electric field sensor. Two corresponding probes 103, electrodes 104, and charge amplifier 105 together form an electric field detector. The electric field detectors in three directions form a three-dimensional electric field detector 106. Two GNSS receivers 107 are located on each pair of cantilever 102. The equipment warehouse 101 is provided with four image collectors 110 and four groups of spectrophotometers 111. The spectrophotometer 111 is provided below the image collector 110. Each group of spectrophotometers 111 is composed of two APD sensors 112, which are respectively connected to a photometric amplifier 113. One APD sensor 112 is equipped with a red light filter, and the other APD sensor 112 is equipped with a blue-violet light filter. The equipment warehouse 101 is also provided with a three-dimensional magnetic field antenna 120, a six-axis sensor 130, and a temperature sensor 140. The three-dimensional magnetic field antenna 120 is composed of three mutually perpendicular magnetic bar coils, and the three magnetic bar coils are respectively parallel to the three pairs of cantilevers 102. The three-dimensional magnetic field antenna 120 is respectively connected to the magnetic field amplifier 121 to form a three-dimensional magnetic field detector 122. The six-axis sensor 130x Axis and y The axes are parallel to the two pairs of horizontal cantilevers 102. z The axis is parallel to the vertical cantilever 102 .

[0007] The three-axis attitude sensor in the six-axis sensor 130 detects the attitude of the six cantilevers 102 and calculates the inclination of the two pairs of horizontal cantilevers 102 with the horizontal plane. The three-axis acceleration sensor measures the magnitude and direction of acceleration during the motion of the detector 100. The two GNSS receiving devices 107 use carrier phase differential (RTK) to measure the phase difference between the antennas to obtain the azimuth of the two GNSS receiving devices relative to true north. After the attitude and inclination correction of the six-axis sensor 130, the ECEF coordinates of the detector 100 are obtained. The true north direction is determined based on the ECEF coordinates. After coordinate conversion, the coordinates are obtained with the ground center 300 as the origin ( x 0, y 0, z 0) of the ENU coordinate system.

[0008] The lightning image position recorded by the image collector 110 is used to obtain the azimuth angle of the lightning relative to the detector 100 in the ENU coordinate system. f and pitch angle i The electric field intensity detected by the electric field detector 106 and the magnetic field intensity detected by the magnetic field detector 122 are used to calculate the distance between the lightning and the detector 100 by using the amplitude spectrum method. r , by the azimuth of the lightning relative to the detector (100) f , pitch angle i and distance r Get the ENU coordinates of the lightning and calculate the azimuth of the lightning relative to the ground center 300 f ′, pitch angle i ′ and distance r ′.

[0009] The viewing angle of the spectrophotometer 111 is the same as that of the image collector 110. The spectrophotometer 111 is equipped with a red light filter and a blue-violet light filter to detect whether the lightning recorded by the image collector 110 is a corona discharge or an arc discharge. If the blue-violet light channel signal is significantly stronger than the red light channel, it corresponds to a corona discharge, and if the red light channel signal is significantly stronger than the blue-violet light, it corresponds to an arc discharge. This is used to analyze the type of tropospheric lightning and study the charge distribution and discharge energy.

[0010] The image collector 110 collects lightning images, the spectrophotometer 111 identifies the type of lightning discharge, the three-dimensional electric field detector 106 detects the vector electric field intensity, and the three-dimensional magnetic field detector 122 detects the vector magnetic field intensity. dE / dt) and the peak value of the magnetic field ( B max), and estimate the discharge energy by energy integration W , forming an integrated optical and electromagnetic tropospheric lightning detection system.

[0011] When the sum of the brightness difference between the two frames before and after the image captured by the image collector 110, the signal strength of the spectrophotometer 111, the electric field strength detected by the three-dimensional electric field detector 106, and the magnetic field strength detected by the three-dimensional magnetic field detector 122 reach the set threshold, they can all serve as trigger signals to trigger the storage of all collected data and mark the coordinates and time difference.

[0012] The detector 100 is provided with a data processing unit 1, including an ADC analog-to-digital converter 2, a calculation module 3, a data storage module 4, a data transmission module 5, and a power supply 6. The lightning image, electric field strength, magnetic field strength, photoelectric signal, ambient temperature, and coordinate data collected by the detector 100 are calculated by the calculation module 3 and stored in the data storage module 4. The data is wirelessly transmitted back to the ground center 300 through the data transmission module 5. The ground center 300 demodulates the time-stamped data to obtain the tropospheric lightning detection results.

[0013] The image collector 110 is set between two adjacent horizontal cantilevers 102 and is equipped with a 150° wide-angle lens. The central axis of the image collector 110 is at an angle of 150° to the vertical direction. α The vertical plane of the central axis forms an angle of 45° with the horizontal cantilever 102 , and the azimuth of the central axis of the image collector 110 is converted by the azimuth angle of the horizontal cantilever 102 .

[0014] The cantilever 102 is made of a glass fiber reinforced plastic hollow tube and is vertically fixed to the outer wall of the equipment compartment 101. The probe 103 is fixed to the outer end of the cantilever 102 using a Teflon support. The electrode 104 is arranged in the cantilever 102, and Teflon brackets are arranged at intervals in the hollow tube to support the electrode 104.

[0015] The equipment bin 101 is made of polystyrene foam, with the inner and outer layers wrapped with high-density polyethylene (HDPE). A platform or bracket for installing equipment is provided inside the equipment bin 101 .

[0016] Coordinate conversion is performed according to the following steps: Beidou coordinates ( E , L , H ) to ECEF geocentric coordinates ( x , y , z ):

[0017] ,

[0018] in, EFor latitude, L For longitude, H is the elevation, N is the radius of curvature of the Maoyou circle, according to the formula calculate, a is the semi-major axis of the Earth's ellipsoid (6378137 meters), e 2 is the square of the first eccentricity of the ellipsoid (0.00669438002290). ECEF coordinate difference calculation:

[0019] ,

[0020] in,( x 0, y 0, z 0) is the coordinate of the ground center 300, ( x , y , z ) is the coordinate of the detector 100 when the lightning occurs;

[0021] Rotation matrix (ECEF→ENU):

[0022] ,

[0023] After coordinate transformation, it is converted to the ENU coordinate system with the ground center 300 as the origin:

[0024] ,

[0025] E , N , U represents the coordinate components of the lightning in the Northeast Celestial (ENU) coordinate system centered at 300° on the ground, where E is the east coordinate (East), N is the north coordinate (North), U is the zenith direction coordinate (Up), R is the rotation matrix that projects the coordinate difference of the Earth-centered Earth-fixed coordinate system (ECEF) to the ENU coordinate system, Δ x ,Δ y ,Δ z is the coordinate difference between the detector 100 and the ground center 300 in the ECEF coordinate system when lightning occurs.

[0026] The azimuth of the lightning relative to the ground center 300 f ′, pitch angle i ′ and distance r 'Calculation, based on the azimuth angle measured by the detector 100 f and pitch angle i, the unit vector of the lightning direction in the detector coordinate system is:

[0027] ,

[0028] The coordinates of the ground center 300 are ( x 0, y 0, z 0), the coordinates of detector 100 are ( x , y , z ), then the position vector of the detector 100 relative to the ground center 300 is:

[0029] ,

[0030] The distance from the lightning to the detector 100 is r , then the position vector of the lightning in the 300° coordinate system at the ground center is:

[0031] ,

[0032] The eastward (E) component of the lightning at 300° above ground level is:

[0033] ,

[0034] The north (N) component is:

[0035] ,

[0036] The vertical (U) component is:

[0037] ,

[0038] The four-quadrant inverse tangent function atan2 is used to calculate the azimuth of lightning relative to the center of the ground. f ′:

[0039] ,

[0040] Find the distance from the lightning bolt to the center of the ground 300 degrees using three-dimensional Euclidean space r ′:

[0041] ,

[0042] Calculate the lightning's pitch angle relative to the ground center based on the ratio of the vertical component to the total distance i ′:

[0043] .

[0044] The brightness difference summation is performed by comparing the brightness difference between two adjacent frames pixel by pixel and accumulating these difference values ​​to obtain the total brightness change. The mathematical expression is:

[0045] ,

[0046] in: Y j ( m , n ) indicates the j Frame images are in rows and columns ( m , n ), Ri Indicates the preset i The calculation area, k The image collector 110 uses a black and white pixel sensor, and the 8 / 10 / 12 bit data of each pixel is the brightness value. Y .

[0047] The beneficial effects of the present invention are as follows: the detection system integrates three types of sensors, namely light (image + spectrophotometry), electricity (three-axis electric field vector), and magnetism (three-dimensional magnetic field), through multi-dimensional technology, breaking through the limitations of a single sensor and being able to simultaneously obtain the spatial form of lightning (wide-angle lens captures the bifurcation and direction of lightning channels), discharge type (red light / blue-violet light intensity ratio distinguishes corona discharge from arc discharge), and electromagnetic field dynamics (electric field intensity gradient reflects charge migration rate, and magnetic field direction calibrates current path). By using vector electric field ( Ex , Hey , Ez ) and the vector magnetic field ( Bx , By , Bz ) to invert the charge polarity and density distribution of thunderstorm clouds, providing direct data support for thunderstorm electrical research. GNSS-RTK and a six-axis sensor are used to calibrate the platform's attitude in real time to improve the accuracy of the electric field vector direction. A spectrophotometer is used to identify lightning discharge types by leveraging the spectral characteristics of different discharge types. Multiple sensors (optical, electrical, and magnetic) are combined with threshold triggering to avoid missing single signals. This overcomes the shortcomings of traditional ground-based lightning detection systems, which are unable to detect horizontal electric fields and the spatial morphology of lightning above clouds. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the system of the present invention;

[0049] Figure 2 This is a three-dimensional diagram of the detector;

[0050] Figure 3 is the vertical cross-section of the detector;

[0051] Figure 4 is the horizontal cross-section of the detector;

[0052] Figure 5 This is the electrical principle block diagram of the present invention.

[0053] In the figure: 1-data processing unit, 2-ADC analog-to-digital converter, 3-arithmetic module, 4-data storage module, 5-data transmission module, 6-power supply, 100-detector, 101-equipment compartment, 102-cantilever, 103-probe, 104-electrode, 105-charge amplifier, 106-electric field detector, 107-GNSS antenna, 110-image collector, 111-spectrophotometer, 112-APD sensor, 113-photometric amplifier, 120-three-dimensional magnetic field antenna, 121-magnetic field amplifier, 122-magnetic field detector, 130-six-axis sensor, 140-temperature sensor, 200-flight platform, 201-suspension rod, 300-ground receiving system. DETAILED DESCRIPTION

[0054] In order for those skilled in the art to better understand the present invention, Figure 1~Figure 5 To further explain the present application, in the description of the present invention, the terms "up", "down", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or directions or positional relationships commonly understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or parts referred to must have a specific direction, be constructed and operated in a specific direction. The contents mentioned in the implementation manner are not limitations of the present invention.

[0055] The integrated optical and electromagnetic tropospheric lightning detection system of the present invention comprises: a detector 100, a flying platform 200, and a ground center 300. Figure 1 The main body of the detector 100 is a spherical equipment bin 101, made of polystyrene foam, with high-density polyethylene HDPE wrapped inside and outside. The inner diameter of the equipment bin 101 is 500~800mm, and the wall thickness is 50~150mm. The equipment bin 101 extends outward with six cantilevers 102, and the cantilever 102 extends out of the equipment bin 101 by 1~1.5m. The six fiberglass cantilevers 102 are orthogonally distributed in three pairs, with two pairs horizontally and one pair vertically. The three pairs of cantilevers 102 are perpendicular to each other. Figure 2 、 Figure 3 、 Figure 4The terms "horizontal" and "vertical" refer to the directions when the detector 100 is stationary. A spherical probe 103 is located at the outer end of each cantilever 102. A strip-shaped electrode 104 is located within the cantilever 102. One end of the electrode 104 is connected to the probe 103, and the other end is connected to a differential charge amplifier 105 via a shielded cable. The probe 103 and electrode 104 form an electric field sensor. Two corresponding probes 103, electrodes 104, and charge amplifier 105 together form an electric field detector. The three-directional electric field detectors form a three-dimensional electric field detector 106, which is used to detect three-dimensional vector electric field intensity. The probe 103 is a hollow sphere made of high-purity copper, with an outer diameter slightly larger than that of the cantilever 102. The electrode 104 is made of high-purity copper strips with a diameter of 3-5 mm. Cantilever 102 is made of a hollow fiberglass tube and is vertically fixed to the outer wall of equipment compartment 101. Probe 103 is fixed to the outer end of cantilever 102 using a Teflon support. Electrodes 104 are located within cantilever 102, and Teflon supports are installed at intervals within the hollow tube to support electrodes 104. The fiberglass tube and Teflon materials are both lightweight and highly insulating, preventing leakage current from probe 103 and electrode 104 from interfering with the electric field signal.

[0056] The detector 100 is provided with a GNSS global satellite navigation system, and two GNSS receiving devices 107 are provided on a pair of cantilevers 102. A six-axis sensor 130 is provided in the equipment compartment 101. x Axis and y The axes are parallel to the two pairs of horizontal cantilevers 102. z The axis is parallel to the vertical cantilever 102. The three-axis attitude sensor in the six-axis sensor 130 detects the attitude of the six cantilevers 102 and calculates the inclination angle of the two pairs of horizontal cantilevers 102 with the horizontal plane, which is used to correct the attitude of the detector 100 during the movement when calculating the azimuth and pitch angles. The three-axis acceleration sensor measures the magnitude and direction of the acceleration during the movement of the detector 100. The corresponding two GNSS receiving devices 107 use carrier phase differential (RTK) to measure the phase difference between the antennas to obtain the azimuth of the two GNSS receiving devices relative to the true north. After the attitude and inclination correction of the six-axis sensor 130, the ECEF coordinates of the detector 100 are obtained, and the true north direction is determined based on the ECEF coordinates. The ground center 300 is also equipped with a GNSS global satellite navigation system, and the coordinates are converted to the ground center 300 as the origin ( x 0, y 0, z The GNSS global satellite navigation system can use China's Beidou Satellite Navigation System (BDS), the US Satellite Navigation System (GPS), the Russian Satellite Navigation System (GLONASS), or the European Union Satellite Navigation System (GALILEO), with BDS or GPS being preferred.

[0057] A three-dimensional magnetic field antenna 120 is installed in the equipment compartment 101, which consists of three mutually perpendicular magnetic rod coils. The three magnetic rod coils are parallel to the three pairs of cantilevers 102 respectively. The three-dimensional magnetic field antenna 120 is connected to the magnetic field amplifier 121 respectively to form a three-dimensional magnetic field detector 122 for detecting the three-dimensional vector magnetic field strength.

[0058] Four image collectors 110 are arranged in the equipment warehouse 101. The image collector 110 uses a black and white pixel sensor and a global shutter CMOS camera. The global shutter CMOS camera is an imaging device that uses synchronous exposure technology. Each pixel of the global shutter CMOS camera is equipped with an independent storage unit. Its core feature is that all pixels start and end exposure at the same time, and transfer the charge to the storage area after the exposure, and then read out the signal line by line, which effectively solves the image deformation problem of the traditional rolling shutter when shooting high-speed moving objects, avoids motion blur, and supports high frame rate. The global shutter CMOS camera prefers Sony IMX925, whose high frame rate and low noise characteristics can accurately capture the trajectory of lightning. The image collector 110 is equipped with a 150° wide-angle lens. The image collector 110 is set between two adjacent horizontal cantilevers 102, see Figure 4 To avoid cantilever 102 blocking, the lightning images captured by the image collector 110 overlap. If the lightning image captured by one image collector 110 is exactly blocked by a cantilever 102, the adjacent image collector 110 can capture a complete lightning image. The vertical plane of the central axis of the image collector 110 forms a 45° angle with the horizontal cantilever 102. The azimuth of the central axis of the image collector 110 is converted by the azimuth angle of the horizontal cantilever 102. Figure 4 The angle α between the central axis of the image collector 110 and the vertical direction is 75°. Figure 3 , Figure 3 Image collector 110 is not directly below cantilever 102, but rather at a 45° angle. The vertical cross-section does not cut through image collector 110; it is drawn at an angle α to the vertical for ease of illustration. The four image collectors 110 provide full 360° horizontal coverage, with the vertical view pointing downwards. The upper view is 60° above the horizontal plane. The area above detector 100 is blocked by flight platform 200 and is not considered.

[0059] The equipment compartment 101 houses four sets of spectrophotometers 111, located below the image acquisition unit 110. Each set of spectrophotometers 111 features a 150° wide-angle lens, mirroring the viewing angle of the image acquisition unit 110. Each set of spectrophotometers 111 consists of two APD sensors 112. These sensors utilize avalanche diodes (APDs), offering a fast response time. Their photoelectric response speed can reach tens of gigahertz, enabling them to rapidly convert optical signals into electrical signals. Each APD sensor 112 is connected to a photometric amplifier 113. One APD sensor 112 is equipped with a red light filter, and the other with a blue-violet light filter. The spectrophotometer 111 is equipped with a red light filter and a blue-violet light filter to detect whether the lightning recorded by the image collector 110 is a corona discharge or an arc discharge. The blue-violet light channel signal is significantly stronger than the red light channel, which corresponds to a corona discharge. The red light channel signal is significantly stronger than the blue-violet light, which corresponds to an arc discharge. This is used to analyze the type of tropospheric lightning and study the charge distribution and discharge energy.

[0060] A temperature sensor 140 is also installed in the equipment compartment 101. The performance of the optical, electrical, and magnetic sensors in the lightning detection system is easily affected by temperature drift. The temperature sensor monitors the ambient temperature in real time and uses an algorithm to compensate for the thermal expansion effect of the optical components and the baseline offset of the electrical / magnetic sensors. Extreme temperature changes (such as strong turbulence in the troposphere) can introduce electromagnetic signal noise. The temperature sensor is related to the electric field vector ( Ex , Hey , Ez ) synchronous measurement, which can distinguish real lightning signals from thermal noise interference.

[0061] The detector 100 is provided with a data processing unit 1, including an ADC analog-to-digital converter 2, an operation module 3, a data storage module 4, a data transmission module 5, and a power supply 6. Figure 5 The data transmission module 5 uses frequency shift keying (FSK) modulation to modulate the signal, converting the binary data into an FSK signal. The modulated signal is transmitted by a transmitter, using the 403 MHz dedicated frequency band for meteorological sounding to wirelessly transmit the detection data in real time. The ground center 300 receives the signal and demodulates the received FSK signal into binary data. The data transmission module 5 processes the lightning image, electric field intensity, magnetic field intensity, photoelectric signal, ambient temperature, and coordinate data collected by the detector 100 through the calculation module 3 and stores them in the data storage module 4. The data is then wirelessly transmitted back to the ground center 300 through the data transmission module 5. The ground center 300 demodulates the time-stamped data to obtain the tropospheric lightning detection results.

[0062] Charge amplifier 105, photometric amplifier 113, and magnetic field amplifier 121 utilize the ADA4530-1 amplifier chip, supporting both current and voltage input modes with a gain range of 0.01 to 1000 mV / pC. Built-in adjustable high-pass (0.3 to 100 Hz) and low-pass (0.3 to 100 kHz) filters optimize the signal-to-noise ratio and maintain low noise (≤5 μV), making it suitable for amplifying weak signals. ADC 2 utilizes the AD7606C converter chip, offering eight analog input channels, 16-bit resolution, and a sampling rate of 1 MSPS, offering excellent performance. This application utilizes a combination of two AD7606C converter chips to rapidly sample and convert multiple signals sequentially, enabling simultaneous sampling of multiple channels. Components of all units and modules are mounted on PCBs according to their function and enclosed in a waterproof enclosure. The interior of the equipment compartment 101 features a platform or bracket for mounting the equipment. The spherical equipment bin 101 is divided into two parts, the lower part accounts for 60-70% of the diameter, ensuring that the cantilever 102 can be firmly installed on the equipment bin 101. The upper part is equivalent to the bin cover. Opening the bin cover facilitates the installation of internal devices. The upper and lower parts are provided with connecting and fixing devices, and there are sealing devices at the connection. The protection level of the equipment bin 101 is IP68.

[0063] The direction of lightning above the cloud cannot be directly observed from the ground. To facilitate the determination of the location of lightning above the cloud at the ground center 300, this application converts the latitude and longitude coordinates of the GNSS satellite navigation system of the detector 100 into an ENU (East-North-Up) coordinate system with the ground center 300 as the origin. The coordinate conversion is performed according to the following steps:

[0064] Beidou coordinates ( E , L , H ) to ECEF geocentric coordinates ( x , y , z ):

[0065] ,

[0066] in, E For latitude, L For longitude, H is the elevation, N is the radius of curvature of the Maoyou circle, according to the formula calculate, a is the semi-major axis of the Earth's ellipsoid (6378137 meters), e 2 is the square of the first eccentricity of the ellipsoid (0.00669438002290); ECEF coordinate difference calculation:

[0067] ,

[0068] in,( x 0, y 0, z 0) is the coordinate of the ground center 300, ( x , y , z ) is the coordinate of the detector 100 when the lightning occurs;

[0069] Rotation matrix (ECEF→ENU):

[0070] ,

[0071] After coordinate transformation, it is converted to the ENU coordinate system with the ground center 300 as the origin:

[0072] ,

[0073] E , N , U represents the coordinate components of the lightning in the Northeast Celestial (ENU) coordinate system centered at 300° on the ground, where E is the east coordinate (East), N is the north coordinate (North), U is the zenith direction coordinate (Up), R is the rotation matrix that projects the coordinate difference of the Earth-centered Earth-fixed coordinate system (ECEF) to the ENU coordinate system, Δ x ,Δ y ,Δ z is the coordinate difference between the detector 100 and the ground center 300 in the ECEF coordinate system when lightning occurs.

[0074] The lightning image position recorded by the image collector 110 is used to obtain the azimuth of the lightning relative to the detector 100 in the ENU coordinate system. f and pitch angle i The electric field intensity detected by the electric field detector 106 and the magnetic field intensity detected by the magnetic field detector 122 are used to calculate the distance between the lightning and the detector 100 using the amplitude spectrum method. r , by the lightning 100 azimuth relative to the detector f , pitch angle i and distance r Get the ENU coordinates of the lightning and calculate the azimuth of the lightning relative to the ground center 300 f ′, pitch angle i ′ and distance r '. Based on the azimuth angle measured by the detector 100 f and pitch angle i , the unit vector of the lightning direction in the detector coordinate system is:

[0075] ,

[0076] The coordinates of the ground center 300 are ( x 0, y 0, z 0), the coordinates of detector 100 are ( x , y , z ), then the position vector of the detector 100 relative to the ground center 300 is:

[0077] ,

[0078] The distance from the lightning to the detector 100 is r , then the position vector of the lightning in the 300° coordinate system at the ground center is:

[0079] ,

[0080] The eastward (E) component of the lightning at 300° above ground level is:

[0081] ,

[0082] The north (N) component is:

[0083] ,

[0084] The vertical (U) component is:

[0085] ,

[0086] The four-quadrant inverse tangent function atan2 is used to calculate the azimuth of lightning relative to the center of the ground. f ′:

[0087] ,

[0088] Find the distance from the lightning bolt to the center of the ground 300 degrees using three-dimensional Euclidean space r ′:

[0089] ,

[0090] Calculate the lightning's pitch angle relative to the ground center based on the ratio of the vertical component to the total distance i ′:

[0091] .

[0092] The sum of the brightness difference between the two frames before and after the image captured by the image collector 110, the signal strength of the spectrophotometer 111, the electric field strength detected by the three-dimensional electric field detector 106, and the magnetic field strength detected by the three-dimensional magnetic field detector 122, when reaching the set threshold, can serve as a trigger signal to trigger the storage of all collected data, and mark the coordinates and time difference. Multiple sensors (light, electricity, and magnetism) are combined with threshold triggering to avoid single signal leakage. The image collector 110 collects lightning images, the spectrophotometer 111 identifies the type of lightning discharge, the three-dimensional electric field detector 106 detects the vector electric field strength, and the three-dimensional magnetic field detector 122 detects the vector magnetic field strength. Combined with the light intensity (spectrophotometer), the electric field change rate ( dE / dt ) and the peak value of the magnetic field ( B max), and estimate the discharge energy by energy integration W , forming an integrated optical and electromagnetic tropospheric lightning detection system.

[0093] The brightness difference summation is achieved by comparing the brightness difference between two adjacent frames pixel by pixel and accumulating these difference values ​​to obtain the total brightness change. Its mathematical expression is:

[0094] ,

[0095] in: Y j ( m , n ) indicates the j Frame images are in rows and columns ( m , n ), Ri Indicates the preset i The calculation area, k The image collector 110 uses a black and white pixel sensor, and the 8 / 10 / 12 bit data of each pixel is the brightness value Y .

[0096] Detector 100 is suspended from a flying platform 200 using a boom 201. Flying platform 200 can be a controllable balloon, fixed-wing drone, or rocket, with controllable balloons being preferred. By integrating advanced materials, intelligent control algorithms, and innovative structural designs, controllable balloons achieve precise control of altitude, position, and functionality, making them suitable for tropospheric lightning detection.

[0097] Power supply 6, powered by a lithium battery, is located at the center of the bottom of compartment 101 to maintain balance. Compartment 101 is insulated with polystyrene foam, and the battery generates heat to maintain the compartment temperature. If the compartment temperature is insufficient for electronic components, a heating element can be placed inside compartment 101 before launch. The simplest solution is to use a hand warmer.

[0098] Before conducting tropospheric lightning detection, the communication between the detector 100 and the ground center 300 is debugged, and the flight platform 200 is launched during an appropriate window period. The detector 100 then enters the troposphere, and the detected lightning image, electric field intensity, magnetic field intensity, discharge type, ambient temperature, ENU coordinates of the detector 100 and the lightning relative to the ground center 300, and the azimuth of the detector 100 relative to the ground center 300 are recorded. f , pitch angle i and distance r , the azimuth of the lightning relative to the center of the ground 300 f ′, pitch angle i ′ and distance r ′, and transmit it back to the ground center 300.

[0099] The description and drawings of this application are only a specific implementation method and are not restrictive. Under the guidance of this application, those skilled in the art can make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the scope of protection of this application.

Claims

1. An integrated optical and electromagnetic tropospheric lightning detection system, characterized by: include: Detector (100), flight platform (200), ground center (300); The detector (100) is mainly a spherical equipment compartment (101). Six cantilevers (102) extend outward from the equipment compartment (101), wherein two pairs are arranged horizontally and one pair is arranged vertically. The three pairs of cantilevers (102) are perpendicular to each other. A spherical probe (103) is arranged at the outer end of each cantilever (102). A strip-shaped electrode (104) is arranged inside the cantilever (102). One end of the electrode (104) is connected to the probe (103), and the other end is connected to a charge amplifier (105) using a shielded wire. The two probes (103) and the corresponding electrodes (104) and a charge amplifier (105) together constitute an electric field detector. The electric field detectors in three directions constitute a three-dimensional electric field detector (106). Two GNSS receiving devices (107) are correspondingly arranged on a pair of cantilevers (102). Four image collectors ( 110) and four groups of spectrophotometers (111), the spectrophotometers (111) are correspondingly arranged below the image collector (110), each group of spectrophotometers (111) is composed of two APD sensors (112), which are respectively connected to the photometric amplifier (113), one APD sensor (112) is equipped with a red light filter, and the other APD sensor (112) is equipped with a blue-violet light filter; a three-dimensional magnetic field antenna (120), a six-axis sensor (130), and a temperature sensor (140) are also arranged in the equipment warehouse (101); the three-dimensional magnetic field antenna (120) is composed of three mutually perpendicular magnetic bar coils, the three magnetic bar coils are respectively parallel to the three pairs of cantilevers (102), the three-dimensional magnetic field antenna (120) is respectively connected to the magnetic field amplifier (121), forming a three-dimensional magnetic field detector (122); the six-axis sensor (130) x Axis and y The axes are parallel to two pairs of horizontal cantilevers (102). z The axis is parallel to the vertical cantilever (102); The three-axis attitude sensor in the six-axis sensor (130) detects the attitude of the six cantilevers (102), calculates the inclination angles of the two pairs of horizontal cantilevers (102) and the horizontal plane, and the three-axis acceleration sensor measures the magnitude and direction of the acceleration of the detector (100) during the movement process; the two GNSS receiving devices (107) use carrier phase differential to measure the phase difference between the antennas to obtain the azimuth angles of the two GNSS receiving devices relative to the true north, and obtains the ECEF coordinates of the detector (100) after the attitude inclination angle correction of the six-axis sensor (130), determines the true north direction based on the ECEF coordinates, and obtains the coordinates with the ground center (300) as the origin ( x 0, y 0, z 0) of the ENU coordinate system; The image collector (110) records the lightning image position and obtains the azimuth angle of the lightning relative to the detector (100) in the ENU coordinate system. φ and pitch angle θ The electric field detector (106) detects the electric field intensity and the magnetic field detector (122) detects the magnetic field intensity, and the distance r of the lightning from the detector (100) is calculated by the amplitude spectrum method, and the azimuth angle of the lightning relative to the detector (100) is calculated. φ , pitch angle θ and distance r Get the ENU coordinates of the lightning and calculate the azimuth of the lightning relative to the center of the ground (300) φ ′, pitch angle θ ′ and distance r '; The viewing angle of the spectrophotometer (111) is the same as that of the image collector (110). The spectrophotometer (111) is equipped with a red light filter and a blue-violet light filter. The detection image collector (110) records whether the lightning is a corona discharge or an arc discharge. The blue-violet light channel signal is significantly stronger than the red light channel, which corresponds to a corona discharge. The red light channel signal is significantly stronger than the blue-violet light, which corresponds to an arc discharge. The type of tropospheric lightning is analyzed and the charge distribution and discharge energy are studied. The image collector (110) collects lightning images, the spectrophotometer (111) identifies the type of lightning discharge, the three-dimensional electric field detector (106) detects the vector electric field intensity, and the three-dimensional magnetic field detector (122) detects the vector magnetic field intensity. The discharge energy W is estimated by energy integration based on the light intensity, electric field change rate, and magnetic field peak value, thereby forming an integrated optical and electromagnetic tropospheric lightning detection system. When the sum of the brightness difference between the two frames before and after the image captured by the image collector (110), the signal strength of the spectrophotometer (111), the electric field strength detected by the three-dimensional electric field detector (106), and the magnetic field strength detected by the three-dimensional magnetic field detector (122) reach a set threshold, they can serve as trigger signals to trigger the storage of all collected data and mark the coordinates and time difference; The detector (100) is provided with a data processing unit (1), comprising an ACD analog-to-digital converter (2), an operation module (3), a data storage module (4), a data transmission module (5), and a power supply (6). Lightning images, electric field strength, magnetic field strength, photoelectric signals, ambient temperature, and coordinate data collected by the detector (100) are calculated by the operation module (3) and stored in the data storage module (4). The data are wirelessly transmitted back to a ground center (300) via the data transmission module (5). The ground center (300) demodulates the time-stamped data to obtain tropospheric lightning detection results.

2. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: The image collector (110) is arranged below the four horizontal cantilevers (102) and is equipped with a 150° wide-angle lens. The angle between the central axis of the image collector (110) and the vertical direction is α The angle is 75°, the vertical plane of the central axis is coplanar with the center of the horizontal cantilever (102), and the orientation of the central axis of the image collector (110) is the same as the orientation of the corresponding horizontal cantilever (102).

3. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: The cantilever (102) is made of a glass fiber reinforced plastic hollow tube and is vertically fixed to the outer wall of the equipment compartment (101). The probe (103) is fixed to the outer end of the cantilever (102) using a Teflon support. The electrode (104) is arranged in the cantilever (102), and Teflon brackets are arranged at intervals in the hollow tube to support the electrode (104).

4. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: The equipment bin (101) is made of polystyrene foam, with the inner and outer layers wrapped with high-density polyethylene (HDPE). A platform or bracket for installing equipment is provided inside the equipment bin (101).

5. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: Coordinate transformation is performed in the following steps: Beidou coordinates (E, L, H) are converted to ECEF geocentric coordinates ( x , y , z ): ， Among them, E is latitude, L is longitude, H is elevation, and N is the radius of curvature of the circle. calculate, a is the semi-major axis of the Earth ellipsoid, e 2 is the square of the first eccentricity of the ellipsoid; ECEF coordinate difference calculation: ， in,( x 0, y 0, z 0) is the coordinate of the ground center (300), ( x , y , z ) is the coordinate of the detector (100) when the lightning occurs; Rotation matrix (ECEF→ENU): ， After coordinate transformation, the coordinate system is converted to the ENU coordinate system with the ground center (300) as the origin: ， E , N , U represents the coordinate components of the lightning in the Northeast Celestial (ENU) coordinate system centered on the ground center (300), where E is the easting coordinate, N is the north coordinate, U is the zenith direction coordinate, R is the rotation matrix that projects the coordinate difference of the Earth-centered Earth-fixed coordinate system ECEF to the ENU coordinate system, Δ x ,Δ y ,Δ z is the coordinate difference between the detector (100) and the ground center (300) in the ECEF coordinate system when lightning occurs.

6. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: The azimuth of the lightning relative to the center of the ground (300) ϕ ′, pitch angle θ ′ and distance r ' is calculated based on the azimuth angle measured by the detector (100) ϕ and pitch angle θ , the unit vector of the lightning direction in the detector coordinate system is: ， The coordinates of the ground center (300) are ( x 0, y 0, z 0), the coordinates of the detector (100) are ( x , y , z ), then the position vector of the detector (100) relative to the ground center (300) is: ， The distance from the lightning to the detector (100) is r , then the position vector of the lightning in the ground center (300) coordinate system is: ， The eastward (E) component of the lightning at the ground center (300) is: ， The north (N) component is: ， The vertical (U) component is: ， The four-quadrant inverse tangent function atan2 is used to calculate the azimuth of lightning relative to the center of the ground. ϕ ′: ， Find the distance from the lightning bolt to the center of the ground (300) using three-dimensional Euclidean space r ′: ， Calculate the lightning's pitch angle relative to the ground center based on the ratio of the vertical component to the total distance θ ′: 。 7. The integrated optical and electromagnetic tropospheric lightning detection system according to claim 1, characterized in that: The brightness difference summation is performed by comparing the brightness difference between two adjacent frames pixel by pixel and accumulating these difference values ​​to obtain the total brightness change. The mathematical expression is: ， in: Y j ( m , n ) indicates the j Frame images are in rows and columns ( m , n ), R i Indicates the preset i The calculation area, k is the total number of preset areas; the image collector (110) uses a black and white pixel sensor, and the 8-bit, 10-bit, or 12-bit data of each pixel is the brightness value Y .

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