JP2012189387A - Lightning discharge position orientation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more improve position orientation accuracy in a lightning discharge position orientation system using an arrival time difference approach.SOLUTION: As a representative configuration of a lightning discharge position orientation system, there are provided an antenna 104 which receives electromagnetic waves including electromagnetic waves with lightning discharge and outputs a differentiation signal of an electric field, a plurality of receiving stations 102 including an integration circuit 114 which outputs an electric field signal and a processing section 112 which specifies an arrival time of electromagnetic waves with lightning discharge, and a central processing unit 134 which orients a position where lightning discharge occurs from the arrival time of the electromagnetic waves with lightning discharge in the plurality of receiving stations. The processing section 112 determines a zero level by averaging the differentiation signals for a predetermined time width sufficiently retroactively from the time of a peak of the electric field signals, determines a peak of differentiation signals at a time preceding to the peak of the electric field signals, and defines a time when the value of the differentiation signal becomes a predetermined value of 40 to 90% from the zero level to the peak of the differentiation signal at the time preceding to the peak of the differentiation signal, as an arrival time of electromagnetic waves with lightning discharge.

Description

  The present invention relates to a lightning discharge position locating system for locating a position where a lightning discharge has occurred with high accuracy using the arrival time of an electromagnetic wave accompanying the lightning discharge.

  When a lightning strike occurs, it is necessary to promptly know the location of the lightning strike in order to investigate damage and perform recovery work. Therefore, the location of lightning strikes has been conventionally performed. The lightning strike location method currently used is performed by a combination of the so-called meeting method and arrival time difference method. In the meeting method, the arrival direction of electromagnetic waves accompanying lightning discharge is detected at two or more receiving stations, and the location of the lightning strike is determined from the intersection. For this reason, even if the electric field change waveform accompanying lightning discharge is complicated or lightning strikes occur at a plurality of locations almost simultaneously, positioning can be performed. The arrival time difference method uses lightning strike location (two-dimensional location) to record the arrival time of electromagnetic waves associated with lightning discharge at three or more receiving stations and determine the location of the lightning strike from the arrival time difference. How to do it. The arrival time difference to each station is recorded with high accuracy using a GPS clock, so lightning strike location can be determined with higher accuracy than the meeting method. Since the position difference accuracy is superior to the arrival time difference method, the position determination is performed by the intersection method only when position determination is difficult by the arrival time difference method in the current system.

  In the current system, each observation station observes electromagnetic waves associated with lightning discharge at a distance of about 100 km or more. However, if the propagation distance is longer than 100 km, the electromagnetic field change waveform is distorted and attenuated due to the influence of the propagation path topography and the ground conductivity, resulting in an error in the position location result. In order to prevent this, the distance between observation stations may be shortened so that the propagation distance is shortened. However, in the current lightning location system, the frequency band to be observed is as low as about 300 kHz or less, and the sampling rate of A / D conversion is as low as about 0.2 μs, so that the interval between receiving stations is shortened so that the propagation distance is shortened. Even if it was narrowed, the positioning accuracy was only about 400 m.

  On the other hand, in Patent Document 1, the reception frequency and the sampling rate are increased, and three or four or more receiving stations are installed within a predetermined radius circle (preferably 50 km) that is relatively close compared to the conventional system. As a result, the positioning accuracy was improved to about 200 m. In addition, due to improved accuracy, three-dimensional positioning is possible when observing at four stations or more, and it is also possible to classify lightning discharges and lightning strikes only in the clouds. Therefore, the conventional two-dimensional positioning system is generally referred to as a “lightning strike positioning system”, whereas the invention disclosed in Patent Document 1 is referred to as a “lightning discharge positioning system”.

JP 2007-121127 A

  One of the typical facilities for checking damage during a lightning strike is a transmission tower. If there is a power transmission tower at a position where lightning strikes are detected by the lightning discharge location system, it is necessary to climb this to check the transmission line. However, in the system of Patent Document 1, even if the positioning accuracy is about 200 m and the interval between adjacent steel towers is about 300 m, it is not possible to specify which steel tower has a lightning strike. In this case, it is necessary to climb up a plurality of steel towers to perform confirmation work, and there is a problem that it takes cost and time.

  As a result of investigations by the inventors, the cause of the decrease in positioning accuracy is that the electromagnetic field change waveform is distorted due to the influence of topography and ground conductivity, and the electric field change waveform that is the electromagnetic wave arrival time in the system of Patent Document 1 is used. This is because an error occurs at the peak time. By using the system of Patent Document 1, this effect can be greatly reduced compared to the current system and the positioning accuracy has been improved, but as described above, it is insufficient and further improvement is required. .

  Accordingly, an object of the present invention is to further improve the positioning accuracy in a lightning discharge positioning system using the arrival time difference method.

  The inventors have examined that even when electromagnetic waves propagate in a relatively short distance of about several tens of kilometers, the change in peak time due to slight distortion of the electromagnetic field change waveform caused by lightning strike is still large, and the peak time This determination is easily affected by noise such as radio broadcast waves. From these facts, it has been considered that there is a limit to improving accuracy in determining the peak time of the electromagnetic field change waveform as the electromagnetic wave arrival time as in the past, and an alternative method for determining the electromagnetic wave arrival time has been studied. The present invention has been completed.

That is, a typical configuration of the lightning discharge location system according to the present invention includes an antenna that receives an electromagnetic wave including an electromagnetic wave accompanying a lightning discharge and outputs an electric field differential signal, and an integration that integrates the differential signal and outputs an electric field signal. A plurality of receiving stations each having a circuit and a processing unit for identifying an arrival time of the electromagnetic wave accompanying the lightning discharge, which is a time when the lightning discharge occurs, and the lightning discharge from the arrival time of the electromagnetic wave accompanying the lightning discharge at the plurality of receiving stations. A central processing unit for locating the generated position, and the processing unit determines the zero level by taking an average of the differential signal having a predetermined time width that goes back sufficiently from the time of the peak of the electric field signal. The peak of the differential signal is determined at the previous time, and the value of the differential signal is a predetermined value between 40% and 90% from the zero level to the peak of the differential signal at the time before the peak of the differential signal. The time of Tsu, characterized in that the electromagnetic wave arrival time caused by lightning discharge.

  According to the above configuration, the influence of waveform distortion due to long-distance propagation of electromagnetic waves can be greatly reduced, and the arrival time difference of electromagnetic waves due to lightning discharge can be acquired accurately and stably. This is because the arrival time is determined from the waveform of the portion that is temporally earlier than the peak time that is the arrival time of the electromagnetic wave accompanying lightning discharge in Patent Document 1, so that the superposition of distortion of the preceding electric field change waveform can be further reduced. Because. This makes it possible to dramatically improve the positioning accuracy of lightning discharge.

  The predetermined value is preferably between 75% and 85% from the zero level to the peak of the differential signal. The predetermined value should be examined and set according to the case between 40 and 90% of the rising portion of the differential waveform of the electric field. In the data obtained with the currently used system, the probability of reaching the arrival time with a good S / N (signal-noise ratio) is high between 75% and 85%. Note that distortion of 40% or less can be reduced due to long-distance propagation, but is not suitable because the signal changes slowly and the S / N decreases. The change is not less than 90% and the S / N is lowered, and the distortion due to the influence of propagation is increased later, which is not suitable.

  It is preferable to provide a digital filter that removes the frequency component of the broadcast wave in the differential signal. Thereby, the noise by broadcast waves, such as a radio broadcast, can be reduced and position location accuracy can be raised more.

  ADVANTAGE OF THE INVENTION According to this invention, the influence of the waveform distortion by the earth conductivity of the propagation path of electromagnetic waves and topography can be reduced, and the arrival time difference of the electromagnetic waves by a lightning discharge can be acquired accurately and stably. Thereby, the positioning accuracy of lightning discharge can be dramatically improved.

It is a figure explaining the principle of the lightning discharge position location system which concerns on embodiment. It is a figure explaining the circuit structure of a receiving station. It is a figure which shows the example of a signal waveform. It is a flowchart explaining specification of the lightning discharge time. It is a figure which shows the example which applied the digital filter to the differential signal. It is a figure explaining acquisition of a zero level. It is a figure explaining a zero level and a zero crossing point. It is a figure explaining how the predetermined value between 40 to 90% which should be the arrival time of the electromagnetic waves accompanying a lightning discharge is set. It is a figure which shows a comparative example and an Example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating the principle of a lightning discharge location system according to the embodiment, and FIG. 2 is a diagram illustrating a circuit configuration of a receiving station. The lightning discharge location system according to the present embodiment uses the arrival time difference method.

  A lightning discharge position locating system 100 shown in FIG. 1 receives electromagnetic waves associated with lightning discharges with an antenna, and receives receiving stations 102 (102a, 102b, 102c, 102d,...) For specifying electromagnetic wave arrival times associated with lightning discharges. Install 4 stations or more in a circle with a radius of 50 km. Each receiving station 102 acquires an electric field signal, specifies an electromagnetic wave arrival time associated with lightning discharge based on the electric field signal, and transmits it to the host device 130 (see FIG. 2). The host device 130 locates the three-dimensional position P where the lightning discharge has occurred by the three-dimensional arrival time difference method using the arrival times of the electromagnetic waves accompanying the lightning discharge at at least four receiving stations 102.

  The host device 130 stores the installation positions of all the receiving stations 102 in the three-dimensional coordinates of the x, y, and z axes, and the arrival time of the electromagnetic waves accompanying the lightning discharge at each receiving station 102 is a three-dimensional arrival time difference. By applying the method, the three-dimensional position P where the lightning discharge has occurred can be determined.

  2, the receiving station 102 includes an electric field antenna 104, a VLF-MF band electric field amplifier 106, an A / D converter 108, a high-precision clock 110, a processing unit 112, an integration circuit 114, a trigger circuit 116, and a communication unit. 118, a digital filter 120 is provided.

  The electric field antenna 104 receives an electromagnetic wave in the VLF-MF band and outputs a differential signal dE / dt of the electric field E as a reception signal. However, since the output of the electric field antenna 104 is weak, the following electric field amplifier 106 is used in order to obtain a dynamic range suitable for sampling in the subsequent stage.

  The antenna may be a magnetic field antenna. In that case, the magnetic field antenna outputs a differential signal of the magnetic field of the electromagnetic wave as a reception signal. Whether to use the electric field antenna 104 or the magnetic field antenna may be selected according to the conditions of the receiving station installation location. In the case of a magnetic field antenna, two components that are parallel to the ground and orthogonal to each other are observed at the same time, but the circuit configuration conforms to FIG.

  The electric field amplifier 106 amplifies the output of the electric field antenna 104. The electric field amplifier 106 has frequency characteristics that can be amplified without attenuation in at least the VLF-MF band (3 kHz to 3 MHz). The VLF band is 3 kHz to 30 kHz, the LF band is 30 kHz to 300 kHz, the MF band is 300 kHz to 3 MHz, the HF band is 3 MHz to 30 MHz, and the VHF band is 30 MHz to 300 MHz.

  The A / D converter 108 converts the differential signal output from the electric field amplifier 106 into time-series digital data. The sampling period of the A / D converter 108 is 100 ns or less.

  The high-precision timepiece 110 is for achieving time synchronization with a similar device accommodated in another receiving station, and is composed of, for example, a rubidium high-precision timepiece. These high-precision clocks 110 may be synchronized with accuracy within 100 ns using a GPS system or the like.

  The processing unit 112 mainly specifies the arrival time of the electromagnetic wave accompanying the lightning discharge to each station. Details of the processing will be described later. As a specific example, the processing unit 112 can be realized by software operating on a general-purpose computer. The processing unit 112 specifies the arrival time of the electromagnetic wave to each station due to lightning discharge only when a lightning discharge event is detected by the trigger circuit 116, that is, only when the trigger signal arrives at the processing unit 112.

  In this embodiment, a digital filter 120 is provided between the A / D converter 108 and the processing unit 112. The digital filter 120 removes known broadcast wave components such as radio broadcasts. Specifically, the frequency of the broadcast wave (carrier frequency) is attenuated by the digital filter 120. At this time, it is possible to attenuate to an appropriate intensity by acquiring in advance the electric field intensity of each broadcast wave that reaches each receiving station 102. Thereby, the noise by a broadcast wave can be reduced and position location accuracy can be improved more.

  The integration circuit 114 integrates the reception signal amplified by the electric field amplifier 106. Since the received signal is the electric field differential signal dE / dt, the output of the integrating circuit 114 obtained by integrating the received signal is an electric field signal representing the magnitude and polarity of the electric field E.

  The trigger circuit 116 is a circuit that determines whether the electric field signal has reached a significant level associated with the occurrence of lightning discharge.

  3A and 3B are diagrams illustrating examples of signal waveforms, in which FIG. 3A illustrates a waveform of a differential signal, FIG. 3B illustrates a waveform of an electric field signal, and FIG. 3C illustrates a differential signal. FIG. 3D is an enlarged view of the waveform of the electric field signal. As shown in FIG. 3A, the reception signal dE / dt has many superimposed pulse waveforms with various amplitudes and periods. Therefore, in dE / dt, it is difficult to determine whether the electric field intensity has reached the intensity associated with the occurrence of lightning discharge. Therefore, when the integration circuit 114 generates an electric field signal by integrating the received signal, a waveform of the electric field signal with few superimposed pulses as shown in FIG. 3B is obtained. The trigger circuit 116 determines whether or not the intensity of the electric field signal has reached a significant level such that lightning discharge is recognized. That is, the trigger circuit 116 detects an event that a lightning discharge has occurred due to the electric field signal (analog signal) intensity exceeding a threshold value. A trigger signal that is an output of the trigger circuit 116 is input to the processing unit 112.

  The peak waveform 122 of the differential signal shown in FIG. 3A and the peak waveform 124 of the electric field signal shown in FIG. 3B are substantially at the same position. However, in detail, as shown in FIGS. 3C and 3D, the peak of the differential signal corresponds to the steepest time of the electric field signal, and the peak of the electric field signal is zero as the differential signal attenuates. Corresponds to the time.

  The communication unit 118 transmits the arrival time of the electromagnetic wave accompanying lightning discharge and the peak value of the electric field signal output from the processing unit 112 to the host device 130 via the data communication network 128 such as the Internet or ISDN.

  The host device 130 includes a communication unit 132 that receives data from a plurality of receiving stations 102 and a central processing unit 134. The host device 130 can use a general-purpose computer as a specific example, and the central processing unit 134 can be realized by software operating on the computer.

  The central processing unit 134 acquires the reception time t (t1, t2, t3, t4) of the electromagnetic wave accompanying the lightning discharge from each receiving station 102 (102a, 102b, 102c, 102d) in FIG. The central processing unit 134 stores the installation positions of all the reception stations 102 in three-dimensional coordinates of the x, y, and z axes, and in the three-dimensional space indicating the installation positions of the reception stations 102, each reception station 102. By applying the reception time t (t1, t2, t3, t4) of the electromagnetic wave accompanying the lightning discharge at (102a, 102b, 102c, 102d) to the three-dimensional arrival time difference method, the three-dimensional position P of the lightning discharge is determined. To do.

  Specifically, the central processing unit 134 calculates a rotating hyperboloid S1 (not shown due to difficulty in illustration) as a set of points that cause the arrival time difference t1-t2 between the receiving stations 102a and 102b. Similarly, rotation hyperboloids S2 and S3 (not shown) based on arrival time differences t2-t3 and t3-t4 are calculated from another set of receiving stations. Since the intersection of these rotation hyperboloids S1, S2, and S3 is the three-dimensional position P, the host device calculates the intersection line K12 of the rotation hyperboloids S1 and S2, and sets the intersection line K23 of the rotation hyperboloids S2 and S3. The three-dimensional position P that is the intersection of the intersection line K12 and the intersection line K23 is calculated.

  Since the rotation hyperboloids S1, S2, and S3 cannot be illustrated, for reference, the intersection line K10 of the rotation hyperboloid S1 and the ground (XY plane), the intersection line K20 of the rotation hyperboloid S2 and the ground, the rotation hyperboloid S3, and An intersection line K30 with the ground is shown. These intersecting lines K10, K20, and K30 are all hyperbolic curves.

上記の式を用いて、各受信局１０２のｃｈｉ−ｓｑｕａｒｅを合算し、最小となる位置、時刻を特定する。なお、最小となる位置の探索方法については、通常の最急降下法では最小解ではなく点在する極に入り込む可能性がある。極に入ることを防止するためには全てのメッシュ点でｃｈｉ−ｓｑｕａｒｅを計算することが理想的だが、それでは計算量が膨大になるため、現実的ではない。そこで、探索区域をある程度粗いメッシュに区切り、そのメッシュでの最小点を探索し、その点を中心として更に細かいメッシュで探索する。これによりローカルな極に入り込むことを防止し、迅速に適切な解を得ることができる。 In actual calculation, it is preferable to divide the entire observation region into meshes, perform error evaluation by chi-square test at each mesh point, and find an optimum point. The formula of the chi-square test is as follows.

Using the above equation, the chi-square of each receiving station 102 is summed to specify the minimum position and time. As for the search method of the minimum position, the normal steepest descent method may enter the scattered poles instead of the minimum solution. Although it is ideal to calculate chi-square at all mesh points in order to prevent entering the pole, this is not realistic because the calculation amount becomes enormous. Therefore, the search area is divided into meshes that are coarse to some extent, the minimum point in the mesh is searched, and the search is performed with a finer mesh centered on that point. As a result, it is possible to prevent entry into a local pole and obtain an appropriate solution quickly.

  In the present embodiment, the number of receiving stations 102 is described as four. If there are four receiving stations, it is possible to determine the three-dimensional lightning discharge position by the arrival time difference method. However, the standard deviation of the positioning error can be reduced as the number of receiving stations 102 increases. Also, if there are 5 or more receiving stations 102, recalculate by excluding data that has become larger when chi-square is calculated (observation of other lightning strikes, data with poor S / N). It is also possible to do. As a result, the number of receiving stations 102 can be higher when the number of receiving stations is five or more.

  In the lightning discharge position locating system 100 configured as described above, the feature of the present embodiment is that the processing unit 112 of the receiving station 102 specifies the arrival time of the electromagnetic wave accompanying the lightning discharge to the receiving station 102.

  In the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2007-121127), the zero cross value of the differential signal (electric field differential waveform) is set as the arrival time. This corresponds to the maximum peak of the integrated electric field signal. However, when the maximum peak time of the electric field signal is used, an error occurs in the arrival time difference to each observation station due to distortion due to long-distance propagation.

  Therefore, in this embodiment, the time at one point of the rising portion of the differential signal is set as the arrival time. Note that the optimum position of this rising portion changes depending on the network configuration, location, and season, so that the differential signal value is sequentially adjusted between 40% and 90% from the zero level to the peak of the differential signal. . The initial value is 80% of the peak.

  FIG. 4 is a flowchart for explaining the specification of the lightning discharge time. First, when a differential signal is received by the antenna 104 (step 200), an electric field signal is acquired by the integrating circuit 114 (step 202). When the lightning discharge event is detected by the trigger circuit 116 (step 204), the processing unit 112 starts specifying the arrival time of the electromagnetic wave accompanying the lightning discharge (step 206). Specifically, the processing unit 112 always accumulates a differential signal, and when a lightning discharge event occurs, the processing unit 112 performs processing on the differential signal from a time point that goes back a predetermined time from the time of the event.

  The processing unit 112 first needs to acquire the zero level of the differential signal. However, a lot of noise is on the received differential signal. There are various causes of noise, but noise due to broadcast waves considered to have the greatest influence is removed by the digital filter 120 (step 208). FIG. 5 is a diagram showing an example in which the digital filter 120 is applied to the differential signal. As shown in FIG. 5, noise can be effectively reduced by reducing noise caused by broadcast waves.

  Next, the processing unit 112 acquires the zero level of the differential signal (step 210). The zero level is determined by taking an average of the differential signal having a predetermined time width that goes back sufficiently before the time of lightning discharge, that is, the time of the peak of the electric field signal. This is because the zero level cannot be determined while the electric field signal due to lightning discharge is observed.

  FIG. 6 is a diagram for explaining the acquisition of the zero level. In FIG. 6, the moving average is taken with 100 data (4 μs), 300 data (12 μs), and 500 data (20 μs) from the beginning of the differential signal (data at a time that goes back a predetermined time from the lightning discharge event). One data is 40 ns. From FIG. 6, since the fluctuation is large in 100 data and 300 data and the fluctuation is small in 500 data, the zero level can be determined using this.

  Next, the processing unit 112 calculates a zero cross point that is an intersection of the differential signal and the zero level (step 212). FIG. 7 is a diagram for explaining the above-described zero level and zero cross point. As shown in FIG. 7, the time when the zero cross point is reached is the peak time of the electric field signal.

  Next, the processing unit 112 detects the peak of the differential signal at a time before the zero cross point (step 214). The peak of the differential signal means that the electric field signal is the steepest. Although there may be a plurality of peaks, the maximum peak is simply detected here.

  Then, the processing unit 112 detects the time when the value of the differential signal becomes a predetermined value between 40% and 90% from the zero level to the peak of the differential signal at the time before the peak of the differential signal. (Step 216).

  That is, the arrival time is not the peak time of the electric field signal (zero cross point of the differential signal) but the time of the rising portion of the differential signal, not the peak time of the differential signal. Since the S / N is good where the differential signal rises rapidly, a stable arrival time can be determined. Accordingly, it is possible to accurately and stably acquire the difference in arrival time of electromagnetic waves accompanying lightning discharge among the plurality of receiving stations 102.

  FIG. 8 is a diagram for explaining how to set a predetermined value between 40% and 90% that should be the arrival time of the electromagnetic wave accompanying lightning discharge. The data shown in FIG. 8 is data obtained by a system operating on a trial basis for verification of the present invention, and was observed in the vicinity of Tochigi Prefecture in the summer. 8A is a diagram showing the orientation position error with respect to the ratio of the predetermined value, FIG. 8B is a diagram showing the waveform of the differential signal of the data 2 shown in FIG. 8A, and FIG. 8C is the estimated current. The figure which shows a value and FIG.8 (d) is a figure which shows chi-square.

  Referring to the total column at the right end of the table shown in FIG. 8A, the error at 40% is large, and the errors at 60% and 80% are equivalent. Therefore, it can be seen that the same result can be obtained even if the predetermined value is 60% or 80%. However, referring to the data individually, as shown in FIG. 8B, the data 2 passes through the position of 60% a plurality of times, and also passes through 60% to the position where there is a deviation of 7 data (280 ns). Data existed. In FIG. 8 (a), the calculation is performed at the time of passing the first time. When there is such data, it is considered that the reliability is higher when the calculation is performed at the position of 80%.

  Further, referring to FIG. 8C, the current value of data 1 is relatively large. Since the intensity of the received electric field change waveform is strong, the S / N is good and the data 1 is most suitable among the data in FIG. 8 to verify the validity of the present invention without being affected by noise. Therefore, paying attention to this, reference is made to FIG. Then, in data 1, the value of chi-square is smaller in 80% than in 60%. For this reason as well, it is appropriate to use 80% as the predetermined value in the series of data at this time.

  As described above, since the optimal position of this rising portion changes depending on the network configuration, location, and season, the differential signal value is between 40% and 90% from the zero level to the peak of the differential signal. It is desirable to perform sequential adjustment. However, it is estimated that the S / N is improved particularly between 75% and 85%, and the predetermined value can be set stably.

(Examples and comparative examples)
FIG. 9 is a diagram showing a comparative example and an example. As a comparative example, a conventional lightning strike location system operated by TEPCO, and as an example, the lightning discharge location system described in the above embodiment was used. When the lightning discharge position was calculated with the system of the comparative example and the example for the same lightning data (both where the lightning strike position was confirmed), the average error in the comparative example was 367 m, and the maximum error was 759 m. The average error was 80 m and the maximum error was 230 m. Therefore, a significant improvement in accuracy was confirmed, with an average error of about 1/5 and a maximum error of about 1/3.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a lightning discharge position locating system for locating a position where a lightning discharge has occurred using an electromagnetic wave arrival time associated with a lightning discharge.

DESCRIPTION OF SYMBOLS 100 ... Lightning discharge location system, 102 ... Receiving station, 104 ... Antenna, 106 ... Electric field amplifier, 108 ... A / D converter, 110 ... High precision clock, 112 ... Processing part, 114 ... Integration circuit, 116 ... Trigger circuit, DESCRIPTION OF SYMBOLS 118 ... Communication part, 120 ... Digital filter, 122 ... Peak waveform, 124 ... Peak waveform, 128 ... Data communication network, 130 ... Host device, 132 ... Communication part, 134 ... Central processing part, t ... Electromagnetic wave reception accompanying lightning discharge Times of Day

Claims (3)

An antenna that receives an electromagnetic wave including an electromagnetic wave accompanying a lightning discharge and outputs a differential signal of an electric field, an integration circuit that integrates the differential signal and outputs an electric field signal, and an electromagnetic wave accompanying a lightning discharge that is the time when the lightning discharge occurs A plurality of receiving stations having a processing unit for identifying the arrival time of
A central processing unit for locating the position where the lightning discharge occurred from the arrival time of the electromagnetic wave accompanying the lightning discharge in the plurality of receiving stations,
The processor is
Determining the zero level by taking an average of the differential signal of a predetermined time width that goes back sufficiently from the peak time of the electric field signal;
Determining the peak of the differential signal at a time prior to the peak of the electric field signal;
The time when the value of the differential signal becomes a predetermined value between 40% and 90% from the zero level to the peak of the differential signal at the time before the peak of the differential signal is the arrival time of the electromagnetic wave accompanying lightning discharge Lightning discharge location system characterized by   The lightning discharge position locating system according to claim 1, wherein the predetermined value is preferably between 75% and 85% from the zero level to the peak of the differential signal.   The lightning discharge position locating system according to claim 1, further comprising a digital filter that removes a frequency component of a broadcast wave in the differential signal.

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