Pulse propagation simulation method and device based on LWPC

Abstract

The invention discloses an LWPC-based pulse propagation simulation method and device, and the method comprises the steps: calculating a lightning source frequency spectrum according to obtained lightning source data; based on an LWPC model, under set ionosphere parameters and path information, respectively simulating each lightning source frequency spectrum to obtain an analog output signal of each lightning source frequency spectrum; and synthesizing the analog output signal of each lightning source frequency spectrum to obtain a signal after the lightning source data is propagated along the low ionosphere-ground waveguide. According to the invention, the signal source is divided into a plurality of single-frequency signals, and the propagation of the single-frequency signals is modeled by using the long-wave propagation capability of each mode in daytime and nighttime, so that the propagation condition of pulses along the low ionosphere-ground waveguide is simulated, and the problems that the cost is too high and the method cannot be used as a conventional means for global low ionosphere monitoring in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pulse propagation, and in particular to a pulse propagation simulation method and device based on LWPC. Background Art

[0002] Lightning, also known as thunder and lightning, is a type of strong discharge phenomenon that occurs during convective weather. The large current and strong electromagnetic pulses generated during its occurrence are very destructive to ground buildings, power systems, various electronic facilities, and life safety. With the development of social economy and the continuous advancement of science and technology, microelectronic devices and large-scale integrated circuits have been widely used in every corner of social life. As a strong electromagnetic radiation source, lightning has an increasingly large impact on human production and life. As one of the important natural disasters facing mankind, lightning disasters are gradually being taken seriously by people. Therefore, the significance of studying lightning is mainly to protect the safety of life and property of the country and the people and to ensure the stable development of the economy and society. Of course, as an important weather phenomenon in nature, lightning has important scientific significance in itself to understand the physical nature of lightning and reveal the connection between lightning and other natural phenomena. In the past decade, lightning research has always attracted much attention from the academic community and the public. As an important branch in the field of atmospheric science research, it has gradually formed many scientific research fields such as lightning physics, lightning detection, and lightning protection. Whether from the perspective of understanding the physical mechanism of lightning or determining the hazards of strong electromagnetic pulses, the measurement of lightning electromagnetic fields is very important. The complex discharge physics process in lightning events determines that they will generate strong electromagnetic radiation energy in a very wide frequency band.

[0003] Correct understanding of the physical process of lightning is inseparable from advanced detection technology and experimental observation. The continuous progress of lightning detection technology, especially lightning location technology, has laid a solid foundation for lightning research. Existing lightning location technologies have enhanced our understanding of the physical process of lightning from different angles, but each has its own advantages and disadvantages: acoustic location can measure the sound waves generated during the formation of the lightning channel, but due to the interference from other sounds at the same time, it is difficult to accurately determine the location of the discharge based on the location results; optical recording can measure the luminescence phenomenon of the lightning discharge process channel and describe the development process of the lightning channel outside the thunderstorm cloud, but due to the obstruction of the cloud layer, it is impossible to measure the discharge process inside the cloud. In short, none of the above observation technologies can achieve a detailed description of the spatiotemporal evolution characteristics of the lightning discharge process. However, the lightning discharge process will produce strong electromagnetic radiation in a wide frequency band. This feature provides us with an important observation method. The main frequency bands of lightning based on ground-based detection are concentrated in the strong VLF / LF and VHF bands during the lightning discharge process. The VHF band radiation of lightning mainly reflects the lightning discharge process of a smaller spatial scale, and is often associated with the development of cloud-to-ground lightning pre-breakdown, leader, streamer and other processes; at the same time, due to line-of-sight transmission, the maximum detection distance of VHF signals is generally hundreds of kilometers. The VLF / LF band radiation of lightning mainly reflects the lightning discharge process of a larger spatial scale, such as return stroke (RS) and continuous current events; at the same time, VLF / LF signals can be propagated in the form of ground waves, or in the form of sky waves at a longer distance in the waveguide reflection propagation formed by the surface-ionosphere (mainly the lowest layer of the ionosphere), and even at a longer distance k, the propagation can still be effectively described by modal analysis, so large-scale network observations can be carried out.

[0004] So far, the well-known ground-based lightning detection systems at home and abroad are: based on the VHF frequency band, such as the SAFIR system in France, the LDAR system of the Kennedy Space Center in the United States, the LMA system of the New Mexico Institute of Mining and Technology in the United States, and the VHF-DITF system of Osaka University in Japan, the VHF broadband interferometer positioning system established by Dong Wansheng and others of the Chinese Academy of Meteorological Sciences, and the VHF radiation source three-dimensional positioning system established by Zhang Guangshu and others of the Institute of Cold and Arid Regions of the Chinese Academy of Sciences. Based on the VLF / LF frequency band, there are the National Lightning Location Network (NLDN) of the United States, the LASA system of the Alamos National Laboratory in the United States, the European Lightning Detection Network (EUCLID), the LINET system established by the University of Munich in Germany, the ZEUS system of the Athens National Observatory, the WWLLN system led by the University of Washington in the United States, and the recently developed antenna networking technology based on the VLF / LF frequency band that can obtain very fine three-dimensional evolution of lightning discharge channels, such as the PBFA system of the University of Mississippi in the United States, the BOLT system of the University of Alabama in the United States, the Meteorological Research Institute of Japan, and the LFI-LMA system of Duke University in the United States. The Chinese Academy of Sciences Space Center, China Meteorological Administration, and State Grid Corporation of China have established their own lightning location systems based on business directions, as well as the Beijing Lightning Comprehensive Detection Network (BLNET) established by Xie Xiushu and others from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, and the Jianghuai Lightning Detection Network established by the Mu Research Group. Each detection system has laid a good equipment foundation for lightning observation and played a vital role in the research and progress of lightning science.

[0005] Lightning discharge is one of the main natural sources of VLF signals. The main frequency range of lightning electromagnetic pulse energy is the extremely low frequency (ELF: 0.3-3 kHz) and very low frequency (VLF: 3-30 kHz) bands. (Kumar et al., 2008; Volland et al., 1987). These pulse signals propagate thousands of kilometers with extremely low attenuation rates (several dB / Mm) (Taylor, 1960; Yamashita M 1978). And propagate through multiple reflections between the ground and the lower ionosphere, which is called the Earth ionospheric waveguide mode (EIWG) (Wait, 1962; Hayakawa, 2002).

[0006] The D region (60-90km) is the upper reflection boundary of the waveguide mode, which is too high for sounding balloons and too low for satellite detection. On the other hand, incoherent scattering and partial reflection radars are not suitable for monitoring the D region because the electron recombination rate and attachment rate in this region are high and the electron density is low [Hargreaves, 1992]. MF radar [Igarashi et al., 2000] and rocket measurements are effective, but both are too expensive to be used as a routine means of global lower ionosphere monitoring. This has also led to more research interest in these lightning sky signals called tweeks (Helliwell RA 1965), so a pulse propagation simulation method based on LWPC is proposed to solve the above-mentioned problems. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a pulse propagation simulation method and device based on LWPC, which divides the signal source into multiple single-frequency signals and uses the long-wave propagation capability of each mode during the day and at night to model its propagation, so as to simulate the propagation of pulses along the low ionosphere-ground waveguide, thereby solving the problem that the prior art is too expensive and cannot be used as a conventional means of global low ionosphere monitoring.

[0008] According to one aspect of the present invention, a pulse propagation simulation method based on LWPC is provided, comprising: Calculate the lightning source spectrum according to the acquired lightning source data; Based on the LWPC model, under the set ionospheric parameters and path information, each lightning source spectrum is simulated to obtain the simulated output signal of each lightning source spectrum; The analog output signals of the spectrum of each lightning source are synthesized to obtain the signal after the lightning source data propagates along the lower ionosphere-ground waveguide.

[0009] As a further technical solution, the method further includes: using a double exponential model to calculate the lightning source spectrum.

[0010] As a further technical solution, the method further includes: pass The pulse signal after synthesis arrives, where A xf is the amplitude, P pxf is the phase of LWPC modeling, f is the frequency, x is the mode number, t is the lightning signal arrival time calculated based on the phase velocity, P sxf is the source phase.

[0011] As a further technical solution, based on the LWPC model, each lightning source spectrum is simulated under the set ionospheric parameters and path information, including: by inputting typical ionospheric parameters during the day and night, and using the long-wave propagation capability of the simulated output signal of each lightning source spectrum during the day and night to model its propagation, so as to simulate the propagation of pulses along the low ionosphere-ground waveguide.

[0012] As a further technical solution, the method further includes: simulating an analog output signal of a lightning source spectrum at each moment.

[0013] According to one aspect of the present invention, there is provided a pulse propagation simulation device based on LWPC, comprising: A calculation module, used for calculating the lightning source spectrum according to the acquired lightning source data; The simulation module is used to simulate each lightning source spectrum based on the LWPC model under the set ionospheric parameters and path information to obtain the simulated output signal of each lightning source spectrum; The synthesis module is used to synthesize the analog output signals of each lightning source spectrum to obtain the signal after the lightning source data propagates along the lower ionosphere-ground waveguide.

[0014] According to one aspect of the present invention, there is provided a pulse propagation simulation device based on LWPC, comprising a memory and a processor, wherein the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the steps of the pulse propagation simulation method based on LWPC.

[0015] According to one aspect of the present invention, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to execute the steps of the LWPC-based pulse propagation simulation method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The pulse propagation simulation method based on LWPC provided by the present invention can divide the signal source into multiple single-frequency signals, and use the long-wave propagation ability of each mode during the day and at night to model its propagation, so as to simulate the propagation of pulses along the low ionosphere-ground waveguide, thereby solving the problem that the existing technology is too expensive and cannot be used as a conventional means of global low ionosphere monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of a pulse propagation simulation method based on LWPC provided in an embodiment of the present invention; Figure 2 The pulse propagation simulation method based on LWPC provided in the embodiment of the present invention provides a lightning source time domain, frequency domain signal and phase diagram; Figure 3 A pulse frequency domain signal simulation result diagram of a pulse propagation simulation method based on LWPC provided in an embodiment of the present invention; Figure 4 A diagram of pulse time domain signal simulation results of the LWPC-based pulse propagation simulation method provided in an embodiment of the present invention.

[0019] Figure 5 A schematic diagram of the structure of a pulse propagation simulation device based on LWPC provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] An embodiment of the present invention provides a pulse propagation simulation method based on LWPC (Long-Wavelength Propagation Capability, a long wave propagation model based on waveguide mode theory). The method first calculates a lightning source spectrum according to acquired lightning source data to divide the signal source into multiple single-frequency signals for subsequent simulation; then, based on the LWPC model, each lightning source spectrum is simulated under set ionospheric parameters and path information to obtain a simulated output signal of each lightning source spectrum, and different simulated output signals are obtained by simulating signals at different frequencies to facilitate subsequent signal synthesis; finally, the simulated signals are synthesized to obtain a signal after the lightning source data propagates along the lower ionosphere-ground waveguide.

[0023] The embodiment of the present invention divides the signal source into multiple single-frequency signals, and performs simulation based on the LWPC model. By inputting typical ionospheric parameters during the day and night, the propagation of each mode is modeled by utilizing the long-wave propagation capability of each mode during the day and night, so as to simulate the propagation of simulated pulses along the low ionosphere-ground waveguide, thereby realizing global low ionosphere monitoring at a relatively low cost.

[0024] It should be noted that the LWPC model can calculate the amplitude and phase of the signal at the receiving station by inputting path information and ionospheric parameters.

[0025] See also Figure 1 The pulse propagation simulation method based on LWPC provided by the embodiment of the present invention comprises the following steps: S1: Calculate the lightning source spectrum using measured / simulated lightning source data.

[0026] Taking the double exponential model as an example, , is the current density, n is the degree, usually 2-10, and are the leading and trailing edge time constants, η is the peak correction factor, the time domain and frequency domain signals of the lightning source are as follows Figure 2 (a)-(c) show that the frequency domain signal is the frequency domain result obtained by Fourier transform of the lightning time domain signal, including the amplitude A corresponding to each frequency of the lightning source sxf and phase information P sxf .

[0027] S2: The LWPC model is used to simulate the amplitude and phase of each frequency at the time of arrival under relevant ionospheric parameters and path information. The pulse frequency domain signal simulation results are as follows: Figure 3 shown.

[0028] Step S1 calculates pulse signals at different frequencies, and inputs these signals into the LWPC model one by one. Under the set ionospheric parameters and path information, the propagation of the pulse along the low ionosphere-ground waveguide is simulated to obtain the corresponding simulated output signal. It should be noted that a signal of one frequency is simulated at each time point, and its long-wave propagation capability during the day and at night can be simulated separately to obtain sufficient propagation simulation results.

[0029] S3: pass The pulse signal after synthesis arrives, where A xf is the amplitude, P pxf is the phase of LWPC modeling, f is the frequency in Hz, x is the mode number in the range of 1-n, t pxf is the arrival time of the lightning signal with frequency f and modulus x calculated based on the propagation speed, P sxf is the source phase mentioned in step S1, and the synthesis result is as follows Figure 4 shown.

[0030] The implementation basis of each embodiment of the present invention is to implement programmed processing through a device with a processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention are encapsulated into various modules. Based on this reality, on the basis of the above embodiments, an embodiment of the present invention provides a pulse propagation simulation device based on LWPC, which is used to execute the pulse propagation simulation method based on LWPC in the above method embodiment.

[0031] See also Figure 5 The device includes: a calculation module, which is used to calculate the lightning source spectrum according to the acquired lightning source data; a simulation module, which is used to simulate each lightning source spectrum based on the LWPC model under the set ionospheric parameters and path information to obtain the simulated output signal of each lightning source spectrum; a synthesis module, which is used to synthesize the simulated output signals of each lightning source spectrum to obtain the signal after the lightning source data propagates along the low ionosphere-ground waveguide.

[0032] The pulse propagation simulation device based on LWPC provided in the embodiment of the present invention aims at the problem that the existing technology is too expensive and cannot be used as a conventional means for global lower ionosphere monitoring. Figure 5 Several modules in the simulation are used to simulate the propagation of pulses along the low ionosphere-ground waveguide by splitting the signal source into multiple single-frequency signals and modeling their propagation using the long-wave propagation capability of each mode during the day and at night.

[0033] It should be noted that the device embodiments provided by the present invention are used to implement the methods in the above method embodiments as well as the methods in other method embodiments provided by the present invention. The only difference is that the corresponding functional modules are set, and the principle is basically the same as the principle of the above device embodiments provided by the present invention. As long as the technical personnel in the field refer to the specific technical solutions in other method embodiments on the basis of the above device embodiments, obtain the corresponding technical means and the technical solutions composed of these technical means by combining the technical features, and on the premise of ensuring the practicality of the technical solutions, improve the modules in the above device embodiments to obtain the corresponding device class embodiments, which are used to implement the methods in other method class embodiments. For example: Based on the content of the above device embodiment, as a preferred embodiment, in the LWPC-based pulse propagation simulation device provided in the embodiment of the present invention, the calculation module is also used to execute the following instructions: The double exponential model is used to calculate the lightning source spectrum.

[0034] Based on the content of the above device embodiment, as a preferred embodiment, in the LWPC-based pulse propagation simulation device provided in the embodiment of the present invention, the synthesis module is further used to execute the following instructions: pass The pulse signal after synthesis arrives, where A xf is the amplitude, P pxf is the phase of LWPC modeling, f is the frequency, x is the mode number, t is the lightning signal arrival time calculated based on the phase velocity, P sxf is the source phase.

[0035] Based on the content of the above device embodiment, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in the embodiment of the present invention, the simulation module is also used to execute the following instructions: By inputting typical ionospheric parameters during the day and night, the propagation of each lightning source source is modeled using the long-wave propagation capability of the simulated output signal during the day and night to simulate the propagation of the pulse along the lower ionosphere-ground waveguide.

[0036] Based on the content of the above device embodiment, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in the embodiment of the present invention, the simulation module is also used to execute the following instructions: At each moment, an analog output signal of the lightning source spectrum is simulated.

[0037] Based on the same inventive concept as the above-mentioned embodiment, an embodiment of the present invention also provides a pulse propagation simulation device based on LWPC, including a memory and a processor, wherein the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the steps of the pulse propagation simulation method based on LWPC.

[0038] In an embodiment of the present invention, the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), etc., or a volatile memory (volatile memory), such as a random-access memory (RAM). The memory is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in an embodiment of the present invention may also be a circuit or any other device that can implement a storage function, for storing program instructions and / or data.

[0039] In the embodiments of the present invention, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the embodiments of the present invention may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0040] Based on the same inventive concept as the above embodiment, an embodiment of the present invention further provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the steps of the LWPC-based pulse propagation simulation method.

[0041] When the above-mentioned computer instructions are implemented in the form of software functional units and sold or used as independent products, they are stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or partly in other words, the part that contributes to the prior art or part of the technical solution is embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for enabling a computer device (a personal computer, a server, or a network device) to perform all or part of the steps of the method described in each method embodiment of the present invention. The aforementioned storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media for storing program codes.

[0042] In summary, the LWPC-based pulse propagation simulation method provided by the present invention can divide the signal source into multiple single-frequency signals, and use the long-wave propagation capability of each mode during the day and at night to model its propagation, so as to simulate the propagation of pulses along the low ionosphere-ground waveguide, thereby solving the problem that the existing technology is too expensive and cannot be used as a conventional means of global low ionosphere monitoring.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. The pulse propagation simulation method based on LWPC is characterized by: include: Calculate the lightning source spectrum according to the acquired lightning source data; Based on the LWPC model, under the set ionospheric parameters and path information, each lightning source spectrum is simulated to obtain the simulated output signal of each lightning source spectrum; The analog output signals of the spectrum of each lightning source are synthesized to obtain the signal after the lightning source data propagates along the lower ionosphere-ground waveguide.

2. The pulse propagation simulation method based on LWPC according to claim 1 is characterized in that: The method further comprises: calculating the lightning source spectrum using a double exponential model.

3. The pulse propagation simulation method based on LWPC according to claim 1 is characterized in that: The method further comprises: pass The pulse signal after synthesis arrives, where A xf is the amplitude, P pxf is the phase of LWPC modeling, f is the frequency, x is the mode number, t is the lightning signal arrival time calculated based on the phase velocity, P sxf is the source phase.

4. The pulse propagation simulation method based on LWPC according to claim 1 is characterized in that: Based on the LWPC model, each lightning source spectrum is simulated under the set ionospheric parameters and path information, including: by inputting typical ionospheric parameters during the day and night, and using the long-wave propagation capability of the simulated output signal of each lightning source spectrum during the day and night to model its propagation, so as to simulate the propagation of pulses along the low ionosphere-ground waveguide.

5. The pulse propagation simulation method based on LWPC according to claim 4 is characterized in that: The method further comprises: simulating a simulated output signal of a lightning source spectrum at each moment.

6. The pulse propagation simulation device based on LWPC is characterized by: include: A calculation module, used for calculating the lightning source spectrum according to the acquired lightning source data; The simulation module is used to simulate each lightning source spectrum based on the LWPC model under the set ionospheric parameters and path information to obtain the simulated output signal of each lightning source spectrum; The synthesis module is used to synthesize the analog output signals of each lightning source spectrum to obtain the signal after the lightning source data propagates along the lower ionosphere-ground waveguide.

7. A pulse propagation simulation device based on LWPC, characterized in that: The invention comprises a memory and a processor, wherein the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the steps of the LWPC-based pulse propagation simulation method according to any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of the LWPC-based pulse propagation simulation method according to any one of claims 1 to 5.

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