Pulse Propagation Simulation Method and Apparatus Based on LWPC

Abstract

This invention discloses a pulse propagation simulation method and apparatus based on Low Wave Propagation Pattern (LWPC). The method includes: calculating the flash source spectrum based on acquired flash source data; simulating each flash source spectrum based on an LWPC model under set ionospheric parameters and path information to obtain the simulated output signal of each flash source spectrum; and synthesizing the simulated output signals of each flash source spectrum to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide. This invention solves the problem of high cost and unsuitability as a conventional method for global low ionospheric monitoring by dividing the signal source into multiple single-frequency signals and modeling their propagation using the long-wave propagation capabilities of each mode during the day and night.

Description

Technical Field

[0001] This invention relates to the field of pulse propagation technology, and more specifically to a pulse propagation simulation method and apparatus based on LWPC. Background Technology

[0002] Lightning, also known as tsunami, is a type of powerful electrical discharge phenomenon that occurs during convective weather. The large currents and strong electromagnetic pulses generated during its occurrence can be highly destructive to ground structures, power systems, various electronic facilities, and human safety. With the development of society and the economy, and the continuous advancement of technology, microelectronic devices and large-scale integrated circuits have been widely applied in all aspects of social life. As a source of strong electromagnetic radiation, lightning's impact on human production and life is increasingly wide-ranging. As one of the major natural disasters facing humanity, lightning disasters have gradually gained attention. Therefore, the significance of studying lightning lies primarily in protecting the safety of national and public life and property, and ensuring the stable development of the economy and society. Of course, as an important weather phenomenon in nature, understanding the physical nature of lightning and revealing its connections with other natural phenomena has significant scientific importance. In the past decade or so, lightning research has received considerable attention from the academic community and the public. As an important branch of atmospheric science research, it has gradually formed numerous research areas, including lightning physics, lightning detection, and lightning protection. Whether from the perspective of understanding the physical mechanisms of lightning or determining the hazards of strong electromagnetic pulses, the measurement of lightning electromagnetic fields is extremely important. The complex physical processes of lightning discharge determine that it generates strong electromagnetic radiation energy across a wide frequency range.

[0003] A correct understanding of the physical processes of lightning relies heavily on advanced detection technologies and experimental observations. The continuous advancements in lightning detection technology, especially lightning location technology, have laid a solid foundation for lightning research. Existing lightning location technologies have enhanced our understanding of the physical processes of lightning from different perspectives, but each has its advantages and disadvantages: acoustic location can measure the sound waves generated during the formation of a lightning channel, but due to interference from other sounds, 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 channel and describe the development process of the lightning channel outside the thunderstorm cloud, but due to cloud cover, it is impossible to measure the discharge process inside the cloud. In short, none of the above observation technologies can provide a detailed description of the spatiotemporal evolution characteristics of the lightning discharge process. However, the characteristic that the lightning discharge process produces strong electromagnetic radiation across a wide frequency band provides us with an important observational approach. The main frequency bands for ground-based lightning 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 on a smaller spatial scale, often associated with the development of processes such as cloud lightning, ground lightning pre-breakdown, leaders, and streaks. Furthermore, due to line-of-sight transmission, the maximum detection range of VHF signals is generally hundreds of kilometers. The VLF / LF band radiation of lightning mainly reflects the lightning discharge process on a larger spatial scale, such as return strokes (RS) and continuous current events. Moreover, VLF / LF signals can propagate as ground waves, or as sky waves over long distances through waveguide reflections in the Earth's surface and ionosphere (mainly the lowermost D layer of the ionosphere). Even at greater distances, propagation can still be effectively described through modal analysis, thus enabling large-scale network observations.

[0004] Currently, some of the more well-known ground-based lightning detection systems both domestically and internationally include: VHF band-based systems such as France's SAFIR system, the US Kennedy Space Center's LDAR system, the US New Mexico Institute of Mining and Technology's LMA system, and Japan's Osaka University's VHF-DITF system; domestically, the VHF broadband interferometer positioning system established by Dong Wansheng et al. of the China Academy of Meteorological Sciences, and the VHF radiation source three-dimensional positioning system established by Zhang Guangshu et al. of the Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences. VLF / LF band-based systems include the US National Lightning Location Network (NLDN), the US Alamos National Laboratory's LASA system, the European Lightning Detection Network (EUCLID), the LINET system established by the University of Munich, Germany, the ZEUS system of the National Astronomical Observatory of Athens, the WWLLN system led by the University of Washington, and the recently developed antenna networking technology based on the VLF / LF band that can obtain very detailed three-dimensional evolution of lightning discharge channels, such as the University of Mississippi's PBFA system, the University of Alabama's BOLT system, the Japan Meteorological Institute's BOLT system, and Duke University's LFI-LMA system. Domestically, the Space Center of the Chinese Academy of Sciences, the China Meteorological Administration, and the State Grid Corporation of China have each established their own operational-oriented lightning location systems. Additionally, the Beijing Lightning Network (BLNET) established by Xie Xiushu and others at the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the Yangtze-Huaihe River Lightning Detection Network established by Mu's research group, among others, provide a solid equipment foundation for lightning observation and play a crucial role in advancing lightning science research.

[0005] Lightning discharges are one of the main natural sources of very low frequency (ELF) 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 for thousands of kilometers with extremely low attenuation rates (several dB / Mm) (Taylor, 1960; Yamashita M 1978) and through multiple reflections between the ground and the lower ionosphere, known as the Earth's ionospheric waveguide mode (EIWG) (Wait, 1962; Hayakawa, 2002).

[0006] The D region (60-90 km), serving as the upper reflection boundary of the waveguide mode, is too high for weather balloons and too low for satellite detection. Furthermore, incoherent scattering and partial reflection radars are unsuitable for monitoring the D region due to its high electron recombination and attachment rates and low electron density [Hargreaves, 1992]. MF radar [Igarashi et al., 2000] and rocket measurements are effective, but their high cost prevents them from being routine methods for global low ionospheric monitoring. This has led to increased research interest in these lightning atmospheric signals known as tweeks (Helliwell RA 1965), prompting the development of pulse propagation simulation methods based on LWPC to address the aforementioned problems. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this invention provides a pulse propagation simulation method and apparatus based on LWPC. By dividing the signal source into multiple single-frequency signals, the propagation of each mode is modeled using its long-wave propagation capability during the day and night. This is used to simulate the propagation of pulses along the low ionosphere-ground waveguide, solving the problem that the existing technology is too costly and cannot be used as a conventional means for global low ionosphere monitoring.

[0008] According to one aspect of the present invention, a pulse propagation simulation method based on LWPC is provided, comprising:

[0009] Calculate the flash power spectrum based on the acquired flash power data;

[0010] Based on the LWPC model, under the set ionospheric parameters and path information, the spectrum of each flash source is simulated to obtain the simulated output signal of each flash source spectrum.

[0011] The analog output signals of each flash source spectrum are synthesized to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide.

[0012] As a further technical solution, the method also includes: calculating the flash power spectrum using a double exponential model.

[0013] As a further technical solution, the method also includes:

[0014] pass The synthesized pulse signal arrives, where A xf P is the amplitude. pxf The phase for LWPC modeling, f is the frequency, x is the mode number, t is the arrival time of the lightning signal calculated from the phase velocity, and P sxf This is the source phase.

[0015] As a further technical solution, based on the LWPC model, under the set ionospheric parameters and path information, the spectrum of each flash source is simulated, including: by inputting typical ionospheric parameters during the day and night, the propagation of each flash source spectrum is modeled using the long-wave propagation capability of the simulated output signal during the day and night, so as to simulate the propagation of the pulse along the low ionosphere-ground waveguide.

[0016] As a further technical solution, the method also includes: simulating the analog output signal of a flash power source spectrum at each moment.

[0017] According to one aspect of the present invention, a pulse propagation simulation device based on LWPC is provided, comprising:

[0018] The calculation module is used to calculate the flash power spectrum based on the acquired flash power data;

[0019] The simulation module is used to simulate the spectrum of each flash source based on the LWPC model, under the set ionospheric parameters and path information, and obtain the simulated output signal of each flash source spectrum.

[0020] The synthesis module is used to synthesize the analog output signals of each flash source spectrum to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide.

[0021] According to one aspect of the present invention, an LWPC-based pulse propagation simulation device is provided, comprising a memory and a processor, wherein the memory stores program instructions that are executed by the processor, and the processor invokes the program instructions to perform the steps of the LWPC-based pulse propagation simulation method.

[0022] According to one aspect of the present invention, a non-transitory computer-readable storage medium is provided, the non-transitory computer-readable storage medium storing computer instructions that cause the computer to perform the steps of the LWPC-based pulse propagation simulation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The pulse propagation simulation method based on LWPC provided by this invention can divide the signal source into multiple single-frequency signals and model their propagation by utilizing the long-wave propagation capability of each mode during the day and night. This method is used to simulate the propagation of pulses along the low ionosphere-ground waveguide, solving the problem that existing technologies are too costly and cannot be used as a routine means for global low ionosphere monitoring. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the pulse propagation simulation method based on LWPC provided in an embodiment of the present invention;

[0027] Figure 2 The following are time-domain, frequency-domain signals and phase diagrams of the flash source provided in the LWPC-based pulse propagation simulation method of the present invention.

[0028] Figure 3 The following is a diagram showing the pulse frequency domain signal simulation results of the pulse propagation simulation method based on LWPC provided in this embodiment of the invention;

[0029] Figure 4 The diagram shows the pulse time-domain signal simulation results of the pulse propagation simulation method based on LWPC provided in the embodiments of the present invention.

[0030] Figure 5 This is a schematic diagram of the structure of a pulse propagation simulation device based on LWPC provided in an embodiment of the present invention. Detailed Implementation

[0031] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0033] This 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 the flash source spectrum based on acquired flash source data to divide the signal source into multiple single-frequency signals for subsequent simulation. Then, based on the LWPC model, under set ionospheric parameters and path information, each flash source spectrum is simulated to obtain the simulated output signal of each flash source spectrum. By simulating signals at different frequencies, different simulated output signals are obtained to facilitate subsequent signal synthesis. Finally, the simulated signals are synthesized to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide.

[0034] This invention, through the division of a signal source into multiple single-frequency signals and simulation based on the LWPC model, can model the propagation of each mode by inputting typical ionospheric parameters during the day and night, utilizing the long-wave propagation capability of each mode during the day and night. This enables the simulation of the propagation of the simulated pulse along the low ionosphere-ground waveguide, thereby achieving global low ionospheric monitoring at a lower cost.

[0035] 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.

[0036] Please see Figure 1 The pulse propagation simulation method based on LWPC provided in this embodiment of the invention includes the following steps:

[0037] S1: Calculate the flash power spectrum using measured / simulated flash power data.

[0038] Taking the double exponential model as an example,

[0039] , It represents the current density, where n is the degree, typically ranging from 2 to 10. and These are the leading and trailing edge time constants. η It is the peak correction factor, for both the time and frequency domain signals of the flash source, such as... Figure 2 As shown in (a)-(c), 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 .

[0040] S2: The amplitude and phase of each frequency arrival under relevant ionospheric parameters and path information are simulated using the LWPC model. The simulation results of the pulse frequency domain signal are as follows: Figure 3 As shown.

[0041] Pulse signals at different frequencies are calculated in step S1. These signals are then input into the LWPC model one by one. Under the set ionospheric parameters and path information, the propagation of these pulses 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 night can be simulated separately to obtain sufficient propagation simulation results.

[0042] S3:

[0043] pass The synthesized pulse signal arrives, where A xf P is the amplitude. pxf The phase for modeling LWPC, where f is the frequency in Hz and x is the mode number, ranging from 1 to n. t pxf P is the arrival time of a lightning signal with frequency f and modulus x calculated based on the propagation speed. sxf The source phase mentioned in step S1 is used to synthesize the following result: Figure 4 As shown.

[0044] The implementation of the various embodiments of the present invention is based on programmed processing through a device with processor functionality. Therefore, in practical engineering, the technical solutions and functions of the various embodiments of the present invention are encapsulated into various modules. Based on this reality, and building upon the above embodiments, the embodiments of the present invention provide an LWPC-based pulse propagation simulation device, which is used to execute the LWPC-based pulse propagation simulation method in the above method embodiments.

[0045] See Figure 5The device includes: a calculation module for calculating the flash source spectrum based on the acquired flash source data; a simulation module for simulating the spectrum of each flash source based on the LWPC model under set ionospheric parameters and path information, to obtain the simulated output signal of each flash source spectrum; and a synthesis module for synthesizing the simulated output signal of each flash source spectrum to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide.

[0046] The pulse propagation simulation device based on LWPC provided in this invention addresses the problem that existing technologies are too costly and cannot be used as a conventional method for global low ionospheric monitoring. Figure 5 Several modules in the simulation model the propagation of pulses along the low ionosphere-ground waveguide by dividing the signal source into multiple single-frequency signals and modeling the propagation of each mode using its long-wave propagation capability during the day and night.

[0047] It should be noted that the device embodiments provided by the present invention, in addition to implementing the methods in the above method embodiments, are also used to implement the methods in other method embodiments provided by the present invention. The difference lies only in the setting of corresponding functional modules. Their principles are basically the same as those of the above device embodiments provided by the present invention. Anyone skilled in the art, based on the above device embodiments and referring to the specific technical solutions in other method embodiments, can obtain corresponding technical means and technical solutions constituted by combining technical features, and, while ensuring the practicality of the technical solutions, can improve the modules in the above device embodiments to obtain corresponding device-type embodiments for implementing the methods in other method-type embodiments. For example:

[0048] Based on the above embodiments, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in this invention further includes a calculation module configured to execute the following instructions:

[0049] The spectrum of the flash source was calculated using a double exponential model.

[0050] Based on the above embodiments, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in this invention further includes a synthesis module configured to execute the following instructions:

[0051] pass The synthesized pulse signal arrives, where A xf P is the amplitude. pxf The phase for LWPC modeling, f is the frequency, x is the mode number, t is the arrival time of the lightning signal calculated from the phase velocity, and P sxf This is the source phase.

[0052] Based on the above embodiments, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in this invention further includes a simulation module configured to execute the following instructions:

[0053] By inputting typical ionospheric parameters during the day and night, the propagation of each flash source spectrum's simulated output signal is modeled using its long-wave propagation capability during the day and night, in order to simulate the propagation of the pulse along the low ionosphere-ground waveguide.

[0054] Based on the above embodiments, as a preferred embodiment, the pulse propagation simulation device based on LWPC provided in this invention further includes a simulation module configured to execute the following instructions:

[0055] At each moment, the analog output signal of a flash power source spectrum is simulated.

[0056] Based on the same inventive concept as the above embodiments, this embodiment of the invention also provides a pulse propagation simulation device based on LWPC, including a memory and a processor. The memory stores program instructions that are executed by the processor, and the processor calls the program instructions to execute the steps of the pulse propagation simulation method based on LWPC.

[0057] In embodiments of the present invention, the memory can be non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), or it can be volatile memory, such as random-access memory (RAM). Memory is any other medium capable of carrying or storing desired program code having an instruction or data structure form and accessible by a computer, but is not limited thereto. The memory in embodiments of the present invention can also be a circuit or any other device capable of implementing a storage function for storing program instructions and / or data.

[0058] In this embodiment of the invention, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components, capable of implementing or executing the methods, steps, and logic block diagrams disclosed in this embodiment of the invention. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in this embodiment of the invention can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0059] Based on the same inventive concept as the above embodiments, this embodiment of the invention also provides a non-transitory computer-readable storage medium that stores computer instructions that cause the computer to execute the steps of the LWPC-based pulse propagation simulation method.

[0060] When the aforementioned computer instructions are implemented as 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 this invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, is embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (a personal computer, server, or network device) to execute all or part of the steps of the methods described in the various method embodiments of this invention. The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks—various media for storing program code.

[0061] In summary, the pulse propagation simulation method based on LWPC provided by this invention can divide the signal source into multiple single-frequency signals and model their propagation using the long-wave propagation capabilities of each mode during the day and night. This is used to simulate the propagation of pulses along the low ionosphere-ground waveguide, solving the problem that existing technologies are too costly and cannot be used as a conventional means for global low ionosphere monitoring.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A pulse propagation simulation method based on LWPC, characterized in that, include: Calculate the flash power spectrum based on the acquired flash power data; Based on the LWPC model, under the set ionospheric parameters and path information, the spectrum of each flash source is simulated to obtain the simulated output signal of each flash source spectrum. Under the set ionospheric parameters and path information, the spectrum of each flash source is simulated, including: by inputting typical ionospheric parameters during the day and night, the propagation of the simulated output signal of each flash source spectrum is modeled using the long-wave propagation capability during the day and night, so as to simulate the propagation of the pulse along the low ionosphere-ground waveguide. The analog output signals of each flash source spectrum are synthesized to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide; among which, pass The synthesized pulse signal arrives, where A xf P is the amplitude. pxf The phase is used to model the LWPC, where f is the frequency, x is the mode number, and t is the arrival time of the lightning signal calculated from the phase velocity. P sxf For the source phase, t pxf The arrival time of the lightning signal with frequency f and modulus x is calculated based on the propagation speed.

2. The pulse propagation simulation method based on LWPC according to claim 1, characterized in that, The method also includes: calculating the spectrum of the flash source using a double exponential model.

3. The pulse propagation simulation method based on LWPC according to claim 1, characterized in that, The method further includes simulating the analog output signal of a flash power source spectrum at each time step.

4. A pulse propagation simulation device based on LWPC, used to implement the method according to any one of claims 1-3, characterized in that, include: The calculation module is used to calculate the flash power spectrum based on the acquired flash power data; The simulation module is used to simulate the spectrum of each flash source based on the LWPC model, under the set ionospheric parameters and path information, and obtain the simulated output signal of each flash source spectrum. The synthesis module is used to synthesize the analog output signals of each flash source spectrum to obtain the signal after the flash source data propagates along the low ionosphere-ground waveguide.

5. A pulse propagation simulation device based on LWPC, characterized in that, It includes a memory and a processor, the memory storing program instructions that are executed by the processor, the processor calling the program instructions to perform the steps of the pulse propagation simulation method based on LWPC as described in any one of claims 1 to 3.

6. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to perform the steps of the LWPC-based pulse propagation simulation method according to any one of claims 1 to 3.

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