Portable VLF radiation efficiency measuring platform and method

Abstract

The invention relates to the technical field of very low frequency communication, and discloses a portable VLF radiation efficiency measurement platform and method. The platform comprises a very-low-frequency receiving antenna, a GNSS antenna, a digital down-conversion receiver, a GNSS receiver, an industrial personal computer and a rotary table. The digital down-conversion receiver is connected with the very-low-frequency receiving antenna and is used for receiving a low-frequency electromagnetic field signal radiated by the very-low-frequency transmitting antenna; the GNSS receiver is connected with the GNSS antenna and is used for receiving the longitude and latitude of a receiving point acquired by the GNSS antenna; the turntable is used for placing and supporting the very-low-frequency receiving antenna; the industrial control computer is connected with the digital down-conversion receiver, the GNSS receiver and the rotary table and used for controlling the direction of the rotary table, adjusting the rotary table to the maximum direction and calculating the radiation efficiency of the very-low-frequency transmitting antenna according to the distance between the transmitting point and the receiving point, the maximum field intensity of the receiving point and the input power of the transmitting point. By adopting the method, the radiation efficiency of the very-low-frequency transmitting antenna can be accurately measured.

Description

Technical Field

[0001] The present application relates to the field of very low frequency communication technology, and more specifically, to a portable VLF radiation efficiency measurement platform, method, industrial control computer, computer-readable storage medium and computer program product. Background Art

[0002] Low-frequency electromagnetic waves have stable propagation and low attenuation, and are widely used in long-distance navigation and communication. Very low frequency (VLF) refers to electromagnetic waves with a frequency band from 3KHz to 30KHz, which are mainly used for communication and command of long-distance underwater targets. In order to effectively radiate very low frequency electromagnetic waves, vertically erected antennas are usually used.

[0003] Radiation efficiency is one of the most important parameters of a very low frequency transmitting antenna. At present, a standard field strength meter is usually used to measure the ground wave field strength at a distance of 20km-60km from the transmitting antenna, and then the radiation efficiency is calculated based on the theoretical formula.

[0004] The current method for measuring the radiation efficiency of very low frequency transmitting antennas has the following problems:

[0005] (1) The antenna has a great influence on the measurement results. Currently, the antennas configured with the field strength meter mainly include loop antennas and whip antennas. According to antenna theory, loop antennas have obvious directivity in the low frequency band, and their maximum receiving direction is the plane where the loop surface is located. Therefore, when using the loop antenna for measurement, it is necessary to manually adjust the direction of the loop antenna first, and judge whether the maximum receiving direction of the loop antenna is aligned with the incoming wave direction of the low-frequency signal by reading the field strength on the field strength meter. During this adjustment process, in order to reduce the influence of human factors on the loop antenna, each time the direction is adjusted, the person must move away from the loop antenna before reading and recording the field strength. The process is cumbersome and requires at least two people to cooperate to complete the measurement task well. In addition, although the whip antenna is non-directional, in order to ensure the accuracy of the received signal, it is usually necessary to configure the whip antenna with a metal plate (aluminum plate) with a radius of at least about 1m to ensure good grounding conditions, which makes the entire measurement equipment bulky. At the same time, considering that the whip antenna is more susceptible to the surrounding electromagnetic environment, loop antennas are usually used for field strength measurement.

[0006] (2) Due to the influence of the electromagnetic environment, there will always be certain fluctuations in the readings of the field strength meter during measurement. It is difficult to grasp certain rules when manually reading and recording. Usually, multiple readings and records are required, which is a cumbersome process and there is also a certain risk of misreading or missing.

[0007] (3) When measuring radiation efficiency, current measurement platforms or equipment do not have the function of directly giving the radiation efficiency. Instead, it needs to be calculated based on the field strength according to the following formula:

[0008]

[0009] Where η is the radiation efficiency of the antenna, E z is the field strength measured at the measuring point, r is the straight-line distance between the measuring point and the transmitting antenna, P in is the input power of the transmitting antenna. Therefore, to deduce the radiation efficiency, it is also necessary to calculate the measurement distance and the input power of the antenna.

[0010] Therefore, the current method for measuring the radiation efficiency of a very low frequency transmitting antenna has problems such as low measurement efficiency and multiple operating procedures. Summary of the invention

[0011] In order to solve the above problems of the radiation efficiency measurement device and method of very low frequency transmitting antenna, the present invention provides a portable VLF radiation efficiency measurement platform, method, industrial control computer, computer-readable storage medium and computer program product, which can realize the functions of automatic search for maximum direction, automatic recording and preservation of field strength signals, automatic calculation of efficiency, etc., thereby improving the measurement efficiency of the radiation efficiency of very low frequency transmitting antenna.

[0012] To achieve the above object, according to a first aspect of the present invention, a portable VLF radiation efficiency measurement platform is provided, the platform comprising:

[0013] Very low frequency receiving antenna, GNSS antenna, digital down-conversion receiver, GNSS receiver, industrial computer, turntable;

[0014] The digital down-conversion receiver is connected to the very low frequency receiving antenna and is used to receive the low frequency electromagnetic field signal radiated by the very low frequency transmitting antenna;

[0015] The GNSS receiver is connected to the GNSS antenna to receive the longitude and latitude of the receiving point collected by the GNSS antenna;

[0016] The turntable is used to place and support the VLF receiving antenna;

[0017] The industrial control computer is respectively connected to the digital down-conversion receiver, the GNSS receiver, and the turntable, and is used to control the direction of the turntable and adjust the turntable to the maximum direction to ensure that the field strength at the receiving point is always the maximum field strength when measuring; based on the longitude and latitude of the very low frequency transmitting antenna and the longitude and latitude of the receiving point, the distance between the transmitting point and the receiving point is calculated; the maximum field strength of the receiving point and the input power of the transmitting point are obtained; and the radiation efficiency of the very low frequency transmitting antenna is calculated according to the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point, and the input power of the transmitting point.

[0018] Furthermore, the very low frequency receiving antenna adopts a magnetic loop antenna.

[0019] Furthermore, the digital down-conversion receiver, the GNSS receiver, and the industrial control computer are all placed in a triple-proof chassis.

[0020] Furthermore, the turntable is equipped with a tripod.

[0021] According to a second aspect of the present invention, there is also provided a portable VLF radiation efficiency measurement method, which is applied to the above-mentioned portable VLF radiation efficiency measurement platform, comprising:

[0022] Obtain low-frequency electromagnetic field signals radiated by very low frequency transmitting antennas;

[0023] Obtain GNSS reception message, which includes the latitude and longitude of the receiving point;

[0024] Based on the low-frequency electromagnetic field signal, the maximum field strength of the receiving point, the longitude and latitude of the transmitting point and the input power are obtained;

[0025] Based on the longitude and latitude of the transmitting point and the longitude and latitude of the receiving point, the distance between the transmitting point and the receiving point is calculated;

[0026] When the distance between the transmitting point and the receiving point meets the preset conditions, the radiation efficiency of the very low frequency transmitting antenna is calculated based on the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point and the input power of the transmitting point.

[0027] Further, based on the longitude and latitude of the transmitting point and the longitude and latitude of the receiving point, the distance between the transmitting point and the receiving point is calculated, including:

[0028] Use the Haversine formula to calculate the distance between the transmitting point and the receiving point:

[0029]

[0030] Where Tx is the longitude of the transmitting point, Rx is the longitude of the receiving point, Ty is the latitude of the transmitting point, and Ry is the latitude of the receiving point.

[0031] Furthermore, the radiation efficiency of the VLF transmitting antenna is calculated based on the distance between the transmitting point and the receiving point, the maximum field strength at the receiving point, and the input power at the transmitting point, including:

[0032]

[0033] Where η is the radiation efficiency of the VLF transmitting antenna, r is the distance between the transmitting point and the receiving point, and E z is the maximum field strength at the receiving point, P in is the input power at the transmitting point.

[0034] According to a third aspect of the present invention, there is also provided an industrial control computer, which includes a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to implement the steps of any one of the above methods.

[0035] According to a fourth aspect of the present invention, there is also provided a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0036] According to a fifth aspect of the present invention, there is also provided a computer program product, comprising a computer program, which implements the steps of any of the above methods when executed by a processor.

[0037] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0038] (1) The present invention provides a portable VLF radiation efficiency measurement platform, which realizes the maximum field strength positioning of a very low frequency receiving antenna through a turntable; and realizes the automatic collection of the longitude and latitude of a receiving point (i.e., the longitude and latitude of a receiving antenna) through a GNSS antenna and a GNSS receiver, thereby calculating the distance between a transmitting point and a receiving point based on the longitude and latitude of a very low frequency transmitting antenna and the longitude and latitude of a receiving antenna, and then calculating the radiation efficiency of the very low frequency transmitting antenna, thereby realizing automatic and accurate measurement of the radiation efficiency of a very low frequency transmitting antenna, and improving the measurement efficiency of the radiation efficiency of a very low frequency transmitting antenna.

[0039] (2) The portable VLF radiation efficiency measurement platform provided by the present invention adopts a magnetic loop antenna as a very low frequency transmitting antenna. Since the magnetic loop antenna has the characteristic of small size, the platform has good portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of the structure of a portable VLF radiation efficiency measurement platform provided in an embodiment of the present application;

[0042] Figure 2 A schematic flow chart of a portable VLF radiation efficiency measurement method provided in an embodiment of the present application;

[0043] Figure 3A schematic diagram of the internal structure of an industrial control computer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] The terms "first", "second", "third", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0046] like Figure 1 As shown, a portable VLF radiation efficiency measurement platform is provided, including a very low frequency receiving antenna, a GNSS (Global Navigation Satellite System) antenna, a digital down-conversion receiver, a GNSS receiver, an industrial control computer, and a turntable (also called an electronic compass). The industrial control computer is respectively connected to the digital down-conversion receiver, the GNSS receiver, and the turntable.

[0047] Preferably, the digital down-conversion receiver, the GNSS receiver, and the industrial control computer are all placed in a triple-proof chassis.

[0048] The triple-proof chassis is waterproof, moisture-proof, and smoke-proof. By placing the digital down-conversion receiver, GNSS receiver, and industrial control computer in the triple-proof chassis, the stability of the portable VLF radiation efficiency measurement platform can be improved.

[0049] The very low frequency receiving antenna is used as a receiving point to receive low frequency electromagnetic field signals.

[0050] The digital down-conversion receiver is connected to the very low frequency receiving antenna and is used for receiving the low frequency electromagnetic field signal radiated by the very low frequency transmitting antenna.

[0051] The GNSS antenna is used as a receiving point to collect the longitude and latitude of the receiving point, that is, the longitude and latitude of the very low frequency receiving antenna. The GNSS antenna is an active antenna with active components such as a low noise amplifier and a filter. The GNSS antenna is preferably placed at a certain distance from the very low frequency receiving antenna to avoid large measurement errors caused by the distance.

[0052] The GNSS receiver is connected to the GNSS antenna and is used to receive the longitude and latitude of the receiving point collected by the GNSS antenna.

[0053] The VLF receiving antenna uses a magnetic loop antenna. A magnetic loop antenna is an antenna that uses the principle of electromagnetic induction to receive and transmit signals. Its structure consists of a small-sized magnetic rod and multiple coils wrapped around the magnetic rod. Compared with a general loop antenna, the size of a magnetic loop antenna is smaller.

[0054] The turntable is used to place and support one or at least two very low frequency receiving antennas to detect low frequency electromagnetic fields in different directions and locate the direction of maximum signal strength (i.e., the direction corresponding to the maximum field strength of the receiving point). Specifically, the direction of the turntable can be controlled by an industrial computer through a control circuit or manually.

[0055] The turntable is equipped with a tripod and an antenna tooling mounting frame. The battery pack installed in the industrial computer can meet the field power supply requirements of all equipment in the entire system.

[0056] The portable VLF radiation efficiency measurement platform realizes the maximum field strength positioning of the very low frequency receiving antenna (i.e., the maximum field strength of the receiving point) through a turntable; realizes the automatic collection of the longitude and latitude of the receiving point through a GNSS antenna and a GNSS receiver; and, by adopting a magnetic loop antenna as the very low frequency receiving antenna, the platform has good portability due to the small size of the magnetic loop antenna.

[0057] like Figure 2 As shown, a portable VLF radiation efficiency measurement method is provided, which is applied to the above-mentioned portable VLF radiation efficiency measurement platform. The method is executed by an industrial control computer and includes the following steps:

[0058] Step 201, obtaining a low frequency electromagnetic field signal radiated by a very low frequency transmitting antenna;

[0059] Step 202, obtaining a GNSS reception message, where the GNSS reception message mainly includes the latitude and longitude of the receiving point;

[0060] Step 203, based on the low-frequency electromagnetic field signal, obtaining the maximum field strength of the receiving point, the longitude and latitude of the transmitting point, and the input power;

[0061] Step 204, calculating the distance between the transmitting point and the receiving point based on the longitude and latitude of the transmitting point and the longitude and latitude of the receiving point;

[0062] Step 205, when the distance between the transmitting point and the receiving point meets the preset conditions, the radiation efficiency of the very low frequency transmitting antenna is calculated according to the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point and the input power of the transmitting point.

[0063] In the above-mentioned portable VLF radiation efficiency measurement method, the industrial control computer calculates the distance between the transmitting point and the receiving point based on the longitude and latitude of the very low frequency transmitting antenna and the longitude and latitude of the receiving point, and then calculates the radiation efficiency of the very low frequency transmitting antenna, thereby being able to realize automatic and accurate measurement of the radiation efficiency of the very low frequency transmitting antenna, thereby achieving the purpose of improving the measurement efficiency of the radiation efficiency of the very low frequency transmitting antenna.

[0064] In one embodiment, the steps for measuring the radiation efficiency of the VLF transmitting antenna are as follows:

[0065] When the acquisition starts, the industrial computer controls the GNSS receiver and the digital down-conversion receiver to start acquisition, and simultaneously collects the RF signal and the GNSS receiving message (including the latitude and longitude of the receiving point), and stores the data in a packaged manner in the hard disk.

[0066] The turntable rotates 180°, and the industrial computer records the magnitude of the electromagnetic field signal measured in different directions, and locates the direction of the maximum signal by finding the maximum value (i.e., the maximum field strength at the receiving point). According to the maximum incoming wave direction (i.e., the direction corresponding to the maximum field strength at the receiving point), the industrial computer adjusts the turntable to the maximum direction through the control circuit to ensure that the measured signal field strength is always the maximum value E. z .

[0067] The GNSS antenna is used to receive position information and automatically record the longitude and latitude (Rx, Ry) of the receiving point. The longitude and latitude (Tx, Ty) of the VLF transmitting antenna can be obtained by inputting the location information of the VLF transmitting antenna or searching historical data.

[0068] Use the Haversine formula to calculate the distance between the transmitting point and the receiving point:

[0069]

[0070] Where Tx is the longitude of the transmitting point, Rx is the longitude of the receiving point, Ty is the latitude of the transmitting point, and Ry is the latitude of the receiving point.

[0071] According to the low-frequency electromagnetic wave propagation theory, the field strength point for measuring the efficiency of very low frequency antennas should be selected in the ground wave area and the single-mode area, because the radio wave working mode in this area is simple, which makes it easy to calculate the efficiency based on the measured field strength. In other areas, the radio wave working mode is complex, the field strength varies with the distance, and the field strength calculation is complex, making it difficult to calculate the efficiency based on the field strength measurement value. That is, the measurement point should be selected in the ground wave area less than 100km and more than 20km away from the transmitter or in the single-mode area more than 4000km away. The best measurement distance is recommended to be about 20-60km. When the measurement distance is greater than 100km, the influence of the ionosphere will increase. When the measurement distance is less than 20km, the field strength contains the induction field component, which affects the measurement accuracy.

[0072] The calculated distance r is compared with 20-60km. When r<20km or r>60km, the industrial control computer prompts through the measurement interface and selects a new measurement point for measurement.

[0073] When the distance between the measuring points meets the requirements (that is, the distance between the transmitting point and the receiving point meets the preset conditions, such as r<20km or r>60km) and the direction of the maximum signal wave is found through the turntable, the field strength is measured and the industrial control computer calculates the radiation efficiency corresponding to each measurement through the following formula.

[0074]

[0075] Where η is the radiation efficiency of the VLF transmitting antenna, r is the distance between the transmitting point and the receiving point, and E z is the maximum field strength at the receiving point, P in is the input power at the transmitting point.

[0076] The data are recorded according to certain rules, as shown in Table 1.

[0077] Table 1

[0078]

[0079] A portable VLF radiation efficiency measurement platform and method provided in this embodiment can realize automatic, fast and accurate measurement of the radiation efficiency of a very low frequency transmitting antenna, and has good portability.

[0080] The present application also provides an industrial control computer. The internal structure diagram of the industrial control computer can be as follows: Figure 3As shown. The industrial computer includes a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input / output interface. The processor of the industrial computer is used to provide computing and control capabilities. The memory of the industrial computer includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the industrial computer is used to exchange information between the processor and an external device. The communication interface of the industrial computer is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a portable VLF radiation efficiency measurement method is implemented. The display unit of the industrial computer is used to form a visually visible picture, and can be a display screen, a projection device or a virtual reality imaging device. The input device of the industrial computer can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the industrial computer shell, or an external keyboard, touchpad or mouse.

[0081] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the industrial control computer to which the solution of the present application is applied. The specific industrial control computer may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0082] like Figure 3 As shown, the present application also provides an industrial control computer, which includes a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to implement the steps in the above-mentioned method embodiments.

[0083] The present application also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a micro drive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic card or an optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0084] The present application also provides a computer program product, including a computer program, which implements the steps in the above-mentioned method embodiments when executed by a processor.

[0085] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0086] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0087] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are only regarded as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

[0088] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A portable VLF radiation efficiency measurement platform, characterized in that: include: Very low frequency receiving antenna, GNSS antenna, digital down-conversion receiver, GNSS receiver, industrial computer, turntable; The digital down-conversion receiver is connected to the very low frequency receiving antenna and is used to receive the low frequency electromagnetic field signal radiated by the very low frequency transmitting antenna; The GNSS receiver is connected to the GNSS antenna and is used to receive the longitude and latitude of the receiving point collected by the GNSS antenna; The turntable is used to place and support the very low frequency receiving antenna; The industrial control computer is respectively connected to the digital down-conversion receiver, the GNSS receiver, and the turntable, and is used to control the direction of the turntable and adjust the turntable to the maximum direction to ensure that the field strength at the receiving point is always the maximum field strength when measuring the field strength at the receiving point; based on the longitude and latitude of the very low frequency transmitting antenna and the longitude and latitude of the receiving point, calculate the distance between the transmitting point and the receiving point; obtain the maximum field strength of the receiving point and the input power of the transmitting point; The radiation efficiency of the very low frequency transmitting antenna is calculated according to the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point and the input power of the transmitting point.

2. The platform according to claim 1, characterized in that The very low frequency receiving antenna adopts a magnetic loop antenna.

3. The platform according to claim 1, characterized in that The digital down-conversion receiver, the GNSS receiver, and the industrial control computer are all placed in a three-proof chassis.

4. The platform according to claim 1, characterized in that The turntable is equipped with a tripod.

5. A portable VLF radiation efficiency measurement method, characterized in that: The portable VLF radiation efficiency measurement platform as claimed in any one of claims 1 to 4 comprises: Obtain low-frequency electromagnetic field signals radiated by very low frequency transmitting antennas; Acquire a GNSS reception message, wherein the GNSS reception message includes the latitude and longitude of a receiving point; Based on the low-frequency electromagnetic field signal, obtaining the maximum field strength of the receiving point, the longitude and latitude of the transmitting point, and the input power; Calculate the distance between the transmitting point and the receiving point based on the longitude and latitude of the transmitting point and the longitude and latitude of the receiving point; When the distance between the transmitting point and the receiving point meets a preset condition, the radiation efficiency of the very low frequency transmitting antenna is calculated according to the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point and the input power of the transmitting point.

6. The method according to claim 5, characterized in that The calculating the distance between the transmitting point and the receiving point based on the longitude and latitude of the transmitting point and the longitude and latitude of the receiving point includes: Use the Haversine formula to calculate the distance between the transmitting point and the receiving point: Where Tx is the longitude of the transmitting point, Rx is the longitude of the receiving point, Ty is the latitude of the transmitting point, and Ry is the latitude of the receiving point.

7. The method according to claim 5, characterized in that The step of calculating the radiation efficiency of the very low frequency transmitting antenna according to the distance between the transmitting point and the receiving point, the maximum field strength of the receiving point and the input power of the transmitting point comprises: Where η is the radiation efficiency of the VLF transmitting antenna, r is the distance between the transmitting point and the receiving point, and E z is the maximum field strength at the receiving point, P in is the input power at the transmitting point.

8. An industrial control computer, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 5 to 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method according to any one of claims 5 to 7 are implemented.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the steps of the method according to any one of claims 5 to 7 when being executed by a processor.

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