A portable VLF radiation efficiency measurement platform and method

Abstract

This application relates to the field of very low frequency (VLF) communication technology and discloses a portable VLF radiation efficiency measurement platform and method. The platform includes a very low frequency (VLF) receiving antenna, a GNSS antenna, a digital down-conversion receiver, a GNSS receiver, an industrial control computer, and a turntable. The digital down-conversion receiver is connected to the VLF receiving antenna and is used to receive the low-frequency electromagnetic field signals radiated by the VLF 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 VLF receiving antenna. The industrial control computer is connected to the digital down-conversion receiver, the GNSS receiver, and the turntable, respectively, and is used to control the turntable's direction and adjust it to its maximum direction. The radiation efficiency of the VLF transmitting antenna is calculated based on the distance between the transmitting and receiving points, the maximum field strength at the receiving point, and the input power at the transmitting point. This method enables accurate measurement of the radiation efficiency of a VLF transmitting antenna.

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 minimal attenuation, making them widely used in long-distance navigation and communications. Very low frequency (VLF) refers to electromagnetic waves in the 3 kHz to 30 kHz band, primarily used for communication and command of long-range underwater targets. To effectively radiate VLF electromagnetic waves, vertically mounted antennas are typically used.

[0003] Radiation efficiency is one of the most important parameters of a very low frequency transmitting antenna. Currently, ground wave field strength is measured using a standard field strength meter with an antenna at a distance of 20km-60km from the transmitting antenna. The radiation efficiency is then calculated using a 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. The antennas currently configured with the field strength meter are mainly loop antennas and whip antennas. According to antenna theory, the loop antenna has obvious directivity in the low frequency band, and its maximum receiving direction is the plane where the loop surface is located. Therefore, when using the loop antenna for measurement, it is necessary to first manually adjust the direction of the loop antenna, and use the field strength reading on the field strength meter to determine whether the maximum receiving direction of the loop antenna is aligned with the incoming wave direction of the low-frequency signal. 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 influence of the surrounding electromagnetic environment, the loop antenna is 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 used, 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 measurement point, r is the straight-line distance between the measurement 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 very low frequency transmitting antennas has problems such as low measurement efficiency and multiple operation 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 antennas, 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 simultaneously realize functions such as automatic maximum direction search, automatic recording and storage of field strength signals, and automatic efficiency calculation, thereby improving the measurement efficiency of the radiation efficiency of very low frequency transmitting antennas.

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

[0013] Very low frequency receiving antenna, GNSS antenna, digital down-conversion receiver, GNSS receiver, industrial control 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] An industrial control computer is connected to a digital down-conversion receiver, a GNSS receiver, and a turntable, respectively, and is used to control the direction of the turntable and adjust it to its maximum direction to ensure that the field strength at the receiving point is always the maximum when measured; the distance between the transmitting point and the receiving point is calculated based on the longitude and latitude of the very low frequency transmitting antenna and the longitude and latitude of the receiving point; 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 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.

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

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

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

[0021] According to a second aspect of the present invention, a portable VLF radiation efficiency measurement method is also provided, 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] 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;

[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] Furthermore, 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, an industrial control computer is provided, 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 further 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 one 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 the very low frequency receiving antenna through a turntable; and realizes the automatic collection of the longitude and latitude of the receiving point (i.e., the longitude and latitude of the receiving antenna) through a GNSS antenna and a GNSS receiver, thereby calculating 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 antenna, and then calculating the radiation efficiency of the very low frequency transmitting antenna, which can realize automatic and accurate measurement of the radiation efficiency of the very low frequency transmitting antenna, and improve the measurement efficiency of the radiation efficiency of the very low frequency transmitting antenna.

[0039] (2) The present invention provides a portable VLF radiation efficiency measurement platform, which uses 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 following briefly introduces the drawings required for use in the embodiments. 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 creative work.

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

[0042] Figure 2 A flowchart 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 the industrial control computer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may be combined with each other as long as they do not conflict with each other.

[0045] The terms "first," "second," "third," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[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 known as an electronic compass). The industrial control computer is connected to the digital down-conversion receiver, the GNSS receiver, and the turntable respectively.

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

[0048] The triple-proof chassis is waterproof, moisture-proof, and smoke-proof. Placing the digital down-conversion receiver, GNSS receiver, and industrial computer within the triple-proof chassis improves the stability of the portable VLF radiation efficiency measurement platform.

[0049] The very low frequency receiving antenna serves as a receiving point for receiving 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, acting as a receiving point, collects the latitude and longitude of the receiving point, i.e., the latitude and longitude of the VLF receiving antenna. The GNSS antenna is an active antenna, incorporating active components such as a low-noise amplifier and filter. The GNSS antenna, acting as a receiving point, should ideally be located a certain distance from the VLF receiving antenna to avoid significant measurement errors due to distance.

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

[0053] The VLF receiving antenna uses a magnetic loop antenna. A magnetic loop antenna uses the principle of electromagnetic induction to receive and transmit signals. Its structure consists of a small magnetic rod surrounded by multiple coils. Compared to a typical loop antenna, a magnetic loop antenna is smaller.

[0054] The turntable is used to house and support one or at least two very low frequency (VLF) receiving antennas, enabling detection of low-frequency electromagnetic fields in different directions and positioning in the direction of maximum signal strength (i.e., the direction corresponding to the maximum field strength at the receiving point). Specifically, the turntable's direction can be controlled by an industrial computer via control circuitry or manually.

[0055] The turntable is equipped with a tripod and antenna mounting bracket. A battery pack is installed in the industrial computer to meet the field power requirements of all equipment in the entire system.

[0056] The portable VLF radiation efficiency measurement platform uses a turntable to locate the maximum field strength of the very low frequency receiving antenna (i.e., the maximum field strength at the receiving point). It also uses a GNSS antenna and a GNSS receiver to automatically collect the longitude and latitude of the receiving point. Furthermore, by using a magnetic loop antenna as the very low frequency receiving antenna, the platform is highly portable due to its small size.

[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: Acquire 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 a preset condition, the radiation efficiency of the VLF 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 achieving 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 a very low frequency transmitting antenna are as follows:

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

[0066] The turntable rotates 180°, and the industrial control 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 control 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 receives position information and automatically records 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 its location information 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 low-frequency electromagnetic wave propagation theory, the field strength points for very low frequency antenna efficiency measurements should be selected in the ground-wave and single-mode regions. This is because the radio wave operating modes in these regions are simple, making it easy to infer efficiency from measured field strength. In other regions, the radio wave operating modes are complex, the field strength varies with distance, and field strength calculation is complex, making it difficult to infer efficiency from measured field strength values. Specifically, the measurement point should be located in the ground-wave region, less than 100 km but greater than 20 km from the transmitter, or in the single-mode region, greater than 4000 km from the transmitter. The recommended optimal measurement distance is approximately 20-60 km. The influence of the ionosphere increases when the measurement distance is greater than 100 km, and the field strength contains induced field components at distances less than 20 km, affecting 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 measurement 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 using 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] Record data according to certain rules, as shown in Table 1.

[0077] Table 1

[0078]

[0079] The portable VLF radiation efficiency measurement platform and method provided in this embodiment can realize automatic, rapid and accurate measurement of the radiation efficiency of a very low frequency transmitting antenna while having 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 control 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 via a system bus, and the communication interface, the display unit and the input device are connected to the system bus via the input / output interface. The processor of the industrial control computer is used to provide computing and control capabilities. The memory of the industrial control 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 control computer is used to exchange information between the processor and external devices. The communication interface of the industrial control 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 image, 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 covering the display screen, or a button, trackball or touchpad set on the industrial computer casing, 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 shown in the figure, or combine certain components, or have a different component arrangement.

[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 having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned method embodiments. 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 microdrive, 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 this application is not limited by the order of the actions described, because according to this 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 this application.

[0086] In the above embodiments, the description of each embodiment has its own focus. 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 description is merely an exemplary embodiment of the present disclosure and is not intended to limit the scope of the present disclosure. That is, any equivalent changes and modifications made in accordance with the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure herein, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not recorded in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0088] The technical features of the above embodiments can 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 merely 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 scope of protection 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 control 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 a 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; calculate 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 obtain the maximum field strength at 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, wherein The very low frequency receiving antenna adopts a magnetic loop antenna.

3. The platform according to claim 1, wherein 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, wherein 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 according to any one of claims 1 to 4 comprises: Obtain low-frequency electromagnetic field signals radiated by very low-frequency transmitting antennas; Obtaining 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; 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; 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, wherein 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, wherein The 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 includes: 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 method 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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