A method for underwater low-frequency electromagnetic wave positioning

Abstract

This application discloses an underwater low-frequency electromagnetic wave positioning method, which includes the following steps: 1. Setting up a low-frequency electromagnetic wave transmitting system on a ship; 2. Arranging electrodes with exposed ends underwater; 3. Installing an electromagnetic wave receiving system on a submersible; 4. Calculating the amplitude of each electromagnetic component at the radiation field point of the transmitting source; 5. Acquiring and processing the received voltage signal; 6. Calculating the amplitude of the electric field Ey component; 7. Obtaining the contour lines of the two transmitting sources at the receiving point; 8. Finding the intersection point of the contour lines, which is the coordinate of the receiving point. This application achieves positioning by setting up a transmitting system on a ship and arranging two wires with exposed ends underwater to form an equivalent electric dipole source, creating an electromagnetic field around it. The submersible is equipped with an electromagnetic wave receiving system, and the relative position of the receiving point to the two transmitting sources is determined based on the magnitude of the electric field components at the receiving point. The positioning equipment has a simple and detachable structure and can be applied to submersible positioning in seawater.

Description

Technical Field

[0001] This application relates to the field of underwater electromagnetic wave positioning, and in particular to an underwater low-frequency electromagnetic wave positioning method. Background Technology

[0002] With the successive exploitation of land resources, people have begun to turn their attention to marine resources. Underwater target positioning technology is of great significance for the development of marine resources. Currently, sound waves are the main method of underwater positioning, with a propagation range of up to tens of kilometers, making it a relatively common positioning technology.

[0003] The existing patent document "CN1614441A Underwater Target Automatic Positioning Method and System" discloses a positioning method, which has some limitations. Sound waves are easily affected by multipath propagation, temperature, water pressure, and turbidity in seawater; the sound wave propagation speed is slow; the sound wave positioning equipment is large; baseline setup is difficult; and underwater sound propagation in seawater is prone to Doppler frequency shift and severe noise. Therefore, to address these problems, an underwater low-frequency electromagnetic wave positioning method is proposed. Summary of the Invention

[0004] This embodiment provides an underwater low-frequency electromagnetic wave positioning method to solve the problems of existing ordinary underwater positioning methods in shallow water, which are easily affected by multipath, temperature, water pressure and turbidity, slow sound wave propagation speed, large size of sound wave positioning equipment, difficulty in baseline layout, and Doppler frequency shift and severe noise when underwater sound propagates in seawater.

[0005] According to one aspect of this application, an underwater low-frequency electromagnetic wave positioning method is provided, the underwater low-frequency electromagnetic wave positioning method comprising the following steps:

[0006] 1. Simultaneously install low-frequency electromagnetic wave transmission systems on ships at two different known locations, with electromagnetic wave transmission frequencies of 10Hz and 100Hz respectively;

[0007] 2. Electrodes with exposed ends in the water are installed underwater, and the electrodes are connected to the ship's transmitting system via wires;

[0008] 3. Install an electromagnetic wave receiving system on the submersible, with the receiving antenna consisting of an electrode whose tip is exposed in the water;

[0009] 4. Calculate the depth of the submersible using a depth sensor. After determining the depth information, use MATLAB to calculate the amplitude of the Ey component of the radiation field at the plane where the submersible is located from the underwater long straight wire emission source.

[0010] 5. Acquire the voltage signal received by the receiving system and separate the voltage signals at two specific frequency points: 10Hz and 100Hz;

[0011] 6. Calculate the amplitude of the electric field Ey component from the amplitudes of the two voltage signals in step 5;

[0012] Compare the calculation results in steps 7 and 6 with those in step 4 to obtain the contour lines of the two transmitters at the receiving point;

[0013] 8. Find the intersection of the contour lines. Since the coordinates of the two sources are known, the intersection of the contour lines is the coordinate of the receiver.

[0014] Furthermore, in step 1, the low-frequency electromagnetic wave transmitting system includes a transmission control system, a drive system, and a power supply system.

[0015] Furthermore, in step 1, the ship is equipped with a calculation system for calculating the receiver coordinates.

[0016] Furthermore, in step 1, there are two low-frequency electromagnetic wave transmitting systems. The two low-frequency electromagnetic wave transmitting systems are set up at different known locations and transmit electromagnetic waves at different frequencies, namely 10Hz and 100Hz.

[0017] Furthermore, in step 2, a wire with both ends exposed in the water is arranged underwater and connected to the equipment on the ship. The wire is connected to the power supply system on the ship, and the power supply system supplies power to the wire. After supplying power to the wire, it can be equivalent to an electric dipole source, forming an electromagnetic field in the surrounding space, thereby realizing the emission of low-frequency electromagnetic waves in the water.

[0018] Furthermore, in step 2, a wire with both ends exposed in the water is arranged underwater and connected to the equipment on the ship. The power supply system supplies power to the wire, which can be equivalent to an electric dipole source to form an electromagnetic field in the surrounding space, thereby realizing the emission of low-frequency electromagnetic waves in the water.

[0019] Further, in step 2, the electromagnetic field strength generated by the galvanic source is:

[0020] Furthermore, in step 3, an electromagnetic wave receiving system is installed on the submersible to detect the magnitude of each component of the electromagnetic field at the receiving point. The electromagnetic wave receiving system is equipped with a water depth sensor to determine the depth of the submersible's location.

[0021] Furthermore, in step 3, the electromagnetic wave receiving system is equipped with a computer, an amplification module, a filtering module, and an analog-to-digital conversion module. The electromagnetic waves are simultaneously received by the receiving system on the submersible, and after amplification, filtering, and analog-to-digital conversion, they enter the computer for data processing.

[0022] Furthermore, in step 4, the depth information of the submersible is obtained by a water depth sensor, and the MATLAB program is used to calculate the radiation field distribution of the plane where the submersible is located to obtain the amplitude of the Ey component at each field point.

[0023] Furthermore, in step 5, the signal received by the receiving system is filtered and subjected to Fourier transform to separate the voltage signals at specific frequencies of the two transmitting sources.

[0024] Furthermore, in step 6, the formula for converting the amplitude of the electric field component to the amplitude of the voltage signal is E = U / d, where d is the distance between the two electrodes at the receiving end.

[0025] Furthermore, in step 7, the calculation results in step 6 are compared with the calculation results in step 4, and points in the calculation results of step 4 with an error of less than 1e-8 are found. Contour lines are drawn using the searched points.

[0026] Furthermore, in step 8, the intersection point of the two contour lines obtained in step 7 is obtained. Since the coordinate positions of the two transmitting sources are known and the contour lines have only one intersection point, this intersection point is the coordinate position of the receiving point.

[0027] Through the above embodiments of this application, by setting up a transmitting system on a ship and arranging two wires with exposed ends underwater to form an equivalent electric dipole source, an electromagnetic field is formed around it. An electromagnetic wave receiving system is equipped on the submersible. Based on the magnitude of the electric field at the receiving point, the relative position of the receiving point and the two transmitting sources is determined to achieve positioning. The positioning device has a simple structure, is detachable, and can be applied to the positioning of submersibles in seawater. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating one embodiment of the present application. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0033] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0035] Please see Figure 1As shown, an underwater low-frequency electromagnetic wave positioning method includes the following steps:

[0036] 1. Simultaneously install low-frequency electromagnetic wave transmission systems on ships at two different known locations, with electromagnetic wave transmission frequencies of 10Hz and 100Hz respectively;

[0037] 2. Electrodes with exposed ends in the water are installed underwater, and the electrodes are connected to the ship's transmitting system via wires;

[0038] 3. Install an electromagnetic wave receiving system on the submersible, with the receiving antenna consisting of an electrode whose tip is exposed in the water;

[0039] 4. Calculate the depth of the submersible using a depth sensor. After determining the depth information, use MATLAB to calculate the amplitude of the Ey component of the radiation field at the plane where the submersible is located from the underwater long straight wire emission source.

[0040] 5. Acquire the voltage signal received by the receiving system and separate the voltage signals at two specific frequency points: 10Hz and 100Hz;

[0041] 6. Calculate the amplitude of the electric field Ey component from the amplitudes of the two voltage signals in step 5;

[0042] Compare the calculation results in steps 7 and 6 with those in step 4 to obtain the contour lines of the two transmitters at the receiving point;

[0043] 8. Find the intersection of the contour lines. Since the coordinates of the two sources are known, the intersection of the contour lines is the coordinate of the receiver.

[0044] Furthermore, in step 1, the low-frequency electromagnetic wave transmitting system includes a transmission control system, a drive system, and a power supply system.

[0045] Furthermore, in step 1, the ship is equipped with a calculation system for calculating the receiver coordinates.

[0046] Furthermore, in step 1, there are two low-frequency electromagnetic wave transmitting systems. The two low-frequency electromagnetic wave transmitting systems are set up at different known locations and transmit electromagnetic waves at different frequencies, namely 10Hz and 100Hz.

[0047] Furthermore, in step 2, a wire with both ends exposed in the water is arranged underwater and connected to the equipment on the ship. The wire is connected to the power supply system on the ship, and the power supply system supplies power to the wire. After supplying power to the wire, it can be equivalent to an electric dipole source, forming an electromagnetic field in the surrounding space, thereby realizing the emission of low-frequency electromagnetic waves in the water.

[0048] Furthermore, in step 2, a wire with both ends exposed in the water is arranged underwater and connected to the equipment on the ship. The power supply system supplies power to the wire, which can be equivalent to an electric dipole source to form an electromagnetic field in the surrounding space, thereby realizing the emission of low-frequency electromagnetic waves in the water.

[0049] Further, in step 2, the electromagnetic field strength generated by the galvanic source is:

[0050] Furthermore, in step 3, an electromagnetic wave receiving system is installed on the submersible to detect the magnitude of each component of the electromagnetic field at the receiving point. The electromagnetic wave receiving system is equipped with a water depth sensor to determine the depth of the submersible's location.

[0051] Furthermore, in step 3, the electromagnetic wave receiving system is equipped with a computer, an amplification module, a filtering module, and an analog-to-digital conversion module. The electromagnetic waves are simultaneously received by the receiving system on the submersible, and after amplification, filtering, and analog-to-digital conversion, they enter the computer for data processing.

[0052] Furthermore, in step 4, the depth information of the submersible is obtained by a water depth sensor, and the MATLAB program is used to calculate the radiation field distribution of the plane where the submersible is located to obtain the amplitude of the Ey component at each field point.

[0053] Furthermore, in step 5, the signal received by the receiving system is filtered and subjected to Fourier transform to separate the voltage signals at specific frequencies of the two transmitting sources.

[0054] Furthermore, in step 6, the formula for converting the amplitude of the electric field component to the amplitude of the voltage signal is E = U / d, where d is the distance between the two electrodes at the receiving end.

[0055] Furthermore, in step 7, the calculation results in step 6 are compared with the calculation results in step 4, and points in the calculation results of step 4 with an error of less than 1e-8 are found. Contour lines are drawn using the searched points.

[0056] Furthermore, in step 8, the intersection point of the two contour lines obtained in step 7 is obtained. Since the coordinate positions of the two transmitting sources are known and the contour lines have only one intersection point, this intersection point is the coordinate position of the receiving point.

[0057] The advantages of this application are:

[0058] By installing a transmitting system on a ship and arranging two wires with their ends exposed underwater to form an equivalent electric dipole source, an electromagnetic field is generated around it. An electromagnetic wave receiving system is installed on the submersible. The relative position of the receiving point and the two transmitting sources is determined based on the magnitude of the electric field at the receiving point, thus achieving positioning. The positioning device has a simple and detachable structure and can be applied to the positioning of submersibles in seawater.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for underwater low-frequency electromagnetic wave positioning, characterized in that: The underwater low-frequency electromagnetic wave positioning method includes the following steps: Step a. Simultaneously set up low-frequency electromagnetic wave transmission systems on ships at two different known locations, with electromagnetic wave transmission frequencies of 10Hz and 100Hz respectively; Step b. Deploy electrodes with exposed tips underwater, and connect the electrodes to the ship's transmitting system via wires; Step c. Install an electromagnetic wave receiving system on the submersible, with the receiving antenna being an electrode whose tip is exposed in the water; Step d. Calculate the depth of the submersible using a depth sensor. After determining the depth information, use MATLAB to calculate the amplitude of the Ey component of the radiation field at the plane where the submersible is located, radiating from the underwater long straight wire source. Step e. Acquire the voltage signal received by the receiving system and separate the voltage signals at two specific frequency points: 10Hz and 100Hz; Step f. Calculate the amplitude of the electric field Ey component from the amplitudes of the two voltage signals in step e; Step g. Compare the calculation results in step f with the calculation results in step d to obtain the contour lines of the two transmitting sources at the receiving point; Step h. Find the intersection of the contour lines. Since the coordinates of the two transmitters are known, the intersection of the contour lines is the coordinate of the receiver.

2. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step a, the low-frequency electromagnetic wave transmitting system includes a transmission control system, a drive system, and a power supply system.

3. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step a, there are two low-frequency electromagnetic wave transmitting systems. The two low-frequency electromagnetic wave transmitting systems are set up at different known locations and transmit electromagnetic waves at different frequencies, namely 10Hz and 100Hz.

4. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step b, a wire with both ends exposed in the water is laid underwater and connected to the equipment on the ship. The wire is connected to the equipment on the ship, and the power supply system supplies power to the wire. After the wire is powered, it can be equivalent to an electric dipole source, forming an electromagnetic field in the surrounding space, thereby realizing the emission of low-frequency electromagnetic waves in the water.

5. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step b, the electromagnetic field strength generated by the galvanic source is: Er = 1 + kr e−kr;Eθ= 1 + kr + kr 2 e−kr;E∅= 1 + kr + kr 2 e−kr.

6. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step c, an electromagnetic wave receiving system is installed on the submersible to detect the magnitude of each component of the electromagnetic field at the receiving point. The electromagnetic wave receiving system is equipped with a water depth sensor to determine the depth of the submersible's location.

7. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step c, the electromagnetic wave receiving system is equipped with a computer, an amplification module, a filtering module, and an analog-to-digital conversion module. The electromagnetic waves are simultaneously received by the receiving system on the submersible, and after amplification, filtering, and analog-to-digital conversion, they enter the computer for data processing.

8. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step d, the depth information of the submersible is obtained by a depth sensor, and the MATLAB program is used to calculate the radiation field distribution of the plane where the submersible is located to obtain the amplitude of the Ey component at each field point.

9. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step e, the signal received by the receiving system is filtered and subjected to Fourier transform to separate the voltage signals at specific frequencies of the two transmitting sources.

10. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step f, the formula for converting the amplitude of the electric field component to the amplitude of the voltage signal is E = U / d, where d is the distance between the two electrodes at the receiving end.

11. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step g, the calculation result in step f is compared with the calculation result in step d, and the result in step d with an error of less than 10 is identified. -8 Use the points found in the search to create contour lines.

12. The underwater low-frequency electromagnetic wave positioning method according to claim 1, characterized in that: In step h, the two contour lines drawn in step g are used to find the intersection point of the two contour lines. Since the coordinates of the two transmitters are known and the contour lines have only one intersection point, this intersection point is the coordinate position of the receiver.

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