Geomagnetic communication positioning system and method

Abstract

The present invention relates to the field of through-the-ground communication and positioning technology, and more particularly to a through-the-ground magnetic communication and positioning system and method. The system includes a transmitting antenna, a receiving antenna, a signal transmitting end control circuit connected to the transmitting antenna, and a signal receiving end control circuit connected to the receiving antenna. The transmitting antenna and the receiving antenna transmit data via static magnetic field coupling. The transmitting antenna includes: a magnetic core, and N transmitting coils wound in parallel on the magnetic core, each transmitting coil having the same length and number of turns; the receiving antenna includes: a plurality of hollow coils, and the hollow coils are arranged in an orthogonal three-axis structure, and each hollow coil has the same number of turns, cross-sectional area, and cable type, so as to construct a regional magnetic induction field underground, providing reliable wireless communication and position perception for personnel in underground spaces. The present invention can achieve miniaturization of through-the-ground magnetic induction communication and positioning equipment, and can penetrate various media such as seawater, reinforced concrete, gravel, coal seams, and demolition to achieve communication positioning.

Description

Technical Field

[0001] The present invention relates to the field of through-the-earth communication positioning technology, and in particular to a through-the-earth magnetic communication positioning system and method. Background Art

[0002] When personnel or equipment are operating in underground facilities (bunkers and deeply buried facilities), tunnels (basic and complex), urban and natural caverns (civil engineering, sewers, basements, and caves), traditional radio waves are absorbed and shielded by the ground or reinforced concrete structures, making it difficult for underground personnel or equipment to communicate with those on the surface. GPS or Beidou signals fail, making it impossible to determine their relative position. Magnetic communication utilizes time-varying magnetic field signals generated by coils in space. Magnetic fields can penetrate non-ferromagnetic media such as soil, gravel, and seawater, making them widely used for underground through-the-earth communication. As early as 1975, the patent for Tunnel Finder Positioning and Communication Device (Patent No.: US3906504) proposed a method for locating and mapping tunnels. A magnetic field transmitting coil is installed in the tunnel, and a receiving coil on the surface receives the magnetic field signal emitted from underground. The amplitude of the signals is calculated to measure the distance between the transmitter and receiver, as well as their relative angle. This provided a reference for the development of through-the-earth magnetic communication and positioning technology. In 1992, a patent titled "Position and Direction Locator / Monitor" (patent number: US5155442) proposed a technology for monitoring and positioning the attitude of underground drill bits. This technology uses a single-axis magnetic rod transmitting antenna installed inside a metal drill pipe with slots cut into the wall, allowing the magnetic field to penetrate from the underground to the surface. A ground-based receiving magnetic sensor, consisting of two vertically positioned orthogonal antennas, continuously measures the magnetic field gradient and calculates an updated magnetic field direction indicator. Calibrated magnetic field strength is used to estimate the distance from the antenna to the receiver. This method, based on an idealized model, suffers from poor noise suppression and low positioning reliability, making it difficult to use for communication and positioning at great depths underground. In 2002, Digital Control Inc. (DCI) of the United States granted a patent for a flux plane in an underground drilling system (patent number: US6496008B1), which proposed a method for rapidly locating the position and attitude of an underground magnetic field transmitting antenna. This method uses the zero point of the magnetic field component of a magnetic dipole in the horizontal plane as the first and second positioning points, then estimates the relative distance from the current measurement point to the underground antenna based on the rate of change of the vertical component of the magnetic field. Based on the horizontally symmetrical distribution characteristics of the magnetic field, a positioning line is constructed as the positioning point, providing intuitive and visual positioning guidance for operators. However, this method has problems such as poor positioning timeliness and a high positioning signal-to-noise ratio threshold. Huangshan Jindi Electronics Co., Ltd. in China has developed a series of patented magnetic communication positioning technologies for trenchless directional drilling, including a broadband underground transmitter (CN202311633889), a guidance method for a trenchless directional drilling instrument (CN201610585864), and a method for determining measurement points for a trenchless directional drilling instrument (CN201610585892). These products generate a magnetic field using a carbon rod installed in the drill pipe. The carbon rod consists of a multi-path, multi-turn coil wound around a magnetic rod. On the ground, two vertically arranged three-axis orthogonal gradient coils serve as ground receiving antennas.This patent is based on the positioning method proposed in patent US6496008B1, introducing an asymmetric magnetic field to improve positioning efficiency and accuracy, and adopting modulation methods such as FSK, PSK or AM for communication. However, there are still problems such as low positioning efficiency, shallow penetration depth of communication due to antenna efficiency, and slow communication rate.

[0003] The existing mature ground-penetrating communication and positioning technology is mainly used for trenchless directional drilling. Due to the limitations of the application scenarios, it has bottlenecks such as shallow ground penetration depth, low communication rate, and slow positioning efficiency, making it difficult to use for real-time communication and positioning between underground and ground personnel. Summary of the Invention

[0004] To this end, the present invention provides a geomagnetic communication positioning system and method to solve the problems of existing geomagnetic communication antennas, such as large size, high energy consumption, weak penetration of steel bars, and lack of positioning function, which lead to limited application scenarios and poor flexibility.

[0005] According to the design scheme provided by the present invention, on the one hand, a geomagnetic communication positioning system is provided, including: a transmitting antenna, a receiving antenna, a signal transmitting end control circuit connected to the transmitting antenna, and a signal receiving end control circuit connected to the receiving antenna. The transmitting antenna and the receiving antenna transmit data through static magnetic field coupling. The transmitting antenna includes: a magnetic core, and N transmitting coils wound in parallel on the magnetic core, N is greater than 1, and the length and number of turns of each transmitting coil are the same; the receiving antenna includes: a plurality of hollow coils, and the plurality of hollow coils are arranged in an orthogonal three-axis structure, and the number of turns, cross-sectional area and cable model of each hollow coil are the same.

[0006] As the geomagnetic communication positioning system of the present invention, further, the N transmitting coils are independently divided into equally spaced areas and wound in parallel on the magnetic core.

[0007] As the geomagnetic communication positioning system of the present invention, further, the N transmitting coils are wound alternately in parallel on the magnetic core.

[0008] As the geomagnetic communication positioning system of the present invention, further, the magnetic core adopts a magnetic core structure of MnZn ferrite, and the diameter of the magnetic core is greater than 20 mm.

[0009] As the geomagnetic communication positioning system of the present invention, further, the several hollow coils have: X-direction hollow coils arranged in the X-axis direction, Y-direction hollow coils arranged in the Y-axis direction and Z-direction hollow coils arranged in the Z-axis direction, and the X-direction hollow coils, Y-direction hollow coils and Z-direction hollow coils are concentrically installed or distributedly installed.

[0010] As the geomagnetic communication positioning system of the present invention, further, the X-direction hollow coils, the Y-direction hollow coils and the Z-direction hollow coils are all arranged in pairs with a differential output structure, and the centers of each pair of hollow coils are aligned.

[0011] As the geomagnetic communication positioning system of the present invention, further, the signal transmitting end control circuit includes a signal acquisition circuit, a phase modulation circuit and a signal encoding circuit; the signal receiving end control circuit includes a signal tuning circuit, a signal gain circuit and a signal demodulation circuit.

[0012] As the geomagnetic communication positioning system of the present invention, further, the signal transmitting end control circuit also includes: an H-bridge driving circuit, which modulates the output of the signal encoding circuit into a square wave signal through a phase modulation circuit and then loads it onto the transmitting antenna using the H-bridge driving circuit; a signal tuning circuit is used to switch the capacitor using a switching element to control different capacitors to be connected to the antenna to form a parallel resonant circuit and adjust the coil resonant frequency.

[0013] In another aspect, the present invention further provides a through-the-earth magnetic communication positioning method for achieving communication and / or positioning between a ground through-the-earth communication device and an underground through-the-earth communication device. The ground through-the-earth communication device and the underground through-the-earth communication device serve as the communicating parties, both of which are equipped with the above-mentioned through-the-earth magnetic communication positioning system. The communication and / or positioning implementation process includes the following:

[0014] Set the geomagnetic communication working mode, and one party uses its own device's transmitting antenna to transmit the information to be communicated to the receiving antenna of the other party;

[0015] If the working mode is the communication mode, the receiving antenna of the other party of communication processes the received magnetic field signal using the signal receiving end control circuit to obtain the information content sent by the communicating party;

[0016] If the working mode is positioning mode, the other party of communication uses the received magnetic field signal parameters and the agreed pilot sequence to estimate the relative positions of the two communicating parties.

[0017] The geomagnetic communication positioning method of the present invention further utilizes the received magnetic field signal parameters and an agreed pilot sequence to estimate the relative positions of the communicating parties, including:

[0018] The received magnetic field signal and the agreed pilot sequence are used to estimate the magnetic field strength and magnetic field direction of the signal transmitted by the communicating party, and the relative distance and position relationship between the communicating parties are obtained based on the magnetic field strength and magnetic field direction.

[0019] Beneficial effects of the present invention:

[0020] Based on improved transmitting antennas and receiving antennas, the present invention can realize the miniaturization of through-the-earth magnetic induction communication and positioning equipment, and cooperate with the efficient waveform design method to provide important support for the portable application of the equipment. It can penetrate various media such as seawater, reinforced concrete, sand and gravel, coal seams, and demonstrations, and has broad application prospects. It can be used for wireless communication and positioning between "underground and ground", and a regional magnetic induction field can be constructed underground. The magnetic induction field can penetrate the internal buildings and covering layers in the underground space, making the underground a "transparent" space, providing reliable wireless communication and position perception means for people in the underground space; it can be used for wireless networking communication in the completely buried environment of coal mine goafs, and to build a wireless fire monitoring network in the goafs. The combination of this solution and existing temperature and gas monitoring modules can solve the problem of real-time fire monitoring in existing coal mine goafs; it can be used for underwater scenarios such as wireless networking communication between underwater UUV formations, information exchange between underwater wireless sensor networks, and "underwater-surface" cross-media communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the principle architecture of the geomagnetic communication positioning system in the embodiment;

[0022] Figure 2 This is a schematic diagram of the transmitting antenna structure in the embodiment;

[0023] Figure 3 This is a schematic diagram of the transmitting antenna structure of the independent parallel winding structure in the embodiment;

[0024] Figure 4 Schematic diagram of the transmitting antenna structure with an interlaced winding structure in the embodiment;

[0025] Figure 5 Schematic diagram of a receiving antenna with an orthogonal three-axis structure in an embodiment;

[0026] Figure 6 Schematic diagram of a differential gradient receiving antenna with an orthogonal three-axis structure in an embodiment;

[0027] Figure 7 Schematic diagram of the adaptive tuning circuit in the embodiment;

[0028] Figure 8 Schematic diagram of the measured performance curves at different resonant frequencies in the embodiment;

[0029] Figure 9 Schematic diagram of the H-bridge driving circuit in the embodiment;

[0030] Figure 10 Schematic diagram of the PWM waveform of the numbers 0 and 1 in the embodiment;

[0031] Figure 11 This is a schematic diagram of waveform modulation in the embodiment;

[0032] Figure 12 This is a waveform diagram of the actual measurement of binary 1 converted to 0 in the embodiment;

[0033] Figure 13 Schematic diagram of the comparison of the waveforms of the voltage signal and current signal measured at both ends of the transmitting antenna in the embodiment;

[0034] Figure 14 This is a schematic diagram of the underground space communication and positioning scenario in the embodiment;

[0035] Figure 15 The figure is a schematic diagram of the underground space communication positioning workflow in the embodiment. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below with reference to the accompanying drawings and technical solutions.

[0037] To meet the urgent need for real-time communication and positioning between personnel or equipment in "underground-to-ground" and "underground-to-underground" scenarios, and to address the problems of shallow penetration depth and poor positioning accuracy in existing geomagnetic communication positioning technology, an embodiment of the present invention provides a geomagnetic communication positioning system, comprising: a transmitting antenna, a receiving antenna, a signal transmitting end control circuit connected to the transmitting antenna, and a signal receiving end control circuit connected to the receiving antenna. The transmitting antenna and the receiving antenna transmit data through static magnetic field coupling. The transmitting antenna comprises: a magnetic core, and N transmitting coils wound in parallel on the magnetic core, where N is greater than 1, and each transmitting coil has the same length and number of turns. The receiving antenna comprises: a plurality of hollow coils, and the plurality of hollow coils are arranged in an orthogonal three-axis structure, and each hollow coil has the same number of turns, cross-sectional area, and cable model.

[0038] like Figure 1 As shown in the figure, the system adopts an integrated transmitting and receiving structure and uses a separate transmitting and receiving antenna. The transmitting part is composed of a miniaturized transmitting magnetic antenna and its connected driving circuit, signal modulation circuit, source and channel coding circuit and control interface circuit, etc. Its function is to send the information to be sent by the terminal through the antenna; the receiving part is mainly composed of a miniature omnidirectional receiving antenna and its connected adaptive tuning circuit, amplification and filtering circuit, data acquisition and adaptive gain control circuit and demodulation and decoding, positioning and control communication circuit, etc., which is used to convert the induced magnetic field signal into information and send it to the terminal device for processing.

[0039] The antenna is the front-end module of the system, including an original miniaturized transmitting antenna and a broadband, omnidirectional, high-sensitivity gradient receiving antenna. The transmitting antenna is used to convert the current carrying information into a spatial induced magnetic field, and the receiving antenna is used to induce the spatial electromagnetic field into a current signal.

[0040] In order to overcome the bottleneck problems of existing large-diameter hollow transmitting magnetic antennas such as large size and complex structure, this embodiment, based on the theoretical model of magnetic antennas, designs a parallel multi-coil transmitting magnetic antenna based on densely wound magnetic cores through the design of high magnetic permeability and large aspect ratio magnetic core structure and the optimization of distributed array coil parameters. This greatly reduces the antenna size without reducing the antenna performance. Figure 2 As shown, it consists of a magnetic core and a coil wound on it, d f is the core diameter, l f is the core length.

[0041] In order to ensure strong ground penetration, the communication frequency generally does not exceed 100kHz. When designing the antenna, materials with good low-frequency response performance, high magnetic permeability, and good temperature characteristics are often selected. In the embodiment of this case, MnZn ferrite materials such as CH5K, CH7K, etc. are selected as the magnetic core, and the magnetic permeability of the material is often above 5000. Due to the limited length of the cylindrical magnetic core, it is equivalent to a magnetic circuit with an air gap being affected by a demagnetization field. Its effective magnetic permeability is less than the material magnetic permeability and only depends on the overall physical size of the coil and the magnetic core. When the material magnetic permeability is large (often greater than 1000), its effective magnetic permeability μ c The calculation formula can be approximately expressed as:

[0042] μ c =1 / N d

[0043] Where, m is the ratio of the core length to diameter. When a core material with a magnetic permeability of 5000 is used and the ratio of the core length to diameter is greater than 10, the effective magnetic permeability μ of the core is c It can be more than 30. The cross-sectional area of ​​the magnetic core determines the maximum diameter of the antenna. On the basis of ensuring that the aspect ratio meets the high effective magnetic permeability, the cross-sectional area of ​​the magnetic core should also be increased to improve the magnetic moment of the transmitting magnetic antenna. In the embodiment of this case, a magnetic core with a diameter greater than 20 mm is selected.

[0044] The N transmitting coils can be independently divided into equally spaced areas and wound in parallel on the magnetic core, or wound in parallel and alternately on the magnetic core.

[0045] The internal magnetic moment of the antenna represents the strongest magnetic field that the antenna can sense. Its calculation formula is M=NIA, where N is the number of coil turns, I is the current passing through the coil, and A is the cross-sectional area of ​​the coil. It can be seen that methods to increase the magnetic moment include increasing the number of turns, increasing the current, or increasing the cross-sectional area of ​​the coil. Among them, the inductance calculation formula is:

[0046]

[0047] It can be seen that the inductance is proportional to the square of the number of coil turns N, but when the total driving power is constant, the current I flowing through the antenna is inversely proportional to the inductance L, that is, inversely proportional to the square of the number of turns N and the cross-sectional area A. As mentioned above, the three parameters N, I, and A are interrelated, and it is difficult to increase the antenna magnetic moment by directly optimizing a single parameter. To improve antenna efficiency, the independent parallel or overlapping parallel antenna winding scheme in this embodiment is as follows Figure 3 、 Figure 4 As shown in Figure 2, the number of coil turns is increased while the total current is increased. Figure 3 In the circuit, coils 1 to N are wound in parallel independently, with no overlap between the coils. Both ends of each coil are directly connected to the drive circuit. All coils have the same number of turns and length to ensure the consistency of the electrical parameters of each coil and thus achieve phase consistency of the current signal of each coil to obtain the best magnetic field synthesis effect. Figure 4 The institute uses an interleaved winding method, with multiple coils alternately wound around the core. This method offers the advantage of ensuring optimal effective magnetic permeability compared to independent parallel winding. Coils can be wound using a variety of cables, including single-core enameled wire and multi-strand field wire, depending on the communication frequency.

[0048] In this solution, the multiple air-core coils in the receiving antenna can be designed to include: X-direction air-core coils arranged in the X-axis direction, Y-direction air-core coils arranged in the Y-axis direction, and Z-direction air-core coils arranged in the Z-axis direction. The X-direction air-core coils, Y-direction air-core coils, and Z-direction air-core coils can be installed concentrically or in a distributed manner. Furthermore, the X-direction air-core coils, Y-direction air-core coils, and Z-direction air-core coils can be arranged in pairs for differential output, with the centers of each pair of air-core coils aligned.

[0049] The design principle of the receiving magnetic antenna is to ensure that the antenna has a large receiving bandwidth, stable amplitude-frequency response, high receiving sensitivity and reliable omnidirectional receiving capability. In view of the strong directionality of the magnetic field signal, the receiving antenna in this embodiment adopts an orthogonal three-axis hollow coil structure to ensure that the antenna can reliably receive the magnetic field signal in any posture. Figure 5 The receiving magnetic antenna with orthogonal three-axis structure is given. Figure 6 What is given is a differential gradient receiving magnetic antenna with an orthogonal three-axis structure. Figure 5 As shown, the receiving antenna consists of mutually perpendicular hollow coils, designated as the X, Y, and Z axes. These three coils are often mounted concentrically or in a distributed configuration. Parameters such as the winding method, cable, number of turns, and cross-sectional area remain consistent across the three coils. The coils can be square, circular, or other shapes. To reduce the distributed capacitance of the coils, single- or double-layer dense winding is often used, typically with no more than three layers. The outer layer of the coil is often covered with a thin metal layer such as copper or aluminum to isolate high-frequency electromagnetic signals from the air.

[0050] Figure 6 The receiving coil of the differential gradient structure is given, and Figure 5 Each axis is composed of centrally aligned hollow coils. The antenna consists of three pairs of orthogonal coils, totaling six coils. The differential coils effectively eliminate common-mode interference and suppress slowly varying interference signals such as geomagnetic fields. Each pair of coils is installed in opposite directions to ensure differential output. All coils use the same winding method and can be installed on an orthogonal non-metallic frame or non-metallic hexahedron. The outer layer is wrapped with non-ferromagnetic metal materials such as copper, tin, or aluminum to isolate high-frequency electromagnetic interference.

[0051] To achieve the transmission and reception of magnetic induction signals, in this embodiment, the signal transmitter control circuit includes a signal acquisition circuit, a phase modulation circuit, and a signal encoding circuit; the signal receiver control circuit includes a signal tuning circuit, a signal gain circuit, and a signal demodulation circuit. The signal transmitter control circuit also includes an H-bridge drive circuit, which modulates the output of the signal encoding circuit into a square wave signal via a phase modulation circuit and then applies it to the transmitting antenna via the H-bridge drive circuit; and a signal tuning circuit, which uses a switching element to switch capacitors to control the connection of different capacitors with the antenna to form a parallel resonant circuit and adjust the coil resonant frequency.

[0052] To improve the receiving antenna gain, an antenna tuning circuit is designed to adjust the coil resonant frequency. Since the system operates in a wideband, an adaptive tuning circuit needs to be designed to meet the needs of different operating frequencies. Assuming that the antenna is a pure inductive device with an inductance of L C , the internal resistance is R0, and the distributed capacitance parameters of the antenna are not considered. In this embodiment, the signal tuning circuit adopts an adaptive receiving tuning circuit, specifically as follows Figure 7 As shown in the figure, the dotted box on the left is the equivalent circuit of the receiving magnetic antenna, and the middle capacitors C1~C N In order to select different capacitors according to different frequencies, S is a switch that switches through the electrical signal C to control different capacitor parameters and the antenna connection to form a parallel resonant circuit. The dotted box on the right side of the figure represents the input impedance of the back-end amplification circuit, which often uses an instrument integrated operational amplifier with an input impedance greater than 1MΩ.

[0053] Figure 8 The test results of the system response at resonant frequencies of 4kHz and 26.5kHz using a low-frequency scalar network analyzer are given. From the figure, we can see that the significant bandpass filtering characteristics have a higher receiving gain only at the resonance point, while showing strong attenuation characteristics in the low-frequency and high-frequency parts. While improving the receiving gain of the desired signal, it also greatly suppresses the out-of-band interference signal. Its 3dB bandwidth is not less than 2kHz.

[0054] Magnetic field conversion efficiency is the core of the transmitting circuit design. As mentioned above, the inductance of the transmitting antenna is often in the order of mH. When operating at a frequency of tens of kHz, its AC impedance will be greater than tens of ohms. If a linear audio drive solution, such as a Class D amplifier, is adopted, a huge static loss will be generated. Considering that the scenarios involved in through-the-ground communication do not require high communication rates, in the embodiment of this case, a pulse width modulation method is introduced to modulate the information to be sent into a square wave signal with different initial phases and a fixed duty cycle, which is sent to the H-bridge chip through the chip IO pin and then loaded onto the transmitting magnetic antenna. The signal is sensed into space in the form of a triangular wave using the antenna's own integral effect. The specific signal connection structure is as follows: Figure 9 As shown in the figure, the processor outputs the PWM signal in differential form through any two digital IO ports IO_1 and IO_2, and the signal is sent to the transmitting magnetic antenna through the intermediate H-bridge drive circuit module.

[0055] Taking BPSK modulation as an example, Figure 10 The PWM waveforms corresponding to the numbers 0 and 1 are given. As shown in the figure, 0 and 1 are only in anti-phase relationship, and the other parameters are the same. The square wave frequency in the figure is the modulation frequency of the signal. A square wave with a fixed duty cycle is often used. The use of a duty cycle waveform greatly improves the circuit conversion efficiency. Figure 11 The modulation waveform of the binary sequence 0011 is given. It can be seen that there is no need to invert the initial phase when the binary 00 and 11 transition, but the PWM waveform needs to be inverted when the binary 01 transition. Figure 12 The figure shows the change in the measured signal waveform when the information is converted from binary 1 to binary 0. It can be seen that the phase of the PWM waveform is reversed at the moment of conversion.

[0056] Figure 13 The waveform comparison of the voltage and current signals at both ends of the actual transmitting magnetic antenna is given. It can be seen that the square wave signal is converted into a current signal in the form of a triangular wave after passing through the antenna through integration, that is, the transmitting magnetic antenna will induce a magnetic field signal in the form of a triangular wave.

[0057] Furthermore, based on the above-mentioned system, an embodiment of the present invention further provides a through-the-earth magnetic communication positioning method for implementing communication and / or positioning between a ground through-the-earth communication device and an underground through-the-earth communication device. The ground through-the-earth communication device and the underground through-the-earth communication device serve as the communicating parties, both of which are deployed with the above-mentioned through-the-earth magnetic communication positioning system. The communication and / or positioning implementation process includes the following contents:

[0058] Set the geomagnetic communication working mode, and one party uses its own device's transmitting antenna to transmit the information to be communicated to the receiving antenna of the other party;

[0059] If the working mode is the communication mode, the receiving antenna of the other party of communication processes the received magnetic field signal using the signal receiving end control circuit to obtain the information content sent by the communicating party;

[0060] If the working mode is positioning mode, the other party of communication uses the received magnetic field signal parameters and the agreed pilot sequence to estimate the relative positions of the two communicating parties.

[0061] Specifically, the received magnetic field signal and the agreed pilot sequence can be used to estimate the magnetic field strength and magnetic field direction of the signal transmitted by the communicating party, and the relative distance and position relationship between the communicating parties can be obtained based on the magnetic field strength and magnetic field direction.

[0062] like Figure 14 As shown in the figure, a ground-based person operating a through-the-ground communication and positioning device communicates with another person operating an underground space-based person to determine the relative direction and position coordinates between the two. The specific communication and positioning process can be described as follows:

[0063] 1. Through-the-ground communication equipment relies on the spatial magnetic lines of force generated by the transmitting magnetic antenna to penetrate the ground composed of media such as soil, reinforced concrete, or sand and gravel into underground spaces such as tunnels and pits, and transmit all transmitted information to the underground through-the-ground communication equipment's omnidirectional magnetic receiving antenna;

[0064] 2. The omnidirectional magnetic receiving antenna located in the underground space receives the magnetic field signal. The X, Y, and Z axis three-channel signals received by the omnidirectional receiving antenna are amplified, filtered, and A / D converted before being combined and processed. The synchronization, demodulation, and decoding modules then retrieve the information sent from the ground.

[0065] 3. The underground receiving module estimates the ground-transmitted magnetic field signal strength, magnetic field direction and other parameters based on the signal sent from the ground, combined with the agreed pilot sequence and other prior information. It also estimates the distance and relative position of the underground communication device relative to the ground device, thereby achieving positioning.

[0066] 4. Ground personnel also upload information wirelessly to the ground through through-the-ground communication equipment.

[0067] like Figure 15As shown in the figure, after the system is started, it is first necessary to set the operating frequency according to the current application scenario (for example, to penetrate non-metallic media such as soil and gravel, a higher communication frequency such as 40kHz can be used; if it is to penetrate ferromagnetic metal materials such as reinforced concrete, a lower frequency such as 4kHz should be selected); then calibrate the distance parameters to support subsequent positioning solutions. The purpose of real-time distance calibration is to eliminate errors caused by system aging, environmental factors and other factors; then set up the system, that is, determine whether positioning or communication is to be performed (if necessary, they can be performed simultaneously). If communication is to be performed, the information is first sent, and then the response is received after waiting for the other party, and then synchronous demodulation and decoding are performed to obtain the information content sent by the other party; if positioning is to be performed, the relative position relationship between the transmitted and received signals is inverted based on the three received magnetic field components, and the distance is estimated based on the magnetic field strength, thereby achieving positioning.

[0068] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0070] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation is not considered to be beyond the scope of the present invention.

[0071] Those skilled in the art will appreciate that all or part of the steps in the above method can be performed by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps in the above embodiment can be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or software functional modules. The present invention is not limited to any specific combination of hardware and software.

[0072] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A geomagnetic communication positioning system, characterized in that: include: A transmitting antenna, a receiving antenna, a signal transmitting end control circuit connected to the transmitting antenna, and a signal receiving end control circuit connected to the receiving antenna. The transmitting antenna and the receiving antenna transmit data through static magnetic field coupling. The transmitting antenna includes: a magnetic core, and N transmitting coils wound in parallel on the magnetic core, N is greater than 1, and each transmitting coil has the same length and number of turns; the receiving antenna includes: a plurality of hollow coils, and the plurality of hollow coils are arranged in an orthogonal three-axis structure, and each hollow coil has the same number of turns, cross-sectional area, and cable model; the signal transmitting end control circuit includes a signal acquisition circuit, a phase modulation circuit, and a signal encoding circuit; the signal receiving end control circuit includes a signal tuning circuit, a signal gain circuit, and a signal demodulation circuit. The signal transmitting end control circuit also includes: an H-bridge driving circuit, which modulates the output of the signal encoding circuit into a square wave signal through a phase modulation circuit and then loads it onto the transmitting antenna using the H-bridge driving circuit; a signal tuning circuit is used to switch the capacitors using a switch element to control different capacitors to be connected to the antenna to form a parallel resonant circuit and adjust the coil resonant frequency.

2. The geomagnetic communication positioning system according to claim 1, characterized in that: The N transmitting coils are independently divided into equally spaced areas and wound in parallel on the magnetic core.

3. The geomagnetic communication positioning system according to claim 1, characterized in that: The N transmitting coils are wound alternately in parallel on the magnetic core.

4. The geomagnetic communication positioning system according to claim 1, characterized in that: The magnetic core adopts a magnetic core structure of MnZn ferrite, and the diameter of the magnetic core is greater than 20 mm.

5. The geomagnetic communication positioning system according to claim 1, characterized in that: The plurality of hollow coils include: X-direction hollow coils arranged in the X-axis direction, Y-direction hollow coils arranged in the Y-axis direction and Z-direction hollow coils arranged in the Z-axis direction, and the X-direction hollow coils, Y-direction hollow coils and Z-direction hollow coils are installed concentrically or distributedly.

6. The geomagnetic communication positioning system according to claim 5, characterized in that: The X-direction hollow coils, the Y-direction hollow coils, and the Z-direction hollow coils are all arranged in pairs with a differential output structure, and the centers of each pair of hollow coils are aligned.

7. A through-the-earth magnetic communication positioning method for realizing communication and / or positioning between a ground through-the-earth communication device and an underground through-the-earth communication device, characterized in that: The ground-through-the-earth communication device and the underground-through-the-earth communication device serve as communicating parties, both of which are equipped with the geomagnetic communication and positioning system according to claim 1. The communication and / or positioning implementation process includes the following: setting a geomagnetic communication working mode, wherein one communicating party uses its own device's transmitting antenna to transmit the information to be communicated to the receiving antenna of the other communicating party; If the working mode is the communication mode, the receiving antenna of the other party of communication processes the received magnetic field signal using the signal receiving end control circuit to obtain the information content sent by the communicating party; If the working mode is positioning mode, the other party of communication uses the received magnetic field signal parameters and the agreed pilot sequence to estimate the relative positions of the two communicating parties.

8. The geomagnetic communication positioning method according to claim 7, characterized in that: Using the received magnetic field signal parameters and the agreed pilot sequence to estimate the relative positions of the communicating parties, including: The received magnetic field signal and the agreed pilot sequence are used to estimate the magnetic field strength and magnetic field direction of the signal transmitted by the communicating party, and the relative distance and position relationship between the communicating parties are obtained based on the magnetic field strength and magnetic field direction.

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