Geomagnetic penetration communication positioning system and method

Abstract

The invention relates to the technical field of through-the-earth communication positioning, in particular to a through-the-earth communication positioning system and method, and the system comprises a transmitting antenna, a receiving antenna, a signal transmitting end control circuit connected with the transmitting antenna, and a signal receiving end control circuit connected with the receiving antenna. The transmitting antenna and the receiving antenna perform data transmission through static magnetic field coupling, the transmitting antenna comprises a magnetic core and N transmitting coils wound on the magnetic core in parallel, and the lengths and the winding turns of the transmitting coils are the same; the receiving antenna comprises a plurality of hollow coils, the plurality of hollow coils are arranged in an orthogonal three-axis structure, and the number of winding turns, the sectional area and the cable model of each hollow coil are the same, so that a regional magnetic induction field is constructed underground, and reliable wireless communication and position sensing are provided for personnel in the underground space. According to the invention, miniaturization of the earth-penetrating magnetic induction communication positioning equipment can be realized, and communication positioning can be realized by penetrating various media such as seawater, reinforced concrete, sandstone, coal seams, demonstration and the like.

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 active in underground facilities (bunkers and deeply buried facilities), tunnels (basic and complex), cities and natural caves (civil engineering, sewers, basements and caves), traditional radio waves will be absorbed and shielded by the strata or reinforced concrete buildings, making it difficult for underground personnel or equipment to establish communication with ground personnel; GPS or Beidou signals fail, and their relative position coordinates cannot be determined. Magnetic communication uses the time-varying magnetic field signals generated by coils in space for communication. The magnetic field can penetrate non-ferromagnetic media such as soil, sand, and seawater, and is widely used for underground through-the-earth communication. As early as 1975, a patent named Tunnel Finder Positioning and Communication Equipment (patent number: US3906504) proposed a method for locating and mapping tunnels. A magnetic field transmitting coil is installed in an underground tunnel, and a receiving coil is used on the ground to receive the magnetic field signal emitted underground. The distance between the transmitter and the receiver and their relative angle information are measured by amplitude calculation, which provides a reference for the development of through-the-earth magnetic communication and positioning technology. In 1992, a patent named Position and Direction Locator / Monitor (patent number: US5155442) proposed a technology for underground drill bit posture monitoring and positioning. The single-axis magnetic rod transmitting antenna is installed inside the metal drill rod and slotted on the rod wall, so that the magnetic field can penetrate from underground to the ground. The ground receiving magnetic sensor consists of two vertically placed orthogonal antennas, which are used to continuously measure the magnetic field gradient, update the calculated magnetic field direction indication, and use the calibrated magnetic field strength to estimate the distance from the antenna to the receiver. This method is based on an ideal model, has poor noise suppression ability and low positioning reliability, and is difficult to use for underground deep communication positioning. In 2002, a patent authorized by Digital Control Inc. (DCI) of the United States was located in the flux plane in the underground drilling system (patent number: US6496008B1), which proposed a method for quickly locating the position and attitude of the underground magnetic field transmitting antenna. This method uses the zero point of the magnetic field component of the magnetic dipole in the horizontal plane as the first and second positioning points, and then estimates the relative distance from the current measurement point to the underground antenna through the rate of change of the vertical component of the magnetic field. According to the horizontal symmetrical distribution characteristics of the magnetic field, a positioning line is constructed as the positioning point to provide intuitive and visual positioning guidance for operators. However, this method has problems such as poor positioning timeliness and high positioning signal-to-noise ratio threshold. Huangshan Jindi Electronics Co., Ltd. in China has developed a series of magnetic communication positioning technologies for trenchless directional drilling, such as broadband underground transmitter (CN202311633889), a guiding method for a trenchless guide instrument (CN201610585864), and a method for determining the measuring point of a trenchless guide instrument (CN201610585892). Its products generate magnetic fields through carbon rods installed in drill pipes, which are composed of multi-path multi-turn coils wound on magnetic rods. On the ground, two vertically arranged three-axis orthogonal gradient coils are used 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 using 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 being large in size, high in energy consumption, weak in steel bar penetration and lacking in positioning function, resulting in 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, wherein 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 are wound in parallel on the magnetic core.

[0007] As the geomagnetic communication positioning system of the present invention, further, the N transmitting coils are alternately wound 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 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 cocentrically 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 switch element to control different capacitors to be connected to the antenna into a parallel resonant circuit and adjust the coil resonant frequency.

[0013] On the other hand, the present invention also provides 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, wherein the ground through-the-earth communication device and the underground through-the-earth communication device are both communicating parties, and both are equipped with the above-mentioned through-the-earth magnetic communication positioning system. The communication and / or positioning realization process includes the following contents:

[0014] The geomagnetic communication working mode is set, and one party uses the transmitting antenna of its own device 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 by using the signal receiving end control circuit to obtain the information content sent by the communicating party;

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

[0017] As the geomagnetic communication positioning method of the present invention, further, using the received magnetic field signal parameters and the agreed pilot sequence to estimate the relative positions of the two communicating parties, it includes:

[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 one communicating party, and the relative distance and position relationship between the two communicating parties are obtained based on the magnetic field strength and magnetic field direction.

[0019] Beneficial effects of the present invention:

[0020] The present invention is based on improved transmitting antennas and receiving antennas, and can realize the miniaturization of the through-the-earth magnetic induction communication positioning equipment. In combination with the efficient waveform design method, it provides 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, and providing reliable wireless communication and position perception means for personnel located in the underground space; it can be used for wireless networking communication in a completely buried environment of the goaf of a coal mine, and a wireless fire monitoring network can be constructed in the goaf. The combination of the present solution and the existing temperature and gas monitoring modules can solve the problem of real-time fire monitoring in the goaf of existing coal mines; it can be used for underwater scenes such as wireless networking communication between underwater UUV formations, information interaction between underwater wireless sensor networks, and "underwater-surface" cross-media communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It 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 It is a schematic diagram of the transmitting antenna structure of the independent parallel winding structure in the embodiment;

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

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

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

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

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

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

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

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

[0032] Fig.12 The waveform diagram of the actual measurement of binary 1 converted to 0 in the embodiment;

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

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

[0035] Fig.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 purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and technical solutions.

[0037] In view of the urgent need for real-time communication and positioning between personnel or equipment in "underground-ground" and "underground-underground" scenarios, and in view of the problems of shallow penetration depth and poor positioning accuracy of existing through-the-earth magnetic communication positioning technology, an embodiment of the present invention provides a through-the-earth magnetic communication positioning system, 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, wherein 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.

[0038] like Figure 1 As shown, the system adopts an integrated transceiver structure and uses a separate transceiver antenna, wherein 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., and 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., and 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 induction magnetic field, and the receiving antenna is used to induce the spatial electromagnetic field into a current signal.

[0040] In order to break through the bottleneck problems of existing large-diameter hollow transmitting magnetic antennas, such as large volume 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 size of the antenna 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 are selected as magnetic cores, such as CH5K, CH7K, etc., and the magnetic permeability of the materials is often above 5000. Since the length of the cylindrical magnetic core is limited, it is equivalent to the magnetic circuit with an air gap being affected by the demagnetization field, and its effective magnetic permeability is less than the material magnetic permeability, which 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] In the formula, m is the ratio of the length to diameter of the core. When a core material with a magnetic permeability of 5000 is used and the ratio of the length to diameter of the core 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 higher effective magnetic permeability, the cross-sectional area of ​​the magnetic core should be increased to increase the magnetic moment of the transmitting magnetic antenna. In the implementation example of this case, a magnetic core with a diameter greater than 20 mm is selected.

[0044] Among them, 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 the 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 directly by optimizing one parameter. In order to improve the antenna efficiency, the independent parallel or overlapping parallel antenna winding scheme in this embodiment is as follows Figure 3 , Figure 4 As shown in the figure, 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 achieve the phase consistency of the current signal of each coil, so as to obtain the best magnetic field synthesis effect. Figure 4 In the institute, the staggered winding method is used, and multiple coils are wound alternately on the magnetic core. Compared with independent parallel winding, the advantage is to ensure the best effective magnetic permeability of the magnetic core. The winding coil can be wound with different cables such as single-core enameled wire, multi-strand excitation wire, etc. according to the communication frequency.

[0048] In the present scheme, the several hollow coils in the receiving antenna can be designed to 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 installed concentrically or distributedly. The X-direction hollow coils, Y-direction hollow coils, and Z-direction hollow coils can be further arranged as paired differential output structures, and the centers of each pair of hollow coils are 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 directivity of the magnetic field signal, the receiving antenna in the embodiment of this case adopts an orthogonal three-axis structure of the hollow coil 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 is composed of mutually perpendicular hollow coils, which are respectively recorded as X, Y, and Z axes. The three coils are often installed concentrically or in a distributed manner. The winding method, the cables used for winding, the number of coil turns, the cross-sectional area and other parameters of the three coils are consistent. The coils can be wound in square, circular or other shapes. In order to reduce the distributed capacitance parameters of the coil, a single-layer or double-layer dense winding method is often used, and usually no more than 3 layers. The outer layer of the coil is often covered with thin metals such as copper and aluminum to isolate high-frequency electromagnetic signals in the air.

[0050] Figure 6 The receiving coil of the differential gradient structure is given, and Figure 5 Different, each axis is composed of hollow coils placed in the center, the antenna consists of 3 pairs of orthogonal coils, a total of 6 coils, the differential coil can better eliminate common mode interference and suppress slow-changing interference signals such as geomagnetism. Each pair of coils is installed in reverse to ensure the differential output of the result. All coils are wound with the same parameters and can be installed on a non-metallic skeleton or a non-metallic hexahedron with an orthogonal structure. The outer layer is wrapped with non-ferromagnetic metal materials such as copper, tin or aluminum to isolate high-frequency electromagnetic interference.

[0051] In order to realize the sending and receiving of magnetic induction signals, in the embodiment of this case, 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. Among them, 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; the signal tuning circuit is used to switch the capacitor 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.

[0052] To improve the gain of the receiving antenna, 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. Assume 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 the embodiment of this case, the signal tuning circuit adopts an adaptive receiving tuning circuit, as shown in the following example. 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 an 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, and an instrument integrated operational amplifier is often used, and its input impedance is 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, it can be seen that the significant bandpass filtering characteristics have a higher receiving gain only at the resonance point, and show a strong attenuation characteristic in the low-frequency and high-frequency parts, which greatly suppresses out-of-band interference signals while improving the receiving gain of the desired signal. Its 3dB bandwidth is not less than 2kHz.

[0054] Magnetic field conversion efficiency is the core of 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 integration effect. The specific signal connection structure is as follows: Fig. 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, Fig.10 The PWM waveforms corresponding to digital 0 and digital 1 are given. As shown in the figure, 0 and 1 are only in an inverse relationship, and the other parameters are the same. The square wave frequency in the figure is the modulation frequency of the signal, and a square wave with a fixed duty cycle is often used. The use of a duty cycle waveform greatly improves the circuit conversion efficiency. Fig.11 The modulation waveform of the 0011 binary sequence 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 01 transition. Fig.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] Fig.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] Further, based on the above system, an embodiment of the present invention also provides a through-the-earth magnetic communication positioning method, which is used to realize 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 are the communication parties, and both are deployed with the above-mentioned through-the-earth magnetic communication positioning system. The communication and / or positioning realization process includes the following contents:

[0058] The geomagnetic communication working mode is set, and one party uses the transmitting antenna of its own device 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 by using the signal receiving end control circuit to obtain the information content sent by the communicating party;

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

[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 one communicating party, and the relative distance and position relationship between the two communicating parties can be obtained based on the magnetic field strength and magnetic field direction.

[0062] like Fig.14 As shown, a scene in which a ground personnel operates a through-the-ground communication positioning device to communicate with a through-the-ground communication positioning device operated by a person in an underground space and determine the relative direction and position coordinates between the two. The specific communication positioning process can be described as follows:

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

[0064] 2. The omnidirectional magnetic receiving antenna located in the underground space receives the magnetic field signal. The three-channel signals of X, Y and Z axes received by the omnidirectional receiving antenna are amplified, filtered and A / D converted, and then combined and processed, and then handed over to the synchronization, demodulation and decoding module to obtain the information content sent from the ground;

[0065] 3. The underground receiving module estimates the field strength and magnetic field direction of the ground-transmitted magnetic field signal according to the signal sent from the ground, combined with the agreed pilot sequence and other prior information, and estimates the distance and relative position of the underground communication equipment relative to the ground equipment to achieve positioning;

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

[0067] like Fig.15As shown in the figure, after the system is started, it is necessary to first set the working frequency according to the current application scenario (for example, to penetrate non-metallic media such as soil, sand 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, is used); then calibrate the distance parameters to support the subsequent positioning solution. The purpose of real-time distance calibration is to eliminate errors caused by system aging, environment and other factors; then set up the system, that is, determine whether positioning or communication is to be performed (if necessary, it can be performed at the same time). If communication is required, the information is sent first, and then the other party is received after a response, and synchronous demodulation and decoding are performed to obtain the information content sent by the other party; if positioning is required, the relative position relationship between the transmitted and received signals is inverted according to the three magnetic field components received, and the distance is estimated according to 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] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0070] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. 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 completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk or an optical disk. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of software function modules. The present invention is not limited to any specific form of combination of hardware and software.

[0072] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope 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 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.

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 are 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 in a distributed manner.

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. The geomagnetic communication positioning system according to claim 1, characterized in that: 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.

8. The geomagnetic communication positioning system according to claim 7, characterized in that: 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 switch element to control different capacitors to be connected to the antenna to form a parallel resonant circuit and adjust the coil resonant frequency.

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

10. The method for positioning by geomagnetic communication according to claim 9, characterized in that: The relative positions of the two communicating parties are estimated by using the received magnetic field signal parameters and the agreed pilot sequence, 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 one communicating party, and the relative distance and position relationship between the two communicating parties are obtained based on the magnetic field strength and magnetic field direction.

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