Fully buried space magnetoelectric near-field coupling type wireless penetration communication system and communication establishment method

Abstract

The present invention belongs to the technical field of through-earth communication, and particularly relates to a fully buried space magnetoelectric near-field coupling type wireless penetration communication system and a communication establishment method. The system includes: a signal transmission module, and a signal reception module that interacts with the signal transmission module. The signal transmission module includes: a transmitter, and a magnetic induction transmission antenna connected to the transmitter for generating and transmitting a preset carrier frequency electromagnetic signal. The signal reception module includes: a receiver, and a magnetic induction reception antenna connected to the receiver for receiving a preset carrier frequency electromagnetic signal. The magnetic induction transmission antenna and the magnetic induction reception antenna both include an insulating housing and a coil disposed on the insulating housing and electrically insulated from the surrounding medium. And a coupled dipole antenna that is non-contact connected to the magnetic induction transmission antenna and the magnetic induction reception antenna is also provided between the magnetic induction transmission antenna and the magnetic induction reception antenna. The present invention realizes wireless communication under extreme conditions of a fully buried space such as underwater or underground by using the magnetoelectric near-field coupling method, which is convenient to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of through-earth communication, and particularly relates to a fully buried space magnetoelectric near-field coupling type wireless penetration communication system and a communication establishment method. Background Art

[0002] Wireless communication can perform long-distance transmission without the need for conductors or cables between multiple nodes. Although we can already communicate with the "Zhu Rong" Mars rover hundreds of millions of kilometers away via radio, wireless communication in environments such as tens of meters to several kilometers underground or underwater is still an area that traditional wireless communication has difficulty reaching, and has become a bottleneck restricting the development of the country's deep-earth and deep-sea strategic industries. During the coal mining process, with the wide application of the fully mechanized caving technology, the scope of the gob area in coal mines has expanded and the thickness of the remaining coal has increased, resulting in an increasing risk of spontaneous fires in the gob area, posing a serious threat to personnel safety and production safety. Effectively and quickly monitoring and preventing gob area fires in coal mines has become an important issue related to coal production safety and even social and economic development. Taking effective monitoring and forecasting measures to accurately find high-temperature fire sources and eliminate potential spontaneous fire hazards is the top priority for coal safety production in China.

[0003] The prevention technology for high-temperature points in the gob area of coal mines based on the temperature method is the mainstream means for gob area fire control. Traditional wired installation forms have problems such as a large number of lines, high costs, high safety risks, and the entire network will be paralyzed once a local line is broken, and thus cannot be widely promoted and applied on a large scale. Networking the temperature acquisition nodes in the gob area through wireless communication will be the most promising method. However, due to the special environment in the gob area, communication nodes will be buried by conductive media such as fallen coal blocks, coal gangue, sandstone, and even groundwater (with a thickness of 5 - 10 meters and a very small gap between the upper sandstone), which poses a great challenge to the design of wireless communication systems. Once buried by a medium with high conductivity, traditional electromagnetic wave communication will face difficulties such as a sharp decrease in the radiation efficiency of the antenna, a sharp increase in path loss, and difficulty in modeling, making it difficult to communicate successfully. If the communication frequency is reduced, the antenna size needs to be increased, which cannot be used in the narrow environment of the gob area.

[0004] Regarding the above-mentioned wireless communication problems in gob areas, domestic and foreign research has focused on theoretical research such as path loss modeling, optimization of node deployment methods, and coverage models of wireless sensor networks. There are few reports on product applications. Russian relevant institutions have studied the problem of through-earth communication between roadways in deep wells, and discussed the electromagnetic environment modeling methods in different geological environments and their influence on electromagnetic wave propagation. Through different tests, it is concluded that the optimal communication frequency is 0.1 - 1.0Mhz, but the antenna size is about 50 meters in length. Magnetic induction communication is a technology recently proposed and can be used for through-earth communication. The research group led by IF Akyildiz at the Georgia Institute of Technology in the United States is one of the earliest teams to start researching magnetic induction communication and has done a lot of fruitful work in magnetic induction communication. This research group has done a lot of work in aspects such as channel characteristics, communication models, system capacity, and experimental analysis of underground magnetic induction communication, and has achieved certain results in fields such as wireless sensor networking for underground oil extraction and underwater communication. In 2017, the doctoral thesis of Niaz Ahmed from the University of Missouri detailedly studied the underwater magnetic induction communication system and its application scheme in underwater wireless sensor networks, analyzed the theoretical model of underwater magnetic induction communication, analyzed the influence of different sensor structures on communication stability and system power consumption, and conducted a low-power and low-cost magnetic induction communication networking experiment at a distance of 40 meters, achieving good results; however, the magnetic field energy decays with the sixth power of distance. If you want to increase the communication distance, you need to increase the transmission power or increase the antenna size by a factor of the sixth power. This determines that magnetic induction communication technology is difficult to be used for wireless communication in gob areas. Summary of the Invention

[0005] Therefore, the present invention provides a completely buried space magnetoelectric near-field coupling type wireless penetration communication system and a communication establishment method, which use the magnetoelectric near-field coupling method to realize wireless communication under extreme conditions of completely buried spaces such as underwater or underground, and solve problems such as wireless communication applications under the buried conditions of coal mine gob areas or horizontal distances of hundreds of meters underwater in the deep sea.

[0006] According to the design solution provided by the present invention, a fully buried space magnetoelectric near-field coupled wireless penetration communication system is provided, comprising: a signal transmission module, and a signal reception module interacting with the signal transmission module. The signal transmission module comprises: a transmitter, and a magnetic induction transmitting antenna connected to the transmitter for generating and transmitting a preset carrier frequency electromagnetic signal. The signal reception module comprises: a receiver, and a magnetic induction receiving antenna connected to the receiver for receiving the preset carrier frequency electromagnetic signal. The magnetic induction transmitting antenna and the magnetic induction receiving antenna both comprise an insulating housing and a coil disposed on the insulating housing and electrically insulated from the surrounding medium. And a coupled dipole antenna non-contact connected to the magnetic induction transmitting antenna and the magnetic induction contact antenna is further disposed between the magnetic induction transmitting antenna and the magnetic induction receiving antenna to perform near-field communication by using the characteristic that the relative magnetic permeability of the conductive medium of the fully buried space buried layer is 1.

[0007] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, the magnetic induction receiving antenna coil adopts a magnetic rod coil wound around a cylindrical magnetic rod and / or a hollow coil wound around an insulating housing.

[0008] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, feeding points for adjusting the optimal communication frequency and connected to the transmitter tuning circuit are provided at both ends of the coils of the magnetic induction transmitting antenna and the magnetic induction receiving antenna, and the feeding points are electrically insulated from the surrounding medium.

[0009] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, the coupled dipole antenna adopts armored cable.

[0010] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, one end of the coupled dipole antenna penetrates through the magnetic induction transmitting antenna coil, and the other end is placed on one side of the magnetic induction receiving antenna.

[0011] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, one end of the coupled dipole antenna is bent into a circular single-loop structure inside the magnetic induction transmitting antenna coil, and the end of the coupled dipole antenna with the circular single-loop structure is parallel to the axis of the magnetic induction transmitting antenna.

[0012] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, when the coupled dipole antenna is located on the magnetic induction receiving side, the minimum distance between the two is 5 cm and the maximum distance is 30 cm, or the dipole antenna passes through the inside of the magnetic induction receiving antenna.

[0013] As the fully buried space magnetoelectric near-field coupled wireless penetration communication system in the present invention, further, the minimum distance between the magnetic induction transmitting antenna and the magnetic induction receiving antenna is 5 m, and the maximum distance is 200 m.

[0014] Further, the present invention also provides a method for establishing a fully buried space magnetoelectric near-field coupled wireless penetration communication, which is implemented based on the above system. The method includes the following contents:

[0015] Set the parameters of the magnetic induction transmitting antenna according to the operating frequency. The parameters of the magnetic induction transmitting antenna include at least one of the following: coil winding, magnetic rod wire diameter, number of coil turns, and coil turn spacing;

[0016] Lay a signal sending module, a signal receiving module, and a coupled dipole antenna in the buried layer of the fully buried space;

[0017] Couple the induced electric field emitted by the magnetic induction transmitting antenna of the signal sending module through the coupled dipole antenna and induce a magnetic field in the vicinity, and use the magnetic induction receiving coil of the signal receiving module to receive the near-field signal of the coupled dipole antenna to establish communication between the signal sending module and the signal receiving module.

[0018] As the method for establishing a fully buried space magnetoelectric near-field coupled wireless penetration communication in the present invention, further, the operating frequencies of the transmitter and the receiver are configured to be 300 kHz to 30 MHz.

[0019] Advantages of the present invention:

[0020] In view of the problems that traditional low-frequency radio communication requires the installation of huge antennas and cannot be used in goaf environments, and that magnetic induction communication technology has a rapid signal energy attenuation with distance and is difficult to achieve long-distance communication under low power conditions, etc., by integrating magnetic induction and electric dipole near-field communication technologies, problems such as large attenuation of magnetic induction communication with distance and large size of low-frequency electromagnetic wave communication antennas are overcome, enabling wireless communication in extreme environments such as completely buried underground and underwater. It can fundamentally solve the problem of impossible long-distance wireless communication due to the complete burial of transceiver antennas, low antenna radiation efficiency, and serious absorption of electromagnetic waves by surrounding media. The characteristics that the relative magnetic permeability of conductive media such as sand, soil, and coal in a completely buried space is 1 can be utilized to ensure a high magnetoelectric conversion efficiency under burial conditions, overcoming the problem of low efficiency caused by the increase in radiation impedance when the electric antenna is buried. Using low-cost and high-strength cables as dipole antennas, the induced electric field of the non-contact coupling transmitting coil is used to induce a magnetic field in the surrounding area, which has strong anti-destruction and penetration capabilities. Based on the highly sensitive and low-cost wireless receiving antenna of the coil rod, the near-field signal of the dipole antenna is received under non-contact conditions, and the receiving performance is not affected by the surrounding high-conductivity media, facilitating the implementation of an adaptive pilot estimation and correction scheme, which can correct the carrier frequency drift caused by clock drift to improve communication stability. Further verified through actual scenarios, the solution of this case can achieve point-to-point wireless communication at a distance of 200 meters in the horizontal direction with an energy consumption of less than 100 mW under completely buried conditions such as goafs, and the node volume of the system equipment can be no larger than 800 cm 3 and the communication rate is not less than 200 bit / s, facilitating deployment in application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a magnetoelectric near-field coupled wireless penetration communication system in a completely buried space in the embodiment;

[0022] Figure 2 Schematic diagram of the connection of magnetic induction antennas of a magnetoelectric near-field coupled wireless penetration communication system in a completely buried space in the embodiment;

[0023] Figure 3 Schematic diagram of the magnetoelectric near-field coupling principle in the embodiment;

[0024] Figure 4 Schematic diagram of the current density distribution of three adjacent round wires in the embodiment;

[0025] Figure 5 Schematic diagram of the distributed capacitance model of a single-layer coil in the embodiment;

[0026] Figure 6 Schematic diagram of the magnetic flux density modulus diagram in the embodiment;

[0027] Figure 7Schematic diagram of the electric field density modulus in the embodiment;

[0028] Figure 8 Schematic diagram of the tuning network of the transmitting antenna in the embodiment;

[0029] Figure 9 Schematic diagram of the standing wave ratio of the transmitting antenna after tuning in the embodiment;

[0030] Figure 10 Schematic diagram of the tuning network of the receiving antenna in the embodiment;

[0031] Figure 11 Schematic diagram of the demodulation principle of the receiver in the embodiment;

[0032] Figure 12 Schematic diagram of the underwater test scenario in the embodiment;

[0033] Figure 13 Schematic diagram of the time-domain waveform of the underwater received signal in the embodiment;

[0034] Figure 14 Schematic diagram of the spectrogram of the underwater received signal in the embodiment;

[0035] Figure 15 Schematic diagram of the demodulation output information of the receiver in the embodiment. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and technical solutions.

[0037] To meet the urgent need for building a wireless temperature monitoring network in the goaf of the underground mine, in view of the problems that the traditional low-frequency radio communication requires installing antennas with huge sizes and cannot be used in the goaf environment, and the signal energy of the magnetic induction communication technology decays rapidly with distance and it is difficult to achieve long-distance communication under low power conditions, etc., the embodiments of the present invention are shown in Figure 1As shown in the figure, a fully buried space magnetoelectric near-field coupled wireless penetration communication system is provided, which includes: a signal sending module and a signal receiving module interacting with the signal sending module. The signal sending module includes: a transmitter and a magnetic induction transmitting antenna connected to the transmitter for generating and transmitting a preset carrier frequency electromagnetic signal. The signal receiving module includes: a receiver and a magnetic induction receiving antenna connected to the receiver for receiving the preset carrier frequency electromagnetic signal. Both the magnetic induction transmitting antenna and the magnetic induction receiving antenna include an insulating housing and a coil disposed on the insulating housing and electrically insulated from the surrounding medium. And a coupled dipole antenna that is non-contact connected to the magnetic induction transmitting antenna and the magnetic induction contact antenna is also provided between the magnetic induction transmitting antenna and the magnetic induction receiving antenna to perform near-field communication by using the characteristic that the relative magnetic permeability of the conductive medium in the fully buried space burial layer is 1. On the basis of comprehensively analyzing the mechanisms of magnetic induction communication and electromagnetic wave communication, the advantages of both are integrated. An alternating electric field is excited in the coil with the magnetic induction coil as the source, and then the dipole antenna non-contact connected to the coil is driven. Finally, the near-field magnetic signal induced around the dipole antenna is received by the induction coil rod, which can solve the problem that magnetic induction communication technology is difficult to be used for wireless communication in extreme environments such as goafs in coal mines and deep seas, and provides important technical support for solving fire monitoring in goafs, etc.

[0038] Further, the magnetic induction receiving antenna coil adopts a magnetic rod coil wound around a cylindrical magnetic rod and / or a hollow coil wound around an insulating housing.

[0039] The magnetic induction transmitting antenna may include: an insulating housing; a hollow coil wound around the housing, which can be wound densely, sparsely, in a single layer or multiple layers, and the wire used can be a single-strand copper wire or an exciting wire; and two feeding points, which are respectively connected to both ends of the coil, so that a current of a specific frequency flows on the coil, generating an alternating magnetic field and an electric field around the coil; wherein, the coil and the feeding points are both insulated from the surrounding medium. The magnetic induction receiving antenna may include at least one of the following: a magnetic rod coil, a cylindrical magnetic rod coil with high magnetic permeability wound around it, with a length less than 100 mm and a diameter less than 20 mm; a hollow coil, a hollow coil wound around an insulating housing, wound densely or sparsely; wherein, the coil is electrically insulated from the surrounding medium; two feeding points, which are connected to a tuning circuit for adjusting the optimal communication frequency; wherein, the feeding points are electrically insulated from the surrounding medium. Different from the traditional dipole antenna, the coupled dipole antenna in this case can be made of highly conductive metals such as aluminum, copper or iron, with a length less than about 2 km and a diameter less than about 5 cm. The electric dipole antenna has a non-contact coupling relationship with the coil and has no electrical connection; there is no feeding point on the electric dipole antenna, that is, no feeding is required; wherein the dipole antenna can be insulated or not insulated from the surrounding medium. The antenna coil and the electric dipole antenna both meet the coal mine safety certification, prevent fire and are convenient for scene application.

[0040] See Figure 2As shown in the figure, a magnetic induction transmitting antenna, a coupled dipole antenna, and a magnetic induction receiving antenna form a wireless communication link. The transmitter and receiver perform functions such as signal encoding, modulation, demodulation, and decoding. The transmitter can be installed inside the magnetic induction transmitting antenna to form a signal transmission module. One end of the coupled dipole antenna penetrates the magnetic induction transmitting antenna, and the other end is non-contact coupled to the magnetic induction receiving antenna.

[0041] Feeding points for adjusting the optimal communication frequency are provided at both ends of the coil of the magnetic induction transmitting antenna and are connected to the tuning circuit of the transmitter, and the feeding points are electrically insulated from the surrounding medium. The magnetic induction transmitting antenna mainly completes electromagnetic conversion, converting the input alternating current into an alternating magnetic field in space (especially inside the solenoid). The magnetic induction transmitting antenna can adopt a cylindrical structure, with parameters: bottom diameter 5 cm, height 10 cm. To ensure sufficient conversion efficiency, two principles need to be followed when designing this antenna: the self-resonant frequency f0 of the antenna is higher than the operating frequency f c , the impedance of the antenna matches the output impedance of the drive circuit. The former reduces the loss of antenna distribution parameters, and the latter ensures maximum power transfer of the driver. Therefore, the antenna size, number of coil turns, turn spacing can be adjusted according to the communication frequency, and an appropriate wire diameter can be selected. The electrical parameters of the magnetic induction transmitting antenna operating at high frequencies mainly include inductance, resistance, and distributed capacitance. The specific calculation formulas are as follows:

[0042] Inductance is composed of self-inductance and mutual inductance. In the case where there is no magnetic medium around the coil, the magnitude of the inductance value only depends on the size and geometric shape of the coil. The calculation formula for the coil inductance is derived according to the vector magnetic potential as follows:

[0043]

[0044] In the formula, L ii represents the self-inductance of the coil, M ij represents the mutual inductance of the coil, N is the number of coil turns, r is the wire diameter, R i and R j are the radii of the i-th and j-th turns of the coil respectively, R P is the distance from point P to the center of the circular line current, k is the integral modulus, K is the complete elliptic integral of the first kind, and E is the complete elliptic integral of the second kind.

[0045]

[0046]

[0047]

[0048] When a high-frequency current passes through the coil, the mutual inductance between the wires will generate an induced current, which will lead to an uneven distribution of the current density inside the wires and increase the coil impedance. Under the combined action of the skin effect and the proximity effect, the current distribution in the conductor is uneven, increasing the AC resistance of the wire. The numerical simulation is as shown in Figure 3 shown. These effects can be described by the skin effect and the proximity effect. Then, the AC resistance R ac of the single-layer spiral coil can be expressed as:

[0049]

[0050] In the formula, d represents the radius of the coil wire, h represents the distance between the centers of two adjacent wires in the coil, N l represents the number of winding layers of the coil, γ is a fitting coefficient related to the wire diameter and skin depth of the coil wire, and R dc is the DC impedance.

[0051] In a high-frequency working environment, the distributed capacitance of the coil cannot be ignored. The equivalent model of the distributed capacitance of the single-layer coil is as shown in Figure 4 shown. It can be seen from the figure that the distributed capacitance can be equivalent to a series-superimposed form. The total distributed capacitance of the single-layer coil can be written as:

[0052]

[0053] In the formula, C ij represents the inter-turn capacitance between two adjacent turns. The inter-turn capacitance between two wires can be expressed as:

[0054]

[0055] In the formula, l is the length of the turn wire, ε is the dielectric constant of air, h is the distance between the centers of two adjacent wires, and r is the radius of the coil wire.

[0056] According to the calculation conclusions of the electrical parameters of the above magnetic induction emission antenna, an antenna with a self-resonant frequency higher than the communication frequency is set up to ensure a high conversion efficiency of the antenna to meet the requirements of near-field communication.

[0057] Different from the traditional antenna that focuses on the far-field radiation efficiency of the antenna, the coupled dipole antenna in the embodiments of this case is mainly used for near-field communication and physically meets the safety requirements of the goaf such as anti-smashing, high temperature resistance, and no static electricity generation. A high-strength armored cable meeting the coal mine safety certification can be selected as the coupled dipole antenna, and the length is adjustable between 30 and 200 meters. As shown in Figure 2As shown in the figure, one side of the coupled dipole antenna penetrates through the magnetic induction transmitting antenna and can be bent into a circular single loop with its axis parallel to the antenna axis inside the coil, so as to couple the alternating electric field signal inside the magnetic induction transmitting antenna. The magnetic induction receiving antenna, that is, the receiving magnetic induction coil rod, is placed on the other side of the dipole antenna and can be 50 - 2000 meters away from the magnetic induction transmitting antenna; the distance between the receiving magnetic induction coil rod and the dipole antenna can be in the range of 5 cm - 30 cm to ensure a stable magnetic field receiving signal. The main principle of the coupled dipole antenna working is as follows:

[0058] 1) Induced electric field inside the magnetic induction transmitting antenna

[0059] According to Figure 3 the principle shown in the figure, a cylindrical coordinate system with the magnetic induction transmitting antenna as the center and the axial direction as the Z-axis is established Then the magnetic fields along the axial and radial directions inside the magnetic induction transmitting antenna can be expressed as:

[0060]

[0061] In the formula, B Z is the axial induced magnetic field intensity, B R is the axial induced magnetic field intensity, J is the internal current density of the magnetic induction transmitting antenna ①, b is the antenna radius, and Z and R respectively represent the unit direction vectors in the axial and radial directions. According to the integral form of Faraday's law of electromagnetic induction and using the radial symmetric structure of the magnetic induction transmitting antenna ①, the calculation formula for the internal electric field can be derived as:

[0062]

[0063] In the formula, E is the induced electric field, which is located in the plane perpendicular to the Z-axis and the direction satisfies the left-hand screw rule with the Z-axis, r c is the radial distance, B = B Z + B R is the induced magnetic field intensity. Equations (8) and (9) are difficult to solve in an analytical form and are often analyzed by numerical calculation methods. Figure 5 and Figure 6 give the magnetic field density map and electric field density map around the magnetic induction transmitting antenna under the buried condition. As Figure 6 shown in the figure, the internal partial electric field in the finite-length magnetic induction transmitting antenna is radially symmetric and the minimum along the axis, which is consistent with the model analysis. That is, the farther away from the axis, the stronger the induced electric field, laying a foundation for the actual design of the dipole antenna structure.

[0064] 2) Near-field induced magnetic field of the coupled dipole antenna

[0065] Since it is buried by a medium with high conductivity and operates in the high-frequency band (≥1.5 MHz), the coupled dipole antenna cannot form a radiation field in the far field. In the embodiments of this case, the near-field induction field is mainly used for communication. When the receiving antenna is at a distance r from the antenna d satisfies r d <λ / 2π is the near field, and the expression of the near-field induction magnetic field is:

[0066]

[0067] In the formula, [I] = I0e jωt , I0e jωt is the alternating current on the antenna, λ is the signal wavelength, r λ = r d / λ. Furthermore, a highly sensitive magnetic induction coil rod is used to receive the signal H φ .

[0068] 3) Transmitting and receiving circuit

[0069] The structure of the transmitting circuit module in the transmitter is as shown in Figure 2 . This module is mainly composed of a communication signal generation module, a radio frequency drive module, a matching circuit, etc., and completes functions such as signal encoding, modulation, power amplification, and impedance matching. The transmitting antenna tuning network is as shown in Figure 7 . It consists of L1 and C1 to form an "L-shaped" tuning network. The antenna standing wave ratio after matching is as shown in Figure 8 , achieving the best transmission efficiency.

[0070] The receiving magnetic induction coil rod is composed of a magnetic rod with a high Q value and a coil wound on it, and is mainly used to receive the near-field magnetic field signal of the coupled dipole antenna. Since the magnetic induction coil rod has a certain directionality, when installing, the direction of maximum sensitivity needs to be parallel to the magnetic field direction. The receiving processing circuit module in the receiver is mainly composed of a tuning and matching circuit, a radio frequency amplification circuit, a mixing circuit, an intermediate frequency filtering and amplification circuit, a second-stage mixing circuit, and a low-frequency filtering and amplification circuit, etc. The receiving process is as follows: First, the tuning and matching circuit adjusts the receiving magnetic induction coil rod to the resonant state to receive the radio frequency signal. Then, the first-stage radio frequency amplification and mixing circuit amplifies the radio frequency signal and converts it to 455 kHz. Then, it passes through a band-pass filtering and amplification circuit with a center frequency of 455 kHz. Finally, after the second-stage mixing and low-pass filtering circuit, the signal becomes a baseband signal and is sent to the sampler for demodulation. The tuning and matching circuit is as shown in Figure 9 . It consists of capacitor C1 and capacitor C2 in parallel and then in series with antenna L2 to form a series resonance network. C1 is the resonant capacitor, and C2 is the distributed capacitance of the antenna. The resonant Q value is 50 at the designed frequency point. Among them, the flow of the demodulation algorithm is as shown in Figure 10As shown in the figure, the specific processing flow is as follows: First, perform carrier detection on the signal after ADC, adaptively estimate the frequency offset of the carrier frequency and compensate and correct it to prevent demodulation failure caused by temperature drift. Then, detect the preamble after carrier frequency estimation, demodulate FSK and perform frame synchronization. Finally, use Hamming code to correct the correctness of demodulation.

[0071] Furthermore, based on the above system, the embodiment of the present invention also provides a method for establishing a fully buried space magnetoelectric near-field coupling type wireless penetration communication, including the following contents:

[0072] Set the parameters of the magnetic induction transmitting antenna according to the working frequency, and the parameters of the magnetic induction transmitting antenna at least include one of the following: coil winding, magnetic rod wire diameter, number of coil turns, and coil turn spacing;

[0073] Deploy a signal transmission module, a signal reception module, and a coupled dipole antenna in the buried layer of the fully buried space;

[0074] Couple the induced electric field emitted by the magnetic induction transmitting antenna of the signal transmission module through the coupled dipole antenna and induce a magnetic field in the surrounding area, and use the magnetic induction receiving coil of the signal reception module to receive the near-field signal of the coupled dipole antenna to establish communication between the signal transmission module and the signal reception module.

[0075] To verify the effectiveness of the solution of this case, the following will be further explained with specific experimental data:

[0076] The test scenario is as Figure 11 shown, with a water depth of 8 meters, a muddy bottom of the lake, a horizontal distance of 170 meters between the transmitting and receiving modules, a transmitting power of 100 mW, a communication rate of 100 bit / s, and a communication interval of 20 s. The specific implementation process is as follows:

[0077] 1. Select the working frequency f, design a magnetic induction transmitting antenna operating at this frequency point and its matching circuit. The magnetic induction transmitting antenna consists of a non-metallic housing certified for coal mine safety and the cable wound around the housing, and the selection of parameters such as wire diameter and turn spacing depends on the working frequency f;

[0078] 2. According to requirements such as communication rate, power consumption, and volume, design a communication transmitting circuit and its algorithm. The transmitting circuit module mainly consists of modules such as a metal housing, a control CPU, power management, and power drive, and realizes functions such as signal modulation and power drive;

[0079] 3. Design a magnetic induction coil rod antenna receiving module according to the frequency and amplitude of the received signal. This module mainly consists of modules such as a coil rod antenna, an amplification, mixing, and filtering circuit, and realizes functions such as signal amplification, analog down-conversion, and filtering;

[0080] 4. Design the communication receiving and processing circuit and its demodulation and decoding algorithm according to interference suppression and other indicators. The communication receiving and processing circuit mainly includes CPU control, AD sampling, power management, and low-pass filtering, etc., and completes functions such as analog-to-digital conversion, digital filtering, demodulation, and decoding of signals.

[0081] The test results are as Figure 12 , Figure 13 and Figure 14 shown. Figure 12 is the received time-domain signal, Figure 13 is the frequency spectrogram of the received signal. It can be seen that when the distance from the emission source is 170 meters, the amplitude of the received time-domain signal is 4 mV, and the spectrogram of 2FSK is clearly visible. Figure 14 is the demodulated information. It can be seen that the interval between adjacent two frames of data is about 20 s, and all demodulations are correct without error.

[0082] It is also applicable to the through-earth communication of the buried layer in coal mines. The transmitter, magnetic induction transmitting antenna, receiver, magnetic induction receiving antenna, and coupled dipole antenna can be completely buried without a net flow space, and the goaf collapse buried layer is composed of sandstone, abandoned coal, etc.; the transmitter and transmitting induction antenna that are completely buried without leaving a net space are used to generate and send electromagnetic field signals of a certain modulation method and specific frequency; the receiver and receiving induction antenna that are completely buried without leaving a net space are used to receive electromagnetic signals of a specific frequency and demodulate and decode. The transmitter and communication machine can be configured for electromagnetic field communication with a frequency between 300 kHz and 30 MHz.

[0083] Unless otherwise specifically stated, the relative steps, numerical expressions, and values of the components and steps described in these embodiments do not limit the scope of the present invention.

[0084] Each embodiment in this specification is described in a progressive manner. The key points of each embodiment are 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 embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0085] The units and method steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those of ordinary skill in the art can use different methods to implement the described functions for each specific application, but such implementation is not considered to exceed the scope of the present invention.

[0086] Those of ordinary skill in the art can understand that all or part of the steps in the above method can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a magnetic disk, or an optical disc, etc. Optionally, all or part of the steps of the above embodiments can also be implemented using one or more integrated circuits. Correspondingly, each module / unit in the above embodiments can be implemented in the form of hardware or in the form of a software function module. The present invention is not limited to any specific form of combination of hardware and software.

[0087] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions described in the foregoing embodiments or easily conceive of changes, or perform equivalent replacements for some of the technical features; 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 all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A fully buried space magnetoelectric near-field coupling type wireless penetration communication system, comprising: a signal sending module, and a signal receiving module that interacts with the signal sending module, characterized in that The signal transmitting module includes: a transmitter, and a magnetic induction transmitting antenna connected to the transmitter for generating and transmitting a preset carrier frequency electromagnetic signal; the signal receiving module includes: a receiver, and a magnetic induction receiving antenna connected to the receiver for receiving a preset carrier frequency electromagnetic signal; both the magnetic induction transmitting antenna and the magnetic induction receiving antenna include an insulating housing and a coil disposed on the insulating housing and electrically insulated from the surrounding medium; and a coupled dipole antenna non-contact connected to the magnetic induction transmitting antenna and the magnetic induction receiving antenna is further disposed between the magnetic induction transmitting antenna and the magnetic induction receiving antenna, so as to perform near-field communication by using the characteristic that the relative magnetic permeability of the conductive medium of the fully buried space buried layer is 1. The minimum distance between the magnetic induction transmitting antenna and the magnetic induction receiving antenna is 5m, and the maximum distance is 200m.

2. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 1, wherein The magnetic induction receiving antenna coil is a magnetic rod coil wound around a cylindrical magnetic rod and / or a hollow coil wound around an insulating housing.

3. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 1, characterized in that Both ends of the coils of the magnetic induction transmitting antenna and the magnetic induction receiving antenna are provided with feeding points connected to the tuning circuit of the transmitter for adjusting the optimal communication frequency, and the feeding points are electrically insulated from the surrounding medium.

4. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 1, wherein The coupled dipole antenna uses armored cable.

5. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 1, wherein One end of the coupled dipole antenna penetrates through the coil of the magnetic induction transmitting antenna, and the other end is placed on one side of or penetrates through the magnetic induction receiving antenna.

6. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 5, characterized in that One end of the coupled dipole antenna is bent into a circular single-loop structure inside the coil of the magnetic induction transmitting antenna, and the end of the coupled dipole antenna with the circular single-loop structure is parallel to the axis of the magnetic induction transmitting antenna.

7. The fully buried space magnetoelectric near-field coupling type wireless penetration communication system according to claim 1, characterized in that When the coupled dipole antenna is on one side of the magnetic induction receiving antenna, the minimum distance between them is 5cm and the maximum distance is 30cm, or the dipole antenna passes through the magnetic induction receiving antenna.

8. A method for establishing a fully buried space magnetoelectric near-field coupling type wireless penetration communication, characterized in that, Based on the implementation of the system described in claim 1, the method includes the following contents: Set the parameters of the magnetic induction transmitting antenna according to the operating frequency, and the parameters of the magnetic induction transmitting antenna at least include one of the following: coil winding, magnetic rod wire diameter, number of coil turns, and coil turn spacing. Arrange the signal transmitting module, the signal receiving module, and the coupled dipole antenna in the fully buried space buried layer. Couple the induced electric field emitted by the magnetic induction transmitting antenna of the signal transmitting module through the coupled dipole antenna and induce a magnetic field in the surrounding area, and use the magnetic induction receiving coil of the signal receiving module to receive the near-field signal of the coupled dipole antenna, so as to establish communication between the signal transmitting module and the signal receiving module.

9. The method for establishing a fully buried space magnetoelectric near-field coupling type wireless penetration communication according to claim 8, wherein The operating frequencies of the transmitter and the receiver are configured to be 300kHz to 30MHz.

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