Distributed array low-frequency communication method, device and system based on mechanical antenna

Abstract

The invention discloses a distributed array low-frequency communication method, device and system based on a mechanical antenna, and relates to the technical field of wireless communication. Comprising the steps that magnetization vectors of all transmitting antenna units are approximately coplanar in the same plane, all the transmitting antenna units rotate around rotation axes which are perpendicular to the plane and consistent in direction, and motion instruction generation, mechanical control signal conversion and mechanical motion execution are achieved through a layered electromechanical architecture. And enabling each transmitting antenna unit to rotate at the same frequency from the preferable initial phase, thereby realizing the focusing of the magnetic field energy of the transmitted signal at the target receiving point. According to the invention, each transmitting antenna unit can independently calculate the optimal initial phase, overall optimization solution is not needed, distributed control is supported, and the energy utilization efficiency is improved. On the basis of a magnetic field energy focusing mechanism, ASK amplitude shift keying modulation and downlink multi-user communication functions can be realized, the method is suitable for cross-medium scenes such as air-underwater and air-underground, and an efficient solution is provided for low-frequency electromagnetic wave communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a distributed group array low-frequency communication method, device and system based on mechanical antennas. BACKGROUND

[0002] A mechanical antenna is a new low-frequency electromagnetic signaling technology that realizes electromagnetic radiation by driving electromagnetism materials such as electrets and permanent magnets to vibrate or rotate mechanically. In recent years, this technology has attracted much attention because it can effectively overcome the application limitations of traditional electrically small antennas caused by excessive size and energy consumption. Mechanical antennas have the characteristics of small size while ensuring high radiation efficiency, and can meet the needs of application scenarios that require mobility and portability. However, the radiation power of a single small mechanical antenna is limited, which makes it difficult to meet the needs of long-distance electromagnetic wave transmission. To improve the radiation power, multiple small mechanical antennas can be used in an array to enhance the magnetic induction intensity at the target receiving point through spatial superposition.

[0003] Currently, the research on "mechanical antenna arrays" at home and abroad is still in its initial stage. Existing research generally realizes the enhancement of radiation capability through the centralized and compact arrangement of multiple transmitting antenna units in an array, which can be regarded as a small-interval mechanical antenna array. However, the transmitting antenna units in the array have force moment interference that changes constantly within the operation cycle, which causes difficulties for the motion excitation and control system, and also causes eddy current effects that attenuate radiation. To reduce eddy current and force moment interference, a reasonable interval is needed between the transmitting antenna units. In addition, as the number of transmitting antenna units increases, the size of the array cannot be ignored relative to the signal propagation distance. At this time, the spatial angle difference between each transmitting antenna unit and the target receiving point varies with the position of the target receiving point, and the phase difference between each mechanical antenna unit significantly affects the magnetic field distribution in space. The centralized mechanical antenna array in the prior art usually sets each transmitting antenna unit to operate at the same phase, but when the size of the antenna array cannot be ignored relative to the signal propagation distance, this method cannot effectively concentrate the magnetic field energy at the target receiving point, resulting in a decrease in energy utilization efficiency.

[0004] Benefiting from the mature application of rare earth permanent magnet materials and rotating drive technology, the mechanical antenna scheme based on rotating permanent magnet has become a research hotspot in the industry. Compared with other mechanical antenna systems, the rotating permanent magnet mechanical antenna has obvious advantages in the radiation intensity of single magnetic field. However, the electromagnetic wave radiated by the rotating permanent magnet mechanical antenna in most application scenarios is an elliptical polarized wave, and the traditional high-frequency beam forming technology mainly faces linear polarized wave, so it is no longer applicable. In addition, how to fully utilize the radiation energy of each transmitting antenna unit and realize the convergence of the radiation magnetic field energy at the specified target receiving point by adjusting the phase of the mechanical antenna is still a technical problem to be solved. Especially in the scene supporting the maneuvering deployment and distributed control of each transmitting antenna unit, the existing technology lacks effective solutions.

[0005] In summary, the existing mechanical antenna array still has significant limitations in the array forming mode and operation mechanism, especially under the condition of a large interval distributed array, it is difficult to realize efficient focusing and flexible regulation of magnetic field energy. Therefore, it is necessary to develop a low-frequency communication method capable of adaptively determining the initial phase of each transmitting antenna unit according to the spatial position of the target receiving point, in order to realize efficient utilization and accurate control of the spatial distribution of magnetic field energy. Such a method not only can significantly improve the signal-to-noise ratio of the system, but also can support more abundant and reliable low-frequency communication methods, opening up a new development path for low-frequency cross-medium communication and detection technology. SUMMARY

[0006] Therefore, the present application provides a distributed array low-frequency communication method, device and system based on a mechanical antenna, aiming to solve the above technical problems.

[0007] In order to achieve the above purpose, the present application adopts the following technical solutions: A distributed array low-frequency communication method based on a mechanical antenna, a transmitting array composed of multiple rotating permanent magnet mechanical antenna units sends signals to a target receiving point, the magnetization vectors of all transmitting antenna units are approximately coplanar on the same plane, each transmitting antenna unit rotates at the same angular frequency from a set initial phase at different times around the rotation axis perpendicular to the plane and in the same direction, so that the magnetic field energy of the transmitted signals at the target receiving point is in a focused state or a non-focused state.

[0008] Further, the focused state refers to that each transmitting antenna unit rotates at the same angular frequency from a set of preferred initial phases calculated based on the position of the target receiving point, so that the radiated signal magnetic field energy converges and enhances at the target receiving point; The non-focusing state is achieved by rotating each transmitting antenna unit at the same angular frequency starting from a set of preferred initial phases calculated based on the positions of other receiving points, or rotating each transmitting antenna unit at the same angular frequency starting from a set of random initial phases, or rotating part of the transmitting antenna units at the same angular frequency starting from a set of preferred initial phases calculated based on the position of the target receiving point, and rotating the rest of the transmitting antenna units at the same angular frequency starting from phases increased or decreased by 180° with respect to the set of preferred initial phases; or rotating each transmitting antenna unit at non-identical angular frequencies starting from a set of specified initial phases.

[0009] Further, the set of preferred initial phases is determined by the following steps: Step one: taking the plane in which the magnetization directions of each transmitting antenna unit are approximately coplanar as the reference plane, and each transmitting antenna unit obtains the target azimuth of the projection of the target receiving point on the reference plane according to its coordinates on the reference plane ; Step two: defining a uniform reference azimuth , and each transmitting antenna unit calculates the included angle between the target azimuth and the reference azimuth ; Step three: each transmitting antenna unit calculates the preferred initial phase of each transmitting antenna unit using the calculation formula of the optimal beam forming criterion , and if the included angle corresponding to a certain transmitting antenna unit is located in a specific interval, the preferred initial phase of the transmitting antenna unit is increased or decreased by 180°, and the range of the specific interval is ; Step four: the preferred initial phase of each transmitting antenna unit is individually increased or decreased by 360°, or the preferred initial phases of all transmitting antenna units are collectively increased or decreased by any value, and the result is still the preferred initial phase.

[0010] Further, according to whether the signal radiated by the transmitting array is in the focusing state or multiple non-focusing states at the position of the target receiving point, the transmitting array is switched between multiple signal radiation modes to dynamically change the modulus of the magnetic induction intensity at the target receiving point, thereby realizing ASK amplitude shift keying modulation; When the receiving end realizes ASK amplitude shift keying demodulation, the modulus of the magnetic induction intensity can be mapped to bit information by the following methods: Manner one: the receiving end calculates the theoretical magnetic induction intensity modulus of the transmitting array at the target receiving point in the focusing radiation mode and multiple non-focusing radiation modes according to the respective position information, the position information of each transmitting antenna unit, and the residual magnetic strength of the permanent magnet; the receiving end selects a decision threshold between each group of numerically adjacent theoretical magnetic induction intensity modulus, divides the spatial magnetic induction intensity modulus into multiple decision intervals corresponding to different bit information respectively by taking all decision thresholds as the division points, and maps the magnetic induction intensity modulus to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus belongs; Manner two: the transmitting array switches the focusing radiation mode and multiple non-focusing radiation modes in a predetermined order before transmitting effective data, the receiving end selects a decision threshold between each group of numerically adjacent magnetic induction intensity modulus received, and divides the spatial magnetic induction intensity modulus into multiple decision intervals corresponding to different bit information respectively by taking all decision thresholds as the division points; when the transmitting array transmits effective data, the receiving end maps the magnetic induction intensity modulus to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus belongs.

[0011] Further, by switching the radiation signals of the transmitting antenna array in different time periods, the magnetic field energy forms a focusing state at different target receiving points, and each target receiving point receives information when it is determined that the magnetic field energy focuses at the position where it is located, thereby realizing downlink multi-user communication. The manner in which each target receiving point determines that the magnetic field energy focuses at the position where it is located is that each target receiving point measures the magnetic induction intensity modulus received by itself in real time during system operation; when the deviation between the measured magnetic induction intensity modulus and the reference magnetic induction intensity modulus corresponding to the expected magnetic field energy focusing state of the target receiving point in a certain time period is not greater than a preset threshold, it is determined that the magnetic field energy focuses at the position where the target receiving point is located in the time period. The threshold is set by comparing the magnetic induction intensity modulus of the target receiving point in the magnetic field energy focusing state with the maximum value of the magnetic induction intensity modulus at the target receiving point when the system focuses the magnetic field energy on other receiving points, and the threshold takes a value not greater than the difference between the two values. The magnetic induction intensity modulus when the magnetic field energy focuses can be obtained in the following manner: Manner one: each target receiving point obtains the magnetic induction intensity modulus when the transmitting array focuses on the receiving point in theory according to the respective position information, the position information of each transmitting antenna unit, and the residual magnetic strength of the permanent magnet, and takes it as the magnetic induction intensity modulus when the magnetic field energy focuses. The second way is that the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in the process, and each target receiving point takes the magnetic induction intensity modulus other than the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus when the magnetic field energy of other target receiving points is focused. The magnetic induction intensity modulus of each target receiving point when the magnetic field energy of other target receiving points is focused can be obtained in the following way: The first way is to obtain the magnetic induction intensity modulus of each target receiving point when the magnetic field energy of other target receiving points is focused in theory according to the position information of all target receiving points, the position information of each transmitting antenna unit and the residual magnetic intensity of the permanent magnet, and take it as the magnetic induction intensity modulus of each target receiving point when the magnetic field energy of other target receiving points is focused. The second way is that the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in the process, and each target receiving point takes the magnetic induction intensity modulus other than the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus when the magnetic field energy of other target receiving points is focused.

[0012] A distributed group array low-frequency communication device based on a mechanical antenna includes a general control center and a plurality of transmitting antenna units. The general control center is equipped with a communication link with each transmitting antenna unit for sending target receiving point coordinates, transmission bits, transmission rate, modulation mode and transmission start time and other information to each transmitting antenna unit. Each transmitting antenna unit adopts a layered mechanical and electrical architecture design, which is composed of a mechanical motion layer, a servo control layer and a motion loading layer. Each layer cooperates with each other to make each transmitting antenna unit cooperatively emit signals as needed.

[0013] Further, the mechanical motion layer includes one or more mechanical rotary motion power devices, and each rotary motion power device is connected to a permanent magnet through a connecting device. The rotary motion power device can be an electric motor. The connecting device is composed of an outer frame, a connector, a bearing and an electromagnetic shielding device. The outer frame is used to fix each execution unit and keep the overall structure stable. The connector is used to realize the transmission between the rotary motion power device and the permanent magnet. The bearing is used for non-contact fixation of the rotating part and the outer frame. The electromagnetic shielding device is used to reduce the influence of the permanent magnet on the rotary motion power device. The permanent magnet is composed of one or more small permanent magnets.

[0014] Further, the servo control layer comprises a servo driver, which is used to convert the motion instruction into a mechanical control signal and transmit it to the mechanical motion layer, so that the rotating motion power device can accurately complete the specified rotating motion according to the motion instruction.

[0015] Further, the motion loading layer comprises a communication interface and a processor, the communication interface is used to receive the target receiving point coordinates, transmission bits, transmission rate, modulation mode and transmission start time and other information sent by the general control center, and the processor calculates the time-domain rotating motion waveform of the permanent magnet, i.e. the motion instruction, according to the above information and transmits it to the servo control layer. The calculation process of the time-domain rotating motion waveform of the permanent magnet comprises the calculation of the preferred initial phase or other initial phase, the mapping of the initial phase on the local coordinate system of each rotating motion power device, and the waveform deduction according to the modulated carrier frequency; the local coordinate system refers to the coordinate system deviated from the global coordinate system as shown in the drawing, with the 0 phase point of the rotating motion power device as the X axis. Figure 1 The time synchronization between the processors of each transmitting antenna unit can be realized in a wired or wireless manner, and the wireless synchronization manner comprises global clock calibration by using an external synchronization signal, or local time consistency by transmitting internal synchronization signals between the processors of the transmitting antenna units.

[0016] A mechanical antenna-based distributed array system comprises a mechanical antenna-based distributed array low-frequency communication device and a receiving device for receiving the signal transmitted by the distributed array low-frequency communication device. The mechanical antenna-based distributed array low-frequency communication device is used to realize signal transmission. The receiving device is used to realize signal receiving and processing, and the process of receiving and processing comprises receiving, synchronizing, amplifying, analog filtering, analog-digital conversion, digital filtering, judging and decoding of the signal.

[0017] Compared with the prior art, the present application realizes effective convergence of magnetic field energy at the specified target receiving point by adjusting the initial phase of each transmitting antenna unit, and improves the energy utilization efficiency. The method supports independent calculation of the initial phase of each transmitting antenna unit, does not need overall optimization solution, and simplifies the system design and implementation process. Based on the magnetic field energy focusing mechanism and the layered mechatronic system architecture, the spatial distribution of the magnetic field can be flexibly regulated, and various functions such as ASK modulation and downlink multi-user communication are supported. In addition, the method is applicable to air-underwater, air-underground and other cross-medium scenarios, realizes magnetic field energy focusing through distributed array of multiple mechanical antenna units, and then realizes cross-medium communication facing targets in a farther distance and a deeper medium. BRIEF DESCRIPTION OF DRAWINGS ​

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings required by the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative work based on the provided drawings are within the scope of the present application.

[0019] Figure 1 A schematic diagram of a mechanical antenna array-based transmission signal magnetic field energy focusing scene is provided.

[0020] Figure 2 A mechanical antenna monomer rotation schematic diagram is provided.

[0021] Figure 3 An electromagnetic propagation schematic diagram of a mechanical antenna-based air-seawater cross-medium space communication scene is provided.

[0022] Figure 4 A mechanical antenna array-based system communication mode schematic diagram is provided.

[0023] Figure 5 A mechanical antenna array in a focusing scene at a certain receiving point, the magnetic induction intensity modulus of the remaining positions compared to the attenuation (dB) when it is focused is provided.

[0024] Figure 6 A mechanical antenna array in an ASK amplitude shift keying modulation communication state, the magnetic induction intensity modulus of the target receiving point changes with time waveform schematic diagram is provided.

[0025] Figure 7 A mechanical antenna array in a downlink multi-user communication state, the magnetic induction intensity modulus of each target receiving point changes with time waveform schematic diagram is provided. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of the present application.

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings required by the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative work based on the provided drawings are within the scope of the present application.

[0028] Embodiment 1: This embodiment provides a method of mechanical antenna distributed array in a uniform medium with similar physical properties and realizing magnetic field energy focusing: A homogeneous medium is a medium environment in which similar electromagnetic propagation characteristics are present throughout the macroscopic area. Examples of homogeneous media include air, seawater, and rocks.

[0029] like Figure 1 , Figure 2 As shown, the magnetization vectors of all transmitting antenna elements are approximately coplanar on the same plane, and rotate around a rotation axis perpendicular to the plane and in the same direction in an approximately homogeneous medium, with the same angular frequency and starting from a preferred initial phase, thereby achieving the focusing of the signal magnetic field energy radiated by the transmitting array to a target receiving point in a specific area of ​​space.

[0030] The magnetic dipole quantities of each antenna element in the transmitting antenna array can be different.

[0031] A specific region in space refers to the area within the medium in which the transmitting antenna array is located, on a plane where the magnetization vectors of each transmitting antenna element are approximately coplanar, and within the near-field range of the electromagnetic radiation of all transmitting antenna elements.

[0032] The near-field region of electromagnetic radiation refers to the distance much smaller than... The area The wavelength of the electromagnetic wave emitted by the transmitting antenna element in a uniform medium. Taking 30Hz as an example, this is the wavelength of the electromagnetic wave in air. The range is 10,000 kilometers. Therefore, for low-frequency electromagnetic waves, the near-field region covers the vast majority of actual propagation scenarios.

[0033] The preferred initial phase is calculated based on the position of each transmitting antenna element and the position of the focused receiving point; The preferred method for calculating the initial phase of each transmitting antenna element includes: Step 1: Take the plane where the magnetization directions of each transmitting antenna element are approximately coplanar as the XOY plane, and obtain the coordinates of each transmitting antenna element and the focused receiving point on the XOY plane.

[0034] Step 2: Define a uniform, arbitrary reference azimuth angle for all transmitting antenna elements. .

[0035] Step 3: Based on the target azimuth angle of each transmitting antenna element pointing towards the focused receiving point. Calculate the target azimuth angle of each transmitting antenna element. With reference azimuth The included angle ,in i This represents the index of the transmitting antenna unit.

[0036] Step 4: Each transmitting antenna element, according to its own included angle... The optimal initial phases are calculated using the optimal beamforming criterion. .

[0037] Step 5: If a certain transmitting antenna element's If the antenna element is located within a specific range, then the preferred initial phase is... Add or subtract 180°.

[0038] Step Six: Optimizing the Initial Phase of Each Transmitting Antenna Element It can add or subtract 360° individually, and can optimize the initial phase of all transmitting antenna elements. Adding or subtracting any value together, after the above operations, still results in the preferred initial phase.

[0039] In step four above, the formula for calculating the optimal beamforming criterion is: ; In step five above, the specific interval is: .

[0040] Example 2: This embodiment provides a method for distributed arraying of mechanical antennas and focusing of magnetic field energy in a cross-medium scenario: Cross-medium communication scenarios specifically refer to electromagnetic waves entering other homogeneous media from air. Common cross-medium communication scenarios include air-underwater and air-underground semi-infinite radiation spaces. The definition of a homogeneous medium is the same as in Example 1.

[0041] like Figure 3 As shown, the magnetization vectors of all transmitting antenna elements are approximately coplanar on the interface of the medium and are in the air. They rotate around a rotation axis that is perpendicular to the interface and has the same direction, with the same angular frequency and starting from the preferred initial phase, thereby realizing the focusing of the signal magnetic field energy radiated by the transmitting array to a target receiving point in a specific area of ​​space. The magnetic dipole quantities of each antenna element in the transmitting antenna array can be different.

[0042] The spatially specific region refers to the far-field region of low-frequency dipole radiation as defined by the CSAMT (Controlled-source Audio-frequency Magnetotellurics) method. The far-field region of low-frequency dipole radiation specifically refers to the region in a non-air medium where, with the interface between the medium and the antenna elements as the horizontal plane, the horizontal distance from all transmitting antenna elements exceeds the wavelength in the non-air medium. The region. Taking 30Hz as an example, the wavelength of this frequency electromagnetic wave in seawater (with a conductivity of 4S / m). about 290 meters, wavelength in rock (assuming conductivity of 0.01 S / m) about 5.8 kilometers.

[0043] The preferred initial phase is calculated according to the position of each transmitting antenna unit and the position of the focused receiving point; The method for calculating the preferred initial phase of each transmitting antenna unit comprises: Step one: take the plane in which the magnetization directions of each transmitting antenna unit are approximately coplanar as the XOY plane, and obtain the coordinates of each transmitting antenna unit on the XOY plane and the projection coordinates of the focused receiving point on the XOY plane.

[0044] Step two: define a uniform and arbitrary reference azimuth angle for all transmitting antenna units .

[0045] Step three: calculate the included angle between the target azimuth angle of each transmitting antenna unit pointing at the projection of the focused receiving point and the reference azimuth angle , where represents the index of the transmitting antenna unit. i

[0046] Step four: each transmitting antenna unit calculates its preferred initial phase according to its own included angle through the optimal beam forming criterion.

[0047] Step five: if the included angle of a certain transmitting antenna unit is located in a specific interval, then add or subtract 180° to the preferred initial phase of the transmitting antenna unit.

[0048] Step six: the preferred initial phase of each transmitting antenna unit can be individually added or subtracted by 360°, or the preferred initial phases of all transmitting antenna units can be collectively added or subtracted by any value, and the preferred initial phase after the above operation is still the preferred initial phase.

[0049] In step four above, the optimal beam forming criterion calculation formula is: ; In step five above, the specific interval is: .

[0050] Embodiment 3: The embodiment provides an ASK amplitude shift keying modulation communication method based on a mechanical antenna distributed array: ​​The arraying manner of the mechanical antenna array and the position of the target receiving point are the same as any one of embodiments 1-2.

[0051] As shown in Figure 4 the motion loading layer receives the target receiving point coordinates, transmission bits, transmission rate, ASK amplitude shift keying modulation mode, and transmission start time, etc. information sent by the general control center through the communication interface, and performs rotation motion calculation to generate motion instructions capable of switching the mechanical antenna transmitting array between multiple signal radiation modes, i.e. the signal magnetic field energy radiated by the mechanical antenna transmitting array at the target receiving point can be switched between the focusing state and multiple non-focusing states. The servo control layer outputs corresponding mechanical control signals according to the motion instructions generated by the motion loading layer and transmits them to the mechanical motion layer, so that the rotation motion power device accurately completes the specified rotation motion according to the motion instructions.

[0052] The communication interface of the motion loading layer can receive signals from the general control center through wired or wireless communication; The rotation motion calculation of the motion loading layer is specifically to set a virtual main shaft in the form of software in the processor, generate a single-frequency signal with an initial phase of 0 as the time-domain phase waveform of the virtual main shaft according to the carrier frequency of ASK modulation and the specific transmission start time, calculate the corresponding different initial phase groups of the signal magnetic field energy radiated by each transmitting antenna unit in the focusing state and multiple non-focusing states according to the target receiving point coordinates and transmission bits, etc. information and map them to the local coordinate system of each rotation motion power device, then switch each transmitting antenna unit to the corresponding different initial phase group according to the transmission rate in different bit information transmission time periods, output the time-domain phase difference waveform of each transmitting antenna unit, superimpose the time-domain phase difference waveform of each transmitting antenna unit and the time-domain phase waveform of the virtual main shaft to form a complete time-domain rotation motion waveform, and take it as a motion instruction. The time-domain phase difference waveform of each transmitting antenna unit is used to describe the phase shift relationship of each transmitting antenna unit relative to the virtual main shaft of the servo driver. For example, the phase difference of a certain transmitting antenna unit relative to the virtual main shaft is y=30°; the time-domain phase waveform of the virtual main shaft represents a function y=at that increases linearly with time; at this time, the actual time-domain rotation phase of the transmitting antenna unit can be obtained by superimposing the time-domain phase waveform of the virtual main shaft and the corresponding time-domain phase difference waveform of each transmitting antenna unit, thereby forming the complete time-domain rotation motion waveform y=at+30° of the transmitting antenna unit. The local coordinate system refers to the coordinate system that is deflected relative to the global coordinate system as shown in Figure 1 .

[0053] The processors of each transmitting antenna unit need to be time-synchronized, which can be achieved by wired or wireless means. The wireless synchronization method includes using an external synchronization signal for global clock calibration, or transmitting an internal synchronization signal between the processors of the transmitting antenna units to achieve local time consistency, thereby ensuring the phase coordination and data timing alignment of the transmitting array operation.

[0054] The external synchronization signal can come from a central control center, a satellite, etc. The switching of the initial phase group is achieved by a smooth phase change curve. When the ASK modulation amplitude needs to be switched, the controller adjusts the time-domain phase difference waveform of each transmitting antenna unit, so that the initial phase group of the transmitting array is smoothly switched between the value corresponding to the focusing state and the value corresponding to the non-focusing state of the magnetic field energy at the target receiving point. The phase smooth curve refers to the fact that due to mechanical movement restrictions, the phase switching cannot be completed instantaneously, but through a changing process. For example, in PLC control, a S-shaped curve command can be used to smoothly change the phase to the set target phase.

[0055] The initial phase of each transmitting antenna unit in the focusing state is a group of preferred initial phases calculated based on the target receiving point. This group of preferred initial phases makes the signal magnetic field energy radiated by the transmitting array focus at the target receiving point. The calculation of the preferred initial phase is the same as any one of embodiments 1-2. By Figure 5 It can be seen that when the transmitting array focuses on the target receiving point, the projection point of the receiving point in the plane where the magnetization vectors of each transmitting antenna unit are approximately coplanar is P, and the magnetic induction intensity modulus value at the position point Q which is centrally symmetric with the projection point P in the plane and takes the geometric center of the transmitting array as the center of symmetry is significantly suppressed compared with the magnetic induction intensity modulus value when the symmetric position Q is focused.

[0056] The specific implementation approach 1 of the non-focusing state is that each transmitting antenna unit starts from a group of preferred initial phases calculated based on a new focusing point position different from the target receiving point, and rotates the new focusing point at the same angular frequency. The new focusing point is preferably the symmetric point Q of the projection point P of the new focusing point on the plane where the magnetization directions of each transmitting antenna unit are approximately coplanar with respect to the geometric center of the transmitting array. The new focusing point is preferably the symmetric point because for any receiving point, focusing on the symmetric point can stably make the magnetic induction intensity modulus value at the receiving point change significantly, so that the receiving point presents an obvious non-focusing state.

[0057] The specific implementation approach 2 of the non-focusing state is that each transmitting antenna unit randomly selects a group of initial phases and rotates at the same angular frequency. The third specific implementation approach of the non-focusing state is that the initial phase of a part of the transmitting antenna units is still a set of preferred initial phases, and the initial phase of another part of the transmitting antenna units is increased or decreased by 180° compared with the set of preferred initial phases, and each transmitting antenna unit rotates at the same angular frequency; The fourth specific implementation approach of the non-focusing state is that each transmitting antenna unit rotates at an angular frequency that is not completely consistent starting from a set of initial phases; The servo control layer outputs a mechanical control signal according to the motion instruction, which means that the servo driver generates a mechanical control signal, such as a three-phase current of a brushless motor, through a servo control algorithm, such as a PID control algorithm, according to the motion instruction from the processor, so as to control the rotating motion power device to complete the rotating motion consistent with the motion instruction; The rotating motion power device of the mechanical motion layer can be a servo motor or other rotating actuator; The mechanical motion layer also includes an outer frame, a connector, a bearing, and an electromagnetic shielding device, which ensures that the rotating motion power device can drive the permanent magnet to complete the rotating motion synchronously; The outer frame fixes each execution unit and keeps the overall structure stable, and can be made of synthetic resin, aluminum alloy, or other materials with high strength; The connector is used to realize the transmission between the rotating motion power device and the permanent magnet, and can be a shaft coupling or a Y-shaped connector, wherein the shaft coupling can be a plum blossom coupling or a diaphragm coupling; The bearing is used for non-contact fixation of the rotating part and the outer frame; The electromagnetic shielding device is used to reduce the influence of the permanent magnet on the rotating motion power device (such as a servo motor), and can be made of a material with high magnetic permeability, such as permalloy, and can semi-enclose or fully enclose the rotating motion power device.

[0058] When the receiving end implements ASK amplitude shift keying demodulation, the magnetic induction intensity modulus can be mapped to bit information in the following ways: The first way is that the receiving end calculates the theoretical magnetic induction intensity modulus of the transmitting array at the target receiving point in the focusing radiation mode and multiple non-focusing radiation modes according to the position information of each receiving end, the position information of each transmitting antenna unit, and the residual magnetism intensity of the permanent magnet. The receiving end selects a decision threshold between each set of adjacent theoretical magnetic induction intensity modulus, and the decision threshold is preferably set as the middle value between the adjacent theoretical magnetic induction intensity modulus. All decision thresholds are taken as segmentation points to divide the spatial magnetic induction intensity modulus into multiple decision intervals corresponding to different bit information. The magnetic induction intensity modulus is mapped to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus belongs. Mode two: the transmitting array switches the focusing radiation mode and the plurality of non-focusing radiation modes in a predetermined order before sending the effective data, the receiving end selects a decision threshold between the adjacent magnetic induction intensity modulus values of each group of received values, the decision threshold is preferably set as the intermediate value between the adjacent theoretical magnetic induction intensity modulus values, and all decision thresholds are taken as the segmentation points to divide the spatial magnetic induction intensity modulus values into a plurality of decision intervals corresponding to different bit information respectively; when the transmitting array sends the effective data, the receiving end maps the magnetic induction intensity modulus value to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus value belongs.

[0059] As shown in Figure 6 the ASK amplitude shift keying modulation waveform, the transmitting antenna array is switched between the focusing state and the different non-focusing states, the magnetic induction intensity modulus values at the target receiving points are different, and different magnetic induction intensity modulus values can be mapped to different bits.

[0060] Embodiment 4: The embodiment provides a downlink multi-user communication method based on a mechanical antenna distributed group array. The group array mode of the mechanical antenna array and the position of the target receiving point are the same as any one of embodiments 1-2.

[0061] As shown in Figure 4 the communication interface of the motion loading layer receives the coordinates of each target receiving point, the transmission bits and the corresponding transmission rate of each target receiving point, the ASK amplitude shift keying modulation mode, and the specific transmission start time of each target receiving point sent by the general control center, the motion loading layer performs rotation motion calculation to generate motion instructions capable of switching the focusing / non-focusing state of the mechanical antenna array to different target receiving points, the servo control layer outputs the corresponding mechanical control signal according to the motion instructions generated by the motion loading layer and transmits it to the mechanical motion layer, so that the rotating motion power device accurately completes the specified rotating motion according to the motion instructions.

[0062] The communication interface of the motion loading layer can receive signals from the general control center through wired or wireless communication mode; The rotation motion calculation of the motion loading layer, specifically, setting a virtual main shaft in the form of software in the processor, generating a complete ASK modulation waveform with initial phase 0 as the time domain phase waveform of the virtual main shaft according to the transmission bit information and the corresponding transmission rate of each target receiving point, the ASK amplitude shift keying modulated carrier frequency, and the specific transmission start time of each target receiving point; the processor calculates the corresponding different initial phase groups of the signal magnetic field energy radiated by each transmitting antenna unit in the focusing state and in various non-focusing states according to the coordinates of each target receiving point and the transmission bits and other information, and maps them to the local coordinate system of each rotating motion power device; then according to the transmission rate, in the time period of transmitting bit information to different target receiving points, each transmitting antenna unit is switched to a corresponding group of preferred initial phases, and the time domain phase difference waveform of each transmitting antenna unit is output; each transmitting antenna unit combines the time domain phase difference waveform with the time domain phase waveform of the virtual main shaft into a complete time domain rotating motion waveform, and uses it as a motion instruction. The local coordinate system refers to the coordinate system created with the 0 phase point of the rotating motion power device as the X axis and deflected relative to the global coordinate system as shown in Figure 1

[0063] Time synchronization is required between the processors of each transmitting antenna unit, which can be achieved in a wired or wireless manner. The wireless synchronization method includes using an external synchronization signal for global clock calibration, or transmitting an internal synchronization signal between the processors of the transmitting antenna units to achieve local time consistency, thereby ensuring the phase coordination and data timing alignment of the transmitting array operation.

[0064] The external synchronization signal can come from a central control center, a satellite, etc. The switching method of the preferred initial phase group is to use a phase change smooth curve to switch the time domain phase difference waveform of each transmitting antenna unit from the preferred initial phase group of the previous target receiving point to the preferred initial phase group of the next target receiving point when the target receiving point needs to be switched. The focusing of the transmitting antenna array on different target receiving points corresponds to a group of preferred initial phases of each transmitting antenna unit, and the preferred initial phase groups corresponding to different target receiving points are different. The calculation method of the preferred initial phase is the same as any one of embodiments 1-2. The way for each target receiving point to determine whether it is focused is that each target receiving point measures the magnetic induction intensity modulus value received by itself in real time during system communication; when the difference between the measured magnetic induction intensity modulus value and the corresponding magnetic induction intensity modulus value of the target receiving point in the focusing state does not exceed a preset threshold within a certain time period, it is determined that the target receiving point is in the focused state within the time period.

[0065] ​The threshold value can be set by comparing the magnetic induction intensity modulus of the target receiving point when it is focused with the maximum value of the magnetic induction intensity modulus of the target receiving point when other receiving points are focused by the system, and the threshold value is a value not exceeding the difference between the two values.

[0066] The magnetic induction intensity modulus of each target receiving point when it is focused can be obtained by the following methods: Method one: each target receiving point obtains the magnetic induction intensity modulus when it is theoretically focused according to its own position information, the position information of each transmitting antenna unit and the residual magnetic intensity of the permanent magnet, and takes it as the magnetic induction intensity modulus when it is focused; Method two: the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in the process, and each target receiving point takes the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus when it is focused; The magnetic induction intensity modulus of each target receiving point when other receiving points are focused can be obtained by the following methods: Method one: the magnetic induction intensity modulus of each target receiving point when other receiving points are focused is obtained according to the position information of all receiving points, the position information of each transmitting antenna unit and the residual magnetic intensity of the permanent magnet, and is taken as the magnetic induction intensity modulus of each target receiving point when other receiving points are focused; Method two: the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in the process, and each target receiving point takes the magnetic induction intensity modulus other than the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus of each target receiving point when other receiving points are focused; The servo control layer outputs mechanical control signals according to motion instructions, which means that the servo driver generates mechanical control signals such as three-phase current of a brushless motor through a servo control algorithm such as PID control algorithm according to motion instructions from the processor, so as to control the rotating motion power device to complete the rotating motion consistent with the motion instructions; The rotating motion power device of the mechanical motion layer can be a servo motor or other rotating actuator; The mechanical motion layer also includes an outer frame, a connector, a bearing, an electromagnetic shielding device and the like to ensure that the rotating motion power device can drive the permanent magnet to complete the rotating motion synchronously; The outer frame fixes each actuator and keeps the overall structure stable, and can be made of high-strength materials such as synthetic resin and aluminum alloy; The connector is used to realize the transmission between the rotating motion power device and the permanent magnet, and can be a shaft coupling and a Y-type connector, wherein the shaft coupling can be a plum blossom shaft coupling or a diaphragm coupling to realize transmission; Bearings are used for non-contact fixing of rotating parts to the outer frame; Electromagnetic shielding devices are used to reduce the influence of permanent magnets on rotary motion power devices (such as servo motors). They can be made of materials with high magnetic permeability, such as permalloy, and can partially or fully surround the rotary motion power device.

[0067] Figure 5 This indicates that if the projections of two points onto a plane in which the magnetization vectors of each transmit antenna element are approximately coplanar are symmetrical about the geometric center of the transmit array, then these two points exhibit good downlink multi-user reception characteristics and can be considered as preferred downlink multi-user reception locations.

[0068] like Figure 7 The downlink multi-user communication waveform shown is such that each target receiving point is focused during reception, the magnetic flux density magnitude is the theoretical maximum value, and different magnetic flux density magnitudes are mapped to different bits when receiving signals.

[0069] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0070] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for low frequency communication based on a mechanical antenna distributed group array, characterized in that, The transmitting array composed of multiple rotary permanent magnet mechanical antenna units sends signals to a target receiving point, the magnetization vectors of all the transmitting antenna units are approximately coplanar in the same plane, each transmitting antenna unit rotates at the same angular frequency from a set initial phase at different time instants, and the magnetic field energy of the signals transmitted in different time periods is in a focused state or an unfocused state at the target receiving point.

2. The method according to claim 1, wherein, The focused state refers to that each transmitting antenna unit rotates at the same angular frequency from a set of preferred initial phases calculated based on the position of the target receiving point, so that the radiated signal magnetic field energy is concentrated and enhanced at the target receiving point. The unfocused state is realized by the following methods: each transmitting antenna unit rotates at the same angular frequency from a set of preferred initial phases calculated based on the positions of other receiving points, or each transmitting antenna unit rotates at the same angular frequency from a set of random initial phases, or part of the transmitting antenna units rotate at the same angular frequency from a set of preferred initial phases calculated based on the position of the target receiving point, and the remaining transmitting antenna units rotate at the same angular frequency from phases increased or decreased by 180° with respect to the set of preferred initial phases; or each transmitting antenna unit rotates at an angular frequency that is not completely consistent with the set of initial phases.

3. The method according to claim 2, wherein, The set of preferred initial phases is determined by the following steps: Step one: taking the plane in which the magnetization directions of each transmitting antenna unit are approximately coplanar as a reference plane, each transmitting antenna unit obtains a target azimuth angle of a projection of a target receiving point on the reference plane according to its own coordinates on the reference plane ; Step two: define a uniform reference azimuth Each transmit antenna unit calculates the target azimuth and the angle between the target azimuth and the reference azimuth Step three: each transmit antenna unit uses the calculation formula of the optimal beam forming criterion The preferred initial phase of each transmit antenna unit is calculated If the included angle corresponding to a certain transmit antenna unit is located in a specific interval, the preferred initial phase of the transmit antenna unit is added or subtracted by 180°, and the range of the specific interval is ; Step four: Preferred initial phase for each transmit antenna element Add or subtract 360° individually, or to the preferred initial phase for all transmit antenna elements Add or subtract any value collectively, the result is still the preferred initial phase.

4. The method according to claim 1, wherein, According to whether the signal magnetic field energy radiated by the transmitting array is in a focused state or multiple unfocused states at the position of the target receiving point, the transmitting array is switched between multiple signal radiation modes to dynamically change the magnetic induction intensity modulus at the target receiving point, thereby realizing ASK amplitude shift keying modulation; When the receiving end realizes ASK amplitude shift keying demodulation, the magnetic induction intensity modulus can be mapped to bit information by the following methods: Method one: the receiving end calculates the theoretical magnetic induction intensity modulus at the target receiving point of the transmitting array in the focused radiation mode and multiple unfocused radiation modes according to the position information of each receiving end, the position information of each transmitting antenna unit, and the residual magnetization intensity of the permanent magnet; the receiving end selects a decision threshold between each set of adjacent theoretical magnetic induction intensity modulus values, divides the spatial magnetic induction intensity modulus into multiple decision intervals corresponding to different bit information by taking all the decision thresholds as division points, and maps the magnetic induction intensity modulus to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus belongs; Method two: the transmitting array switches the focused radiation mode and multiple unfocused radiation modes in a predetermined order before transmitting valid data, the receiving end selects a decision threshold between each set of adjacent magnetic induction intensity modulus values received, and divides the spatial magnetic induction intensity modulus into multiple decision intervals corresponding to different bit information by taking all the decision thresholds as division points; When the transmitting array transmits valid data, the receiving end maps the magnetic induction intensity modulus to the corresponding bit information according to the decision interval to which the received magnetic induction intensity modulus belongs.

5. The method according to claim 1, wherein, By switching the radiation signal of the transmitting antenna array in different time periods, the magnetic field energy is focused at different target receiving points, and each target receiving point receives information when it determines that the magnetic field energy is focused at its location, thereby realizing downlink multi-user communication. The manner in which each target receiving point determines that the magnetic field energy is focused at its location is that each target receiving point measures the magnetic induction intensity modulus received by itself in real time during system operation; when the deviation between the measured magnetic induction intensity modulus and the reference magnetic induction intensity modulus corresponding to the expected magnetic field energy focusing state of the target receiving point is not greater than a preset threshold in a time period, it is determined that the magnetic field energy is focused at the location of the target receiving point in the time period. The threshold is set by comparing the magnetic induction intensity modulus of the target receiving point in the magnetic field energy focusing state with the maximum value of the magnetic induction intensity modulus at the target receiving point when the system focuses the magnetic field energy on other receiving points, and the threshold is not greater than the difference between the two values. The magnetic induction intensity modulus when the magnetic field energy is focused can be obtained in the following manner: Manner one: each target receiving point obtains the theoretical magnetic induction intensity modulus when the transmitting array focuses on the receiving point according to its own location information, the location information of each transmitting antenna unit, and the residual magnetism of the permanent magnet, and takes it as the magnetic induction intensity modulus when the magnetic field energy is focused; Manner two: the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in this process, and takes the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus when the magnetic field energy is focused. The magnetic induction intensity modulus of each target receiving point when the magnetic field energy is focused on other receiving points can be obtained in the following manner: Manner one: the theoretical magnetic induction intensity modulus of each target receiving point when the magnetic field energy is focused on other receiving points is obtained according to the location information of all receiving points, the location information of each transmitting antenna unit, and the residual magnetism of the permanent magnet, and is taken as the magnetic induction intensity modulus of each target receiving point when the magnetic field energy is focused on other receiving points; Manner two: the transmitting array focuses on each target receiving point in turn before sending specific information to each target receiving point, and each target receiving point obtains the change of the magnetic induction intensity modulus in this process, and takes the magnetic induction intensity modulus other than the maximum magnetic induction intensity modulus as the magnetic induction intensity modulus of each target receiving point when the magnetic field energy is focused on other receiving points.

6. A mechanical antenna based distributed array low frequency communication device, adapted to any of the mechanical antenna based distributed array low frequency communication methods of claims 1-5, characterized in that, The device includes a general control center and a plurality of transmitting antenna units, and the general control center is equipped with a communication link with each transmitting antenna unit for sending target receiving point coordinates, transmission bits, transmission rates, modulation modes, and transmission start times to each transmitting antenna unit. Each transmitting antenna unit adopts a layered electromechanical architecture design, which is composed of a mechanical movement layer, a servo control layer, and a movement loading layer, and each layer cooperates with each other to make each transmitting antenna unit cooperatively emit signals as needed.

7. The distributed group array low frequency communication device based on mechanical antenna according to claim 6, characterized in that, The mechanical movement layer comprises one or more mechanical rotary movement power devices, each rotary movement power device being connected to a permanent magnet through a connecting device; The rotary movement power device can be an electric motor; The connecting device is composed of an outer frame, a connector, a bearing and an electromagnetic shielding device; The outer frame is used to fix each execution unit and keep the overall structure stable; The connector is used to realize the transmission between the rotary movement power device and the permanent magnet; The bearing is used to non-contact fix the rotating part and the outer frame; The electromagnetic shielding device is used to reduce the influence of the permanent magnet on the rotary movement power device; The permanent magnet is composed of one or more small permanent magnets.

8. The distributed group array low frequency communication device based on mechanical antenna according to claim 6, characterized in that, The servo control layer comprises a servo driver, which is used to convert the movement instruction into a mechanical control signal and transmit it to the mechanical movement layer, so that the rotary movement power device accurately completes the specified rotary movement according to the movement instruction.

9. The distributed group array low frequency communication device based on mechanical antenna according to claim 6, characterized in that, The movement loading layer comprises a communication interface and a processor, the communication interface is used to receive the target receiving point coordinates, transmission bits, transmission rate, modulation mode and transmission start time and other information sent by the general control center, and the processor calculates the time-domain rotary movement waveform of the permanent magnet, i.e. the movement instruction, according to the above information and transmits it to the servo control layer; The calculation process of the time-domain rotary movement waveform of the permanent magnet by the processor comprises the calculation of the preferred initial phase or other initial phase, the mapping of the initial phase on the local coordinate system of each rotary movement power device, and the waveform deduction according to the modulated carrier frequency; the local coordinate system refers to the coordinate system deviated from the global coordinate system by taking the 0 phase point of the rotary movement power device as the X axis; The time synchronization between the processors of each transmitting antenna unit is realized in a wired or wireless manner, the wireless synchronization manner comprises using an external synchronization signal to calibrate the global clock, or transmitting an internal synchronization signal between the processors of the transmitting antenna units to realize the local time consistency.

10. A mechanically antenna based distributed group array low frequency communication system, characterized in that, The system comprises the mechanical antenna-based distributed array low-frequency communication device of claim 6 and a receiving device for receiving the radiated signal; The mechanical antenna-based distributed array low-frequency communication device is used to realize the transmission of signals; The receiving device is used to realize signal receiving and processing, and the process of receiving and processing comprises receiving, synchronizing, amplifying, analog filtering, analog-digital conversion, digital filtering, judging and decoding the signal.

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