Extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method

Abstract

The present application relates to an extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method, the device includes a controller, an antenna module including an antenna body, an excitation unit and a mutual induction unit, and an analog-to-digital conversion module, the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is in an excitation state and a mutual induction state respectively, when the antenna module is in an excitation state, the controller obtains data to be transmitted, and converts the data to be transmitted into an excitation signal according to the encoding rule of the extremely low frequency pulse sequence, and transmits the excitation signal to the excitation unit, so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body, when the antenna module is in a mutual induction state, the controller receives an induction signal through the antenna body, and analyzes the received data in the induction signal according to the encoding rule of the extremely low frequency pulse sequence, thereby realizing the excitation and mutual induction process of the device. The device is applied to realizing bidirectional communication between inside and outside in a shielded area, and can improve the quality of data transmission.

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application filed with the State Intellectual Property Office on February 6, 2023, bearing application number 202310063774.8 and entitled "Extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of magnetically excited mutual induction, and more particularly to an extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method. [Background technology]

[0003] Extremely low frequency (EFF) is a radio wave with a frequency between 3 Hz and 30 Hz and a wavelength between 100,000 and 1,000,000 kilometers. EFF signals can penetrate media such as seawater, rock, and metal, and are used in fields such as resource exploration, earthquake prediction, drilling surveys, and submarine communications. EFF electromagnetic waves have low propagation loss, with atmospheric attenuation of less than 1 dB per thousand kilometers.

[0004] Fluxgate sensors measure weak magnetic fields by utilizing the nonlinear relationship between the magnetic induction strength of a high-permeability core and the magnetic field strength when the measured field is saturated with an AC magnetic field. Fluxgate sensors, also known as magnetometers, consist of a probe and an interface circuit. Compared to other magnetic measuring instruments, fluxgate sensors offer high resolution, the ability to measure weak magnetic fields over a wide range, high reliability, simplicity, cost-effectiveness, and durability. The main research area for extremely low frequencies is eddy current inspection. Eddy current inspection nondestructively evaluates conductive materials and their specific performance by measuring changes in induced eddy currents within the test object. It is used for flaw detection, material screening, thickness measurement, dimensional measurement, and physical quantity measurement (e.g., radial amplitude, axial displacement, and motion trajectory measurement).

[0005] Extremely low frequency signals can be used to convert magnetic field strength into electrical signals and analyze them, taking full advantage of their transmission characteristics, and are used for flaw detection, thickness measurement, and motion trajectory detection, but they cannot realize two-way communication between the inside and outside of a shielded area. Summary of the Invention [Problem to be solved by the invention]

[0006] The present application provides an extremely low frequency electromagnetic wave bidirectional magnetic sensing device to solve the problem of not being able to realize bidirectional communication between the inside and outside of a shielded area. [Means for solving the problem]

[0007] In order to solve the above problems, in a first aspect, the extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to the present application comprises a controller, an antenna module including an antenna body, an excitation unit, and a mutual induction unit, and an analog-to-digital conversion module, wherein the controller is connected to the antenna module via the analog-to-digital conversion module, the antenna body has a solenoid structure formed by winding a conductor multiple times, and the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is in an excitation state and a mutual induction state, respectively; The controller When the antenna module is in an excited state, obtain data to be transmitted, convert the data to be transmitted into an excitation signal according to the encoding rule of the extremely low frequency pulse sequence, and send the excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body; when the antenna module is in a mutual induction state, receive the induction signal through the antenna body; configured to analyze received data within the induced signal according to an encoding rule of the extremely low frequency pulse sequence; The coding rule of the extremely low frequency pulse sequence represents the data to be transmitted by the number of symbol packets and / or the position and / or pulse count of null symbols; The induction signal is a digital signal generated by induction of the antenna body and converted by the analog-to-digital conversion module.

[0008] In some embodiments, the data to be transmitted or received is an n-ary data group, where n is an integer greater than one.

[0009] In some embodiments, the extremely low frequency electromagnetic wave bidirectional magnetic sensing device further includes an active filter module for processing the extremely low frequency radio electromagnetic wave mutual induction signal, the active filter module including a narrowband bandpass filter unit for performing frequency selection on the induced signal, and the narrowband bandpass filter unit has one end connected to the antenna body and the other end connected to the analog-to-digital conversion module.

[0010] In some embodiments, the active filter module further comprises a double notch unit for suppressing interference signals of different frequencies, the double notch unit being connected at one end to the narrowband bandpass filter unit and at the other end to the analog-to-digital conversion module.

[0011] In some embodiments, the controller further comprises: determining a symbol packet type, including valid and invalid symbol packets, by the pulse count; If the pulse count does not reach the standard value, the symbol packet type is determined to be an invalid symbol packet; When the pulse count reaches a standard value, the symbol packet type is determined to be a valid symbol packet; It is configured to discard or re-receive invalid symbol packets.

[0012] In some embodiments, the antenna body includes a magnetic core made of Permalloy material.

[0013] In some embodiments, the antenna module further comprises an upper PMOS and a lower NMOS, where the upper PMOS and the lower NMOS form a half-bridge circuit for controlling the antenna body.

[0014] In some embodiments, the antenna module further comprises a magnetic reset diode connected in parallel with the antenna body for completing a magnetic reset when the antenna body is switched between the excited state and the mutual induction state.

[0015] In some embodiments, the analog-to-digital conversion module comprises a gate resistor, a gate-source resistor, a lower NMOS, a pull-up resistor, a current-limiting resistor, a high-speed optocoupler, and a reverse clamp diode; The induced signal is divided by the gate resistor and the gate-source resistor to control the on / off of the lower NMOS. The pull-up resistor is used to remove the floating voltage when the bottom NMOS is turned off, The reverse clamp diode is used to prevent breakdown of the infrared LED due to the induced voltage generated by the parasitic inductance when the lower NMOS is turned off.

[0016] A method for extremely low frequency electromagnetic wave bidirectional magnetic sensing according to a second aspect is applied to an extremely low frequency electromagnetic wave bidirectional magnetic sensing device including a controller, an antenna module including an antenna body, an excitation unit, and a mutual induction unit, and an analog-to-digital conversion module; acquiring data to be transmitted when the antenna module is in an excited state; converting the data to be transmitted into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence; sending an excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body; receiving an induction signal through the antenna body when the antenna module is in a mutual induction state; analyzing the received data in the induced signal according to the coding rule of the extremely low frequency pulse sequence; The coding rule of the extremely low frequency pulse sequence represents the data to be transmitted by the number of symbol packets and / or the position and / or pulse count of null symbols; The induction signal is a digital signal generated by induction of the antenna body and converted by the analog-to-digital conversion module. [Effects of the Invention]

[0017] According to the above technical configuration, the present application provides an extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method, the device comprising: a controller; an antenna module including an antenna body, an excitation unit, and a mutual induction unit; and an analog-to-digital conversion module, the controller is connected to the antenna module via the analog-to-digital conversion module, the antenna body has a solenoid structure formed by winding a conductor multiple times, the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is respectively in an excited state and a mutual induction state, wherein the controller, when the antenna module is in an excited state, obtains data to be transmitted and outputs an extremely low frequency pulse. The apparatus is configured to convert data to be transmitted into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence, transmit the excitation signal to the excitation unit so that the excitation unit is activated to generate an excitation electromagnetic wave in the antenna body, receive an induction signal via the antenna body when the antenna module is in a mutual induction state, and analyze the received data in the induction signal according to an encoding rule of an extremely low frequency pulse sequence, the encoding rule of the extremely low frequency pulse sequence representing the data to be transmitted as a number of symbol packets and / or a position of a null symbol and / or a pulse count, the induction signal being a digital signal generated by induction in the antenna body and converted by an analog-to-digital conversion module. This apparatus is applicable to realizing two-way communication between inside and outside a shielded area and can improve the quality of data transmission. [Brief explanation of the drawings]

[0018] In order to more clearly explain the technical configuration of the present application, the drawings necessary for the embodiments will be briefly described below, and those skilled in the art can derive other drawings from these drawings without any creative efforts. [Figure 1] FIG. 1 is a first schematic diagram of an extremely low frequency antenna module. [Figure 2] FIG. 2 is a second schematic diagram of an extremely low frequency antenna module. [Figure 3] FIG. 2 is a schematic diagram of communication between a master station and a slave station. [Figure 4] FIG. 2 is a schematic diagram of a narrow-band bandpass filter unit. [Figure 5] FIG. 2 is a schematic diagram of a first notch unit. [Figure 6] FIG. 10 is a schematic diagram of a second notch unit. [Figure 7] FIG. 2 is a schematic diagram of an analog-to-digital conversion module. [Figure 8] FIG. 1 is a schematic diagram of the identification of extremely low frequency symbol sequences and pulse sequences. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following detailed description of the embodiments is provided by way of example only, and examples thereof are shown in the drawings. When the following description refers to the drawings, the same numbers in different drawings refer to the same or similar elements unless otherwise specified. The embodiments described in the following examples do not represent all embodiments consistent with the present application, but are merely examples of systems and methods consistent with some aspects of the present application, as detailed in the claims.

[0020] In order to more easily understand the technical configuration of the embodiments of the present application, before describing specific implementation forms of the embodiments of the present application, some terms in the technical field to which the embodiments of the present application belong will be briefly explained.

[0021] Extremely low frequency: Extremely low frequency is radio waves with a frequency between 3 Hz and 30 Hz and a wavelength between 100,000 kilometers and 1,000,000 kilometers.

[0022] Solenoid: A solenoid is a conductor wound with multiple turns, which may be hollow or may have a metal core inside. When a current flows through the conductor, a uniform magnetic field is generated inside the solenoid.

[0023] Magnetic core: A magnetic core is a magnetically conductive material placed in the magnetic circuit of an induction coil to increase the magnetic induction strength of an electromagnet.

[0024] Excitation: Excitation provides an operating magnetic field to electrical devices such as generators that operate on the principle of electromagnetic induction.

[0025] Coil: A coil is a wire wound, usually in a circular shape, and is used in motors, inductances, transformers, loop antennas, etc.

[0026] Dotted end: When the winding directions of the primary coil and secondary coil are the same, the starting ends of both coils become dotted ends. Here, when winding the primary coil and secondary coil around a pair of sides of a rectangular core, the winding directions are defined as being the same if both conductors are inserted into the core from the observer side when winding begins.

[0027] Mutual induction: When the current in one coil changes, an induced electromotive force is generated in the adjacent coil. This phenomenon is called mutual induction.

[0028] Filter: A filter can effectively filter out a specific frequency point or frequencies other than that in a circuit, to obtain a power signal of a specific frequency or to remove power signals above a specific frequency.

[0029] Q factor: The quality factor of a filter, expressed as the ratio of the filter's center frequency F to its -3 dB bandwidth B, and indicates its ability to separate adjacent frequency components in a signal.

[0030] Optical coupler: Also known as an optical coupler, this is a device that transmits electrical signals using light as a medium, and typically consists of a light emitter (infrared light emitting diode LED) and a light receiver (photosensitive semiconductor tube, photoresistor) packaged in the same tube. When a power signal is input to the input terminal, the light emitter emits light, and when the light receiver receives the light, a photocurrent is generated and flows out from the output terminal, achieving "electric-optical-electric" control.

[0031] Pulse modulation: refers to the process by which the parameters of the pulse itself (amplitude, width, phase) are varied in response to a signal.

[0032] Pulse sequence: A pulse sequence is a pulse program consisting of RF (radio frequency, radio frequency) pulses with specific bandwidths and specific amplitudes and gradient pulses.

[0033] Digital Signal Processing: is the technology of using digital methods to analyze, transform, filter, detect, modulate, demodulate, and perform high-speed algorithms on signals.

[0034] A method for tracking and locating a pipeline mobile robot based on extremely low-frequency magnetic field signals is widely used in fields such as nondestructive detection of pipeline defects. This method for tracking and locating a pipeline mobile robot based on extremely low-frequency magnetic field signals comprises two components: a signal transmitter and a signal receiver. The robot continuously moves within the pipeline, and the signal transmitter attached to the robot continuously transmits an extremely low-frequency single-frequency magnetic field signal. The signal can penetrate the metal pipeline and soil layer to reach the signal receiver on the ground. The signal receiver performs frequency-selective amplification on the received weak signal, filters out out-of-band noise, and then performs detection and judgment based on the amplified and filtered signal to produce a judgment result. When the signal receiver detects the extremely low-frequency single-frequency magnetic field signal transmitted by the signal transmitter, it records the current time as the time the pipeline robot passed under the signal receiver, thereby realizing tracking and locating of the pipeline mobile robot.

[0035] Extremely low frequency signals can be used to convert magnetic field strength into electrical signals and analyze them, taking full advantage of their transmission characteristics, and are used for flaw detection, thickness measurement, and motion trajectory detection, but they cannot realize two-way communication between the inside and outside of a shielded area.

[0036] In order to solve the above problem, in a first aspect, referring to Figures 1 and 2, an extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to some embodiments of the present application includes a controller, an antenna module, and an analog-to-digital conversion module, the controller is connected to the antenna module via the analog-to-digital conversion module, the antenna module includes an antenna body, an excitation unit, and a mutual induction unit, the antenna body has a solenoid structure formed by winding a conductor multiple times, the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is in an excited state and a mutual induction state, respectively, wherein the controller, when the antenna module is in the excited state, obtains data to be transmitted, and outputs an extremely low frequency pulse The antenna module is configured to convert data to be transmitted into an excitation signal according to an encoding rule of the sequence, send the excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body, receive the induction signal through the antenna body when the antenna module is in a mutual induction state, and analyze the received data in the induction signal according to an encoding rule of the extremely low frequency pulse sequence, wherein the encoding rule of the extremely low frequency pulse sequence represents data to be transmitted by the number of symbol packets and / or the position and / or pulse count of null symbols, and the induction signal is a digital signal generated by the induction of the antenna body and converted by the analog-to-digital conversion module.

[0037] By switching between the excitation state and the mutual induction state, the antenna body realizes the integration of transmission and reception, and does not require separate signal switching, which is convenient, fast, and more efficient in the communication process. In some embodiments, when the antenna body is divided into two parts, a transmitting antenna and a receiving antenna, additional hardware for circuit switching is required.

[0038] In some embodiments, the antenna module further comprises a pull-up resistor R0, a gate resistor Rg2, a second gate-source resistor Rgs2, a first gate-source resistor Rgs1, a current-limiting resistor R1, and an optical coupler OP1.

[0039] For ease of understanding, please refer to Figures 3 and 8. Figure 3 is a schematic diagram of communication between a master station and a slave station, and Figure 8 is a schematic diagram of identifying extremely low frequency symbol sequences and pulse sequences. When communication with a robot in a pipeline is required, the devices are configured as a master station and a slave station, respectively, with the master station installed outside the pipeline and the slave station installed inside the pipeline. When robot monitoring is required, the controller expresses the information to be transmitted as the number of symbol packets and / or the position of the null symbol and / or the pulse count. For example, the number of symbol packets is five. Or, when robot monitoring needs to be paused, for example, the number of symbol packets is four and the position of the null symbol is third. When the robot needs to return a monitoring image, for example, the number of symbol packets is four and the position of the null symbol is second. Regarding the specific number of symbol packets, the position of the null symbol, and the pulse count, the communication protocol can be set according to actual circumstances to control the information to be transmitted. The greater the number of symbol packets, the greater the number of positions where null symbols and pulse counts can be changed, and the greater the amount of data that can be displayed, enabling more convenient communication. In Figure 3, the master station and slave stations can each include not only an antenna, but also a controller for generating data to be transmitted and analyzing the data, and the controller that controls the master station can also be considered as a higher-level system independent of the master station and slave stations.

[0040] 8, transmitting data is writing data, and receiving data is reading data. For example, when the master station transmits data, if the number of symbol packets in the data is 5 and the number of symbol packets in the data transmitted by the slave station is 0, it can be understood that when the master station is transmitting data, the slave station is not transmitting data or is receiving data. When the slave station transmits data, if the number of symbol packets in the data is 4 and the number of symbol packets in the data transmitted by the master station is 0, it can be understood that when the slave station is transmitting data, the master station is not transmitting data or is receiving data.

[0041] In some embodiments, the data to be transmitted or received is an n-ary data group, where n is an integer greater than one.

[0042] When n is 2, the data to be transmitted and the received data are binary data groups. Specifically, the time sequence of pulse counts is received based on the number of symbol packets. For example, the number of symbol packets ranges from 1 to 5, and the received pulse count ranges from 20 to 40. For valid symbol packets, the sequence of symbol packets is 2 to the power of 5 (i.e., 32 combinations), thereby diversifying the transmitted information. The 32 combinations represent 32 status data. Excluding the case where all values ​​are 0, 31 status data remain. These status data may be used for status feedback or for system commands within or outside the pipeline. For more complex systems, a carrier in the pipeline, such as a robot, may send commands to a control system outside the pipeline. To distinguish between commands and status feedback, the first symbol packet can be used as a distinguisher between commands and status information, and the other symbol packets can be used for specific information content. For example, if there is a first symbol packet, it means that it is command information, and the other symbol packets are specific commands; if the first symbol packet is in a null symbol position, it means that it is status feedback, and the other symbol packets are current carrier status information, which is convenient for users to distinguish. n can also be 16, in which case the data to be sent and the received data are hexadecimal data groups.

[0043] In some embodiments, the device further comprises an active filter module for processing extremely low frequency radio electromagnetic wave mutual induction signals, the active filter module comprising a narrow-band band-pass filter unit for performing frequency selection on the induced signals, one end of the narrow-band band-pass filter unit being connected to the antenna body and the other end being connected to the analog-to-digital conversion module.

[0044] In some embodiments, the active filter module further comprises a double notch unit for suppressing interference signals of different frequencies, the double notch unit being connected at one end to the narrowband bandpass filter unit and at the other end to the analog-to-digital conversion module.

[0045] The number of cascades of the active filter module can be selected according to the gain requirements. The active filter module selects and amplifies the induced signal, suppressing signals of different frequencies, before sending it to the analog-to-digital conversion module. Specifically, the induced signal passes through a narrowband bandpass filter unit. (See FIG. 4.) The induced signal is divided by R1_i and R2_i, then passes through R3_i, C1_i, and C2_i before being combined to obtain a gain value, a high-resistance frequency value, and a low-resistance frequency value. The induced signal then passes through a double-notch unit. (See FIGS. 5 and 6.) The double-notch unit includes a first notch unit and a second notch unit. For example, if the main frequency of the ultra-low frequency is 25 Hz, the first notch unit can achieve a band rejection of 20 to 23 Hz, and the second notch unit can achieve a band rejection of 27 to 30 Hz. Capacitors C_1A, C_2A, C_1B, and C_2B are frequency-selective capacitors at the notch center frequency. Resistors R_3A, R_5A, R_6A, R_3B, R_5B, and R_6B are used to adjust the Q factor. R3_A is also used to adjust the notch band rejection. Resistors R_1A, R_2A, R_4A, R_7A, R_8A, R_1B, R_2B, R_4B, R_7B, and R_8B correspond to the signal gain before and after the notch, respectively. OP_i, OP_1A, OP_2A, OP_3A, OP_1B, OP_2B, and OP_3B in FIGS. 4, 5, and 6 are all voltage followers for impedance matching. Here, Vin represents the power supply. In some embodiments, the number of notch units can be multiple to better suppress signals of different frequencies. Regarding the specific signal flow direction, in Figure 4, the input of the induced signal is Vi_i and the output is Vo_i, in Figure 5, the input is Vi_A and the output is Vo_A, and in Figure 6, the input is Vi_B and the output is Vo_B.

[0046] In some embodiments, the active filter module is replaced by multiple filters.

[0047] In some embodiments, the controller is further configured to determine a symbol packet type, including valid symbol packets and invalid symbol packets, according to the pulse count, determine the symbol packet type to be an invalid symbol packet when the pulse count does not reach a standard value, determine the symbol packet type to be a valid symbol packet when the pulse count reaches the standard value, and discard or re-receive the invalid symbol packet.

[0048] In Figure 8, situations like those indicated by circled numbers 1 and 2 may occur during the data transmission stage, or they may occur during the data reception process. For circled number 1, it is possible to determine whether a valid symbol packet exists based on the distance from the dead zone, and for circled number 2, it is possible to determine whether a standard value has been reached based on the pulse count. If the standard value is not reached, the symbol packet is invalid and is discarded.

[0049] In some embodiments, the antenna body includes a magnetic core made of permalloy material, which has a high magnetic permeability so as to effectively reduce eddy current losses in the magnetic core.

[0050] In some embodiments, the antenna module further comprises an upper PMOS and a lower NMOS, which form a half-bridge circuit for controlling the antenna body, and which further comprise gates g1 and g2, sources s1 and s2, drains d1 and d2, and body diodes D1 and D2.

[0051] In some embodiments, the antenna module further includes a magnetic reset diode D3 connected in parallel with the antenna body to complete magnetic reset when the antenna body switches between the excited state and the mutual induction state. The magnetic reset diode D3 can not only limit the overvoltage of the power transistor, but also remove residual energy from the magnetic core.

[0052] 1 and 2, when the antenna body is in an excited state, the signal flows in the direction of State 1 (i.e., A in the figure), passing through the upper PMOS, the antenna body (dotted end), the lower NMOS, and the reference ground in that order. When the magnetic field is reset, the signal flows in the direction of State 2 (i.e., B in the figure), passing through the antenna body (non-dotted end), the magnetic reset diode D3, and the antenna body (dotted end) in that order. When the antenna body is in a mutual induction state, the signal flows in the direction of State 3 (i.e., C in the figure), passing through the antenna body (dotted end), the active filter module, and the antenna body (non-dotted end) in that order. When the magnetic field is clamped (when the magnetic field is constant), the signal flows in the direction of State 4 (i.e., D in the figure), passing through the reference ground, the lower NMOS, the antenna body (non-dotted end), the antenna body (dotted end), the upper PMOS, and the power supply in that order. As can be seen from the signal flow, when the antenna bodies are in an excited state and mutually inductive state, they share the same antenna and perform magnetic reset and induced overvoltage clamping protection.

[0053] In some embodiments, referring to FIG. 7 , the analog-to-digital conversion module includes a gate resistor Rg3, a gate-source resistor Rgs3, a lower NMOS, a pull-up resistor R3, a current-limiting resistor R4, a high-speed photocoupler OP2, and a reverse clamp diode D4, where an induced signal is divided by the gate resistor Rg3 and the gate-source resistor Rgs3 to control the on / off of the lower NMOS, the pull-up resistor R3 is used to remove a floating voltage when the lower NMOS is turned off, and the reverse clamp diode D4 is used to prevent insulation breakdown of the infrared LED due to an induced voltage generated by parasitic inductance when the lower NMOS is turned off, and the lower NMOS further includes a gate g3, a source s3, a body diode D3, and a drain d3.

[0054] An extremely low frequency electromagnetic wave bidirectional magnetic sensing method according to some embodiments of the present application is applied to the extremely low frequency electromagnetic wave bidirectional magnetic sensing device, which includes a controller, an antenna module including an antenna body, an excitation unit, and a mutual induction unit, and an analog-to-digital conversion module; acquiring data for transmission when the antenna module is in an excited state; converting transmission data into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence; sending an excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body; receiving an induction signal through the antenna body when the antenna module is in a mutual induction state; analyzing the received data in the induced signal according to the coding rule of the extremely low frequency pulse sequence; the coding rule of the extremely low frequency pulse sequence expresses the data to be transmitted by the number of symbol packets and / or the position of null symbols and / or pulse counts; The induction signal is generated by induction of the antenna body and is a digital signal converted by an analog-to-digital conversion module.

[0055] According to the above technical configuration, this embodiment provides an extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method, the device comprising: a controller, an antenna module, and an analog-to-digital conversion module; the controller is connected to the antenna module via the analog-to-digital conversion module; the antenna module comprises an antenna body, an excitation unit, and a mutual induction unit; the antenna body has a solenoid structure formed by winding a conductor multiple times; the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is in an excited state and a mutual induction state, respectively; wherein, when the antenna module is in an excited state, the controller outputs data to be sent. The apparatus is configured to acquire data to be transmitted, convert the data to be transmitted into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence, and transmit the excitation signal to the excitation unit so that the excitation unit is activated to generate an excitation electromagnetic wave in the antenna body. When the antenna module is in a mutual induction state, the antenna body receives an induction signal, and analyzes the received data in the induction signal according to an encoding rule of an extremely low frequency pulse sequence, the encoding rule of the extremely low frequency pulse sequence representing the data to be transmitted as the number of symbol packets and / or the position of null symbols and / or the pulse count. The induction signal is a digital signal generated by the induction of the antenna body and converted by an analog-to-digital conversion module. This apparatus is applicable to realizing two-way communication between inside and outside a shielded area, and can improve the quality of data transmission.

[0056] Similar parts between the examples of the present application can be mutually referenced, and the specific embodiments mentioned above are merely examples based on the general idea of ​​the present application and do not limit the scope of protection of the present application. Those skilled in the art can understand that all other embodiments obtained based on the technical configuration of the present application without creative efforts also fall within the scope of protection of the present application.

Claims

1. An extremely low frequency electromagnetic wave bidirectional magnetic sensing device, a controller, an antenna module including an antenna body, an excitation unit, and a mutual induction unit, and an analog-to-digital conversion module; the controller is connected to the antenna module via the analog-to-digital conversion module; the antenna body has a solenoid structure formed by winding a conductor multiple times, the excitation unit and the mutual induction unit are connected to the antenna body so that the antenna module is in an excitation state and a mutual induction state, respectively; The extremely low frequency electromagnetic wave bidirectional magnetic sensing device further includes an active filter module for processing extremely low frequency wireless electromagnetic wave mutual induction signals; the active filter module comprises a narrow bandpass filter unit for performing frequency selection on the induced signal; the narrowband bandpass filter unit has one end connected to one end of the antenna body and the other end connected to one end of the analog-to-digital conversion module; The other end of the analog-to-digital conversion module is connected to the other end of the antenna body; The controller When the antenna module is in an excited state, it acquires data to be transmitted; converting the data to be transmitted into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence; Sending the excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body; When the antenna module is in a mutual induction state, it receives an induction signal through the antenna body; configured to analyze received data within the induced signal according to an encoding rule of the extremely low frequency pulse sequence; the coding rule of the extremely low frequency pulse sequence expresses the data to be transmitted by the number of symbol packets and / or the position of null symbols and / or pulse counts; The extremely low frequency electromagnetic wave bidirectional magnetic sensing device is characterized in that the induced signal is generated by induction of the antenna body and is a digital signal converted by the analog-to-digital conversion module.

2. 2. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to claim 1, wherein the data to be transmitted or the received data is an n-ary data group, where n is an integer greater than 1.

3. The active filter module further comprises a double notch unit for suppressing interference signals of different frequencies; 3. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to claim 2, wherein one end of the double notch unit is connected to the narrow bandpass filter unit and the other end is connected to the analog-to-digital conversion module.

4. When the waiting data is represented by a pulse count, the controller further determining a symbol packet type, including valid symbol packets and invalid symbol packets, based on the pulse count; If the pulse count does not reach a standard value, the symbol packet type is determined to be an invalid symbol packet; determining that the symbol packet type is a valid symbol packet when the pulse count reaches a standard value; The extremely low frequency electromagnetic wave bidirectional magnetic sensing device of claim 1 , configured to discard or re-receive the invalid symbol packets.

5. 2. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to claim 1, wherein the antenna body is provided with a magnetic core made of permalloy.

6. The antenna module further comprises an upper PMOS and a lower NMOS; 2. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to claim 1, wherein the upper PMOS and the lower NMOS form a half-bridge circuit for controlling the antenna body.

7. 2. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device of claim 1, wherein the antenna module further comprises a magnetic reset diode connected in parallel with the antenna body for completing a magnetic reset when the antenna body switches between an excited state and a mutual induction state.

8. the analog-to-digital conversion module comprises a gate resistor, a gate-source resistor, a lower NMOS, a pull-up resistor, a current limiting resistor, a high-speed photocoupler and a reverse clamp diode; the induced signal is divided by the gate resistor and the gate-source resistor to control the on / off of the lower NMOS; The pull-up resistor is used to remove the floating voltage when the lower NMOS is turned off; 2. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device of claim 1, wherein the reverse clamp diode is used to prevent dielectric breakdown of the infrared LED due to an induced voltage generated by a parasitic inductance when the lower NMOS is turned off.

9. An extremely low frequency electromagnetic wave bidirectional magnetic sensing method, comprising: an antenna module including a controller, an antenna body, an excitation unit, and a mutual induction unit; an analog-to-digital conversion module; and an active filter module, wherein the controller is connected to the antenna module via the analog-to-digital conversion module, the excitation unit and the mutual induction unit are connected to the antenna body, and the active filter module includes a narrow-band band-pass filter unit, one end of the narrow-band band-pass filter unit is connected to one end of the antenna body and the other end is connected to one end of the analog-to-digital conversion module, and the other end of the analog-to-digital conversion module is connected to the other end of the antenna body, acquiring data to be transmitted when the antenna module is in an excited state; converting the data to be transmitted into an excitation signal according to an encoding rule of an extremely low frequency pulse sequence; sending the excitation signal to the excitation unit so that the excitation unit is driven to generate an excitation electromagnetic wave in the antenna body; receiving an induction signal through the antenna body when the antenna module is in a mutual induction state; analyzing received data within the induced signal according to the encoding rule of the extremely low frequency pulse sequence; The extremely low frequency electromagnetic wave bidirectional magnetic sensing method is executed by the controller, the coding rule of the extremely low frequency pulse sequence expresses the data to be transmitted by the number of symbol packets and / or the position of null symbols and / or pulse counts; The extremely low frequency electromagnetic wave bidirectional magnetic sensing method is characterized in that the induced signal is generated by induction of the antenna body and is a digital signal converted by the analog-to-digital conversion module.

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