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 titled "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 magnetic mutual induction, and in particular to an extremely low frequency electromagnetic wave bidirectional magnetic sensing device and method. [Background technology]

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

[0004] A fluxgate sensor is a sensor that measures weak magnetic fields by utilizing the nonlinear relationship between the magnetic induction strength of a high permeability core in a measurement magnetic field under saturation excitation of an AC magnetic field and the magnetic field strength. A fluxgate sensor is also called a magnetometer and is composed of a probe and an interface circuit. Compared with other magnetic measuring instruments, a fluxgate sensor has features such as high resolution, the ability to measure weak magnetic fields over a wide range, high reliability, simplicity, economy, and high durability. The main research direction of extremely low frequencies is eddy current inspection. Eddy current inspection is used to nondestructively evaluate conductive materials and specific performance by measuring the changes in induced eddy currents in the test object, and is used for flaw detection, material selection, thickness measurement, dimensional measurement, and physical quantity measurement (e.g., measurement of radial amplitude, axial displacement, and motion trajectory).

[0005] Extremely low frequency signals can be used to convert magnetic field strength into electrical signals and analyze them, taking full advantage of their penetration characteristics, and are used for flaw detection, thickness measurement, motion trajectory detection, etc., 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 that bidirectional communication between inside and outside a shielded area cannot be realized. [Means for solving the problem]

[0007] In order to solve the above problems, in a first aspect, an extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to the present application 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 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 such that the antenna module is in an excitation state and a mutual induction state, respectively, The controller is 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 the received data in 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 of null symbols and / or the pulse count, 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 includes 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 a valid symbol packet and an invalid symbol packet 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 either discard or re-receive invalid symbol packets.

[0012] In some embodiments, within the antenna body is a magnetic core 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 includes 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 eliminate 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 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; and analyzing the received data in the induced signal according to the coding rule of the extremely low frequency pulse sequence; The coding rule for the extremely low frequency pulse sequence represents the data to be transmitted by 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 induction of the antenna body and converted by the analog-to-digital conversion module. Effect 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 obtains data to be transmitted when the antenna module is in an excited state, and outputs an extremely low frequency pulse to the antenna module. The apparatus is configured to convert the 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 driven to generate an excitation electromagnetic wave in the antenna body, receive an 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 an extremely low frequency pulse sequence, the encoding rule of the extremely low frequency pulse sequence representing the data to be transmitted in a number of symbol packets and / or a position of a null symbol and / or a pulse count, and the induction signal is a digital signal generated by the induction of the antenna body and converted by an analog-to-digital conversion module. The apparatus is applied to realizing two-way communication between inside and outside in a shielded area, and can improve the quality of data transmission. [Brief description 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. [Diagram 2] FIG. 2 is a second schematic diagram of an extremely low frequency antenna module. [Diagram 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. [Diagram 5] FIG. 4 is a schematic diagram of a first notch unit. [Figure 6] FIG. 13 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. 2 is a schematic diagram of identification of extremely low frequency symbol sequences and pulse sequences. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The following describes the embodiments in detail, examples of which 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 stated. The embodiments described in the following examples do not represent all the embodiments consistent with the present application. They 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 described.

[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 wire wound multiple times, which may be hollow or may have a metal core inside. When a current flows through the wire, 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 is the process by which an operating magnetic field is provided to electrical devices such as generators that work on the principle of electromagnetic induction.

[0025] Coil: A coil is a winding of wire, 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 the primary coil and secondary coil are wound 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 certain frequency point or frequencies other than that in a circuit, to obtain a power signal of a certain frequency or to remove power signals above a certain frequency.

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

[0030] Optical coupler: Also called an optical coupler, this is a device that transmits electrical signals using light as a medium, and usually 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 end, the light emitter emits light, and when the light receiver receives light, a photocurrent is generated, which flows out from the output end, achieving "electricity-light-electricity" control.

[0031] Pulse Modulation: refers to the process in 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] The position tracking and positioning method for pipeline mobile robots based on extremely low frequency magnetic field signals is widely used in fields such as non-destructive detection of pipeline defects. The position tracking and positioning method for pipeline mobile robots based on extremely low frequency magnetic field signals includes two parts: a signal transmitter and a signal receiver. The robot in the pipeline moves continuously, and the signal transmitter attached to the robot continuously transmits an extremely low frequency single frequency magnetic field signal. The corresponding signal can penetrate the metal pipeline and the soil layer to reach the signal receiver on the ground. The signal receiver performs frequency selective amplification on the received weak signal, filters out the out-of-band noise, and then makes a detection judgment based on the amplified and filtered signal to output 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 when the pipeline robot passed under the signal receiver, thereby realizing the position tracking and positioning of the pipeline mobile robot.

[0035] Extremely low frequency signals can be used to convert magnetic field strength into electrical signals and perform analysis by making full use of their penetration characteristics, and are used for flaw detection, thickness measurement, motion trajectory detection, etc., but they cannot realize two-way communication between the inside and outside of a shielded area.

[0036] In order to solve the above problems, in a first aspect, refer 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 excitation state and a mutual induction state, respectively, where the controller obtains data to be transmitted when the antenna module is in an excitation state, 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 extremely low frequency pulse 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 an 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, the encoding rule of the extremely low frequency pulse sequence representing data to be transmitted in 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 an analog-to-digital conversion module.

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

[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 convenience of understanding, please refer to FIG. 3 and FIG. 8. FIG. 3 is a schematic diagram of communication between a master station and a slave station, and FIG. 8 is a schematic diagram of identification of an extremely low frequency symbol sequence and a pulse sequence. When communication with a robot in a pipeline is required, the devices are respectively a master station and a slave station, the master station is provided outside the pipeline, and the slave station is provided inside the pipeline. When monitoring by the robot is required, the controller expresses the information to be transmitted in 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 monitoring by the robot needs to be suspended, for example, the number of symbol packets is four, and the position of the null symbol is the 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 the second. For the specific number of symbol packets, the position of the null symbol, and the pulse count, a communication protocol can be set according to the actual situation to control the information to be expressed. The more the number of symbol packets, the more the positions of null symbols and the positions where the pulse count can be changed, and the more data can be displayed, which can realize more convenient communication. In FIG. 3, the master station and the slave station can 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 be understood as a higher-level system independent of the master station and the slave station.

[0040] Referring to Figure 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 transmits 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 transmits 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 the pulse count is received based on the number of symbol packets, for example, the number of symbol packets ranges from 1 to 5, the received pulse count ranges from 20 to 40, and when it is a valid symbol packet, the sequence of the symbol packets is 2 to the power of 5 (i.e., 32 combinations), so that the transmitted information is diversified. The 32 combinations mean 32 status data, and except for the case where all are 0, there are 31 status data remaining, and these status data may be used for status feedback or may be used for system commands inside 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 leading symbol packet may be used as a distinguishing sign between commands and status information, and the other symbol packets may be used as 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 a null symbol position, it means that it is status feedback, and the other symbol packets are the 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 the extremely low frequency radio electromagnetic wave mutual induction signal, the active filter module comprises a narrow-band band-pass filter unit for performing frequency selection on the induced signal, one end of the narrow-band band-pass filter unit is connected to the antenna body and the other end is 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 active filter module can select the number of cascades according to the gain requirements. The induced signal is frequency selected and amplified by the active filter module, and signals of different frequencies are suppressed, and then sent to the analog-to-digital conversion module. Specifically, the induced signal passes through the narrowband bandpass filter unit. Referring to FIG. 4, the induced signal is divided by R1_i and R2_i, and then passes through R3_i, C1_i, and C2_i before being merged to obtain a gain value, a high resistance frequency value, and a low resistance frequency value. After that, the induced signal passes through the double notch unit. Referring to FIG. 5 and FIG. 6, the double notch unit includes a first notch unit and a second notch unit. For example, if the extremely low frequency is 25 Hz as the main frequency of communication, the first notch unit can realize a band rejection process of 20 to 23 Hz, and the second notch unit can realize a band rejection process of 27 to 30 Hz. Capacitors C_1A, C_2A, C_1B, and C_2B are frequency-selective capacitors at the notch center frequency point, resistors R_3A, R_5A, R_6A, R_3B, R_5B, and R_6B are used to adjust the Q value, and R3_A is also used to adjust the notch band rejection, and 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 FIG. 4, FIG. 5, and FIG. 6 are all voltage followers for impedance matching. Here, Vin represents the power supply. In some embodiments, the number of notch units can also be multiple, so that the effect of suppressing signals of different frequencies is better. 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, by 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 addition, in Fig. 8, situations like those at the circled numbers 1 and 2 may occur in the data transmission stage, and may also occur in the data reception process. For the circled number 1, it can be determined whether a valid symbol packet exists based on the distance from the dead zone, and for the circled number 2, it can be determined whether a standard value has been reached based on the pulse count; if the standard value is not reached, it is an invalid symbol packet, and the invalid symbol packet will be 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, the upper PMOS and the lower NMOS forming a half-bridge circuit for controlling the antenna body, the upper PMOS and the lower NMOS further comprising gates g1, g2, sources s1, s2, drains d1, d2 and body diodes D1, 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 is switched between the excitation state and the mutual induction state. The magnetic reset diode D3 can not only limit the overvoltage of the power transistor, but also eliminate the residual energy of 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), where the signal flows through the upper PMOS, the antenna body (dotted end), the lower NMOS, and the reference ground in that order. When the magnetism is reset, the signal flows in the direction of state 2 (i.e., B in the figure), where the signal flows 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), where the signal flows through the antenna body (dotted end), the active filter module, and the antenna body (non-dotted end) in that order. When the magnetism is clamped (when the magnetism is constant), the signal flows in the direction of state 4 (i.e., D in the figure), where the signal flows 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 in a mutual induction 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, 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 eliminate 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 a 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] According to some embodiments of the present application, there is provided an extremely low frequency electromagnetic wave bidirectional magnetic sensing method, which is applied to the extremely low frequency electromagnetic wave bidirectional magnetic sensing device, the 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 for transmission when the antenna module is in an excited state; converting data for transmission 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; and 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 in terms of 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 induction of the antenna body and converted by an analog-to-digital conversion module.

[0055] According to the above technical configuration, the present 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 the controller outputs waiting-to-transmit data to the antenna module when the antenna module is in an excited state. The apparatus is configured to obtain a signal from the antenna body, 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 driven to generate an excitation electromagnetic wave in the antenna body, receive an 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 an extremely low frequency pulse sequence, the encoding rule of the extremely low frequency pulse sequence representing data to be transmitted in a number of symbol packets and / or a position of a null symbol and / or a pulse count, and the induction signal is a digital signal generated by the induction of the antenna body and converted by an analog-to-digital conversion module. The apparatus is applied to realizing two-way communication between inside and outside in a shielded area, and can improve the quality of data transmission.

[0056] Similar parts between the embodiments of the present application can be mutually referenced, and the specific embodiments mentioned above are merely some 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 without creative efforts based on the technical configuration of the present application also belong to the scope of protection of the present application.

Claims

1. An extremely low frequency electromagnetic wave bidirectional magnetic sensing device, The antenna module includes a controller, 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 controller: When the antenna module is in an excited state, acquiring data to be transmitted; converting said to-be-transmitted data 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, the antenna module 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 in terms of 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, 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 to-be-sent data or received data is an n-ary data group, where n is an integer greater than 1.

3. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device further includes an active filter module for processing an extremely low frequency radio electromagnetic wave mutual induction signal; The active filter module includes a narrow band pass filter unit for performing frequency selection on the induced signal; The extremely low frequency electromagnetic wave bidirectional magnetic sensing device according to claim 1 , wherein one end of the narrow band pass filter unit is connected to the antenna body and the other end is connected to the analog-to-digital conversion module.

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

5. When the pulse count indicates the pending data, the controller further determining a symbol packet type including a valid symbol packet and an invalid symbol packet according to the pulse count; If the pulse count does not reach a standard value, determining that the symbol packet type is 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.

6. 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.

7. 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.

8. The extremely low frequency electromagnetic wave bidirectional magnetic sensing device of claim 1, characterized in that 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 an excited state and a mutual induction state.

9. The analog-to-digital conversion module includes 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 a gate-source resistor to control the on / off of the lower NMOS; The pull-up resistor is used to eliminate 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.

10. A method for bidirectional magnetic sensing of extremely low frequency electromagnetic waves, comprising: The present invention is applied to an extremely low frequency electromagnetic wave bidirectional magnetic sensing device including a controller, an antenna 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 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; and analyzing 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 in terms of 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, 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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