Frequency domain electromagnetic transmitting and receiving device and method based on symmetrical arrangement of double receiving coils
By employing a symmetrically arranged dual-receiving coil structure and differential processing technology, the complexity of coil compensation design in frequency domain electromagnetic detection is solved, enabling precise positioning and stable detection of underground targets, and making it suitable for complex electromagnetic environments.
Patent Information
- Application Number
- CN202511390758.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2025-11-14
AI Technical Summary
In existing frequency domain electromagnetic detection, the compensation design of dual receiving coils has stringent requirements for electrical parameters and spatial configuration accuracy, and the primary field signal cancellation effect is difficult to achieve an ideal state, affecting the detection sensitivity.
A symmetrical dual-receiving coil structure is adopted. Abnormal signals are extracted through differential processing technology, simplifying coil compensation design, reducing dependence on electrical parameters and spatial configuration, and achieving precise positioning by utilizing the relative position difference of the receiving coils.
It achieves precise positioning of underground targets, simplifies system design, reduces system complexity, improves detection stability and anti-interference capability, and is suitable for complex electromagnetic environments.
Smart Images
Figure CN120949330A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electromagnetic transceiver compensation technology, and in particular to a frequency domain electromagnetic transceiver device and method based on a symmetrical arrangement of two receiving coils. Background Technology
[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.
[0003] Frequency-domain electromagnetic method is a geophysical exploration method that detects underground targets based on the differences in conductivity and magnetic permeability between them and the surrounding medium. This technique involves applying alternating currents of different frequencies to the underground target area using a transmitting coil to generate a primary field. As the primary field propagates outward, it encounters the underground target and excites it to generate a secondary field. A receiving coil collects both the primary and secondary field signals.
[0004] Typical transceiver devices for frequency domain electromagnetic methods include Figure 1 As shown, Figure 1 (a) in the diagram represents a horizontally coplanar device. Figure 1 (b) in the diagram represents a vertically coplanar device. Figure 1 (c) in the diagram represents a vertical coaxial device. A horizontal coplanar device means that the transmitting coil and the receiving coil are located on the same horizontal plane, while a vertical coplanar device means that the transmitting coil and the receiving coil are located on the same vertical plane. In a vertical coaxial device, the centers of the transmitting coil and the receiving coil are located on the same straight line.
[0005] In the signal acquisition process of frequency domain electromagnetic sensors, the receiving coil simultaneously captures primary and secondary field signals. Among them, the intensity of the primary field signal is much greater than that of the secondary field signal, and only the secondary field signal carries effective information about underground anomalies. Therefore, how to extract the secondary field signal with high precision has become a key technical bottleneck in frequency domain electromagnetic detection.
[0006] Existing technologies primarily achieve primary field signal cancellation through two methods: coil compensation and software processing. Coil compensation technology is further subdivided into transmit compensation and receive compensation schemes. For example... Figure 2 and Figure 3 As shown, Figure 2 As a receiving compensation device, the compensation coil and the transmitting and receiving coils are located in the same plane. By adjusting the geometric parameters (coil area, number of turns) and spatial layout parameters (transmitting and receiving distance) of the compensation coil and the receiving coil, the amplitude of the induced electromotive force generated by them in a uniform space is made equal, thereby achieving effective cancellation of the primary field signal. Figure 3 The transmission compensation device includes a receiving coil, a first transmitting coil, and a second transmitting coil. It adopts a dual transmitting coil structure that is centrally located and connected in opposite directions, so that a magnetic cavity is formed in the central region of the coils, and the receiving coil is placed in this region, thus forming a compact sensor system with zero transmit and receive distance.
[0007] However, in practical applications, the aforementioned compensation devices place stringent requirements on the electrical parameters (such as resistance and inductance) and spatial configuration accuracy of the compensation coil. Furthermore, the induced voltage phase shift between the compensation coil and the transmitting or receiving coil makes it difficult to achieve ideal cancellation of the primary field signal, thus affecting the instrument's detection sensitivity.
[0008] In summary, how to simplify the design of existing coil compensation devices, reduce the dependence on the electrical parameters and spatial configuration accuracy of dual receiving coils, and achieve more accurate target detection has become an urgent problem to be solved by existing technologies. Summary of the Invention
[0009] To address the shortcomings of existing technologies, the present invention aims to provide a frequency domain electromagnetic transceiver device and method based on a symmetrical arrangement of dual receiving coils, which aims to extract the characteristic signals of underground targets through the differential principle and achieve precise positioning of underground targets.
[0010] To achieve the above objectives, the present invention is implemented through the following technical solution: The first aspect of this invention provides a frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils, comprising the following steps: The number of turns of the transmitting coil in the frequency domain electromagnetic transceiver is obtained based on the transmitting magnetic moment, and the transmitting and receiving distance of the frequency domain electromagnetic transceiver is obtained based on the mutual inductance coefficient. The receiving coil is a double receiving coil arranged symmetrically. A receiving system is used to acquire the differential signal from the frequency domain electromagnetic transceiver. The frequency domain electromagnetic transceiver is moved, and the abnormal signal is analyzed in stages based on the distance between the frequency domain electromagnetic transceiver and the target. The location of the target body is determined by analyzing the characteristics of changes in abnormal signals.
[0011] Furthermore, the specific steps for obtaining the number of turns of the transmitting coil in the frequency domain electromagnetic transceiver based on the transmitting magnetic moment, and for obtaining the transmit-receive distance of the frequency domain electromagnetic transceiver based on the mutual inductance coefficient, are as follows: Arrange frequency domain electromagnetic transceivers; Calculate the inductance, coil impedance, and transmitting magnetic moment of the transmitting coil, and set the number of turns of the transmitting coil based on the transmitting magnetic moment; The transmission and reception distance is set based on the mutual inductance effect between the transmitting and receiving coils.
[0012] Furthermore, the specific steps for moving the frequency domain electromagnetic transceiver are as follows: keep the relative positions of the transmitting coil and the dual receiving coils fixed, move the frequency domain electromagnetic transceiver to the right at a constant speed along the horizontal direction and pass through the underground target body, wherein the receiving coil located to the left of the transmitting coil is denoted as the first receiving coil, and the receiving coil located to the right of the transmitting coil is denoted as the second receiving coil.
[0013] Furthermore, based on the distance between the frequency domain electromagnetic transceiver and the target, the changes in the abnormal signal are divided into five stages: In the first stage, the distance between the frequency domain electromagnetic transceiver and the target is greater than the first threshold for the first time. In the second stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil and the first receiving coil gradually approach the underground target, and the distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target. In the third stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target. In the fourth stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is greater than the distance between the first receiving coil and the underground target. In the fifth stage, the second receiving coil and the first receiving coil gradually move away from the underground target, and the distance from the first receiving coil to the underground target is less than the distance from the second receiving coil to the underground target.
[0014] Furthermore, the specific steps for determining the location of the target object based on the characteristics analyzed by changes in abnormal signals are as follows: When the second receiving coil is moved directly above the underground target, the differential abnormal signal is at its maximum value. When the first receiving coil moves directly above the underground target, the differential abnormal signal is at its minimum value.
[0015] When the transmitting coil moves directly above the underground target, the distances between the first and second receiving coils and the underground target are equal, and the differential abnormal signal is zero.
[0016] The second aspect of the present invention provides a frequency domain electromagnetic transceiver device based on the frequency domain electromagnetic transceiver method of the first aspect with symmetrical arrangement of dual receiving coils, comprising: a transmitting coil and a receiving coil, the receiving coil including a first receiving coil and a second receiving coil, the transmitting coil being in the center, the first receiving coil and the second receiving coil being symmetrically distributed on both sides of the transmitting coil, and the transmitting coil and the receiving coil being located in the same horizontal plane, forming a horizontal coplanar structure.
[0017] Furthermore, the shapes of the transmitting and receiving coils are configured according to the requirements of different detection scenarios.
[0018] Furthermore, both the transmitting and receiving coils employ a hollow coil structure.
[0019] Furthermore, PLA material is used as the frame for both the transmitting and receiving coils.
[0020] Furthermore, the transmitting and receiving coils are made of enameled copper wire and are wound in layers, with each layer having a uniform and dense inner coil.
[0021] The above one or more technical solutions have the following beneficial effects: This invention discloses a frequency-domain electromagnetic transceiver device and method based on a symmetrical arrangement of dual receiving coils. Utilizing the relative positional difference between the two coils and an underground target, differential processing technology is employed to extract anomalous signals, thereby achieving precise positioning of the underground target. This invention significantly reduces the dependence on the electrical parameters and spatial configuration accuracy of the dual receiving coils. Furthermore, it avoids the phase synchronization problem between multi-coil systems, simplifying system design complexity. The frequency-domain electromagnetic transceiver device based on the symmetrical arrangement of dual receiving coils has a simple structure, low implementation difficulty, and significant engineering application value.
[0022] This invention solves the technical challenges of strong primary field interference and difficulty in extracting the secondary field by employing a symmetrically arranged dual-receiving coil structure. Compared with existing compensation methods, this invention eliminates the need for complex compensation design and phase calibration, features a simple structure, is easy to implement, and possesses excellent stability and anti-interference capabilities. It is particularly suitable for detecting underground anomalies in complex electromagnetic environments and has broad engineering application prospects.
[0023] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0025] Figure 1 This is a schematic diagram of a typical transceiver device using the existing frequency domain electromagnetic method. in, Figure 1 (a) in the diagram represents a horizontally coplanar device. Figure 1 (b) in the diagram represents a vertically coplanar device. Figure 1 (c) in the diagram represents a vertical coaxial device; Figure 2 For existing receiving compensation devices; Figure 3 For existing launch compensation devices; Figure 4 This is a schematic diagram showing the position of the transceiver coil in Embodiment 1 of the present invention; Figure 5 The curve showing the relationship between the emitted magnetic moment and the frequency; Figure 6 This is a schematic diagram of the equivalent circuit of the transmitter. Figure 7 This is a schematic diagram of the equivalent circuit of the receiving coil; Figure 8 This is a schematic diagram of abnormal signal changes in Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the abnormal signal amplitude results. Detailed Implementation
[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0028] Example 1: Embodiment 1 of the present invention provides a frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils, comprising the following steps: Step 1: Obtain the number of turns of the transmitting coil in the frequency domain electromagnetic transceiver based on the transmitting magnetic moment, and obtain the transmit / receive distance of the frequency domain electromagnetic transceiver based on the mutual inductance coefficient. Specifically, consider the transmitting magnetic moment and reasonably select the number of turns of the transmitting coil; consider the influence of the mutual inductance effect between the transmitting and receiving coils and reasonably set the transmit / receive distance; use a receiving system to obtain abnormal signals in the frequency domain electromagnetic transceiver.
[0029] Step 1.1: Set up the frequency domain electromagnetic transceiver.
[0030] In one specific implementation, this embodiment employs a frequency domain electromagnetic transceiver, using a "one-transmitter-two-receiver" configuration, such as... Figure 4 As shown, the system includes a transmitting coil and a receiving coil, with the receiving coils arranged symmetrically as a dual-receiving coil configuration. The receiving coils consist of a first receiving coil and a second receiving coil, which are identical. The transmitting coil is centered, and the first and second receiving coils are symmetrically distributed on either side of the transmitting coil. The receiving coil located to the left of the transmitting coil is designated as the first receiving coil, and the receiving coil located to the right is designated as the second receiving coil. Both the transmitting and receiving coils are located in the same horizontal plane, forming a horizontally coplanar structure. The shapes of the transmitting and receiving coils can be configured according to different detection scenario requirements, supporting various geometric shapes such as circular, rectangular, and elliptical. The transmitting and receiving coils employ a hollow coil structure, featuring no magnetic saturation, light weight, and wide bandwidth.
[0031] The transmitting and receiving coils use polylactic acid (PLA) as the frame. Both coils are made of enameled copper wire and are wound using a layered winding process, with each layer containing a uniformly densely wound coil. This embodiment uses a circular coil as an example. The coil parameters are shown in Table 1.
[0032] Table 1. Coil Parameters
[0033] Step 1.2: Calculate the inductance, coil impedance, and transmitting magnetic moment of the transmitting coil, and set the number of turns of the transmitting coil based on the transmitting magnetic moment.
[0034] In one specific implementation, the inductance of the circular transmitting coil can be approximated as: (1).
[0035] In the formula, For coil inductance, d is the number of turns of the coil; d is the coil diameter, in meters. h Height of the transmitting coil cross-section , Wire diameter, in meters (m); The permeability of free space, H / m.
[0036] The impedance of a circular transmitting coil can be expressed as: (2).
[0037] In the formula, For coil impedance, The coil's internal resistance is expressed in Ω. Angular frequency, in rad / s. ; The transmission frequency is expressed in Hz. The coil inductance is expressed in voltmeters (H). i This is an imaginary number. At high frequencies, the coil impedance can be approximated as the inductive reactance. .
[0038] The transmitting magnetic moment is an important parameter characterizing the ability of a coil to generate a magnetic field, and it is closely related to the transmitting current, the number of turns, and the area of the coil. At high frequencies, the transmitting magnetic moment can be approximated as: (3) In the formula, S The area of the transmitting coil, I The amplitude of the transmitting current. V Z represents the transmission voltage, and Z represents the impedance amplitude.
[0039] Limited by the power amplifier's voltage output capability, the transmit voltage V There is an upper limit. Under the conditions of a maximum output voltage of 12V and a maximum output current of 2A, for a specific-sized transmitting coil (diameter 0.1m, cross-sectional height 0.01m), the relationship between the transmitting magnetic moment and frequency under different coil turns is as follows: Figure 5 As shown.
[0040] With a constant transmission frequency and the same coil diameter, the transmitting magnetic moment is inversely proportional to the inductance. The inductance value, in turn, is non-linearly positively correlated with the number of coil turns. This means the transmitting magnetic moment is primarily controlled by the number of coil turns. At low frequencies, when the output current reaches its peak and the output voltage is not saturated, the transmitting magnetic moment increases with the number of coil turns. However, as the transmission frequency increases and the output voltage reaches its upper limit, the transmitting magnetic moment decreases with the number of coil turns.
[0041] When the transmission frequency is 2125Hz, the number of turns of the transmitting coil is designed to be 100 in order to ensure the transmission magnetic moment.
[0042] The transmitting system consists of a direct digital frequency synthesizer, a bandpass filter, a power amplifier, and a transmitting coil. Powered by a lithium battery, the generator first produces a sinusoidal voltage signal with a frequency of 2125Hz and an initial amplitude of 0.26V. This signal is then filtered by a bandpass filter to remove spurious frequency components, ensuring that the spectral energy is concentrated near the transmitting frequency. The signal is then amplified 50 times by the power amplifier, increasing the output amplitude to 13V, and finally drives the transmitting coil to achieve efficient energy transfer.
[0043] To facilitate the calculation of the transmitting current, a 1Ω external resistor is connected in series outside the transmitting coil. The voltage across the external resistor is measured to be 0.415V using an oscilloscope. The transmitting current is calculated to be 0.415A using Ohm's law (I=U / R).
[0044] Since the capacitance of the transmitting coil is much smaller than its internal resistance and inductance, it can be equivalently represented as an RL-type load. The equivalent circuit of the transmitting end is constructed using Simulink simulation software, as follows: Figure 6 As shown in the figure, the transmitted waveform was set to a sine wave, the transmission frequency was 2125Hz, and the amplitude was 13V. The simulation results show that the theoretical transmission current is 0.411A. The error between the measured result and the theoretical result is 1.1%, which verifies the reliability of the transmission system.
[0045] Step 1.3: Set the transmission and reception distance based on the mutual inductance effect between the transmitting coil and the receiving coil.
[0046] In this embodiment, due to the mutual inductance effect between the transmitting and receiving coils, the mutual inductance coefficient decreases as the transmit-receive distance increases. For a circular transmitting coil, in order to suppress mutual inductance interference, the transmit-receive distance should be no less than 10 times the radius of the transmitting coil.
[0047] When the transmit / receive distance is much larger than the coil radius, the transmit / receive distance between the transmitting and receiving coils can be approximated as: (4).
[0048] In the formula, The number of turns of the transmitting coil. The number of turns of the receiving coil. The radius of the transmitting coil, The radius of the receiving coil, M is the mutual inductance coefficient.
[0049] When the transmitting coil has 100 turns and a radius of 0.05m, and the receiving coil has 400 turns and a radius of 0.05m, the transmit-receive distance is designed to be 0.62m to reduce the influence of mutual inductance.
[0050] Step 2: Use a receiving system to acquire the differential signal from the frequency domain electromagnetic transceiver.
[0051] The equivalent circuit of the receiving coil is as follows: Figure 7 As shown, the system, equivalent to the LCR model, is a linear time-invariant second-order dynamic system composed of internal resistance, inductance, and distributed capacitance. At high frequencies, the resonance effect formed by the inductance and distributed capacitance can cause signal waveform distortion and even self-oscillation, severely limiting the stability of the detection system. To suppress such high-frequency interference, a matching resistor is connected in parallel outside the receiving coil. This component adjusts the system damping coefficient, allowing the circuit to operate in a critically damped or overdamped state, thereby improving system stability.
[0052] In one specific implementation, since the two receiving coils are identical and their distances from the transmitting coil are equal, the induced voltage amplitudes of the two receiving coils are equal under uniform spatial conditions.
[0053] The amplitude of the induced voltage in the circular receiving coil can be expressed as: (5).
[0054] In the formula, The induced voltage of the receiving coil, S The area of a single-turn coil, in units of ; Magnetic field strength, unit: A / m; The magnitude of the magnetic flux density, in Wb / ; The diameter of the circular receiving coil is in meters (m).
[0055] After synchronously acquiring the induced voltage signals of the first and second receiving coils, the induced voltages of the two receiving coils are differentially processed to obtain an abnormal signal. By analyzing the abnormal signal, the location of the underground target can be determined.
[0056] (6).
[0057] In the formula, The abnormal signal after differentiation This is the induced voltage signal of the second receiving coil. This is the induced voltage signal of the first receiving coil.
[0058] The receiving system consists of receiving coils, a bandpass filter, an operational amplifier, and a quadrature demodulator. First, the induced voltages of the two receiving coils are differentially processed to obtain the abnormal signal. Since the amplitude of the secondary field signal is only in the microvolt range, if it is directly input into the synchronous acquisition device, the signal is easily overwhelmed by noise, and the inherent noise of the coil will further degrade the signal quality. Therefore, a bandpass filter is used to suppress high-frequency interference and improve the signal-to-noise ratio. Subsequently, a first-stage amplification (300x gain) enhances the signal strength, followed by a bandpass filter to select the effective frequency band, and then a second-stage amplification (50x gain) to ensure the signal meets the requirements of subsequent processing. Finally, an orthogonal demodulator extracts the real part e and the imaginary part q of the secondary field signal.
[0059] Using the real and imaginary parts, the amplitude and phase of the abnormal signal are further calculated: (7) (8) Step 3: Move the frequency domain electromagnetic transceiver and analyze the changes in the abnormal signal in stages based on the distance between the frequency domain electromagnetic transceiver and the target.
[0060] Step 3.1: Move the frequency domain electromagnetic transceiver.
[0061] In one specific implementation, the steps for moving the frequency domain electromagnetic transceiver are as follows: keeping the relative positions of the transmitting coil and the dual receiving coils fixed, and moving the frequency domain electromagnetic transceiver to the right at a constant speed of 0.3 m / s along the horizontal direction and passing the underground target body.
[0062] Step 3.2: Divide the changes in the abnormal signal into five stages based on the distance between the frequency domain electromagnetic transceiver and the target.
[0063] In one specific implementation, such as Figure 8 As shown, during the detection process, when the transceiver moves horizontally to the right at a constant speed and passes the underground target, the abnormal signal exhibits a significant five-stage change characteristic. Specifically: In the first stage, the distance between the frequency domain electromagnetic transceiver and the target object is greater than the first threshold for the first time.
[0064] In the second stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil and the first receiving coil gradually approach the underground target, and the distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target.
[0065] In the third stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target.
[0066] In the fourth stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is greater than the distance between the first receiving coil and the underground target.
[0067] In the fifth stage, the second receiving coil and the first receiving coil gradually move away from the underground target, and the distance from the first receiving coil to the underground target is less than the distance from the second receiving coil to the underground target.
[0068] Step 4: Analyze the characteristics of the abnormal signal to determine the location of the target.
[0069] In the first stage, when the distance between the transceiver and the underground target is very far, exceeding the set first threshold, both receiving coils capture a field signal. .
[0070] In the second stage, as the transceiver moves to the right, the second receiving coil approaches the underground target first. The distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target. Gradually increase and exceed ,at this time When the second receiving coil moves directly above the underground target, the differentially differentiated abnormal signal... It is the maximum value; In the third stage, as the transceiver device continues to move to the right, the second receiving coil gradually moves away from the underground target. The size gradually decreases, while the first receiving coil gradually approaches the underground target. Gradually increase, at this time The distance gradually decreases. When the transmitting coil moves directly above the underground target, the distances between the first and second receiving coils and the underground target are equal. The abnormal signal after differentiation is zero. .
[0071] In the fourth stage, the transceiver continues to move to the right. Continuously increasing and Continuous reduction, leading to The value turns negative and its absolute value gradually increases. When the first receiving coil moves directly above the underground target, the differentially differentiated abnormal signal... It is the minimum value.
[0072] In the fifth stage, the transceiver moves further away from the underground target, and the distance from the first receiving coil to the underground target is less than the distance from the second receiving coil to the underground target. , When the transceiver is far from the underground target, both receiving coils capture the primary field signal. Reset to zero again.
[0073] Based on the above analysis, when the differentially derived abnormal signal exhibits a clear five-stage change curve, the presence of an underground target can be accurately determined. The location of the measuring point corresponding to the center zero point of this curve is the location of the underground target. (Known movement speed) v (0.3 m / s) and detection time t According to the displacement formula for uniform linear motion ( The abscissa of the underground target body is calculated.
[0074] To better demonstrate the technical effects of the above method, this embodiment is illustrated through the following specific implementation scheme: Both the transmitting and receiving coils have a circular frame made of PLA material and are wound with enameled copper wire. The transmitting coil's circular frame has an inner diameter of 0.1m and an axial height of 10mm in the winding area. The coil uses a layered winding process, with 20 turns per layer, stacked in 5 layers for a total of 100 turns. The receiving coil's circular frame has an inner diameter of 0.1m and an axial height of 17mm in the winding area, with 25 turns per layer, stacked in 16 layers for a total of 400 turns. The inductance and internal resistance parameters of the coils were measured using an LCR digital bridge at a frequency of 2000Hz and a voltage level of 1V, as shown in Table 1. Due to slight deviations in the winding process, the measured parameters of coils with the same nominal number of turns show slight fluctuations.
[0075] The fabricated coils were integrated into a frequency domain electromagnetic instrument, with the distance between the dual receiving coils and the transmitting coil both 0.62m. Field tests were conducted near a 50cm diameter manhole cover. A 5m long measuring line was laid out along a north-south direction. The instrument was held handheld and slowly moved at a constant speed from the starting point to the end point of the measuring line. The measured abnormal signal amplitude curve is shown below. Figure 9 As shown, the amplitude curve exhibits a clear five-stage variation characteristic, and the measuring point position at 6.6 seconds corresponds to the actual position of the manhole cover, verifying the reliability of this device design.
[0076] Example 2: Embodiment 2 of the present invention provides a frequency domain electromagnetic transceiver device based on the frequency domain electromagnetic transceiver method of symmetrical arrangement of dual receiving coils as described in Embodiment 1. The device includes a transmitting coil and a receiving coil. The receiving coil includes a first receiving coil and a second receiving coil. The transmitting coil is centered. The first receiving coil and the second receiving coil are symmetrically distributed on both sides of the transmitting coil. The transmitting coil and the receiving coil are both located in the same horizontal plane, forming a horizontal coplanar structure.
[0077] In one specific implementation, the shapes of the transmitting and receiving coils are configured according to the requirements of different detection scenarios. Both the transmitting and receiving coils employ a hollow coil structure. PLA material is used as the skeleton for both the transmitting and receiving coils. Enamelled copper wire is used to wind the coils, employing a layered winding process, with the coil uniformly and densely wound within each layer.
[0078] The steps involved in the above embodiment two correspond to those in embodiment one. For specific implementation details, please refer to the relevant description section of embodiment one.
[0079] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application. In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data processing device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, an optical medium, or a semiconductor medium, etc. The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils, characterized in that, Includes the following steps: The number of turns of the transmitting coil in the frequency domain electromagnetic transceiver is obtained based on the transmitting magnetic moment, and the transmitting and receiving distance of the frequency domain electromagnetic transceiver is obtained based on the mutual inductance coefficient. The receiving coil is a double receiving coil arranged symmetrically. A receiving system is used to acquire the differential signal from the frequency domain electromagnetic transceiver. The frequency domain electromagnetic transceiver is moved, and the abnormal signal is analyzed in stages based on the distance between the frequency domain electromagnetic transceiver and the target. The location of the target body is determined by analyzing the characteristics of changes in abnormal signals.
2. The frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils as described in claim 1, characterized in that, The specific steps for obtaining the number of turns of the transmitting coil in the frequency domain electromagnetic transceiver based on the transmitting magnetic moment, and for obtaining the transmit-receive distance of the frequency domain electromagnetic transceiver based on the mutual inductance coefficient, are as follows: Arrange frequency domain electromagnetic transceivers; Calculate the inductance, coil impedance, and transmitting magnetic moment of the transmitting coil, and set the number of turns of the transmitting coil based on the transmitting magnetic moment; The transmission and reception distance is set based on the mutual inductance effect between the transmitting and receiving coils.
3. The frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils as described in claim 1, characterized in that, The specific steps of moving the frequency domain electromagnetic transceiver are as follows: keep the relative positions of the transmitting coil and the dual receiving coils fixed, move the frequency domain electromagnetic transceiver to the right at a constant speed along the horizontal direction and pass through the underground target body, wherein the receiving coil located to the left of the transmitting coil is referred to as the first receiving coil, and the receiving coil located to the right of the transmitting coil is referred to as the second receiving coil.
4. The frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils as described in claim 1, characterized in that, The changes in the abnormal signal are divided into five stages based on the distance between the frequency domain electromagnetic transceiver and the target: In the first stage, the distance between the frequency domain electromagnetic transceiver and the target is greater than the first threshold for the first time. In the second stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil and the first receiving coil gradually approach the underground target, and the distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target. In the third stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is less than the distance between the first receiving coil and the underground target. In the fourth stage, the distance between the frequency domain electromagnetic transceiver and the target is less than or equal to the first threshold. The second receiving coil gradually moves away from the underground target, while the first receiving coil gradually moves closer to the underground target. The distance between the second receiving coil and the underground target is greater than the distance between the first receiving coil and the underground target. In the fifth stage, the second receiving coil and the first receiving coil gradually move away from the underground target, and the distance from the first receiving coil to the underground target is less than the distance from the second receiving coil to the underground target.
5. The frequency domain electromagnetic transceiver method based on a symmetrical arrangement of dual receiving coils as described in claim 1, characterized in that, The specific steps for determining the location of a target based on the analysis of changes in abnormal signals are as follows: When the second receiving coil is moved directly above the underground target, the differential abnormal signal is at its maximum value. When the first receiving coil moves directly above the underground target, the differential abnormal signal is at its minimum value. When the transmitting coil moves directly above the underground target, the distances between the first and second receiving coils and the underground target are equal, and the differential abnormal signal is zero.
6. A frequency domain electromagnetic transceiver device based on a frequency domain electromagnetic transceiver method with symmetrical arrangement of dual receiving coils as described in any one of claims 1-5, characterized in that, include: The system includes a transmitting coil and a receiving coil. The receiving coil includes a first receiving coil and a second receiving coil. The transmitting coil is located in the center, and the first and second receiving coils are symmetrically distributed on both sides of the transmitting coil. The transmitting coil and the receiving coil are both located in the same horizontal plane, forming a horizontal coplanar structure.
7. The frequency domain electromagnetic transceiver as described in claim 6, characterized in that, The shapes of the transmitting and receiving coils are configured according to the requirements of different detection scenarios.
8. The frequency domain electromagnetic transceiver as described in claim 6, characterized in that, The transmitting and receiving coils adopt a hollow coil structure.
9. The frequency domain electromagnetic transceiver as described in claim 6, characterized in that, The transmitting and receiving coils use PLA material as the frame.
10. The frequency domain electromagnetic transceiver as described in claim 6, characterized in that, The transmitting and receiving coils are made of enameled copper wire and are wound in layers, with each layer having a uniform and dense inner coil.