Calibration method and system for transient electromagnetic instrument

Abstract

The application discloses a kind of calibration method and system of transient electromagnetic instrument, belong to geophysical exploration technical field.The method includes: in standard test field, for multiple different sizes of launch source generation standard response data, and acquisition measured response data of the whole system of instrument to be calibrated;Contrast standard and measured data, calculate the dynamic calibration coefficient varying with time;According to the coefficient, the calibration model built in the instrument is constructed.In actual operation, the instrument obtains the dynamic calibration coefficient according to the current launch source size, if the size is not preset, it is determined by interpolation, and the collected data is corrected in real time using the coefficient.The application realizes the real-time automatic correction of the data collected by different size launch source by comprehensive calibration of the whole system, improves the data accuracy and consistency.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration technology, specifically relating to a calibration method and system for transient electromagnetic instruments. Background Technology

[0002] Transient electromagnetic methods (TEM) are geophysical approaches that detect underground electrical structures by transmitting a pulsed magnetic field into the ground and measuring the secondary attenuation field generated by induced eddy currents. Calibration is a crucial step in the quality control of TEM instruments. Existing calibration methods typically involve testing the performance of individual components of the instrument, such as the receiving coil or the receiving probe. For example, a standard magnetic field source is used to determine the sensitivity and frequency response of the receiving sensor.

[0003] In the calibration of transient electromagnetic instruments, the current common practice is to calibrate the receiving coil or receiving probe separately. This involves measuring individual technical specifications such as sensitivity, frequency response, and background noise of the receiving sensor using a standard magnetic field source or signal source to ensure the accuracy of the receiving device itself. This type of calibration treats the receiving end as an independent sensor. However, a transient electromagnetic detection system is a complete system consisting of multiple components, including the transmitting source (including the transmitting coil and transmitter), the receiving sensor, and the data acquisition and processing host. Calibrating only the receiving probe cannot reflect the impact of variations in the transmitting source size, magnetic moment differences, turn-off time distortion, and changes in transmit-receive coupling conditions on the final measurement results. In other words, the calibration of a single component cannot guarantee the consistency and comparability of the output data of the entire instrument system under different transmitting source configurations.

[0004] In transient electromagnetic exploration, to adapt to the actual needs of different detection depths and resolutions, operators often need to change the transmitter coils with different side lengths according to the target burial depth. However, changes in the transmitter size significantly affect the emitted magnetic moment, the spatial distribution of the primary field, and the turn-off time characteristics of the emitted current, leading to drastic changes in the secondary field response generated in the same underground medium. Therefore, accurate calibration of the entire instrument system must be performed considering the transmitter size to ensure the reliability of subsequent data interpretation. Summary of the Invention

[0005] The purpose of this application is to provide a calibration method and system for transient electromagnetic instruments, aiming to solve the technical problem in the prior art that it is difficult to calibrate the entire instrument system while taking into account the size of the emission source.

[0006] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a calibration method for a transient electromagnetic instrument, characterized by comprising: Obtain the background electrical parameters of the standard test field; Based on the background electrical parameters, standard transient electromagnetic response data corresponding to each of the multiple emission sources of different preset sizes are generated. Measured transient electromagnetic response data corresponding to emission sources of different preset sizes are obtained. The measured transient electromagnetic response data is used to detect the standard test field by a transient electromagnetic instrument to be calibrated. During the detection process, the transient electromagnetic instrument uses emission sources of different preset sizes. The transient electromagnetic instrument is a complete detection system including an emission source, a receiving probe, and a data acquisition host. For each preset size transmitter, the dynamic calibration coefficient of each preset size transmitter is calculated by comparing its standard transient electromagnetic response data and measured transient electromagnetic response data. Based on the dynamic calibration coefficients of multiple emission sources of different preset sizes, a calibration model is constructed and built into the instrument. The calibration model is used to perform real-time correction on the transient electromagnetic response data actually collected by the transient electromagnetic instrument.

[0007] Secondly, this application provides a transient electromagnetic instrument system, including a transmitter, a receiver probe, a data acquisition unit, and a control unit, wherein the control unit internally includes: A memory for storing a calibration model obtained by the calibration method for transient electromagnetic instruments described in the first aspect; The processor, connected to the memory, is configured to: receive the actual size of the currently used transmitter input by the user; determine the corresponding dynamic calibration coefficients from the calibration model based on the actual size; receive transient electromagnetic response data acquired by the receiving probe; and perform real-time correction on the received transient electromagnetic response data using the determined dynamic calibration coefficients.

[0008] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the calibration method for the transient electromagnetic instrument described in any one of the above.

[0009] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the calibration method for the transient electromagnetic instrument described above.

[0010] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the calibration method for the transient electromagnetic instrument described above.

[0011] According to the specific embodiments provided in this application, the following technical effects are disclosed: 1. By comprehensively calibrating the entire transient electromagnetic instrument system, including the emission source, rather than just calibrating individual components, the calibration results can truly reflect the response characteristics of the system under actual working conditions. This fundamentally solves the technical defect of "compliant components but inaccurate system" and ensures the accuracy of the data.

[0012] 2. By calculating and applying dynamic calibration coefficients that vary with the emitter size and time, it is possible to accurately quantify and compensate for turn-off time distortion and nonlinear response caused by changes in emitter size (such as changes in inductance). Compared with traditional static proportional coefficient correction, this significantly improves the accuracy of data correction, especially in the early time channels.

[0013] 3. By constructing a calibration model built into the instrument and combining it with interpolation to process transmitters of non-preset sizes, real-time and automated calibration of transmitters of any size is achieved. Operators do not need to perform additional data post-processing after changing transmitters, which greatly improves the efficiency of field operations and the intelligence level of the instrument, and enhances the comparability and consistency of data collected under different working conditions. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments 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.

[0015] Figure 1 A flowchart illustrating the calibration method for the transient electromagnetic instrument provided in this application.

[0016] Figure 2 This is a schematic diagram of the layout of the water body standard test site calibration platform in one embodiment of this application.

[0017] Figure 3 This is a graph showing the standard transient electromagnetic response data corresponding to each preset size emission source in one embodiment of this application.

[0018] Figure 4 This is a graph showing the measured transient electromagnetic response data corresponding to each preset size emission source in one embodiment of this application.

[0019] Figure 5 This is a graph showing the dynamic calibration coefficients corresponding to each preset size transmitter in one embodiment of this application.

[0020] Figure 6This is a comparison chart of measured transient electromagnetic response data before and after correction in one embodiment of this application. Detailed Implementation

[0021] 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 skilled in the art without creative effort are within the scope of protection of this application.

[0022] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] This invention provides a calibration method for transient electromagnetic instruments, aiming to solve the fundamental problem that existing calibration schemes only target individual components and cannot reflect the changes in the response characteristics of the entire system when different sized transmitters are used. This method ensures the consistency and accuracy of data from transient electromagnetic instruments under various operating configurations by establishing a complete closed-loop process from standard field construction to real-time field application.

[0024] The calibration method for transient electromagnetic instruments provided by the present invention specifically includes steps S110 to S150.

[0025] Step S110: Obtain the background electrical parameters of the standard test field.

[0026] Step S120: Based on background electrical parameters, generate standard transient electromagnetic response data for multiple emission sources of different preset sizes. Each emission source consists of a transmitter and a transmitting coil. The size of the emission source refers to the size of the emission frame enclosed by the transmitting coil; when the emission frame is square, the side length can be used to represent the size.

[0027] Step S130: Obtain measured transient electromagnetic response data corresponding to emission sources of different preset sizes. The measured transient electromagnetic response data is used to detect the standard test field through the transient electromagnetic instrument to be calibrated. During the detection process, the transient electromagnetic instrument uses emission sources of different preset sizes. The transient electromagnetic instrument is a complete detection system including an emission source, a receiving probe and a data acquisition host.

[0028] Step S140: For each preset-size transmitter, the dynamic calibration coefficients are calculated by comparing its standard transient electromagnetic response data with the measured transient electromagnetic response data. It should be noted that the transient electromagnetic response data is a time-varying data sequence, and the corresponding dynamic calibration coefficients are also a time-varying coefficient sequence. The coefficients at each time point in the sequence are used to correct the electromagnetic response at the same time point.

[0029] Step S150: Based on the dynamic calibration coefficients of multiple emission sources of different preset sizes, a calibration model built into the instrument is constructed. The calibration model is used to perform real-time correction on the transient electromagnetic response data actually collected by the transient electromagnetic instrument.

[0030] In the above technical solution, the method first requires establishing a standard field and benchmark. The purpose is to create a stable environment with known physical properties, serving as a "ruler" for measuring instrument performance. Specifically, operators select a uniform conductive medium as the standard test field and accurately obtain the background electrical parameters of this test field. These benchmark parameters are the basis for all subsequent theoretical calculations. Subsequently, based on these background electrical parameters, standard transient electromagnetic response data are generated for multiple emission sources of different sizes through theoretical calculations. These standard data represent the results that a perfect instrument should measure under ideal conditions, constituting the theoretical benchmark for calibration.

[0031] After establishing a standard test field and its background electrical parameters, the next step is to collect measured data from the system within the same standard test field. Unlike existing techniques that only calibrate the receiving probe, this method emphasizes operating the entire transient electromagnetic instrument system to be calibrated. This system includes at least a transmitter, a receiving probe, and a data acquisition unit. During operation, multiple transmitters of different preset sizes, identical to those used when generating standard transient electromagnetic response data, are sequentially used to perform actual electromagnetic field excitation and data acquisition, thereby obtaining a series of measured transient electromagnetic response data. The purpose of this step is to allow the transient electromagnetic instrument to operate in a configuration similar to field operations, thereby exposing any systematic deviations, including comprehensive errors caused by transmitter performance, transmitter electrical characteristics, receiving probe sensitivity, and coupling effects between components.

[0032] After obtaining the theoretical standard data and the actual measured transient electromagnetic response data, the next step is to calculate the dynamic calibration coefficients. For each transmitter of a preset size, this method compares its standard transient electromagnetic response data with the measured transient electromagnetic response data. This comparison is usually performed time-channel by time, because the instrument's response deviation may change with signal attenuation. Through this comparison, a set of dynamic calibration coefficients that vary with time can be calculated. The physical meaning of this set of coefficients is that it precisely quantifies the degree of deviation of the measured data from the standard data at each moment. By calculating such a set of dynamic calibration coefficients for each transmitter of a preset size, the complex law of system error variation with transmitter size and time is captured.

[0033] Finally, the method constructs and applies a calibration model to the calculated coefficients. First, based on all the dynamic calibration coefficients calculated for multiple transmitters of different preset sizes, a calibration model built into the instrument is constructed. This calibration model systematically stores the results of the calibration work. In subsequent practical operations, when the transient electromagnetic instrument acquires new transient electromagnetic response data, it obtains the corresponding dynamic calibration coefficients based on the actual size of the transmitter currently in use, using this calibration model, and then uses the acquired dynamic calibration coefficients to perform real-time correction on the newly acquired data. This step demonstrates the intelligence and practicality of the invention, transforming the complex calibration process into an automated correction function transparent to the user, thereby achieving the effect of "one-time calibration, long-term use, real-time correction".

[0034] Accordingly, in actual detection operations, if the actual size of the transmitter used by the transient electromagnetic instrument is one of the preset sizes, the dynamic calibration coefficients stored in the calibration model corresponding to the actual size are used to correct the actual transient electromagnetic response data in real time. If the actual size of the transmitter used by the transient electromagnetic instrument is not one of the preset sizes, the dynamic calibration coefficients corresponding to the actual size are determined by interpolation of the dynamic calibration coefficients stored in the calibration model, so as to correct the actual transient electromagnetic response data in real time.

[0035] Specifically, when the actual emitter size is not preset when generating standard response data—that is, when the size is a "non-standard" size—the transient electromagnetic instrument does not simply refuse to work or use the closest coefficient. Instead, it accurately determines the dynamic calibration coefficients for the current actual size by interpolating the coefficients of preset sizes adjacent to the actual size stored in the calibration model. This design greatly enhances the universality and flexibility of the method, achieving effective coverage of a continuous size range through finite discrete-point calibration, thus solving the problem that existing technologies cannot handle non-standard emitters.

[0036] In some embodiments, the interpolation operation employs a linear interpolation algorithm.

[0037] Linear interpolation is the simplest and fastest interpolation method. It assumes that the calibration coefficients vary linearly between two known calibration nodes. In many cases, when the size intervals of the calibration nodes are sufficiently dense, the accuracy of linear interpolation is sufficient to meet engineering requirements. Using linear interpolation minimizes the computational demands on the instrument's processor, ensuring smooth real-time calibration even in low-power embedded systems, demonstrating a good balance between performance and cost.

[0038] In some embodiments, the standard test field is a water body standard test field, and the background electrical parameter is the water resistivity.

[0039] Water bodies were chosen as the standard test site because large-scale stagnant water bodies (such as lakes and reservoirs) have natural electrical homogeneity, and their electromagnetic noise levels are far lower than those of terrestrial environments, providing an extremely "clean" background for calibration. By measuring the resistivity of the water body as a benchmark, an accurate geophysical model can be easily established, laying a solid foundation for the subsequent generation of high-precision standard response data.

[0040] Furthermore, the depth of the water standard test site is more than three times the largest of several different preset sizes.

[0041] Transient electromagnetic methods detect responses within a certain depth range underground. If the water is too shallow, electromagnetic reflection signals from the bottom boundary will arrive at the receiving probe prematurely, superimposing with secondary field signals from the water itself. This contaminates the measurement data, preventing it from representing a uniform half-space response. By ensuring sufficient water depth, it is guaranteed that the bottom reflection waves have not yet arrived within the instrument's main data recording window, effectively creating a uniform medium environment across the entire space. This significantly improves the purity and accuracy of the calibration reference.

[0042] In some embodiments, standard transient electromagnetic response data are generated by numerical forward modeling.

[0043] Numerical forward modeling, based on Maxwell's equations, uses computer simulations to model the propagation and induction of electromagnetic waves under a given model (in this case, a homogeneous body of water). Compared to relying on simplified analytical formulas or empirical tables, numerical forward modeling programs can more accurately consider the geometry of the emission source, current waveforms, and three-dimensional spatial effects, thereby generating standard transient electromagnetic response data that closely matches physical reality. By using this high-precision "computation" instead of "measurement" to obtain standard transient electromagnetic response data, potential manufacturing errors and performance drift inherent in the standard source itself are avoided, ensuring the absoluteness and stability of the calibration reference.

[0044] In some embodiments, the dynamic calibration coefficients are obtained by dividing the value of the standard transient electromagnetic response data by the value of the measured transient electromagnetic response data.

[0045] The above methods allow the calibration process to be completed with a simple multiplication operation: Corrected data = Measured data × Dynamic calibration coefficient. This means the dynamic calibration coefficient directly represents the proportion by which the measured value needs to be amplified or reduced to restore its theoretical standard value. This is a widely used, efficient, and robust calibration strategy in signal processing.

[0046] In some embodiments, the calibration model includes a multidimensional lookup table storing dynamic calibration coefficients corresponding to multiple different preset sizes.

[0047] Organizing calibration results into a multidimensional lookup table is a commonly used and efficient data structure in computer science. This lookup table typically has at least two dimensions: the size of the emission source and the time trace. When calibration coefficients for a specific size and time point are needed, the processor can quickly locate the corresponding values ​​through efficient indexing operations. This structure provides an ideal data organization for subsequent real-time lookup and interpolation operations.

[0048] This invention also provides a transient electromagnetic instrument system, which serves as the physical carrier for the aforementioned calibration method. This system typically includes a transmitter (transmitter and transmitting coil), a receiving probe, a data acquisition unit, and a core control unit. The key feature is that the control unit is specially configured to implement the calibration method provided by this invention. Specifically, the control unit contains a memory and a processor, which work together to complete the automated calibration process. It should be noted that the data acquisition unit and the control unit can be implemented using the same computing device.

[0049] In this host, the memory is used to store a calibration model, which is obtained by the calibration method of transient electromagnetic instruments provided by this invention.

[0050] The processor, connected to the memory, is configured to perform a series of intelligent operations. These include: receiving the actual size of the currently used transmitter input by the user; determining the corresponding dynamic calibration coefficients from the calibration model based on the actual size; receiving transient electromagnetic response data acquired by the receiving probe; and performing real-time correction on the received transient electromagnetic response data using the determined dynamic calibration coefficients.

[0051] In some embodiments, determining the corresponding dynamic calibration coefficient from the calibration model based on the actual size specifically includes: if the actual size is one of the preset sizes, obtaining the dynamic calibration coefficient corresponding to the actual size stored in the calibration model; if the actual size is not one of the preset sizes, determining the dynamic calibration coefficient corresponding to the actual size by performing interpolation operation on the dynamic calibration coefficient stored in the calibration model.

[0052] Specifically, the processor first receives the actual size of the currently used transmitter, input by the user; this is a prerequisite for accurate calibration. Next, based on this input size, the processor retrieves the corresponding dynamic calibration coefficients from the calibration model stored in memory. During this process, if the actual size happens to be one of the preset sizes in the model, it is directly retrieved; otherwise, the processor automatically executes an interpolation algorithm to calculate the dynamic calibration coefficients applicable to the current size. After obtaining the dynamic calibration coefficients, the processor receives transient electromagnetic response data acquired in real-time by the receiving probe and immediately uses the acquired dynamic calibration coefficients to perform point-by-point real-time calibration on this raw data. This seamless integration of operations makes the entire calibration process completely transparent to external operators, achieving automated operation from data acquisition to outputting high-precision results.

[0053] In some embodiments, the calibration model is stored in the firmware of the data acquisition and control host. Firmware is software embedded in the hardware device, typically stored in read-only memory or flash memory. Storing the calibration model in firmware, rather than in ordinary user-accessible storage, offers several advantages. First, it significantly improves the security of calibration data, preventing accidental deletion or modification by users and ensuring the long-term metrological stability of the instrument. Second, the firmware loads quickly, allowing the instrument to enter a calibration-ready state immediately upon power-on. This design ensures that the calibration model, as an inherent property of the instrument, is inseparable from the instrument itself, thereby guaranteeing the long-term stability and reliability of the calibration results.

[0054] This invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it can implement the calibration method for transient electromagnetic instruments provided by this invention. The storage medium can be any physical device capable of storing program code, such as a read-only memory (ROM), random access memory (RAM), hard disk, solid-state drive (SSD), optical disk (such as CD, DVD), or flash drive (USB flash drive). This type of embodiment is intended to protect the software implementation of the method of this invention, covering scenarios where the functionality of this invention is given to existing or new hardware devices through software upgrades or installations.

[0055] The calibration method for transient electromagnetic instruments provided by the present invention will be illustrated in more detail below through a preferred embodiment.

[0056] In a preferred embodiment, the calibration method for transient electromagnetic instruments specifically includes: S1. Construct a standard water test site: Select a water body with low resistance and approximately homogeneous medium conditions (such as a deep lake, reservoir, or calm nearshore area) as the standard test site. The water depth H of this water body is required to meet the following condition: H ≥ 3~5 times the side length of the maximum emission source to be calibrated (i.e., if the side length of the maximum emission source is 100 meters, the water depth needs to reach 300 meters to 500 meters) in order to eliminate the reflection interference of the bottom boundary on the secondary field. Use a CTD (temperature, salinity, depth) profiler to measure the conductivity distribution over the entire water depth range and determine the water resistivity as the background electrical parameter, which is used as the reference electrical environment for calibration.

[0057] S2. Generate a standard attenuation reference curve: In a standard water test field, place the receiving probe at the water surface. Using a numerical forward modeling program, based on the water resistivity measured in step S1, and within the effective time window excluding the arrival times of air waves and bottom reflected waves, sequentially change the transmitting source of different sizes. Below, each time slot is calculated along the time axis (logarithmically equally spaced time gates). Standard transient electromagnetic response data A set of "standard decay reference curves" reflecting the half-space response of pure water is calculated and generated as the absolute benchmark for subsequent comparisons. These curves are data sequences of induced electromotive force decaying over time.

[0058] S3. Staged Multi-Size Transmitter Calibration: Place the transient electromagnetic instrument to be calibrated (a complete system consisting of a transmitter, transmitting coil, receiving probe, and acquisition host) on the water surface. Replace the transmitters with different sizes sequentially, repeating the transmission and data acquisition multiple times (e.g., 50 times). Obtain the size of each transmitter. And every time path Measured transient electromagnetic response data .

[0059] S4. Dynamic calibration coefficient calculation: For each transmitter size The measured transient electromagnetic response data obtained in step S3 Compared with the standard transient electromagnetic response data obtained in step S2 Perform a full-time-domain time-channel comparison and calculate each time channel. Correction factor The calculation formula is: .

[0060] This generates a multidimensional dynamic calibration coefficient array related to the size and time channel of the transmitter, which contains the dynamic calibration coefficients corresponding to transmitters of different sizes.

[0061] S5. Construct a lookup table and embed it into the instrument: Compile all the dynamic calibration coefficients corresponding to different dimensions obtained in step S4 into a fixed multidimensional lookup table. This lookup table is stored in the memory of the instrument's main control chip through firmware burning or other methods.

[0062] S6. Automatic table lookup and correction in the field: During actual operation, the actual size of the transmitter being used can be input through the human-machine interface. Transient electromagnetic instruments automatically retrieve built-in lookup tables: If With the table If nodes overlap, the corresponding dynamic calibration coefficients are directly used to correct the measured data; if Between two calibration nodes, the system activates the built-in interpolation algorithm to perform linear interpolation on the dynamic calibration coefficients of the two adjacent nodes in the same time channel, calculates and applies correction coefficients in real time, and outputs the corrected transient electromagnetic response.

[0063] In one application example, the calibration procedure for transient electromagnetic instruments is as follows: S1. Establish a calibration platform in the central area of ​​a deep lake with a known maximum depth of 500 meters (e.g., Figure 2 (As shown). The maximum side length (dimension) of the emission source is 100 meters. The current water depth meets the requirement of being greater than 3 times the side length, so the influence of the lake bottom boundary can be ignored. On-site CTD measurements show that the resistivity of the water layer 10 to 300 meters below the surface is stable at... This serves as the reference electrical environment for calibration.

[0064] S2. In a standard water test field, place the receiving probe at the water surface. Using a numerical forward modeling program, based on the measured water resistivity... Within the effective time window excluding the arrival times of air waves and underwater reflected waves, emitters of different side lengths (20 meters, 30 meters, 40 meters, ..., 100 meters, a total of 9 sizes) are sequentially replaced. At each emitter size... Next, calculate each time slot along the time axis. Standard transient electromagnetic response data ,like Figure 3 As shown.

[0065] S3. Place the transient electromagnetic instrument to be calibrated on the water surface. Connect nine standard-customized transmitters with side lengths of 20 meters, 30 meters, ..., 100 meters sequentially for excitation and reception. Collect 50 data points at each size node, superimpose and average them to obtain the size of each transmitter. and every time path Measured transient electromagnetic response data ,like Figure 4 As shown.

[0066] S4. For each transmitter size The size of the transmitter was calculated by comparing the measured transient electromagnetic response data with the standard transient electromagnetic response data time-by-time. The calibration coefficients, such as Figure 5 As shown. The calibration coefficients for all dimension nodes (20 meters, 30 meters, ..., 100 meters) and all time tracks are calculated using this method. Generate a multidimensional dynamic calibration coefficient array.

[0067] S5. Compile all dynamic calibration data corresponding to the 9 sets of dimensions (20 meters to 100 meters) obtained in step S4 into a fixed multidimensional lookup table, and store it in the memory of the instrument's main control chip by firmware burning.

[0068] S6. In a certain exploration operation, a side length was used. = 75-meter non-standard customized transmitter. The instrument's central processing unit executes the following interpolation process: retrieves the built-in lookup table, reads... =70 meters and =80 meters coefficient table; for any time channel Performing linear interpolation yields time channels The following calibration coefficients: .

[0069] like Figure 6 As shown, by combining the calibration coefficients from each time channel, a complete dynamic calibration coefficient is obtained, which is then applied to the current measured transient electromagnetic response data (corresponding to...). Figure 6 The measured curves in the data are corrected in real time and the corrected measured transient electromagnetic response data is output (corresponding to the actual curves in the data). Figure 6 (calibration curve in the text).

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A calibration method for a transient electromagnetic instrument, characterized in that, include: Obtain the background electrical parameters of the standard test field; Based on the background electrical parameters, standard transient electromagnetic response data corresponding to each of the multiple emission sources of different preset sizes are generated. Measured transient electromagnetic response data corresponding to emission sources of different preset sizes are obtained. The measured transient electromagnetic response data is used to detect the standard test field by a transient electromagnetic instrument to be calibrated. During the detection process, the transient electromagnetic instrument uses emission sources of different preset sizes. The transient electromagnetic instrument is a complete detection system including an emission source, a receiving probe, and a data acquisition host. For each preset size transmitter, the dynamic calibration coefficient of each preset size transmitter is calculated by comparing its standard transient electromagnetic response data and measured transient electromagnetic response data. Based on the dynamic calibration coefficients of multiple emission sources of different preset sizes, a calibration model built into the instrument is constructed. The calibration model is used to perform real-time correction on the transient electromagnetic response data actually collected by the transient electromagnetic instrument. The standard test site is a water body standard test site, and the background electrical parameter is the water resistivity; The depth of the water standard test field is greater than 3 times the largest of the multiple different preset sizes; The standard transient electromagnetic response data is generated through numerical forward modeling.

2. The calibration method for transient electromagnetic instruments according to claim 1, characterized in that, In actual detection operations, if the actual size of the transmitter used by the transient electromagnetic instrument is one of the preset sizes, the dynamic calibration coefficients stored in the calibration model corresponding to the actual size are used to correct the actual acquired transient electromagnetic response data in real time. If the actual size of the transmitter used by the transient electromagnetic instrument is not one of the preset sizes, the dynamic calibration coefficients stored in the calibration model are interpolated to determine the dynamic calibration coefficients corresponding to the actual size, so as to correct the actual acquired transient electromagnetic response data in real time.

3. The calibration method for transient electromagnetic instruments according to claim 1, characterized in that, The dynamic calibration coefficient is obtained by dividing the value of the standard transient electromagnetic response data by the value of the measured transient electromagnetic response data.

4. The calibration method for transient electromagnetic instruments according to claim 1, characterized in that, The calibration model includes a multidimensional lookup table that stores dynamic calibration coefficients corresponding to the multiple different preset sizes.

5. The calibration method for transient electromagnetic instruments according to claim 2, characterized in that, The interpolation operation uses a linear interpolation algorithm.

6. A transient electromagnetic instrument system, comprising a transmitter, a receiver probe, a data acquisition unit, and a control unit, characterized in that, The control host is internally equipped with: A memory for storing a calibration model, which is obtained by the calibration method of the transient electromagnetic instrument as described in claim 1; The processor, connected to the memory, is configured to receive user input of the actual size of the currently used transmitter. Based on the actual dimensions, determine the corresponding dynamic calibration coefficients from the calibration model; receive transient electromagnetic response data collected by the receiving probe; and use the determined dynamic calibration coefficients to perform real-time correction on the received transient electromagnetic response data.

7. The transient electromagnetic instrument system according to claim 6, characterized in that, Based on the actual dimensions, the corresponding dynamic calibration coefficients are determined from the calibration model, specifically including: If the actual size is one of the preset sizes, then obtain the dynamic calibration coefficients corresponding to the actual size stored in the calibration model; If the actual size is not one of the preset sizes, then the dynamic calibration coefficient corresponding to the actual size is determined by interpolation of the dynamic calibration coefficients stored in the calibration model.

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