A step point repairing method applied to superconducting transient electromagnetic signals

Abstract

The application discloses a step point repairing method applied to superconducting transient electromagnetic signals, and comprises the following steps: step S1, performing phased similarity detection on the SQUID magnetometer output signal obtained by the superconducting transient electromagnetic device to obtain signal step points caused by lock loss in the electromagnetic signal; step S2, calculating the similarity of the interval before the step point and the interval after the step point according to the position of the signal step point, so as to determine the length of the step interval; step S3, calculating the length of the interval with the step point and completing the data segment with the step point by using the nearby data; and step S4, after repairing the data segment with the step point, calculating the direct current offset caused by the repairing and compensating the corresponding offset value.

Description

Technical Field

[0001] This invention relates to the field of superconducting electromagnetic application technology, and in particular to a method for repairing step points in superconducting transient electromagnetic signals. Background Technology

[0002] Superconducting quantum interference devices (SQUIDs) are currently the most sensitive magnetic sensors known, with sensitivity reaching the fT level. They are the ideal signal receivers for transient electromagnetics, significantly improving the accuracy and depth of detection. Therefore, superconducting transient electromagnetics have a wide range of applications.

[0003] Because a squid device is a nonlinear element, meaning the voltage output and the input of a changing ambient magnetic field are not linearly related, a negative feedback control circuit is necessary to convert the input and output of the squid into a linear relationship and improve sensitivity. However, when the input of the ambient magnetic field exceeds the control level of the negative feedback circuit, a "latch-off" phenomenon occurs. This manifests as a step or discontinuity in the measured signal, resulting in completely distorted data that is unusable. Therefore, step removal becomes a crucial step in transient electromagnetic signal processing.

[0004] Current methods for removing outliers primarily target bad pixels, and are not ideal for step points and faults in the data. Step point repair mainly relies on manual removal, which is slow, prone to errors, and cannot automatically and accurately eliminate step points of different amplitudes, thus limiting its application in practical transient electromagnetic signal processing. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a step point repair method for superconducting transient electromagnetic signals. It is mainly based on the regional similarity characteristics of transient electromagnetic signals. By performing phased similarity detection on the original signal, the location and interval length of the step point are determined. Data near the step point are used to complete the data of the entire interval, and the DC offset caused by the step is compensated.

[0006] This invention is achieved through the following technical solution:

[0007] A method for repairing step points in superconducting transient electromagnetic signals includes the following steps:

[0008] Step S1: Perform phased similarity detection on the output signal of the SQUID magnetometer obtained by superconducting transient electromagnetic acquisition to obtain the signal step point caused by loss of lock in the electromagnetic signal;

[0009] Step S2: Calculate the similarity between the interval before and after the step point for the location where the signal step point occurs, thereby determining the length of the step interval.

[0010] Step S3: Calculate the length of the interval with the step point and fill in the data segment with the step point with nearby data;

[0011] Step S4: After repairing the data segment with step points, calculate the DC offset caused by the repair and compensate for the corresponding offset value.

[0012] As a further preferred embodiment of the present invention, in step S1, firstly, a magnetic field signal B is obtained based on superconducting transient electromagnetics. A number of periods N is selected for B as the number of periods for calculating similarity. The interval formed by these N periods is called Q. Starting from the first point of the signal, the first interval Q is selected and its length is calculated. Then, the root mean square of interval Q and the interval Q' of the same length after Q is calculated.

[0013] When the root mean square is greater than a certain threshold, it means that a fault or step point has appeared in the next interval, and the process moves to the step point step.

[0014] If the root mean square is less than the threshold, it means that the data in the next interval is normal. After that, select N period groups from interval Q to form a new interval Q and repeat step S1 until the data ends.

[0015] Specifically, the method for calculating interval similarity is as follows: starting from the first data point, count N periods forward to form an interval Q and mark the length of Q as m. Count m data points forward from the end of Q and calculate the root mean square (RMS) of this data segment Q' and Q. The larger the RMS, the less similar the two data segments are. When the calculated RMS is greater than a threshold, proceed to the step point processing step. If the RMS is less than the threshold, it means that the m data points forward from the end of Q are normal data. At this point, count N periods forward from the end of Q to form a new interval Q and update the corresponding length m. Repeat the above process until the data ends.

[0016] Specifically, the formula for calculating similarity is the mean squared error, and the specific formula is as follows:

[0017]

[0018] As a further preferred embodiment of the present invention, in step S2, after entering the step point processing flow, the similarity between the data Q' of the same length after the interval Q and the interval Q is calculated using the interval Q as the standard. If the similarity does not reach the threshold, the starting point of Q' is moved to the right and the similarity is calculated again until the threshold is reached. The formula for calculating the similarity in the step point processing flow is the same as the formula for calculating the similarity in step S1.

[0019] As a further preferred embodiment of the present invention, in step S3, after calculating the length and position of the step interval in the previous step, the last period of the complete period closest to the step interval, i.e., the Q interval, is copied several times, and the data of the step interval is replaced by the copied data. The method for determining the number of period copies is as follows: let the length of the step interval be L, the length of a single copied period be n, and the number of copies be t.

[0020]

[0021] As a further preferred embodiment of the present invention, in step S4, after the step interval replacement and repair is completed, the difference between the previously calculated average values ​​of Q and Q' is subtracted from all data after the repaired step interval to eliminate DC offset. Step S1 is repeated from the last point of the repaired step interval until the data ends.

[0022] This invention discloses a step point repair method for superconducting transient electromagnetic signals, which, compared with existing technologies:

[0023] This technical solution can automatically locate and repair step points without disrupting the periodicity of the overall data. It can automatically and accurately eliminate step points of different amplitudes, thus stabilizing the output of superconducting transient electromagnetic signals. Attached Figure Description

[0024] Figure 1 This is a flowchart of a step point repair method for superconducting transient electromagnetic signals provided in an embodiment of this application;

[0025] Figure 2 This is the process for finding step points provided in the embodiments of this application;

[0026] Figure 3 This is a flowchart of the step point processing method, which replaces the step interval with the data adjacent to the step point, provided in an embodiment of this application.

[0027] Figure 4 This is a schematic diagram of a superconducting transient electromagnetic output signal with a step point provided in an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of step interval positioning provided in an embodiment of this application;

[0029] Figure 6 This is a schematic diagram comparing the step point removal before and after, provided in an embodiment of this application.

[0030] Figure 7 These are detailed comparison images of the step point repair before and after provided in the embodiments of this application. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0033] See Figure 1 As shown, this invention proposes a step point repair method for superconducting transient electromagnetic signals, comprising the following steps:

[0034] Step S1: Perform phased similarity detection on the output signal of the SQUID magnetometer obtained by superconducting transient electromagnetic acquisition to obtain the signal step point caused by loss of lock in the electromagnetic signal;

[0035] Step S2: Calculate the similarity between the interval before and after the step point for the location where the signal step point occurs, thereby determining the length of the step interval.

[0036] Step S3: Calculate the length of the interval with the step point and fill in the data segment with the step point with nearby data;

[0037] Step S4: After repairing the data segment with step points, calculate the DC offset caused by the repair and compensate for the corresponding offset value.

[0038] See Figure 2 As shown, step S1 mainly includes: firstly, acquiring a magnetic field signal B based on superconducting transient electromagnetics; selecting a period N for B as the period number for calculating similarity; and calling the interval formed by these N periods Q. Since the length of each period in the original data varies slightly, the length of Q also varies depending on the starting point. Starting from the first point of the signal, the first interval Q is selected, and its length is calculated. Then, the root mean square (RMS) of interval Q and the interval Q' of the same length after Q is calculated. When the RMS is greater than a certain threshold, it indicates that a fault or step point has occurred in the next interval, and the process proceeds to the step point step. If the RMS is less than the threshold, it indicates that the data in the next interval is normal. At this time, N periods are selected from interval Q to form a new interval Q, and step S1 is repeated until the data is finished.

[0039] Specifically, the method for calculating interval similarity is as follows: Starting from the first data point, count N periods forward to form an interval Q and denote the length of Q as m. Count m data points forward from the end of Q and calculate the root mean square (RMS) of this data segment Q' and Q. The larger the RMS, the less similar the two data segments are. If there is no fault, the similarity between the two data segments will be very high, and their RMS will be very small. When the calculated RMS is greater than a threshold, proceed to the step point processing step. If the RMS is less than the threshold, it means that the m data points forward from the end of Q are normal data. At this time, count N periods forward from the end of Q to form a new interval Q and update the corresponding length m. Repeat the above process until the data ends.

[0040] Specifically, the formula for calculating similarity is the mean squared error, and the specific formula is as follows:

[0041]

[0042] Using the above step S1, refer to Figure 4 As shown, Figure 4 This is a schematic diagram of the superconducting transient electromagnetic output signal with a step point. By performing phased similarity detection on the SQUID magnetometer output signal acquired by the superconducting transient electromagnetic signal, the signal step point caused by the loss of lock in the electromagnetic signal is obtained, which facilitates the subsequent determination of the duration of the step interval.

[0043] See Figure 3 As shown, step S2 mainly includes: after entering the step point processing flow, calculating the similarity between the data Q' of the same length after interval Q and interval Q using interval Q as the standard; if the similarity does not reach the threshold, shifting the starting point of Q' one position to the right (keeping the length unchanged) and recalculating the similarity until the threshold is reached; when the similarity of Q' to Q is sufficiently high, the step interval can be considered to be between the last point of Q and the first point of Q', thus completing the calculation of the length of the step interval; the formula for calculating the similarity in the step point processing flow is consistent with the formula for calculating the similarity in step S1; furthermore, it is worth noting that since the step point will cause a DC offset, it is necessary to calculate the average value of Q and Q' separately before calculating the similarity, and subtract the difference between the average values ​​of Q and Q' from the values ​​of all data points in Q' before calculating the similarity, in order to eliminate the influence of the DC offset.

[0044] Specifically, the method for calculating the difference in average values ​​is as follows:

[0045]

[0046] Using step S2 above, refer to Figure 5 As shown, Figure 5This diagram illustrates the location of a step interval. By calculating the similarity between the interval before and after the step point based on the location of the signal step point, the length of the step interval is determined, which facilitates the subsequent completion of the step point data.

[0047] Furthermore, step S3 mainly includes: after calculating the length and position of the step interval in the previous step, copying the last cycle of the complete cycle closest to the step interval, i.e., the Q interval, several times, and replacing the data in the step interval with the copied data. The method for determining the number of cycle copies is as follows: let the length of the step interval be L, the length of a single copied cycle be n, and the number of copies be t.

[0048]

[0049] The copied data will be slightly longer than the step interval length. During replacement, the first L points of the copied data are truncated to make it equal to the step interval length.

[0050] Furthermore, step S4 mainly includes: after the step interval replacement and repair is completed, subtracting the difference between the previously calculated average values ​​of Q and Q' from all data after the repaired step interval to eliminate DC offset, and repeating step S1 from the last point of the repaired step interval until the data ends.

[0051] See Figure 6 As shown, Figure 6 A schematic diagram showing the before and after removal of the step point. Figure 6 The image above is a schematic diagram of the original output of the superconducting transient electromagnetic signal before the step point is removed. Figure 6 The following diagram is a schematic diagram of the output of the superconducting transient electromagnetic signal after the step point has been removed. Figure 6 It can be seen that by adopting the above-mentioned step point repair method, no step or fault will appear in the measured signal, realizing the automatic location and repair of step points, while not destroying the periodicity of the overall data.

[0052] See Figure 7 As shown, Figure 7 The image shows a detailed comparison before and after the step point repair. By using the above-mentioned step point repair method, it can be seen that before the repair, the curve of the step interval fluctuated frequently and was very unstable. After the repair, the curve of the step interval became stable, which means that the output of the superconducting transient electromagnetic signal is relatively stable.

[0053] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0054] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for repairing step points in superconducting transient electromagnetic signals, characterized in that, Includes the following steps: S1. Perform phased similarity detection on the output signal of the SQUID magnetometer acquired by superconducting transient electromagnetics to obtain the signal step points caused by loss of lock in the electromagnetic signal: First, acquire the magnetic field signal based on superconducting transient electromagnetics. ,right Select a number of cycles As the number of periods used to calculate similarity, this The interval consisting of several cycles is called Then, starting from the first point of the signal, select the first interval. Calculate its length, then calculate the interval. and Then the same length The root mean square (RMS) is calculated; when the RMS is greater than a certain threshold, it indicates that a fault or step point has occurred in the next interval, and the process proceeds to step S2; when the RMS is less than the threshold, it indicates that the data in the next interval is normal, and at this time, the data is calculated from the interval... Selected Each cycle forms a new interval. Repeat step S1 until the data is finished; S2. Calculate the similarity between the interval before and after the signal step point to determine the length of the step interval: After proceeding to step S2, use the interval... As the standard, calculate the interval Subsequent data of the same length and interval The similarity is calculated, and if the similarity does not reach the threshold, then... The similarity is calculated again by moving the starting point one data point backward, until the target is met; when Similarity and When it is high enough, the step interval can be considered to be in The last point and Between the first point, the length of the step interval has now been calculated. S3. Calculate the length of the interval containing the step point and complete the data segment containing the step point using nearby data: After calculating the length and position of the step interval in step S2, select the nearest completed cycle to the step interval. The last period of the interval is copied several times, and the copied data is used to replace the data in the step interval. The method for determining the number of periodic copies is as follows: Let the length of the step interval be... The length of a single replication cycle is The number of copies is , ; S4. After repairing the data with step points, calculate the DC offset caused by the repair and compensate for the corresponding offset value.

2. The step point repair method for superconducting transient electromagnetic signals according to claim 1, characterized in that, The method for calculating the root mean square is as follows: Starting from the first data point, count backwards... The interval consists of several cycles. and put The length is counted as ,from Counting from the end Data points, this data and Calculate the root mean square (RMS). A larger RMS indicates greater dissimilarity between the two data segments. If the calculated RMS is greater than a threshold, proceed to step S2; if the RMS is less than the threshold, it means... Counting from the end The data points are normal data; at this point, from... Counting from the end Each cycle forms a new interval. And update the corresponding length. Repeat the above steps until the data is finished.

3. The step point repair method for superconducting transient electromagnetic signals according to claim 1, characterized in that, In step S4, after the step interval is repaired, all data after the repaired step interval are subtracted from the previously calculated value. and The difference between the average values, and The difference between the average values ​​refers to the interval The average minus the interval The average value is used to eliminate DC flow offset. Step S1 is repeated starting from the last data point of the repaired step interval until the data ends.

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