Vibration and Noise Suppression Method Based on Vector Total Field Synthesis and Magnetic Field Detection System

Abstract

The present invention provides a vibration and noise suppression method and a magnetic field detection system based on vector total field synthesis for magnetic field detection, including: respectively collecting magnetic field quantities in a first direction, a second direction, and a third direction of a magnetic field to be measured; any two of the first direction, the second direction, and the third direction are perpendicular to each other; calculating the total magnetic field quantity after adding the preset bias quantity corresponding to each direction to the magnetic field quantity in each direction, and calculating the segmented power spectrum of the total magnetic field quantity according to the spectrum estimation method; based on the segmented power spectrum in the concerned frequency band and the mapping relationship between the bias quantity in each direction and the noise bias value of the total magnetic field, solving for the minimum value of the noise bias value in the concerned frequency band and the corresponding bias quantity in each direction, so as to obtain the total magnetic field quantity after noise reduction. The present invention can effectively weaken the attitude sensitivity brought by the vector detector, and at the same time make the low-frequency noise of the synthesized total field smaller, thereby improving the anti-interference ability and sensitivity of the detector.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field detection, and particularly to a vibration noise suppression method and a magnetic field detection system based on vector total field synthesis. Background Art

[0002] Compared with total field magnetic detectors, vector magnetic field sensors such as superconducting quantum interference devices (hereinafter referred to as SQUIDs), fluxgates, and giant magnetoresistive sensors have many advantages. For example, the detection is directional and often has a larger bandwidth. However, precisely because the detection is directional, they are much more sensitive to the attitude. This makes the vector detection results more susceptible to factors such as vibration, thus introducing more low-frequency noise caused by vibration in the vector detection system.

[0003] In actual experiments, in order to reduce the influence of the vibration of the vector sensor system on the test results, physical vibration damping measures are taken for the system. Usually, the system is buried or semi-buried underground and equipped with a wind shield to reduce the influence of ground vibration and wind noise. However, there are still great deficiencies in vibration damping and noise reduction only from the physical level.

[0004] Based on this, the present invention intends to propose a vibration noise suppression method and a magnetic field detection system based on vector total field synthesis to solve the problem that the low-frequency part of the current vector detector is easily affected by vibration noise and cannot be solved by physical noise reduction measures.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely explaining the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a vibration noise suppression method and a magnetic field detection system based on vector total field synthesis to solve the problem that the low-frequency part of the vector detector in the prior art is easily affected by vibration noise and cannot be solved by physical noise reduction measures.

[0007] To achieve the above object and other related objects, the present invention provides a vibration noise suppression method based on vector total field synthesis, including: S1. respectively collecting the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured; any two of the first direction, the second direction, and the third direction are perpendicular to each other;

[0008] S2. Add the magnetic field amounts in each direction with the corresponding preset bias amounts in each direction respectively, calculate the total magnetic field amount, and calculate the segmented power spectrum of the total magnetic field amount according to the spectrum estimation method;

[0009] S3. Based on the segmented power spectrum and the mapping relationship between the bias amounts in each direction and the noise bias value of the total magnetic field, solve the minimum value of the noise bias value in the concerned frequency band and the corresponding bias amounts in each direction, and then obtain the total magnetic field amount after noise reduction.

[0010] Optionally, step S1 further includes a preprocessing step after the magnetic field amounts in each direction are collected; the preprocessing step includes at least one of the three steps of filtering, sampling, and cropping.

[0011] Optionally, in step S2, the preset bias amounts in each direction are set randomly.

[0012] Optionally, the total magnetic field amount satisfies the following relational expression: where B’ TMI is the total magnetic field amount, Bx, By, and Bz respectively represent the magnetic field amount in the first direction, the magnetic field amount in the second direction, and the magnetic field amount in the third direction; Bxo, Byo, and Bzo respectively represent the bias amount in the first direction, the bias amount in the second direction, and the bias amount in the third direction; where B’ TMI is the total magnetic field amount, Bx, By, and Bz respectively represent the magnetic field amount in the first direction, the magnetic field amount in the second direction, and the magnetic field amount in the third direction; Bxo, Byo, and Bzo respectively represent the bias amount in the first direction, the bias amount in the second direction, and the bias amount in the third direction; in step S2, Bxo, Byo, and Bzo respectively represent the preset bias amounts in the first direction, the preset bias amounts in the second direction, and the preset bias amounts in the third direction; in step S3, Bxo, Byo, and Bzo respectively represent the bias amounts in the first direction, the bias amount in the second direction, and the bias amount in the third direction corresponding to the minimum of the noise bias value in the concerned frequency band

[0013] Optionally, in step S2, the spectrum estimation method is set to any one of the periodogram method, the autocorrelation function method, the Bartlett method, the Welch method, and the Nuttall method.

[0014] Optionally, in step S2, when the spectrum estimation method is set to the Welch method, the expression of the segmented power spectrum of the total magnetic field amount is set to:

[0015]

[0016] where L is the total magnetic field amount data B’ TMIThe number of segments of (n), and the length of each segment of data is set to M, P xx (e jω ) is the power spectrum estimate value, I i (w) is the periodogram of the i-th segment;

[0017] Calculate I i (w) The expression is:

[0018] Among them, U is the normalization factor, B’ TMI (n) is the total magnetic field quantity data, w(n) is the window function, and B’ is the total magnetic field quantity data TMI (n) is the number of segments, M is the data length, and n is the position of the data point for value taking;

[0019] The expression for calculating U is:

[0020] Optionally, in step S3, the gradient of the bias in each direction with respect to the noise bias value is solved by the gradient descent algorithm to obtain the minimum value of the noise bias value..

[0021] The present invention also provides a magnetic field detection system for implementing the above vibration noise suppression method based on vector total field synthesis, including: a magnetic field data acquisition unit and a magnetic field data processing unit;

[0022] The magnetic field data acquisition unit includes a superconducting quantum interference triaxial vector magnetometer and a readout circuit; the superconducting quantum interference triaxial vector magnetometer is arranged in a low-temperature environment and electrically connected to the readout circuit, and transmits the detected magnetic field quantities in the first direction, the second direction, and the third direction to the readout circuit;

[0023] The readout circuit is electrically connected to the magnetic field data processing unit and is used to read the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured;

[0024] The magnetic field data processing unit is used to process the signal output by the readout circuit to obtain the total magnetic field quantity after noise reduction.

[0025] Optionally, the magnetic field detection system is statically placed in the detection environment.

[0026] Optionally, all or part of the superconducting quantum interference triaxial vector magnetometer is buried underground.

[0027] Optionally, the magnetic field detection system further includes a physical vibration damping mechanism; the physical vibration damping mechanism covers the outside of the magnetic field data acquisition unit and the magnetic field data processing unit and is used to reduce the external mechanical vibration of the magnetic field detection system.

[0028] As described above, the vibration and noise suppression method and magnetic field detection system based on vector total field synthesis of the present invention have the following

[0029] Advantages:

[0030] 1. The vibration and noise suppression method based on vector total field synthesis of the present invention effectively weakens the attitude sensitivity brought by the vector detector by setting the data processing method for synthesizing the total field from three-axis vector data. At the same time, by solving the minimum value of the noise bias value, the low-frequency noise of the synthesized total field is made smaller, thereby suppressing the low-frequency noise caused by factors such as vibration.

[0031] 2. The magnetic field detection system of the present invention has a simple structure. Based on the superconducting quantum interference three-axis vector magnetometer, the performance of the detector is further improved, effectively enhancing the anti-interference ability and sensitivity of the detector, so that the magnetic field detector can better serve the field of detecting low-frequency signals such as magnetic anomaly detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It shows a flowchart of the vibration and noise suppression method based on vector total field synthesis of the present invention.

[0033] Figure 2 It shows a schematic diagram of the magnetic field power spectral density before and after total field synthesis of the present invention.

[0034] Figure 3 It shows a schematic diagram of the structure of the magnetic field detection system of the present invention.

[0035] Description of Component Labels

[0036] 1 Magnetic field detection system

[0037] 11 Magnetic field data acquisition unit

[0038] 111 Superconducting quantum interference three-axis vector magnetometer

[0039] 112 Readout circuit

[0040] 113 Liquid helium

[0041] 12 Magnetic field data processing unit DETAILED DESCRIPTION OF THE INVENTION

[0042] The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0043] Please refer to Figures 1 to 3It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0044] As Figure 1 shown, this embodiment provides a vibration and noise suppression method based on vector total field synthesis for magnetic field detection, including:

[0045] S1. Respectively collect the magnetic field quantities in the first direction (in this embodiment, as Figure 3 shown, it is the X direction), the second direction (in this embodiment, as Figure 3 shown, it is the Y direction), and the third direction (in this embodiment, as Figure 3 shown, it is the Z direction) of the magnetic field to be measured; any two directions among the first direction, the second direction, and the third direction are perpendicular to each other.

[0046] Specifically, the magnetic field quantity data in three directions collected are output through multiple channels and output to the readout circuit 112 for debugging and reading (as Figure 3 shown). The magnetic field quantities in each direction are respectively denoted as Bx, By, and Bz. Any two directions among the three directions are perpendicular, which is convenient for synthesizing the magnetic field quantities in the three collected directions to obtain the total field and eliminate noise. This is because the Earth's total field has good time-invariant characteristics, especially in the mechanical vibration frequency band during magnetic field detection, and it can be considered not to change with time. Therefore, after the vector synthesis of the data detected by the superconducting quantum interference triaxial vector magnetometer 111 to obtain the total field, the total field result should not be affected by the vibration of the sensor itself. Therefore, the data processing method of synthesizing the triaxial vector data into the total field can weaken the attitude sensitivity brought by the vector detector.

[0047] As Figure 3 shown, as an example, the superconducting quantum interference triaxial vector magnetometer 111 includes at least three superconducting rings. The planes where the three superconducting rings are located are respectively perpendicular to the first direction (X direction), the second direction (Y direction), and the third direction (Z direction), that is: the magnetic field quantity in any direction is perpendicular to the plane where the superconducting ring is located and is detected by the superconducting ring. In this embodiment, the superconducting ring is set as a double-junction superconducting ring formed by two Josephson junctions connected in parallel. The magnetic field in each direction is detected by the superconducting ring and converted into a voltage signal and transmitted to the readout circuit. It should be noted that the superconducting ring can also be set as including but not limited to a single-junction superconducting ring, a three-junction superconducting ring, and other structures.

[0048] More specifically, step S1 further includes a preprocessing step after the magnetic field amounts in all directions are collected; the preprocessing step includes at least one of the three steps of filtering, sampling, and cropping. By filtering the total magnetic field amount, some data that is significantly disturbed or has obvious measurement errors is removed, making the subsequent total magnetic field noise reduction more accurate; by sampling the total magnetic field amount, the data of the total magnetic field amount is averaged, facilitating subsequent data processing and making the total magnetic field noise reduction more accurate; by cropping the data of the total magnetic field amount to cut out some areas, the truly required data is used as the research data, reducing unnecessary data from participating in the operation and improving the accuracy of subsequent noise reduction. Optimizing the collected magnetic field amount data through the preprocessing step maximizes the subsequent noise reduction effect.

[0049] S2. Add the magnetic field amounts in all directions to the corresponding preset bias amounts in all directions respectively, and calculate the total magnetic field amount, and calculate the segmented power spectrum of the total magnetic field amount according to the spectrum estimation method.

[0050] Specifically, the magnetic field amounts in all directions are respectively added to the corresponding preset bias amounts in all directions. The preset bias amounts in the three directions are respectively represented as Bxo, Byo, and Bzo. The preset bias amounts facilitate the subsequent solution of the segmented power spectrum of the total magnetic field. In this embodiment, the superconducting quantum interference triaxial vector magnetometer 111 is set as a superconducting quantum interference device. Since superconducting quantum interference devices, as vector detectors, are all vulnerable to vibration, by finding a suitable noise bias value, the low-frequency noise of the synthesized total field can be made smaller, thereby suppressing the low-frequency noise brought by factors such as vibration. And superconducting quantum interference devices only measure the relative change amount of the magnetic field. When calculating the total field, a corresponding preset bias amount needs to be added to each direction respectively. After obtaining the power spectrum of the total magnetic field, the optimal bias amount in each direction is found through optimization to minimize the noise of the total field.

[0051] Specifically, the total magnetic field amount satisfies the following relational expression:

[0052]

[0053] where, B’ TMI is the total magnetic field amount, Bx, By, and Bz respectively represent the magnetic field amount in the first direction, the magnetic field amount in the second direction, and the magnetic field amount in the third direction; in step S2, Bxo, Byo, and Bzo respectively represent the preset bias amount in the first direction, the preset bias amount in the second direction, and the preset bias amount in the third direction.

[0054] As an example, the preset bias amounts in all directions are randomly set, and the three bias amounts (i.e., Bxo, Byo, and Bzo) are independent of each other. Set the bias amounts in all directions and substitute them into the total magnetic field amount formula (1), and then the power spectrum calculation of the total magnetic field amount can be continued on the basis of formula (1).

[0055] Specifically, in step S2, the spectral estimation method is set to any one of the periodogram method, the autocorrelation function method, the Bartlett method, the Welch method, and the Nuttall method.

[0056] As an example, the spectral estimation method is set to the Welch method: the data string x(n) of length N of the total magnetic field amount, where n takes 0, 1,..., N - 1, is divided into L segments, and each segment has M data lengths; among them, L is set to a natural number greater than or equal to 2. Since the more the data points are segmented, the higher the accuracy of the final noise reduction. For more accurate noise reduction, the number of segments L is preferably set to to In this embodiment, if the data length of the total magnetic field amount is 100,000 data points, the number of segments L is set to 10,000 to 50,000 segments. The number of segments for dividing the data of the total magnetic field amount can be set according to actual needs. After adding a window function to each segment of data and performing smoothing processing, the periodogram of each segment is obtained. In this embodiment, the periodograms of each segment are set to be independent of each other, and finally the power spectrum estimate Pxx of the segmented power spectrum is calculated, that is: the average value of the windowed and smoothed periodograms of each segment. The L segments of data respectively correspond to L segmented power spectral densities Pxx. When solving the concerned frequency band, substituting the corresponding segmented power spectral estimate density Pxx, after converting the vector magnetic field into the total field, the numerical value of noise optimization can be further solved through the segmented power spectrum, that is, the noise bias value.

[0057] The expression of the segmented power spectrum of the total magnetic field amount is set as:

[0058]

[0059] where L is the number of segments of the total magnetic field amount data B’ TMI (n), and the data length of each segment is set to M, and P xx (e jω ) is the power spectrum estimate value, and I i (w) is the periodogram of the i-th segment; that is, when calculating, first divide the data B’ TMI (n) into L segments so that the data length of each segment is M.

[0060] The expression for calculating I i (w) is:

[0061]

[0062] where U is the normalization factor, B’ TMI (n) is the total magnetic field quantity data, w(n) is the window function, and L is the number of segments of the total magnetic field quantity data B’ TMI (n), M is the data length, and n is the position of the data point for value taking;

[0063] The expression for calculating U is:

[0064]

[0065] In this embodiment, the operation code of the Welch method is as follows:

[0066] % Plot power spectrum parameters

[0067] nwindow = 100000; % Window length

[0068] nfft = nwindow;

[0069] overlap = 0.5;

[0070] coe = 1;

[0071] % Plot power spectrum

[0072] [Px1, f11] = psdwelch(YOriginal, coe, Fs, nwindow, nfft, overlap);

[0073] X = sqrt(Px1 * 2);

[0074] Figure(5); loglog(f11, x);

[0075] Among them, psdwelch is a function of the spectral estimation algorithm of Welch, nwindow is the set window function length, and nwindow = 100000 means that the window function length is set to 100000 data points; nfft = nwindow means converting the window function into the number of discrete Fourier transform (DFT) points for power spectrum estimation; overlap represents the overlap length between data segments and needs to be a positive integer. In this embodiment, it is set to 0.5. Since the data is rounded, it is equivalent to setting the overlap length between data segments to 0 at this time, that is, there is no overlap between data segments; YOriginal represents the original data for which the power spectrum needs to be solved, coe represents multiplying the data by a parameter, which belongs to the data processing function and has nothing to do with solving the power spectrum at this time; Fs represents the sampling rate of the data. By calling the psdwelch function (its function reference parameters include parameters such as YOriginal, coe, Fs, nwindow, nfft, overlap, etc.), the corresponding power spectrum diagram is drawn, which is convenient for subsequent solving of the minimum noise value.

[0076] S3. Based on the segmented power spectrum and the mapping relationship between the bias in each direction and the noise bias value of the total magnetic field, solve for the minimum value of the noise bias value in the concerned frequency band and the corresponding bias in each direction, and then obtain the total magnetic field amount after noise reduction.

[0077] Specifically, first set the concerned frequency band, and obtain the power spectrum estimate Pxx of the segmented power spectrum within the concerned frequency band according to formula (2). Since formula (2) is derived from formulas (1), (3) and (4), it can be considered that there is a certain mapping relationship between the bias amounts in each direction and the spectral estimate density of the segmented power spectrum at this time. Take the bias amounts in each direction as a set of values (Bxo, Byo, Bzo). These three values are not correlated with each other, but each of these three values has a certain mapping relationship with the total magnetic field and the power spectrum obtained by converting the total magnetic field. That is to say, there is a certain mapping relationship between the three bias amounts (Bxo, Byo, Bzo) and the total magnetic field amount, that is, changing any one of the bias amounts will cause a corresponding change in the total magnetic field. Since formula (2) has given the relational expression satisfied by the segmented power spectrum of the total magnetic field, that is: there is also a certain mapping relationship between the three bias amounts and the segmented power spectrum (2) of the total magnetic field. There is a value for evaluating the noise of a specific frequency band of the total field, which is the noise bias value MB. MB is expressed as MB(Bxo, Byo, Bzo), that is, it includes the mapping relationship between the bias amounts in each direction and the total magnetic field. By solving the minimum value of this mapping relationship, the bias amounts in each direction corresponding to the minimum total field noise in a specific frequency band can be obtained. In this embodiment, the minimum value of the noise bias value is solved by the gradient descent algorithm, that is, the minimum value of the value for evaluating the noise of a specific frequency band of the total field. By simultaneously solving the gradients of Bxo, Byo, Bzo with respect to the noise bias value MB, the calculation moves in the gradient direction that makes MB smaller, and finally the minimum MB value found is the one sought. The optimal noise bias value MB(Bxo, Byo, Bzo) obtained at this time can make the value of the segmented power spectrum of the total magnetic field the smallest in the concerned frequency band, achieving noise reduction. It should be noted that at this time, the bias amounts in each direction can also be solved by direct solution (for example, by changing the bias amount in any one direction and substituting it into formulas (1) to (4), the change trend of the total magnetic field amount can be obtained, and by synthesizing the change trends in the three directions, the optimal solution of the bias amounts in each direction corresponding to the best noise optimization effect of the total magnetic field amount can be solved).

[0078] This embodiment suppresses the total field vibration noise through a data processing method, improves the anti-low-frequency vibration ability of the triaxial vector sensor, and further improves the performance of the detector. At the same time, the lower the frequency of the signal interval, the better the noise suppression effect. Therefore, this embodiment is well applicable to low-frequency signal detection fields such as magnetic anomaly detection.

[0079] In this embodiment, a superconducting quantum interference device (SQUID) is used to collect magnetic field quantities in all directions. SQUIDs are the most sensitive magnetic sensors currently known. Low-temperature SQUIDs can achieve sensitivities better than 1 fT / Hz1 / 2, while high-temperature SQUIDs reach 10 fT / Hz1 / 2. These sensors are important high-end application sensors, widely used in fields such as geophysical exploration, biomedicine, and basic research. SQUIDs operating at low temperatures already have very low intrinsic noise. Combining this method with the removal of low-frequency vibrations can further improve system noise. Compared to detectors such as optical pumps, SQUIDs also possess broadband detection capabilities. Combining this method allows SQUIDs to measure low-noise, broadband total fields.

[0080] Combine Figure 2 The noise suppression effect of this embodiment is analyzed. TMI is the noise of the total magnetic field, Bx / By / Bz are the noise in each direction respectively. At this time, the noise curves detected in each direction are basically the same. At the same mechanical vibration frequency f, the magnetic field power density B(nT / rtHZ) of the total magnetic field (i.e., noise) is less than the magnetic field power density B(nT / rtHZ) (i.e., noise) in each direction. In addition, B' TMI The greater the difference between the curve where the Bx / By / Bz is located at the same frequency, the greater the magnetic field power density (ie, the better the noise reduction effect). In this embodiment, the frequency f of the mechanical vibration is less than or equal to 10 -2 HZ time B' TMI The difference between the curve where it is located and the curve where Bx / By / Bz is located at the same frequency is greater than the frequency f of the mechanical vibration and is greater than 10 -2 HZ time B' TMI The difference between the curve where the Bx / By / Bz is located and the curve where the Bx / By / Bz is located at the same frequency. That is, the vibration noise suppression method based on vector total field synthesis in this embodiment has a better noise reduction effect as the frequency is lower.

[0081] like Figure 3 As shown, this embodiment provides a magnetic field detection system 1 for implementing the above-mentioned vibration noise suppression method based on vector total field synthesis, including: a magnetic field data acquisition unit 11 and a magnetic field data processing unit 12.

[0082] Specifically, the magnetic field data acquisition unit 11 includes a superconducting quantum interference triaxial vector magnetometer 111 and a readout circuit 112; the superconducting quantum interference triaxial vector magnetometer 111 is disposed in a cryogenic environment and electrically connected to the readout circuit 112, and transmits the detected magnetic field quantities in the first direction, the second direction, and the third direction (in this embodiment, the X direction, the Y direction, and the Z direction respectively) to the readout circuit 112. The readout circuit 112 is electrically connected to the magnetic field data processing unit 12 and is used to read out the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured; the magnetic field data processing unit 12 is used to process the signals output by the readout circuit to obtain the total magnetic field quantity after noise reduction.

[0083] Further, in order to enable the machine to detect more accurately, the magnetic field detection system 1 is placed statically in the detection environment. In this embodiment, in order to further reduce physical noise, all or part of the superconducting quantum interference triaxial vector magnetometer is buried or semi-buried underground. As an example, the superconducting quantum interference triaxial vector magnetometer 111 is disposed in liquid nitrogen 113. It should be noted that the superconducting quantum interference triaxial vector magnetometer 111 can be disposed in a cryogenic environment including but not limited to liquid nitrogen or directly disposed in a cryogenic environment manufactured by a refrigerator, as long as it can enable the superconducting quantum interference triaxial vector magnetometer 111 to work in a cryogenic environment for magnetic field detection, which is within the protection scope of this embodiment.

[0084] Further, the magnetic field detection system 1 further includes a physical vibration damping mechanism (not shown in the figure). The physical vibration damping mechanism covers the outside of the magnetic field data acquisition unit and the magnetic field data processing unit and is used to reduce the external mechanical vibration of the magnetic field detection system. In this embodiment, the physical vibration damping mechanism is set as a wind shield to further improve the anti-interference ability of the magnetic field detection system.

[0085] In summary, the present invention provides a vibration and noise suppression method and a magnetic field detection system based on vector total field synthesis for magnetic field detection, including: respectively collecting the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured; any two of the first direction, the second direction, and the third direction are perpendicular to each other; calculating the total magnetic field quantity after adding the preset bias quantities corresponding to each direction to the magnetic field quantities in each direction, and calculating the segmented power spectrum of the total magnetic field quantity according to the spectral estimation method; based on the segmented power spectrum in the concerned frequency band and the mapping relationship between the bias quantity in each direction and the noise bias value of the total magnetic field, solving the minimum value of the noise bias value in the concerned frequency band and the corresponding bias quantity in each direction, and further obtaining the total magnetic field quantity after noise reduction. The present invention can effectively weaken the attitude sensitivity brought by the vector detector, and at the same time make the low-frequency noise of the synthesized total field smaller, thereby improving the anti-interference ability and sensitivity of the detector.. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0086] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A vibration and noise suppression method based on vector total field synthesis for magnetic field detection, characterized in that The vibration and noise suppression method based on vector total field synthesis at least includes: S1. Collect the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured respectively; any two of the first direction, the second direction, and the third direction are perpendicular to each other. S2. Add the preset bias quantity corresponding to each direction to the magnetic field quantity in each direction respectively, then calculate the total magnetic field quantity, and calculate the segmented power spectrum of the total magnetic field quantity according to the spectrum estimation method. S3. Based on the segmented power spectrum in the concerned frequency band and the mapping relationship between the bias quantity in each direction and the noise bias value of the total magnetic field, solve the minimum value of the noise bias value in the concerned frequency band and the corresponding bias quantity in each direction, and then obtain the total magnetic field quantity after noise reduction.

2. The vibration and noise suppression method based on vector total field synthesis according to claim 1, wherein: Step S1 further includes a preprocessing step after collecting the magnetic field quantities in each direction; the preprocessing step includes at least one of the three steps of filtering, sampling, and cropping.

3. The vibration and noise suppression method based on vector total field synthesis according to claim 1, characterized in that: In step S2, the preset bias quantity in each direction is randomly set.

4. The vibration and noise suppression method based on vector total field synthesis according to claim 1, characterized in that: The total magnetic field quantity satisfies the following relational expression: Among them, B’ TMI is the total magnetic field quantity, B x , B y , B z respectively represent the magnetic field quantity in the first direction, the magnetic field quantity in the second direction, and the magnetic field quantity in the third direction; Bxo, Byo, and Bzo respectively represent the bias in the first direction, the bias in the second direction, and the bias in the third direction; in step S2, Bxo, Byo, and Bzo respectively represent the preset bias in the first direction, the preset bias in the second direction, and the preset bias in the third direction; in step S3, Bxo, Byo, and Bzo respectively represent the bias in the first direction, the bias in the second direction, and the bias in the third direction corresponding to the minimum of the noise bias value in the frequency band of interest.

5. The vibration and noise suppression method based on vector total field synthesis according to claim 1, characterized in that: In step S2, the spectrum estimation method is set to any one of the periodogram method, the autocorrelation function method, the Barlett method, the Welch method, and the Nuttall method.

6. The vibration and noise suppression method based on vector total field synthesis according to claim 4, characterized in that: In step S2, when the spectrum estimation method is set to the Welch method, the segmented power spectrum of the total magnetic field quantity satisfies the following relational expression: Among them, L is the total magnetic field quantity data B’ TMI (n) is the number of segments, and the length of each segment of data is set to M, P xx (e jω ) is the power spectrum estimate value, I i (w) is the periodogram of the i-th segment; Calculation I i (w) is expressed as: where U is the normalization factor, B’ TMI (n) is the total magnetic field quantity data, w(n) is the window function, and L is the number of segments of the total magnetic field quantity data B’ TMI (n), M is the data length, and n is the position of the data point for the value; The expression for calculating U is:

7. The vibration and noise suppression method based on vector total field synthesis according to claim 1, characterized in that: In step S3, use the gradient descent algorithm to solve the gradient of the bias quantity in each direction with respect to the noise bias value, and obtain the minimum value of the noise bias value.

8. A magnetic field detection system for implementing the vibration and noise suppression method based on vector total field synthesis according to any one of claims 1 to 7, characterized in that, The magnetic field detection system includes: a magnetic field data acquisition unit and a magnetic field data processing unit; The magnetic field data acquisition unit includes a superconducting quantum interference triaxial vector magnetometer and a readout circuit; the superconducting quantum interference triaxial vector magnetometer is arranged in a low-temperature environment and electrically connected to the readout circuit, and transmits the magnetic field quantities in the first direction, the second direction, and the third direction detected to the readout circuit. The readout circuit is electrically connected to the magnetic field data processing unit, and is used to read out the magnetic field quantities in the first direction, the second direction, and the third direction of the magnetic field to be measured. The magnetic field data processing unit is used to process the signal output by the readout circuit to obtain the total magnetic field quantity after noise reduction.

9. The magnetic field detection system according to claim 8, characterized in that: The magnetic field detection system is placed statically in the detection environment.

10. The magnetic field detection system according to claim 9, wherein: All or part of the superconducting quantum interference triaxial vector magnetometer is buried underground.

11. The magnetic field detection system according to any one of claims 8 to 10, characterized in that: The magnetic field detection system further includes a physical vibration damping mechanism; the physical vibration damping mechanism covers the outside of the magnetic field data acquisition unit and the magnetic field data processing unit, and is used to reduce the external mechanical vibration of the magnetic field detection system.

Images