Electrical source semi-aerial transient electromagnetic method receiving coil noise correction method and system

Abstract

The present invention discloses a method and system for noise correction of a receiving coil in an electrical source semi-aerial transient electromagnetic method, including: the transmitting source emits according to a predetermined waveform to generate a mutual inductance effect with the receiving coil, and based on the influence generated by the mutual inductance effect, mutual inductance noise is obtained; according to the change in the position of the receiving coil, the coupling change between the receiving coil and the ground is obtained; according to the coupling change, the motion noise formed by the induced voltage generated in the receiving coil is obtained; based on the mutual inductance noise and the motion noise, correction is performed to achieve noise correction of the receiving coil. Compared with the prior art, the present invention has the advantages of high precision, strong real-time performance and easy operation; it can realize the time synchronization of received data, which is convenient for on-site data processing and analysis by staff on the basis of ensuring data consistency, so as to take corresponding compensation measures to achieve the purpose of suppressing motion noise.

Description

Technical Field

[0001] The present invention belongs to the field of electrical prospecting, and particularly relates to a method and system for correcting the noise of a receiving coil in an electrical source semi-airborne transient electromagnetic method. Background Art

[0002] The semi-airborne transient electromagnetic method (S-ATEM) is a hybrid system that uses a loop source or grounded wire source laid on the ground surface to emit electromagnetic pulse signals and uses a manned or unmanned aircraft to carry receiving equipment to receive signals in the air. The emission source laid on the ground surface uses pulsed current to excite the earth, and at the same time, the response of the earth is collected through the receiving system in the air, and the underground target is determined through the response of the underground medium. The S-ATEM method has both the advantages of large emission power and large detection depth of the ground electromagnetic method (EM) and the advantages of high detection efficiency and wide application range of the airborne electromagnetic method (AEM). It is widely used in basic geological surveys, mineral resource exploration, oil and gas exploration, as well as hydrological, engineering, and environmental exploration. However, there are still some deficiencies in the existing detection systems during use:

[0003] In the pod-type helicopter semi-airborne transient electromagnetic exploration system, the transmitting coil is suspended by a helicopter to emit a high-power magnetic field signal to excite the underground medium, and the underground medium will generate a secondary field due to the eddy current effect. At the same time, the receiving device is used to receive the secondary field signal to realize the interpretation of the resistivity structure of the underground medium. The Z-component receiving coil is the core detection component of the time-domain airborne electromagnetic exploration system, which is fixed on a cross-shaped bracket. During flight, due to the influence of wind, attitude changes such as yaw, pitch, and roll will occur, and the induced magnetic flux changes due to cutting the geomagnetic field, presenting interference of motion noise in the measured data. Therefore, accurately obtaining the real-time change amount of the induced magnetic flux of the Z-component receiving coil to suppress the motion noise has become an important research direction in the airborne time-domain electromagnetic exploration system. Summary of the Invention

[0004] To achieve the above object, the present invention provides the following: A method and system for correcting the noise of a receiving coil in an electrical source semi-airborne transient electromagnetic method, including:

[0005] The emission source emits a mutual inductance effect with the receiving coil according to a predetermined waveform, and based on the influence generated by the mutual inductance effect, mutual inductance noise is obtained;

[0006] According to the position change of the receiving coil, obtain the coupling change between the receiving coil and the ground; according to the coupling change, obtain the motion noise formed by the induced voltage generated in the receiving coil.

[0007] Based on the mutual inductance noise and the motion noise, perform correction to achieve noise correction of the receiving coil.

[0008] Preferably, the process of the transmitting source emitting with a mutual inductance effect on the receiving coil according to a predetermined waveform includes that the transmitting sources S1S2 emit current according to the transmitting waveform, the direction is the X-axis direction, and the source length is l; the position coordinates of the center point A of the receiving coil are (x, y, z), the point where the plane passing through point A and perpendicular to the X-Y plane intersects S1S2 is A0, with coordinates (x, 0, 0), and the included angles are The included angles with the X-axis are θ1 and θ2 respectively.

[0009] Preferably, the process of obtaining the mutual inductance noise based on the influence of the mutual inductance effect includes,

[0010] When the transmitting source starts to transmit and the current amplitude suddenly increases, a mutual inductance current generated by the transmitting front appears in the receiving coil Rx. Based on the mutual inductance current, Rx acts as a magnetic dipole source and emits an electromagnetic field to the ground; when the transmitting source stops power supply and the current amplitude suddenly decreases, there is mutual inductance between the transmitting source and Rx. Rx is a very small coil with the center point A, generating a Bp mutual inductance magnetic field; when the current amplitude is zero, Rx acts as a magnetic dipole source and continuously receives the signal generated by the coupling of the electromagnetic field emitted by the transmitting source with the ground. Rx receives the coupling signal of the electromagnetic field emitted by the transmitting source and Rx with the ground to obtain the mutual inductance noise.

[0011] Preferably, the magnitude of the influence of the mutual inductance effect is judged by calculating the mutual inductance magnetic field value, voltage and current based on the mutual inductance formula;

[0012] The mutual inductance formula includes:

[0013]

[0014]

[0015]

[0016] Ψ=NMI source

[0017]

[0018] Φ R =SB zp

[0019] S m = NS

[0020] where ε mutual is the mutual inductance voltage induced by mutual inductance in the coil, I mutual is the mutual inductance current, R is the coil resistance, L is the total length of the coil, S section is the cross-sectional area of the coil wire, ρ is the resistivity of the coil, Ψ is the magnetic flux linkage, M is the mutual inductance coefficient of the emission source at Rx, Φ R is the mutual inductance magnetic flux passing through Rx, and the effective area S m is obtained by multiplying the coil area S by the number of turns.

[0021] Preferably, the process of obtaining the coupling change between the receiving coil and the ground according to the position change of the receiving coil includes

[0022] establishing a Cartesian inertial coordinate system X-Y-Z. When the receiving coil flies in the air, due to changes in wind, air resistance, and the attitude of the aircraft, the relative position between the receiving coil and the flying device changes, causing the coordinate system to change to X'-Y'-Z';

[0023] The receiving coil includes an X-receiving device, a Y-receiving device, and a Z-receiving device;

[0024] According to the position change of the receiving coil, different motion forms are obtained; the motion forms include swinging, tilting, and yawing.

[0025] Preferably, the process of obtaining the motion noise formed by the induced voltage generated in the receiving coil according to the coupling change includes

[0026] obtaining a motion coefficient matrix based on different motion forms, and reducing the dimension of the motion coefficient matrix to obtain a reduced-dimensional matrix;

[0027] obtaining the secondary field generated by the emission source and the voltage in the receiving coil based on the reduced-dimensional matrix; obtaining the voltage relationship formula of the receiving coil before and after motion based on the voltage, and obtaining the corresponding motion noise according to the voltage relationship formula.

[0028] An electrical source semi-aerial transient electromagnetic method receiving coil noise correction system includes:

[0029] A noise acquisition module for acquiring mutual inductance noise and motion noise;

[0030] A noise correction module for correcting based on the mutual inductance noise and motion noise to achieve noise correction of the receiving coil.

[0031] Preferably, the noise acquisition module includes a mutual inductance noise acquisition unit and a motion noise acquisition unit;

[0032] The mutual inductance noise acquisition unit is used to generate a mutual inductance effect between the transmitting source and the receiving coil according to a predetermined waveform, and obtain mutual inductance noise based on the influence generated by the mutual inductance effect;

[0033] The motion noise acquisition unit is used to obtain the coupling change between the receiving coil and the ground according to the position change of the receiving coil; and obtain the motion noise formed by the induced voltage generated in the receiving coil according to the coupling change.

[0034] The present invention discloses the following technical effects:

[0035] A method and system for correcting the noise of a receiving coil in an electrical source semi-aerial transient electromagnetic method provided by the present invention. The transmitting source emits a mutual inductance effect with the receiving coil according to a predetermined waveform, and obtains mutual inductance noise based on the influence generated by the mutual inductance effect; obtains the coupling change between the receiving coil and the ground according to the position change of the receiving coil; obtains the motion noise formed by the induced voltage generated in the receiving coil according to the coupling change; and performs correction based on the mutual inductance noise and the motion noise to realize the noise correction of the receiving coil. Compared with the prior art, the present invention has the advantages of high precision, strong real-time performance and easy operation; can realize the time synchronization of received data, is convenient for on-site data processing and analysis by staff on the basis of ensuring data coincidence, and thus takes corresponding compensation measures to achieve the purpose of suppressing motion noise. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 Schematic diagram of the receiving device according to an embodiment of the present invention;

[0038] Figure 2 Schematic diagram of the emission waveform according to an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of the mutual inductance between the emission power supply and the receiving coil according to an embodiment of the present invention;

[0040] Figure 4 Schematic diagram of the forward emission waveform according to an embodiment of the present invention;

[0041] Figure 5 Schematic diagram of the influence of the mutual inductance response in a homogeneous half-space according to an embodiment of the present invention;

[0042] Figure 6Layered low-resistance mutual inductance response influence diagram of the embodiments of the present invention;

[0043] Figure 7 Layered high-resistance mutual inductance response influence diagram of the embodiments of the present invention;

[0044] Figure 8 Schematic diagrams of different motion forms of the receiving device of the embodiments of the present invention;

[0045] Figure 9 Broken line graph of the receiving device affected by the geomagnetic field in the embodiments of the present invention;

[0046] Figures 10(a)-(f) are broken line graphs of the receiving device affected by the geometric response of coils with different motion forms in the embodiments of the present invention. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0049] As Figure 1-2 shown, the present invention provides a method for correcting the noise of the receiving coil of the electrical source semi-aerial transient electromagnetic method, including:

[0050] When the transmitting power supply emits according to a predetermined waveform, a mutual inductance effect between the transmitting source S and the receiving coil Tx will be generated due to the emission and turn-off in a very short time. As Figure 2 shown, the current will rise to Isource in a very short time and will also become zero in the turn-off time, and the order of magnitude of this very short time is in the nanometer level. In this way, a relatively strong mutual inductance voltage will be generated in the receiving coil, and the generation of the voltage will cause the receiving coil to act as the function of the transmitting power supply, thereby affecting the signal received by the receiving coil from the electromagnetic field coupled with the earth.

[0051] As Figure 3 shown, a Cartesian coordinate system is established. The transmitting sources S1S2 emit a series of currents according to the transmitting waveform, and the direction is the X-axis direction, and the source length is l. The position coordinates of the center point A of the receiving coil are (x, y, z). The point where the plane passing through point A and perpendicular to the X-Y plane intersects S1S2 is A0, and the coordinates are (x, 0, 0), and the included angle is The angles with the X-axis are θ1 and θ2 respectively.

[0052] As Figures 4-7 shown, assuming the duty cycle of the transmitted waveform is 0.5, when the transmitter starts transmitting, the current amplitude suddenly increases steeply. A counterclockwise mutual inductance current generated by the transmission front will appear in the receiving coil Rx. The existence of the mutual inductance current in the coil will temporarily make Rx act as a magnetic dipole transmitter, emitting an electromagnetic field to the ground (the upward-emitted electromagnetic field is not considered temporarily). At this time, the transmitter continues to supply power, and the current stabilizes at Isource. The mutual inductance current is submerged in the short-term steady current. During this period, Rx receives the signal that it emits itself and then couples with the ground. We believe that the primary field signal is much larger than the signal just brought by self-inductance. Therefore, the mutual inductance effect brought by the transmission front does not bring "noise".

[0053] When the transmitter stops supplying power and the current amplitude drops steeply, during the turn-off time, the transmitters S1S2 and Rx are mutually inductive again. If Rx is a very small coil that can be considered as a coil with the center point A, a mutual inductance magnetic field Bp can be generated. However, if Rx is a horizontally placed coil with an effective area of Sm at this time, the relationship of the vertical mutual inductance magnetic field Bzp is

[0054]

[0055] When the current amplitude is zero, Rx becomes a "magnetic dipole transmitter" again. At this time, Rx has to continuously receive the signal generated by the coupling of the electromagnetic field emitted by the transmitting power supply and the ground. After a very short period of time, what Rx receives is the coupled signal of the electromagnetic fields emitted by the transmitter and Rx and coupled with the ground. This brings "noise".

[0056] Therefore, first, the mutual inductance magnetic field value, voltage, and current need to be calculated, and then the magnitude of the influence of the mutual inductance effect can be known. The mutual inductance formulas include:

[0057]

[0058]

[0059]

[0060] Ψ = NMI source

[0061]

[0062] Φ R = SB zp

[0063] S m = NS

[0064] In the above formula, ε mutual is the mutual inductance voltage induced by mutual inductance in the coil, I mutual is the mutual inductance current, R is the coil resistance, L is the total length of the coil, S section is the cross-sectional area of the coil wire, ρ is the resistivity of the coil, Ψ is the magnetic flux linkage, M is the mutual inductance coefficient of the emission source at Rx, Φ R is the mutual inductance magnetic flux passing through Rx, and the effective area Sm is obtained by multiplying the coil area S by the number of turns.

[0065] When there is mutual inductance between a finite straight wire and a coil, according to the Biot-Savart law

[0066]

[0067]

[0068]

[0069]

[0070] Of course, the above formula is for the receiving coil laid parallel to the ground in the air, denoted by Z-, and of course there are also the Y- parallel to the X-Z plane and the X- parallel to the Y-Z device forms. So the formula can be written as

[0071]

[0072] v can respectively represent the X-, Y-, Z- device forms as (1, 0, 0) T , (0, 1, 0) T , (0, 0, 1) T .

[0073] The noise generated when the receiving coil moves is called motion noise. When the pod or the fixed coil changes its position, it will change the coupling between the coil and the ground, and due to this sudden change of the coil in the geomagnetic field, the effective area of the geomagnetic field passing through the coil is changed, resulting in an induced voltage in the receiving coil and thus forming noise.

[0074] The receiving device of the electrical source airborne transient electromagnetic method is as Figure 1 shown. In the Cartesian inertial coordinate system, the receiving device can be divided into three rigid device forms: X-, Y-, and Z-. When the coil is flying in the air, due to wind, air resistance, sudden changes in the aircraft attitude, etc., the receiving coil shows as Figure 8The three basic motion forms shown (Roll, Pitch, and Yaw), with the flight direction being consistent with the X-axis. When there is relative motion between the receiving device and the flying device, the coordinate system changes, and X-Y-Z becomes X'-Y'-Z'.

[0075] Taking the Z-device as an example, rolling (Roll) means that when the coil is flying, it is subjected to forces on both sides of the flight direction (in the Y-axis direction) and makes a pendulum motion in the Y-Z plane with the Z-axis as the rotation axis. This force may be caused by lateral wind or sudden left-right movement of the aircraft, etc. Pitching (Pitch) means that the working coil is subjected to forces above and below the flight direction. Different from Roll, the coil makes a pendulum motion in the X-Z plane. The reasons for this motion are that the aircraft is subjected to resistance or sudden acceleration, sudden stop, etc. in the flight direction. Yawing (Yaw) means that due to the change in the flight direction of the coil, that is, the X-axis is suddenly affected by wind on both sides or the aircraft turns, etc., causing the coil to have a displacement around the Z-axis in the X-Y plane. Generally, scholars will think that the changes of the above three coils only affect the signal received from the coupling of the earth and the transmitting current, ignoring the role of the geomagnetic field.

[0076] Based on the derivation in the formula, how will the above-mentioned motion of the coil occur? When there is relative motion between the receiving device and the flying device, the Cartesian inertial coordinate system X-Y-Z becomes X'-Y'-Z'. Therefore, the physical quantities in the coordinate system before and after the motion can be expressed as B = CB', where C Roll 、C Pitch 、C Yaw represent three motion forms respectively, and we can call it the motion coefficient matrix

[0077]

[0078]

[0079]

[0080] B' T =(B' x ,B' y ,B' z ,ΔB' x ,ΔB' y ,ΔB' z ,ε x ,ε y ,ε z ),

[0081] B=(B x ,B y ,B z ),

[0082] εγx = 0,

[0083]

[0084]

[0085]

[0086]

[0087] ε αx = 0,

[0088] ε βx = ε βy = ε βz = 0,

[0089] where B is the unchanged magnetic induction intensity, B' is the magnetic induction intensity after the coil moves, and ΔB' x , ΔB' y , ΔB z ' are the changes in the magnetic induction intensity caused by the spatial displacement of the coordinate system after the coil moves due to the inhomogeneity of the underground medium; ε x , ε y , ε z are the induced voltages generated due to the movement and change.

[0090] During the actual flight exploration process, since the displacement of the coil center point is much smaller than the point distance and the geological body or change reflected by the signal remains unchanged, we can consider that when the coil makes a relative movement with the aircraft, it is only a rotational change and the displacement of the center point can be ignored. The change in the magnetic induction intensity caused by the inhomogeneity of the underground medium can be considered zero. Thus, we can reduce the above formula (motion coefficient matrix) to

[0091]

[0092]

[0093]

[0094] B' T = (B' x , B' y , B' z , ε x , ε y , ε z ),

[0095] As can be seen from the above formula, C can be composed of two sub - matrices A is a rotation matrix and E is the identity matrix. According to Euler’s Theory, in coordinate transformation, any rotation transformation can be reduced to a combination of rotations along the coordinate axes. The number of combinations does not exceed three, and two adjacent rotations must be along different coordinate axes. Therefore, a transformation can be represented by three angles of rotation along the coordinate axes. According to the relationship between these angles (Euler angles) and the rotation matrix, the change of any vector in the original coordinate system is equivalent to the action of a rotation matrix. Any movement of the coil can be characterized by these three basic movements and can be expressed as the product of the corresponding three rotation matrices, that is, it can be represented by B = A Roll A Pitch A Yaw B'p T , where p represents the X-, Y-, and Z-device forms as (1, 0, 0), (0, 1, 0), and (0, 0, 1) respectively according to different devices.

[0096] According to Faraday’s law of electromagnetic induction, the secondary field generated by the emission source and the voltage in the receiving coil can be expressed as

[0097] V = -iωS m Bp T ,

[0098] When there is no movement of the coil, the signal we should obtain is as follows. When there is coil movement, the signal we obtain is

[0099] V' = -iωS m B'p T +εp T ,

[0100] When we substitute the formula (Roll device form) (rotation matrix) into the above formula

[0101] V x = V' x ,

[0102] V y = cosγ(V' y -ε γy ) - sinγV' z ,

[0103] V z = cosγ(V' z -ε γz ) + sinγV' y ,

[0104] The above formula is the voltage relationship in the coil of the three receiving devices before and after the Roll motion. Obviously, the signal received by the X-device is not affected by the Roll motion. The receiving coil does not produce a change in the effective area on the X-axis, but there are changes on the Y-axis and Z-axis, thus introducing the influence of the geomagnetic field. And the previously measured signal is now mixed with signals in other directions. The signal received by the Y-device is not only the signal in the Y direction but also doped with the signal in the Z direction. The Z-device also has such a phenomenon.

[0105] Substitute the formula (Pitch device form) (rotation matrix) into the above formula (secondary signal formula)

[0106] V x = cosα(V' x - ε αx ) + sinαV' z ,

[0107] V y = V' y ,

[0108] V z = cosα(V' z - ε αz ) - sinαV' x ,

[0109] The above formula is the voltage relationship in the coil of the three receiving devices before and after the Pitch motion. The signal of the Y-device does not change after the Pitch motion. The Pitch motion mixes the X-component and Z-component of the received signal, which is the same as the influence of the Roll motion.

[0110] Substitute the formula (Yaw device form) (rotation matrix) into the above formula (secondary signal formula)

[0111] V x = cosβV' x + sinβV' y ,

[0112] V y = cosβV' y - sinβV' x ,

[0113] V z = V' z ,

[0114] In the voltage relation formulas of each device circle after the above Yaw movement, the signal received by the Z-device remains unchanged, and the phenomenon of signal mixing still occurs. That is to say, when a certain device moves, if the mixing of signals in other directions is ignored, the actual signal and the target signal are in a cosine (or cotangent) relationship. It is of great significance to correct the receiving coil according to the relationship between the actual signal and the target signal.

[0115] Substitute the parameters of the geomagnetic field at a certain place into the geomagnetic field influence expression. The magnetic-field strength is 52508.7 nT, the declination is -3°39', the inclination is 52°53', and Δt is taken as 1 s, and the normalized voltage diagram of each receiving device affected by the geomagnetic field and changing with the angle is obtained. As Figure 9 shown, only two coil movement modes (Roll and Pitch) can have the influence of the geomagnetic field and are positively correlated with the angle; in the Roll movement, only the Y- and Z-devices are affected by the geomagnetic field, and the X-device does not have a change in the effective receiving area due to the Roll movement; in the Roll movement, the influence of the geomagnetic field changes periodically with the angle, and the period is 2π. The extreme value of the Y-device affected by the geomagnetic field is at and the extreme value of the Z-device is at ; in the Pitch movement, the Y-device is not affected by the geomagnetic field, and the extreme value of the X-device is at and the extreme value of the Z-device is at When the receiving coil undergoes small angle changes, the Z-device has a stronger ability to resist geomagnetic field interference than the X- and Y-devices; from the amplitude point of view, the Roll and Pitch movements can have a serious impact on the late stage of the response attenuation curve.

[0116] Using the one-dimensional forward response of a homogeneous half-space with a resistivity of 100 Ωm for analysis, the emission source is 1000 m, the emission current is 10 A, and the offset is 500 m. The normal response and the response when the receiving coil undergoes a 5-degree Roll movement (without considering the influence of the geomagnetic field) are obtained. It can be seen that in the case of the Y-device, the most obvious influence of the Roll movement is when receiving the return current; by analyzing the relationship between the response and the movement change angle at two moments of 0.0001 s and 0.1 s, it can be seen that the affected signal changes periodically. When affected by a small angle, as the angle increases, the affected signal moves farther away from the normal signal. In the Z-device, the response after a 5-degree Roll movement is greatly affected in the early stage. The presence of Roll causes the response to suddenly change from a positive value to a negative value in the early stage; and, whether in the early or late stage, the response finally shows a negative value as the angle changes. This shows that when a negative sign appears in the measured data, it may be caused by movement noise.

[0117] When the receiving coil undergoes Pitch motion, the X-device will exhibit a false return current phenomenon, and its influence in the late stage is much greater than that in the early stage; the Z-device is slightly more affected in the early stage. When Yaw motion occurs, the X-device will also exhibit a false return current phenomenon due to a negative response.

[0118] Therefore, when only coil motion occurs, the response of the Z-device will change sign during Roll motion; when the X-device is affected by coil motion, at a certain angle, the response will definitely change sign, thus resulting in a false return current phenomenon; the Y-device will not have a sign change. In small-angle changes, the influence of the Z-device in the early stage is greater than that in the late stage; the time when the Y-device is most affected is the moment when the return current has the greatest influence. The line graphs showing the geometric responses of the receiving device to coils of different motion forms are as shown in each of the figures in Figure 10.

[0119] The embodiments described above are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for correcting the noise of a receiving coil in the electrical source semi-aerial transient electromagnetic method, characterized in that, Including: The emission source emits according to a predetermined waveform and generates a mutual inductance effect with the receiving coil. Based on the influence generated by the mutual inductance effect, mutual inductance noise is obtained. According to the position change of the receiving coil, the coupling change between the receiving coil and the ground is obtained; according to the coupling change, the motion noise formed by the induced voltage generated in the receiving coil is obtained. Based on the mutual inductance noise and the motion noise for correction, the noise correction of the receiving coil is realized. The process of obtaining the motion noise formed by the induced voltage generated in the receiving coil according to the coupling change includes Obtaining a motion coefficient matrix based on different motion forms, reducing the dimension of the motion coefficient matrix, and obtaining a reduced-dimension matrix. Based on the reduced-dimension matrix, the secondary field generated by the emission source and the voltage in the receiving coil are obtained. Based on the voltage, the voltage relationship formula of the receiving coil before and after motion is obtained. According to the voltage relationship formula, the corresponding motion noise is obtained.

2. The method for correcting the noise of the receiving coil of the electrical source semi-aerial transient electromagnetic method according to claim 1, characterized in that The process of the emission source emitting a current that generates a mutual inductance effect with the receiving coil according to a predetermined waveform includes: the emission sources S1 and S2 emit a current according to the emission waveform, with the direction along the X-axis and the source length being l; the center point A of the receiving coil has position coordinates (x, y, z), the point where the plane passing through point A and perpendicular to the X-Y plane intersects S1S2 is A0, with coordinates (x, 0, 0), and the included angles are The included angles with the X-axis are θ1 and θ2 respectively.

3. The method for correcting the noise of the receiving coil of the electrical source semi-aerial transient electromagnetic method according to claim 1, characterized in that The process of obtaining the mutual inductance noise based on the influence generated by the mutual inductance effect includes When the emission source starts to emit, the current amplitude suddenly increases, and the receiving coil Rx has a mutual inductance current generated by the emission front. Based on the mutual inductance current, the Rx acts as a magnetic dipole emission source and emits an electromagnetic field underground; when the emission source stops power supply, the current amplitude suddenly decreases, and there is mutual inductance between the emission source and the Rx. The Rx is a coil with a very small center point A, generating a Bp mutual inductance magnetic field; when the current amplitude is zero, the Rx acts as a magnetic dipole emission source and continuously receives the signal generated by the coupling of the electromagnetic field emitted by the emission source with the ground. The Rx receives the coupling signals of the electromagnetic fields emitted by the emission source and the Rx with the ground, and obtains the mutual inductance noise.

4. The method for correcting the noise of the receiving coil of the electrical source semi-aerial transient electromagnetic method according to claim 1, characterized in that The magnitude of the influence of the mutual inductance effect is judged by calculating the mutual inductance magnetic field value, voltage and current based on the mutual inductance formula. The mutual inductance formula includes: Φ R = SB zp S m = NS Where, ε mutual is the mutual inductance voltage resulting from mutual inductance within the coil, I mutual is the mutual inductance current, R is the coil resistance, L is the total length of the coil, S section is the cross-sectional area of the coil wire, ρ is the resistivity of the coil, Ψ is the magnetic flux linkage, M is the mutual inductance coefficient of the emission source at Rx, Φ R is the mutual inductance magnetic flux passing through Rx, and the effective area S m is obtained by multiplying the coil area S by the number of turns.

5. The method for correcting the noise of the receiving coil of the electrical source semi-aerial transient electromagnetic method according to claim 1, characterized in that The process of obtaining the coupling change between the receiving coil and the ground according to the position change of the receiving coil includes Establishing a Cartesian inertial coordinate system X-Y-Z. When the receiving coil flies in the air, due to the influence of wind, air resistance, and the change of the aircraft attitude, the position of the receiving coil relative to the flying device changes, causing the coordinate system to change to X'-Y'-Z'. The receiving coil includes an X-receiving device, a Y-receiving device, and a Z-receiving device. According to the position change of the receiving coil, different motion forms are obtained; the motion forms include swinging, tilting, and yawing.

6. An electrical source semi-aerial transient electromagnetic method receiving coil noise correction system for implementing the method according to any one of claims 1-5, characterized in that, Including: A noise acquisition module for acquiring mutual inductance noise and motion noise. A noise correction module for correcting based on the mutual inductance noise and the motion noise to realize the noise correction of the receiving coil.

7. The noise correction system for the receiving coil of the electrical source semi-aerial transient electromagnetic method according to claim 6, characterized in that the noise acquisition module includes a mutual inductance noise acquisition unit and a motion noise acquisition unit; the mutual inductance noise acquisition unit is configured to generate a mutual inductance effect between the transmitting source and the receiving coil by transmitting according to a predetermined waveform, and obtain mutual inductance noise based on the influence generated by the mutual inductance effect; the motion noise acquisition unit is configured to obtain the coupling change between the receiving coil and the ground according to the position change of the receiving coil; and obtain the motion noise formed by the induced voltage generated in the receiving coil according to the coupling change.

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