A kind of aviation mixed field source electromagnetic detection system and method

Abstract

The present invention discloses an aerial mixed-field source electromagnetic detection system and method. The system uses a helicopter as a carrier platform, and adopts a mode of ground electrical source and aerial magnetic source excitation, aerial high-sensitivity small-bandwidth coil and aerial low-sensitivity large-bandwidth coil reception. The high-sensitivity small-bandwidth coil can sense the weak signal generated by the high-power electrical source and the natural field source exciting the earth, and has the advantages of high-power transmission, large detection depth, light mounting, high sensitivity, etc., and is mainly used for deep earth detection; the low-sensitivity large-bandwidth coil is coplanar with the transmitting coil of the magnetic source transmitter, and has the advantages of accuracy, high signal-to-noise ratio, high resolution, etc., and is mainly used for medium and shallow earth detection. The present invention gives full play to the advantages of the helicopter's flexible maneuverability, high-power ground power supply, and rich natural field source spectrum components, and combines the advantages of magnetic source, electrical source and natural field source electromagnetic detection systems to achieve fast, large-area, and large-depth detection range of all-round refined electromagnetic exploration.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic detection, and in particular relates to an aviation mixed-field source electromagnetic detection system and method. Background Art

[0002] At present, the main domestic and foreign aviation electromagnetic detection instruments include airborne magnetic source detection systems with integrated transmitters and receivers, ground-based high-power transmission drones equipped with low-sensitivity and wide-bandwidth electrical source detection systems, and airborne natural field source detection systems with only receiving systems. The three systems are used for detection of medium-shallow, medium-deep, and deep earth layers, respectively. In order to combine the advantages of the three systems for large-depth electromagnetic detection, three modes have been developed: frequency domain multi-transmission system multi-frequency combination transmission, electrical source and magnetic source switching transmission, and time domain and frequency domain combination transmission.

[0003] CN101369025B discloses a method of electromagnetic depth sounding in the frequency domain of a combined field source and artificial source, which describes a method of performing a multi-frequency combination test by arranging two or more sets of electromagnetic excitation signal sending devices at each sending position, and simultaneously sending electromagnetic excitation signals of different frequency groups and different powers to the underground, which belongs to a multi-transmitting frequency combination transmission mode. However, the spectrum components of the excitation source of this method are still far behind those of the natural field and the magnetic source pulse excitation field.

[0004] CN101303415B discloses a "combined field source transmitting device for mixed field source electromagnetic method", which describes a combined field source transmitting device that can switch between electrical source and magnetic source. However, when the device is placed on the ground, it will lose important advantages such as the suppression of the primary field by the integrated structure of magnetic source transceiver and the time synchronization between the magnetic source transmitting system and the receiving system. When placed on an aircraft, it will be limited by the power supply of the helicopter, resulting in the limitation of the transmitting magnetic moment, which further affects the detection depth.

[0005] WO / 2019 / 084862 discloses an "AIR CODE HYBRID-SOURCE ELECTROMAGNETIC DETECTION SYSTEM", and CN107894620A discloses an "Aviation Coded Hybrid-Source Electromagnetic Detection System", which describes a high- and low-frequency time-sharing hybrid-source electromagnetic detection system, which emits high-frequency pseudo-random currents during the period when the transient electromagnetic detection system's emission current is turned off. The transient electromagnetic detection system is responsible for deep detection, and the low-frequency pseudo-random emission system is responsible for shallow detection, with combined emission in the time domain and the frequency domain. However, due to the small peak emission magnetic moment caused by the power supply limitation of the helicopter, the detection depth of the system generally does not exceed 800m. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an aerial mixed-field source electromagnetic detection system and method. The system uses a helicopter as a carrier platform, and adopts an aerial high-sensitivity small-bandwidth coil to collect the induction signals generated by the natural field source and the ground high-power electrical source to excite the earth, and an aerial low-sensitivity large-bandwidth coil to collect the induction signals generated by the magnetic source periodic bipolar pulse current to excite the earth. In terms of deep detection, the advantages of the continuous and rich spectrum of the natural field source and the large magnetic moment excitation of the ground electrical source are combined to improve the system resolution while improving the system detection depth; in terms of shallow detection, the use of an integrated transceiver magnetic source electromagnetic detection system solves the problem of the ground electrical source electromagnetic detection system exploring the blind area within 3 times the skin depth from the source. Therefore, the present invention gives full play to the advantages of the helicopter's flexible maneuverability and ground high-power power supply, the rich spectrum components of the natural field source, and the fine detection of the shallow layer by the integrated transceiver of the magnetic source, and realizes a fast, large-area, and deep detection range of all-round electromagnetic exploration.

[0007] The present invention is achieved in this way.

[0008] An aerial mixed-field source electromagnetic detection system uses a helicopter as a carrier, and includes ground instruments and aerial instruments. The ground instruments include an electrical source transmitter, two transmitting electrodes, a ground station three-component receiving sensor, and a ground reference station. The electrical source transmitter and the transmitting electrode are located on the same straight line. The ground reference station is used to receive the natural field three-component magnetic field data collected by the ground station three-component receiving sensor.

[0009] The aerial instrument includes an electrical source receiver and auxiliary system, an electrical source and natural field source receiving coil, a magnetic source transmitter, a receiver and auxiliary system, a compensation coil, a magnetic source receiving coil, a transmitting coil and two sets of attitude testers, wherein the electrical source receiver and auxiliary system are placed in a helicopter, and carry an electrical source and natural field source receiving coil, and work simultaneously with the electrical source transmitter; the magnetic source transmitter, receiver and auxiliary system are placed in a helicopter, and carry a compensation coil, a magnetic source receiving coil, and a transmitting coil, and the attitude testers are respectively arranged on the electrical source and natural field source receiving coil and the magnetic source receiving coil.

[0010] Furthermore, the Z-axis sensor of the three-component receiving sensor of the ground station is arranged parallel to the earth and completely buried, and the X-axis and Y-axis sensors are oriented in the north-south and east-west directions respectively.

[0011] Furthermore, on the ground, the electrical source transmitter emits periodic bipolar multi-frequency pseudo-random waves, and the farthest end of the survey area and the ground reference station are both within the influence range of the electrical source excitation field; in the air, the magnetic source transmitter, receiver and auxiliary system emit periodic bipolar trapezoidal, triangular or sinusoidal pulse waves along the survey line, and the two transmission systems do not work at the same time.

[0012] Furthermore, when the electrical source transmitter is working, the signals induced by the electrical source and the natural field source receiving coil are used for deep earth detection; the signals induced by the magnetic source receiving coil are used for medium and shallow earth detection. The two sets of receiving systems are independently tested along the same survey line, and the imaging results of the survey area are obtained after the fusion processing of the two sets of data.

[0013] An aerial mixed-field source electromagnetic detection method, the method comprising:

[0014] Design survey lines at equal intervals in the survey area according to the detection target and expected resolution, design round-trip repeated lines in key survey areas, and arrange the farthest end of the survey area, the three-component receiving sensor of the ground station and the ground reference station within the range of influence when the electrical source transmitter is working. When the system is working, the ground reference station collects the signals induced by the three-component receiving sensor of the ground station in real time;

[0015] After the electric source transmitter has been turned on and works normally for more than 30 minutes, and the signal corresponding to the preset transmission frequency can be stably observed at the electric source, the natural field source receiving coil and the ground reference station, turn on the attitude tester and start the flight;

[0016] In normal operation, the electrical source receiver and auxiliary system in the cabin collect electromagnetic signals from the electrical source and natural field source receiving coils through cables over 100m long and use timestamps to bind the GPS / Beidou positioning information, radar altitude, pressure altitude and electromagnetic data transmitted from the optical fiber. The electrical source and natural field source receiving coils are more than 100m above the ground while flying along the survey line.

[0017] After the flight, first shut down the airborne system and retrieve the electromagnetic and auxiliary information data, then shut down the attitude tester and retrieve the attitude data, and finally shut down the electrical source transmitter, and the ground reference station retrieves the current and ground three-component electromagnetic data respectively;

[0018] Replace the airborne system with a magnetic source transmitter, receiver and auxiliary system, compensation coil, magnetic source receiving coil and transmitting coil;

[0019] Before starting the flight, use the ground power supply, turn on the equipment and test the abnormal loop response and noise. When the system is confirmed to be working properly, turn on the attitude tester. After the helicopter starts to be stably powered, disconnect the ground power supply and switch to the helicopter power supply to start the flight. When the helicopter returns to the base, fly back and forth at the same flight altitude, repeating the measurement line centered on the artificial anomaly or closed coil.

[0020] After the flight, the electromagnetic data and various auxiliary information collected by the transient electromagnetic system are taken out, and the attitude tester is turned off to take out the attitude data;

[0021] The frequency related to the electrical source emission is extracted from the signal induced by the receiving coil of the electrical source and the natural field source; then the frequency related to the natural field frequency is calculated by the dipole response with the ground reference station signal, and then the apparent resistivity ρ is calculated. 天然场 , 电 ; Then calculate the apparent resistivity of the signal induced by the magnetic source receiving coil on the same measuring line to obtain ρ 磁 , and perform the final apparent resistivity imaging.

[0022] Furthermore, the Z-axis sensor of the three-component receiving sensor of the ground station is completely buried parallel to the earth, and the X-axis and Y-axis sensors are oriented in the north-south and east-west directions respectively.

[0023] Furthermore, the apparent resistivity imaging also includes:

[0024] Under the same geoelectric model, the forward modeling and apparent resistivity calculation are performed using the electric source and natural field source excitation, the aerial receiving and magnetic source transmission and reception integrated structure, and the corresponding apparent resistivity ρ is obtained. 天然场 , 电 and ρ 磁 ; Calculate the theoretical resistivity under various terrains, divide the training set and the test set, convert the three apparent resistivities into the depth domain according to the depth relationship of different types of resistivity imaging, then perform principal component analysis or modal decomposition on the three apparent resistivities, extract the feature vector as the pseudo-apparent resistivity, use the pseudo-apparent resistivity and the earth model parameters as input and output respectively, train the neural network, and obtain the apparent resistivity imaging model;

[0025] The measured apparent resistivity ρ 天然场 , 电 and ρ 磁 Input into the apparent resistivity imaging model to obtain the apparent resistivity imaging.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention uses a helicopter as a carrier platform, has the advantage of flexibility and mobility, and can quickly conduct large-area geological exploration in complex terrains such as mountains, plateaus, and uninhabited areas.

[0028] The mode of excitation by ground electrical source and aerial magnetic source, reception by aerial high-sensitivity small-bandwidth coil and aerial low-sensitivity large-bandwidth coil is adopted. The high-sensitivity small-bandwidth coil can sense the weak signal generated by the high-power electrical source and natural field source exciting the earth. It has the advantages of high-power transmission, large detection depth, light mounting, high sensitivity, etc., and is mainly used for deep earth detection; the low-sensitivity large-bandwidth coil is coplanar with the transmitting coil of the magnetic source transmitter, and has the advantages of accuracy, high signal-to-noise ratio, high resolution, etc., and is mainly used for medium and shallow earth detection. The present invention gives full play to the advantages of the helicopter's flexible maneuverability, high-power ground power supply, and rich spectrum components of natural field sources, and combines the advantages of magnetic source, electrical source and natural field source electromagnetic detection systems to achieve fast, large-area, and deep detection range of all-round refined electromagnetic exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural diagram of an aerial mixed-field source electromagnetic detection system according to an embodiment of the present invention;

[0030] Figure 2 The electric source emission current waveform described in the embodiment of the present invention;

[0031] Figure 3 The magnetic source emits a current waveform according to the embodiment of the present invention;

[0032] Figure 4 The structure diagram of the receiving coil of the electrical source and the natural field source according to the embodiment of the present invention DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] See also Figure 1 As shown, an aerial mixed-field source electromagnetic detection system includes: a helicopter 1, an electrical source receiver and auxiliary system 2, an electrical source and natural field source receiving coil 4, an electrical source transmitter 5, a transmitting electrode 6, a ground station three-component receiving sensor 7, a ground reference station 8, a magnetic source transmitter, a receiver and auxiliary system 9, a compensation coil 10, a magnetic source receiving coil 11, a transmitting coil 12 and an attitude tester 13.

[0035] The electrical source transmitter and the transmitting electrode are located on the same straight line, and the ground reference station is used to receive the natural field three-component magnetic field data collected by the three-component receiving sensor of the ground station;

[0036] The aerial instrument includes an electric source receiver and auxiliary system, an electric source and natural field source receiving coil, a magnetic source transmitter, a receiver and auxiliary system, a compensation coil, a magnetic source receiving coil, a transmitting coil and two sets of attitude testers, wherein the electric source receiver and auxiliary system are placed in a helicopter, and carry the electric source and natural field source receiving coil, and work simultaneously with the electric source transmitter; the magnetic source transmitter, receiver and auxiliary system are placed in a helicopter, and carry the compensation coil, the magnetic source receiving coil, and the transmitting coil, and the attitude testers are respectively arranged on the electric source and natural field source receiving coil and the magnetic source receiving coil.

[0037] The Z-axis sensor of the three-component receiving sensor of the ground station is arranged parallel to the earth and completely buried, and the X-axis and Y-axis sensors are oriented north-south and east-west respectively. The ground reference station has two functions. First, it is used to monitor and collect the three-component magnetic field transformation of the natural field in the survey area in real time, and to correct the data of the induction signal of the electrical source receiving coil in the survey area; secondly, the ground reference station can observe the stable electrical source excitation field signal of fixed frequency, which is used to monitor the working condition of the electrical source transmitter.

[0038] On the ground, the electrical source transmitter emits periodic bipolar multi-frequency pseudo-random waves. The farthest end of the survey area and the ground reference station are both within the influence range of the electrical source excitation field. In the air, the magnetic source transmitter, receiver and auxiliary system emit periodic bipolar trapezoidal, triangular or sinusoidal pulse waves along the survey line. The two transmission systems do not work at the same time.

[0039] When the electrical source transmitter is working, the signals induced by the electrical source and the natural field source receiving coil are used for deep earth detection; the signals induced by the magnetic source receiving coil are used for medium and shallow earth detection. The two sets of receiving systems are tested independently along the same survey line, and the imaging results of the survey area are obtained after the fusion processing of the two sets of data.

[0040] The auxiliary systems and receivers of the electric source receiver and auxiliary system 2 and the magnetic source transmitter, receiver and auxiliary system 9 can be replaced with each other. Among them, the auxiliary system mainly includes GPS and Beidou receivers, radar altimeters, barometric altimeters and wireless communication modules. The electric source receiver and auxiliary system 2, the electric source and natural field source receiving coil 4 and the attitude tester 13 can simultaneously collect the signals fed back by the underground medium after the electric source and the natural field source excite the earth.

[0041] The electrical source and natural field source receiving coil 4 is a high-sensitivity, small-bandwidth hollow coil, with a 3dB bandwidth greater than 1kHz, and a static noise level within the frequency band that is much smaller than the intensity of the natural magnetic field.

[0042] See also Figure 4As shown, the electric source receiver and auxiliary system 2 are placed in the helicopter 1. The distance between the helicopter and the electric source and the natural field source receiving coil 4 is greater than 100m. The electric source and the natural field source receiving coil 4 are connected inside, and between the receiving coil and the rope through a multi-stage elastic rope or a non-magnetic spring 3. Each functional circuit in the electric source receiver and the auxiliary system 2 is powered by an independent power supply, and all auxiliary signals are transmitted between the receiver and the receiver through optical fiber.

[0043] An aerial mixed-field source electromagnetic detection method, using the present invention to carry out preliminary exploration of mountain tunnel engineering, the main process is as follows:

[0044] A. Survey area planning and ground instrument deployment

[0045] According to the entrance and exit of the preset mountain tunnel, a survey line is planned, and then 5 survey lines are arranged on the left and right with the survey line as the center and at intervals of 50m.

[0046] In terms of ground instrument layout, the transmitting electrodes are laid out along the nearest road or valley in the survey area, with a straight-line distance of 3km. The electrical source transmitter 5 is placed at the center of the line connecting the two transmitting electrodes. The farthest end of the laid survey line is 15km away from the vertical distance of the transmitting electrode line. The ground reference station 8 is selected at a place with less human noise interference, about 10km away from the vertical distance of the transmitting electrode line; the Z-axis sensor of the three-component receiving sensor 7 of the ground station is arranged parallel to the earth and has a certain burial depth, and the X-axis and Y-axis sensors are north-south and east-west respectively.

[0047] B. Flight test of deep earth detection instrument of airborne mixed-field source electromagnetic detection system

[0048] First, turn on the electrical source transmitter 5 to transmit Figure 2 The peak value of 20A is shown as a periodic bipolar pseudo-random current with frequencies of 16Hz, 32Hz, 64Hz, 128Hz, 256Hz, etc. After it works normally for more than 30 minutes and the signals generated by the excitation of these transmission frequencies can be stably observed at the electrical source and the natural field source receiving coil 4 and the ground reference station 8, the attitude tester 13 is set and turned on to transmit the attitude test rate at a rate of 200Hz, and then the flight experiment is started.

[0049] During normal operation, the electrical source receiver and auxiliary system 2 in the cabin collect electromagnetic signals from the electrical source and natural field source receiving coil 4 through a cable of more than 100m and use timestamps to bind the GPS / Beidou positioning information, radar altitude, barometric altitude and electromagnetic data transmitted from the optical fiber.

[0050] After the flight, first shut down the air system and extract the electromagnetic and auxiliary information data, then shut down the attitude tester 13 and extract the attitude data, and finally shut down the electrical source transmitter, and the ground reference station extracts the current and ground three-component electromagnetic data respectively.

[0051] C. Flight test of the medium-shallow earth detection instrument of the airborne mixed-field source electromagnetic detection system

[0052] After the deep earth exploration instrument completes the flight test of the survey area or a certain survey line, the aerial system is replaced with the magnetic source transmitter, the receiver and auxiliary system 9, the compensation coil 10, the magnetic source receiving coil 11 and the transmitting coil 12.

[0053] Before starting the flight, use the ground power supply to power the magnetic source transmitter, receiver and auxiliary system 9. The magnetic source transmitter transmits Figure 3 The bipolar trapezoidal pulse current with a base frequency of 25 Hz is shown, and the presence or absence of underground abnormal bodies is simulated by manually controlling the closing / opening of the abnormal loop. When the system is confirmed to be working normally, the attitude tester 13 is turned on, and after the helicopter starts to be stably powered, the ground power supply is disconnected and switched to the helicopter power supply, and the flight experiment is started.

[0054] When the helicopter returns to the field, it will fly back and forth at the same altitude, repeating the survey line centered on the electrical source and the natural field source receiving coil 4 or other artificial anomaly.

[0055] After the flight experiment is over, the equipment is turned off, the helicopter is shut down, and finally the electromagnetic data and various auxiliary information collected by the transient electromagnetic system are taken out, and the attitude tester 13 is turned off to take out the attitude data therein.

[0056] A. Data Processing and Image Interpretation

[0057] In terms of apparent resistivity mapping, it is first necessary to establish a relationship between the fused apparent resistivity obtained from the induced signals under different electromagnetic excitation sources and the ideal terrain.

[0058] Under the same geoelectric model, the forward modeling and apparent resistivity calculation are performed using the electric source and natural field source excitation, the aerial receiving and magnetic source transmission and reception integrated structure, and the corresponding resistivity ρ is obtained. 天然场 , 电 and ρ 磁 . Calculate the theoretical resistivity under various terrains and divide them into training sets and test sets. According to the depth relationship of different types of resistivity imaging, convert the three resistivities into the depth domain, then perform principal component analysis or modal decomposition on the three resistivities, extract the feature vector as the apparent resistivity, use the apparent resistivity and the earth model parameters as input and output respectively, train the neural network, and then sample the verification set to verify the accuracy of the neural network.

[0059] Secondly, the measured signal needs to be preprocessed.

[0060] (1) Data alignment. An aerial mixed-source electromagnetic detection system takes electromagnetic data as the core. Based on the distribution of measurement points and GPS / Beidou timing as the standard, it resamples and interpolates GPS / Beidou positioning information, radar altitude information, pressure altitude information, and attitude information to ensure the alignment of auxiliary information and electromagnetic information at each measurement point.

[0061] (2) Data filtering and correction. According to the test requirements and relevant specifications, basic processing such as data superposition, channel extraction, filtering, polynomial fitting, field value normalization, phase check and correction is performed. In terms of profile processing of the survey line, basic processing such as data leveling, zero drift baseline correction and attitude correction is required.

[0062] (3) Extract the frequency related to the electrical source emission from the signal induced by the electrical source and the natural field source receiving coil 4; then calculate the frequency related to the natural field frequency and the ground reference station signal to calculate the apparent resistivity ρ 天然场 , 电 Then the signal induced by the magnetic source receiving coil 11 on the same survey line is calculated for apparent resistivity, and ρ 磁 .

[0063] (4) The three resistivities obtained in (3) are input into the neural network trained in 1 to obtain the final apparent resistivity imaging or inversion imaging result.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An aerial mixed-field source electromagnetic detection system, characterized in that: A helicopter is used as a carrier, including ground instruments and aerial instruments, wherein the ground instruments include an electrical source transmitter, two transmitting electrodes, a ground station three-component receiving sensor, and a ground reference station, wherein the electrical source transmitter and the transmitting electrode are located on the same straight line, and the ground reference station is used to receive the natural field three-component magnetic field data collected by the ground station three-component receiving sensor; The aerial instrument includes an electrical source receiver and auxiliary system, an electrical source and natural field source receiving coil, a magnetic source transmitter, a receiver and auxiliary system, a compensation coil, a magnetic source receiving coil, a transmitting coil and two sets of attitude testers, wherein the electrical source receiver and auxiliary system are placed in the helicopter, and carry the electrical source and natural field source receiving coil, and work simultaneously with the electrical source transmitter; the magnetic source transmitter, receiver and auxiliary system are placed in the helicopter, and carry the compensation coil, the magnetic source receiving coil, and the transmitting coil, and the attitude testers are respectively arranged on the electrical source and natural field source receiving coil and the magnetic source receiving coil; On the ground, the electric source transmitter emits periodic bipolar multi-frequency pseudo-random waves, and the farthest end of the survey area and the ground reference station are both within the influence range of the electric source excitation field; in the air, the magnetic source transmitter, receiver and auxiliary system emit periodic bipolar trapezoidal, triangular or sinusoidal pulse waves along the survey line, and the two transmission systems do not work at the same time; When the electrical source transmitter is working, the signals induced by the electrical source and the natural field source receiving coil are used for deep earth detection; the signals induced by the magnetic source receiving coil are used for medium and shallow earth detection. The two sets of receiving systems are tested independently along the same survey line, and the imaging results of the survey area are obtained after the fusion processing of the two sets of data.

2. The airborne mixed-field source electromagnetic detection system according to claim 1, characterized in that: The Z-axis sensor of the three-component receiving sensor of the ground station is arranged parallel to the earth and completely buried, and the X- and Y-axis sensors are oriented north-south and east-west respectively.

3. An aerial mixed-field source electromagnetic detection method, characterized in that: The method includes: Design survey lines at equal intervals in the survey area according to the detection target and expected resolution, design round-trip repeated lines in key survey areas, and arrange the farthest end of the survey area, the three-component receiving sensor of the ground station and the ground reference station within the range of influence when the electrical source transmitter is working. When the system is working, the ground reference station collects the signals induced by the three-component receiving sensor of the ground station in real time; After the electric source transmitter has been turned on and works normally for more than 30 minutes, and the signal corresponding to the preset transmission frequency can be stably observed at the electric source, the natural field source receiving coil and the ground reference station, turn on the attitude tester and start the flight; In normal operation, the electrical source receiver and auxiliary system in the cabin collect electromagnetic signals from the electrical source and natural field source receiving coils through cables over 100m long and use timestamps to bind the GPS / Beidou positioning information, radar altitude, pressure altitude and electromagnetic data transmitted from the optical fiber. The electrical source and natural field source receiving coils are more than 100m above the ground while flying along the survey line. After the flight, first shut down the airborne system and retrieve the electromagnetic and auxiliary information data, then shut down the attitude tester and retrieve the attitude data, and finally shut down the electrical source transmitter, and the ground reference station retrieves the current and ground three-component electromagnetic data respectively; Replace the airborne system with a magnetic source transmitter, receiver and auxiliary system, compensation coil, magnetic source receiving coil and transmitting coil; Before starting the flight, use the ground power supply, turn on the equipment and test the abnormal loop response and noise. When the system is confirmed to be working properly, turn on the attitude tester. After the helicopter starts to be stably powered, disconnect the ground power supply and switch to the helicopter power supply to start the flight. When the helicopter returns to the base, fly back and forth at the same flight altitude, repeating the measurement line centered on the artificial anomaly or closed coil. After the flight, the electromagnetic data and various auxiliary information collected by the transient electromagnetic system are taken out, and the attitude tester is turned off to take out the attitude data; The frequency related to the electrical source emission is extracted from the signal induced by the receiving coil of the electrical source and the natural field source; then the frequency related to the natural field frequency is calculated by the dipole response with the ground reference station signal, and then the apparent resistivity ρ is calculated. 天然场 , 电 ; Then calculate the apparent resistivity of the signal induced by the magnetic source receiving coil on the same measuring line to obtain ρ 磁 , and perform the final apparent resistivity imaging.

4. The method for electromagnetic detection using an aerial mixed-field source according to claim 3, characterized in that: The Z-axis sensor of the three-component receiving sensor of the ground station is completely buried parallel to the earth, and the X- and Y-axis sensors are oriented north-south and east-west respectively.

5. The method for electromagnetic detection using an aerial mixed-field source according to claim 3, characterized in that: Apparent resistivity imaging also includes: Under the same geoelectric model, the forward modeling and apparent resistivity calculation are performed using the electric source and natural field source excitation, the aerial receiving and magnetic source transmission and reception integrated structure, and the corresponding apparent resistivity ρ is obtained. 天然场 , 电 and ρ 磁 ; Calculate the theoretical resistivity under various terrains, divide the training set and the test set, convert the three apparent resistivities into the depth domain according to the depth relationship of different types of resistivity imaging, then perform principal component analysis or modal decomposition on the three apparent resistivities, extract the feature vector as the pseudo-apparent resistivity, use the pseudo-apparent resistivity and the earth model parameters as input and output respectively, train the neural network, and obtain the apparent resistivity imaging model; The measured apparent resistivity ρ 天然场 , 电 and ρ 磁 Input into the apparent resistivity imaging model to obtain the apparent resistivity imaging.

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