Small volume high sensitivity orthogonal three-component airborne natural field electromagnetic detection system

Abstract

The application relates to the technical field of geophysical electromagnetic detection, and provides a small-volume high-sensitivity orthogonal three-component airborne natural field electromagnetic detection system. The system realizes high-sensitivity signal observation of the vertical component of the airborne natural field electromagnetic field by adopting a flat polygon or circular hollow core type induction magnetic sensor; the slender cylindrical magnetic core is installed on the flat polygon or circular hollow core magnetic sensor flight pod structure plane in an orthogonal distribution installation mode, so that the mutual crosstalk of the three-component magnetic sensor is reduced without increasing the volume of the whole three-axis magnetic sensor; the flat polygon or circular design realizes a small-volume, low-drag, convenient and safe take-off and landing, low-motion-noise sensor pod, and the flight operation data collection quality, flight operation safety and efficiency of the airborne natural field electromagnetic detection system are improved.

Description

Technical Field

[0001] This application relates to the field of geophysical electromagnetic detection technology, and in particular to a small-volume, highly sensitive orthogonal three-component airborne natural field electromagnetic detection system. Background Technology

[0002] Airborne natural electromagnetic field detection systems utilize natural electromagnetic fields—which have a wide signal distribution range, broad bandwidth, and enormous energy, but are weak and highly random—to detect underground geological structures and mineral and water resources. The weak nature of natural electromagnetic field signals and the complex electromagnetic responses of underground electrical structures necessitate the use of low-noise, three-dimensional magnetic sensors for stable reception. Conducting natural electromagnetic signal observations from airborne platforms leverages the high efficiency of airborne detection technology, making it suitable for fields such as mineral resource exploration, geological disaster early warning, and groundwater detection.

[0003] Existing airborne electromagnetic detection systems for natural fields have the following drawbacks:

[0004] 1) The noise level of small-sized magnetic sensor coils does not meet the requirements. Most of the airborne natural field electromagnetic detection systems proposed between 2001 and 2005 adopted three-component magnetic sensor development schemes. The triaxial sensors developed during this period were mostly small spherical or square structures. The small size of the triaxial three-dimensional sensor reduced air resistance during flight and improved flight stability, but its noise level was too high to meet the requirements for weak natural field signal acquisition (on the order of fT / √Hz). In addition, the miniaturized and highly integrated triaxial magnetic sensors had strong crosstalk between their components. Therefore, these prototypes or experimental test prototypes failed to achieve engineering and practical applications.

[0005] 2) Single-component large-size sensor pods cannot achieve three-component signal reception. With technological advancements, large-size sensor pods have emerged. For example, a certain company's airborne natural field electromagnetic detection system uses a 7.4-meter diameter sensor coil to achieve low-noise, wide-bandwidth signal reception, thus meeting the requirements for acquiring weak electromagnetic signals from natural fields (on the order of fT / √Hz). However, due to the large size of the 7.4-meter diameter sensor coil, it is difficult to design and develop an orthogonal three-component airborne magnetic sensor. Designing and developing ultra-large, three-dimensional flight pods places extremely high demands on structural material strength and structural stability. The complex, ultra-large three-dimensional flight pod structure inevitably generates numerous unstable and unsafe factors during system takeoff, landing, and flight. The complex, ultra-large three-dimensional flight pod structure makes aerodynamic optimization difficult, and the sensor pod is easily affected by various environmental factors, resulting in significant system motion noise. Ultimately, this reduces the signal-to-noise ratio of the acquired signals, thus failing to leverage the advantages of large-size, low-noise magnetic sensors. Large, cross-shaped triaxial orthogonal hollow coils are bulky and generate significant wind resistance, making them difficult to integrate with aircraft flight pod platforms and ensure safe suspension during flight. When encountering substantial wind resistance during flight, these large triaxial orthogonal hollow coils inevitably experience severe vibration, deformation, and swaying, affecting flight safety and generating significant electromagnetic interference noise, thus failing to meet the requirements for highly sensitive reception of signals from underground targets.

[0006] Furthermore, the 7.4-meter diameter sensor coil is a flat, single-component magnetic sensor. This flat sensor pod has a small frontal surface during flight, is less affected by localized unstable airflow, and its aerodynamic stability can be improved through various flexible aerodynamic tail fins, thus achieving a highly stable sensor pod system. To achieve the reception of the three-component magnetic field signal, the system deploys two sensors at fixed ground points to observe the horizontal magnetic field. This signal observation method assumes that the horizontal component of the magnetic field is the same throughout the entire exploration area; therefore, the horizontal magnetic field observed synchronously at the ground fixed points is approximated to the horizontal magnetic field value at the location of the aerial pod. This scheme facilitates the development of the aerial sensor pod and enhances flight stability; however, its assumptions and approximations regarding the horizontal magnetic field signal component inevitably introduce systematic errors in data processing, affecting the accuracy and reliability of data processing and interpretation results, and even leading to erroneous data interpretation results.

[0007] 3) Large-size three-component sensors exhibit poor flight stability and high dynamic noise during flight. Some companies have developed products that can receive three-component electromagnetic field signals from the natural airfield. For example, one product adopted a large-size magnetic sensor design, combining three inductive magnetic sensors with a side length of 3.04 meters to form a regular hexahedral orthogonal three-component magnetic sensor. While this sensor has a large size and therefore a low noise level, its assembly creates a large three-dimensional structure, resulting in a significant drag surface during flight. Furthermore, it lacks aerodynamically stable structures or guides, making it difficult to adapt to complex aerodynamic environments, thus causing significant vibration and attitude instability. To address the sensor's vibration problem, this product added a damping vibration reduction structure to the sensor's mounting support structure.

[0008] Because large-sized, three-dimensional, triaxial orthogonal magnetic sensors generate significant rotational motion during flight operations, this motion introduces substantial induced dynamic noise into the background geomagnetic field. The movement of a high-sensitivity magnetic sensor within the geomagnetic field inevitably generates a large induced electromotive force (EMF). This EMF is fed into a signal receiver for acquisition and data storage. To prevent the receiver from saturating when acquiring large induced EMF signals (as the receiver's dynamic range is limited), the sensor's sensitivity must be reduced. A low-sensitivity sensor can only convert weak external magnetic field signals into relatively small induced EMFs, making it difficult to suppress the receiver's own background noise, ultimately reducing the signal-to-noise ratio.

[0009] Meanwhile, due to the relatively large rotational noise during flight operations, the noise suppression performance of various noise suppression technologies, noise suppression algorithms, and attitude correction methods is limited and cannot completely eliminate motion noise. Therefore, it is difficult to obtain high-precision weak natural field vertical component magnetic field signals, and ultimately, it is impossible to obtain high-precision and reliable tilter parameters.

[0010] Therefore, the technical problem that needs to be solved is how to design an airborne natural field electromagnetic detection system that can simultaneously include low noise, wide bandwidth, high sensitivity, and meet the requirements of three-component magnetic field signal observation, obtain stable, reliable, and high-precision Tipper detection parameters, and meet the requirements of dynamic flight stability, system operation safety, assembly, and transportation portability. Summary of the Invention

[0011] In view of this, the present application provides a small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system to solve the problem in the prior art that airborne magnetic sensors are difficult to simultaneously meet the requirements of low noise, high sensitivity, wide bandwidth, and three-component low wind resistance stable flight pods when performing electromagnetic detection of airborne natural field sources.

[0012] A first aspect of this application provides a small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system. The detection system includes a hollow magnetic sensor, a magnetic core magnetic sensor, a flat polygonal or circular flight pod, and a suspension cable.

[0013] Hollow-core magnetic sensors and magnetic core magnetic sensors are combined to form an orthogonal three-component magnetic sensor;

[0014] The flight pod is used to support or fix hollow magnetic sensors and magnetic core magnetic sensors, and the flight pod is flexibly suspended below the flight platform by suspension cables;

[0015] The orthogonal three-component magnetic sensor is obtained by combining a hollow magnetic sensor and two magnetic core magnetic sensors;

[0016] The hollow magnetic sensor is a flat polygonal or circular structure, which is installed in a shape that overlaps with the outer structure of the flight pod; the two magnetic core magnetic sensors are cylindrical or strip-shaped structures, and are both installed horizontally on the plane of the flight pod structure.

[0017] The two magnetic core type magnetic sensors are orthogonal to each other, and the two magnetic core type magnetic sensors are respectively orthogonal to the hollow type magnetic sensor.

[0018] In some implementations, two magnetic core sensors are horizontally mounted on different sides of the polygonal flight pod structure;

[0019] Alternatively, two magnetic core magnetic sensors are horizontally mounted on different central connecting rods of the polygonal flight pod structure;

[0020] Alternatively, two magnetic core sensors can be horizontally mounted on different central connecting rods of a circular flight pod structure.

[0021] In some implementations, the hollow magnetic sensor includes a multi-turn flexible wire and a low-noise preamplifier;

[0022] The total length of the multi-turn flexible conductor is less than a preset length threshold to achieve low-noise signal reception.

[0023] In some embodiments, the hollow magnetic sensor is used to measure the vertical component of the natural field electromagnetic signal, and the magnetic core magnetic sensor is used to measure the horizontal component of the natural field electromagnetic signal.

[0024] The orthogonal three-component magnetic sensor acquires orthogonal three-component natural field electromagnetic signals to detect the tipper parameter of the natural field electromagnetic field.

[0025] In some embodiments, the flight pod structure is a hollow structure, and the diagonal of the polygonal flight pod structure and the diameter of the circular flight pod structure are both greater than a preset size threshold.

[0026] A first-stage high-frequency damping device is configured between the hollow magnetic sensor and the flight pod structure to suppress local high-frequency vibration noise of the flight pod structure.

[0027] In some implementations, the suspension cable includes a main suspension cable and n branch cables; n is a positive integer greater than 2.

[0028] One end of the main suspension cable is connected to the flight platform below the flight platform, and the other end is connected to one end of each branch cable;

[0029] One end of each branch cable is connected to the main suspension cable, and the other end is connected to different parts of the flight pod structure.

[0030] The length of each branch cable is determined based on the speed of the flight platform, the wind resistance of the flight pod structure, and the weight of the flight pod structure.

[0031] In some implementations, a second-stage vibration damping device is provided at the connection between the flight pod structure and each branch cable to isolate mid-frequency vibration and attitude rotation noise.

[0032] The connection between the main suspension cable and each branch cable is equipped with a third-level low-frequency vibration damping device to suppress low-frequency displacement velocity changes and attitude changes caused by changes in flight platform speed and airflow, and to suppress low-frequency motion noise of the flight pod structure.

[0033] In some implementations, the system also includes a signal acquisition unit, a pod status auxiliary information measurement unit, and a system real-time status monitoring unit;

[0034] The signal acquisition unit is used to acquire electromagnetic signals, including natural field electromagnetic signals.

[0035] The pod status auxiliary information measurement unit is used to acquire flight pod status information in real time.

[0036] The system real-time status monitoring unit is used to send the system's data acquisition status information and flight pod status information to the flight platform in real time, so that the flight platform can control the flight pod to maintain stability based on the received information.

[0037] In some implementations, the signal acquisition unit is mounted on a flight pod or on a flight platform, and the signal acquisition gain is matched with the power spectrum of the natural field electromagnetic signal using a frequency-band multi-gain matching signal acquisition method.

[0038] In some implementations, the pod status auxiliary information measurement unit is mounted on the flight pod;

[0039] The flight pod status information includes at least the flight pod's position coordinates, attitude information, and altitude above the ground.

[0040] The beneficial effects of the embodiments in this application compared with the prior art are:

[0041] This application embodiment achieves high-sensitivity signal observation of the vertical component of the electromagnetic field of airborne natural fields by employing a flat polygonal or circular hollow inductive magnetic sensor. A slender cylindrical magnetic core is orthogonally distributed and mounted on the flat polygonal or circular hollow magnetic sensor flight pod structure, reducing crosstalk between the three components of the magnetic sensor without increasing the overall volume of the triaxial magnetic sensor. The flat polygonal or circular design achieves a small-volume, low-drag, convenient and safe takeoff and landing, and low-noise sensor pod, improving the data acquisition quality, flight operation safety, and efficiency of the airborne natural field electromagnetic detection system. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram illustrating the constraint relationship between the number of coil turns, coil diameter, and noise level under a fixed sensitivity condition.

[0044] Figure 2 This is a schematic diagram of the structure of a small-volume, highly sensitive orthogonal three-component airborne natural field electromagnetic detection system provided in an embodiment of this application.

[0045] Figure 3 This is a schematic diagram of the assembly method of the orthogonal three-component magnetic sensor provided in the embodiments of this application.

[0046] Figure 4 This is a schematic diagram of a method for calculating the length of each branch suspension cable provided in an embodiment of this application.

[0047] Figure 5 This is a schematic diagram of the three-stage vibration reduction scheme provided in the embodiments of this application.

[0048] Figure 6 This is a schematic diagram of the frequency-band multi-gain matched signal acquisition method provided in the embodiments of this application. Detailed Implementation

[0049] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0050] The following describes in detail, with reference to the accompanying drawings, a small-volume, highly sensitive orthogonal three-component airborne natural field electromagnetic detection system according to an embodiment of this application.

[0051] As mentioned above, airborne natural electromagnetic field detection systems can be used in fields such as mineral resource exploration, geological disaster early warning, and groundwater detection. Natural electromagnetic fields propagate underground and generate electromagnetic induction effects with non-uniform electrical media or electrical targets underground, thereby generating secondary induced electromagnetic fields in the underground electrical media. These weak secondary induced electromagnetic fields are reflected upwards and can be received by low-noise magnetic sensors on the airborne platform. Finally, through processing, model inversion, and data interpretation of the received electromagnetic field signals, the spatial distribution morphology and electrical property parameters of the underground media can be obtained.

[0052] The implementation of natural source electromagnetic detection technology on the ground, often referred to as ground-based magnetotelluric (MTD) detection, typically involves deploying orthogonal electric and magnetic field sensors on the ground and conducting continuous signal observations at fixed points. Through noise removal, signal extraction, spectrum analysis, impedance parameter estimation, and other data processing and inversion techniques, information on the variation of subsurface geological parameters with depth at the observation points can be obtained. The implementation of natural source electromagnetic detection technology on an airborne platform, also known as airborne tilting electromagnetic detection, typically involves observing magnetic field signals (primarily the components perpendicular to the ground) on an airborne platform while simultaneously observing orthogonal horizontal magnetic field signals at fixed ground points. Noise removal, signal extraction, and spectrum analysis of the ground and airborne magnetic field signals are typically performed to calculate the tilting parameters (also known as tippers) of the magnetic vector between the ground and airborne magnetic field signals.

[0053] Tipper parameters can be used to inversely deduce and interpret the physical properties and spatial distribution characteristics of underground electrical structures. Airborne tiltmeter detection technology was first proposed in 1958. Airborne natural audiomagnetic method (AFMAG) technology using airborne platforms was also proposed after 1960. However, due to insufficient technology at the time, the noise level of magnetic sensors and the stabilization platform of the airborne sensor pods were insufficient to meet the requirements for observing the natural electromagnetic field response signals of underground electrical targets. After more than 40 years of technological updates, it wasn't until 2005 that the first commercially viable airborne natural source electromagnetic detection system capable of effectively detecting deep underground geological structures was successfully developed.

[0054] Airborne electromagnetic field detection technology is a method for continuous observation of electromagnetic field signals on an airborne platform. The signal observation frequency range is limited by the continuous movement of the airborne platform and the strength of the natural field signal. The main signal measurement frequency band is from 10 Hz to 20 kHz, with signal strength on the order of several picotes per ohm (pT / √Hz) to several femtotes per ohm (fT / √Hz). Within this signal frequency band, hollow inductive magnetic sensors have absolute advantages over other types of magnetic sensors (such as fluxgate sensors and atomic magnetic sensors) in terms of low noise and wide bandwidth. These sensors are also easier to manufacture and more stable, making them highly suitable for broadband, low-noise magnetic field signal observation in natural field source electromagnetic detection systems.

[0055] The natural electromagnetic field signals are weak, and the electromagnetic response of underground electrical structures is complex. Therefore, it is necessary to use low-noise, three-component magnetic sensor signals for observation to acquire weak and complex electromagnetic field signals from deep underground geological structures, complex terrains, complex geological bodies, and aircraft motion platforms.

[0056] The main technical requirements for applications of airborne electromagnetic surveying and detection of natural fields include the following:

[0057] 1) Technical requirements for low noise, wide bandwidth, and high sensitivity.

[0058] In the observation signal frequency band of 10Hz to 20kHz, inductive magnetic sensors have a significant advantage in noise level compared to other types of magnetic sensors. Therefore, hollow inductive magnetic sensors are used in the design and development of almost all airborne electromagnetic exploration and detection systems for natural fields.

[0059] The formula for the induced electromotive force of an inductive magnetic sensor is: ;in, This refers to the number of coil turns. This refers to the effective cross-sectional area of ​​the coil, which is directly related to the coil size. , The radius of the coil; The vacuum permeability; is the rate of change of the magnetic field.

[0060] The sensitivity of the sensor and The sensitivity is directly proportional to the sensor's surface area and the number of turns. This increases the sensor's sensitivity, effectively suppressing the noise level of the system's signal acquisition unit (signal receiver) and ultimately reducing the overall noise level of the detection system. Increasing the sensor size... and number of turns This can effectively increase the sensitivity of the sensor. However, increasing the size of the sensor also increases the sensitivity. And increase the number of turns This is more conducive to quickly improving the sensitivity of the sensor.

[0061] The noise of inductive magnetic sensors operating in this frequency band is mainly controlled by thermal noise (Johnson noise) and 1 / f noise. ;in, For the noise level of the sensor, Boltzmann's constant, Absolute temperature The resistance of the sensor coil wire, For bandwidth. During detection, sensitivity can be increased by increasing the equivalent area. If a long cable is used to wind multiple turns of the coil to increase the equivalent area, thermal noise will increase, making it impossible to simultaneously meet the low noise requirement. However, if a large-size coil is used to increase the equivalent area, the increase in coil length is smaller, resulting in a smaller increase in thermal noise, which can meet the low noise requirement.

[0062] Number of sensor turns and size An increase in the length of the coil wire will result in an increase in the coil wire length. The increase in resistance of the coil wire This increases the noise level of the sensor. Under the premise of a certain sensitivity requirement ( By increasing the sensor size This can reduce the length of the sensor coil. resistance of coil wire Reduce, thereby lowering the sensor noise level. Another approach is to use a smaller sensor size. In this case, by increasing the number of sensor turns This can meet the design sensitivity requirements, but it will significantly increase the length of the magnetic sensor coil. resistance of coil wire This significantly increases the noise level of the sensor, which in turn significantly increases the sensitivity. Sensor noise level under certain conditions Sensor size The relationship between the number of turns of the sensor coil is shown in the figure below. Figure 1 As shown.

[0063] Furthermore, since the inductance of the sensor coil is proportional to the square of the number of turns of the coil (the inductance of the sensor coil...) Increasing the number of turns in the sensor coil will reduce the sensor's receiving bandwidth, which may result in failure to meet the requirements of broadband electromagnetic detection technology for natural field sources in aviation.

[0064] Therefore, to achieve low-noise, high-sensitivity, and broadband signal observation, a design scheme with a large-size magnetic sensor is required to optimize the relationship between sensor bandwidth, sensitivity, and noise, and effectively meet the signal sensing requirements of the airborne natural field source electromagnetic detection system.

[0065] 2) Requirements for Three-Component Magnetic Field Signal Observation. Airborne natural field electromagnetic detection systems primarily focus on Tipper parameter detection, i.e., observing the three-component broadband magnetic field signal generated by underground geological structures under the excitation of natural electromagnetic fields, and analyzing the Tipper parameters of its three orthogonal magnetic field components. The relationship between the Tipper parameters and the observed three-component magnetic field signal is as follows: ;in, , , The observed three-component orthogonal magnetic field signal corresponds to the horizontal X, Y components and the vertical Z component, respectively. , These are the tilt parameters, corresponding to the tilt parameters of the vertical magnetic field component and the two horizontal components, respectively.

[0066] Airborne electromagnetic detection systems for natural fields require real-time observation of orthogonal ternary magnetic field signals. Through multiple data measurements, a system of two linear equations is constructed, and parameter estimation algorithms (such as least squares parameter estimation algorithms) are used to obtain the Tipper parameters. The Tipper parameters can reflect the electrical inhomogeneity of the subsurface medium, thereby enabling the construction of a subsurface electrical model, data inversion, and ultimately the acquisition of the distribution characteristics of the subsurface structure.

[0067] 3) Requirements for Dynamic Flight Stability. Airborne natural field electromagnetic detection systems utilize helicopter platforms equipped with highly sensitive, low-noise magnetic sensors for continuous and stable flight operations. Due to the presence of various broadband electromagnetic interferences on helicopter platforms, the highly sensitive, low-noise magnetic sensors must be kept away from electromagnetic interference sources. This is typically achieved by suspending the sensors below the helicopter platform. In airborne natural field electromagnetic detection systems, to reliably observe weak underground electromagnetic response signals, the highly sensitive magnetic sensors are suspended at a distance of approximately 100 meters. At this distance, electromagnetic interference from the helicopter platform is negligible, ensuring a certain level of aerodynamic flight safety, takeoff and landing safety, and stability.

[0068] During dynamic flight, the sensor pod interacts with the Earth's magnetic field, generating a dynamic induced electromotive force and creating dynamic electromagnetic noise. The intensity of the dynamic electromagnetic noise generated by a high-sensitivity magnetic sensor moving in the Earth's magnetic field is much greater than the natural electromagnetic field response signal of the underground medium. Therefore, improving the flight stability of the sensor pod can effectively improve the system's signal reception performance.

[0069] During dynamic flight, the sensor pod is simultaneously subjected to flight traction force F, air resistance T, and gravity G. Helicopter platforms must adapt to changes in various environmental parameters, such as terrain, altitude, wind speed, and temperature, during flight. The flight platform needs to make appropriate maneuvers to ensure flight safety and maintain the required flight altitude, speed, and yaw parameters for system operations. Changes in environmental conditions will cause corresponding changes in the flight platform's altitude and speed, ultimately leading to changes in the traction force between the flight platform and the sensor pod, affecting the pod's dynamic stability.

[0070] During the operation of an airborne electromagnetic field detection system, the constantly changing environmental conditions, such as wind speed and airflow, within the survey area inevitably affect the stability of the sensor pod. The larger the sensor pod's geometry, the larger its windward surface, the greater the difficulty in optimizing the aerodynamic stability of the pod's structure, and the more sensitive it is to local airflow changes within the measured area. To minimize the impact of environmental factors on the pod and make it less sensitive to environmental factors and flight platform control states, it is necessary to minimize the pod's windward surface, increase its weight, and reduce its sensitivity to small, unstable airflows. This improves the pod's environmental adaptability and ultimately achieves stable flight. Reducing the sensor's geometry and the windward surface of the pod structure are crucial solutions for achieving stable flight of the sensor pod.

[0071] 4) System operational safety, assembly, and portability requirements. In addition to providing excellent data observation performance during flight operations, the airborne natural field electromagnetic detection system also needs to achieve portable transportation of the sensor pod, rapid assembly, safe and stable flight, and safe takeoff and landing, ultimately enabling the system's engineering application. Large-sized, three-dimensional triaxial magnetic sensors are difficult to assemble quickly and accurately.

[0072] In summary, to meet the application requirements of electromagnetic detection of natural field sources in air, on the one hand, it is necessary to adopt a hollow magnetic sensor development technology to achieve a low-noise, high-sensitivity, and broadband airborne magnetotelluric sensor; on the other hand, it is necessary to achieve the reception of airborne three-component orthogonal magnetic field signals to achieve the goal of tilting detection; and thirdly, it is necessary to reduce the volume of the three-axis airborne magnetic sensor pod, reduce wind resistance, improve flight stability, and achieve safe flight during takeoff, landing, and operation.

[0073] Some existing technologies propose a three-component solution for electromagnetic detection of natural fields. For example, patent document CN202211437106.9 discloses a three-component electromagnetic signal observation system assembled from three small-sized hollow coils. However, this three-component electromagnetic signal observation system uses a three-dimensional magnetic sensor structure, which generates significant wind resistance during aerial flight operations. Therefore, it is difficult to increase the sensor size, making it difficult to achieve low-noise signal observation.

[0074] In view of this, this application provides a small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system. This system is a low-noise, high-sensitivity, three-component orthogonal, small-volume, low-drag, and safe-to-take-off and land-safe airborne natural field electromagnetic detection system achieved by using a hybrid hollow-core and magnetic-core magnetic sensors. This system overcomes the problems of large size, difficult assembly, difficult transportation, high risk of system flight take-off and landing, or difficulty in improving sensor noise performance and high dynamic noise associated with three-dimensional large-size hollow coil or small-size spherical sensor pod technologies. Compared with small-size spherical, cubic, or three-dimensional frame sensor pod systems, it is more conducive to improving the technical performance indicators of sensitivity and noise level.

[0075] Figure 2 This is a schematic diagram of the structure of a small-volume, highly sensitive orthogonal three-component airborne natural field electromagnetic detection system provided in an embodiment of this application. Figure 2 As shown, the detection system includes a hollow magnetic sensor, a magnetic core magnetic sensor, a flat polygonal or circular flight pod, and a suspension cable.

[0076] The hollow magnetic sensor and the magnetic core magnetic sensor are combined to form an orthogonal three-component magnetic sensor. The flight pod is used to support or fix the hollow magnetic sensor and the magnetic core magnetic sensor, and the flight pod is flexibly suspended below the flight platform by suspension cables.

[0077] The orthogonal three-component magnetic sensor is composed of one hollow magnetic sensor and two magnetic core magnetic sensors. The hollow magnetic sensor is a flat polygonal or circular structure, which is installed in a shape that overlaps with the outer structure of the flight pod. The two magnetic core magnetic sensors are cylindrical or elongated structures, both of which are horizontally mounted on the plane of the flight pod structure.

[0078] Furthermore, the two magnetic core type magnetic sensors are orthogonal to each other, and the two magnetic core type magnetic sensors are orthogonal to the hollow type magnetic sensor respectively.

[0079] In other words, the airborne natural field electromagnetic detection system provided in this application embodiment may include one hollow magnetic sensor, two magnetic core magnetic sensors, one flat polygonal or circular flight pod, and one set of suspension cables.

[0080] Among them, one hollow magnetic sensor and two magnetic core magnetic sensors are combined to form an orthogonal three-component magnetic transmitter. The flat polygonal or circular hollow magnetic sensor is conducive to optimizing the performance parameters of low noise, wide bandwidth and high sensitivity. It can also realize the detection of Tipper parameters and meet the signal observation and acquisition requirements of the airborne natural field electromagnetic detection system for the weak electromagnetic response (fT / √Hz level) of deep underground geological bodies.

[0081] Meanwhile, the orthogonal three-component magnetic sensor also has a flat structure, so the large size design will not increase wind resistance during flight, thereby further reducing detection noise.

[0082] In some embodiments of this application, the polygonal or circular flight pod structure is assembled from non-metallic structural components to form a rigid polygonal or circular structure for supporting (fixing) hollow magnetic sensors and magnetic core magnetic sensors. The hollow magnetic sensor and the regular polygonal pod are installed coplanarly, with the sensor overlapping and conforming to the outer structure of the regular polygonal pod. The magnetic core magnetic sensor is a cylindrical or elongated structure, horizontally mounted on the plane of the polygonal flight pod structure (e.g., fixed to one side of the polygon). The relative installation angle between the two magnetic core magnetic sensors on the polygonal flight pod structure is 90 degrees; they are orthogonal to each other and orthogonal to the direction of the magnetic field received by the polygonal or circular hollow magnetic sensor (i.e., the vertical direction). For example, the two magnetic core magnetic sensors can be positioned along the X and Y coordinate directions of the three-dimensional coordinate system, respectively, while the hollow magnetic sensor is positioned along the Z coordinate direction of the three-dimensional coordinate system.

[0083] Figure 3 This is a schematic diagram of the assembly method of the orthogonal three-component magnetic sensor provided in the embodiments of this application. Figure 3As shown, two magnetic core sensors are horizontally mounted on different sides of the polygonal flight pod structure; or, two magnetic core sensors are horizontally mounted on the same central connecting rod of the polygonal flight pod structure; or two magnetic core sensors are horizontally mounted on different central connecting rods of the circular flight pod structure.

[0084] Since the flight pod structure is mounted in the same shape as the hollow magnetic sensor, the orthogonal three-component magnetic sensor can also be assembled in the following ways: two magnetic core sensors are horizontally mounted on different sides of the polygonal hollow magnetic sensor; or two magnetic core sensors are horizontally mounted on different central connecting rods of the polygonal hollow magnetic sensor; or two magnetic core sensors are horizontally mounted on different central connecting rods of the circular hollow magnetic sensor.

[0085] In some embodiments of this application, the hollow magnetic sensor includes a multi-turn flexible wire and a low-noise preamplifier. The total length of the multi-turn flexible wire is less than a preset length threshold to achieve low-noise signal reception. The specific value of the preset length threshold can be determined based on the noise level of the designed hollow magnetic sensor, and is not limited here.

[0086] In some embodiments of this application, a hollow magnetic sensor can be used to measure the vertical component of the natural field electromagnetic signal, and a magnetic core magnetic sensor can be used to measure the horizontal component of the natural field electromagnetic signal; an orthogonal three-component magnetic sensor can detect the tipper parameter of the natural field electromagnetic signal by acquiring the orthogonal three-component natural field electromagnetic signal.

[0087] In other words, the flat hollow magnetic sensor coil can be composed of flexible multi-turn wires and combined with a low-noise preamplifier to form a low-noise, wide-bandwidth magnetic sensor. The flat hollow core can be designed with a larger geometric size on a large horizontal plane, thereby achieving a larger equivalent receiving area and improving receiving sensitivity. This effectively limits the sensor's noise level without significantly increasing the length of the coil wire.

[0088] Noise level of hollow inductive magnetic sensor operating in the electromagnetic detection band of airborne natural field Mainly controlled by the thermal noise of the coil wire and 1 / f noise ( Significantly limiting the increase in coil wire length can effectively control the sensor's noise level, thereby achieving an extremely low noise level that meets the signal observation performance requirements for airborne natural field electromagnetic detection. The noise level of the designed hollow magnetic sensor determines the preset total length threshold of the multi-turn flexible wire.

[0089] The flexible, flat, hollow magnetic sensor coil, made of multi-turn wires, can be installed inside the polygonal or circular flight pod structure. Various vibration reduction techniques can be used to isolate the magnetic sensor coil from the flight pod structure, reducing the impact of flight pod vibration noise on the high-sensitivity magnetic sensor and lowering motion noise.

[0090] In some embodiments of this application, the magnetic core sensor includes a core made of soft magnetic material. For a cylindrical magnetic core sensor, the aspect ratio of the core is 50 ≤ ≤100, and the initial permeability of the soft magnetic material is greater than or equal to 50000; where m is the aspect ratio of the magnetic core.

[0091] In other words, for core-type magnetic sensors, in order to obtain highly sensitive magnetic field reception, it is necessary to make the magnetic field reception as sensitive as possible. maximum.

[0092] To obtain the largest possible effective permeability, an initial permeability is used. High permeability of soft magnetic materials, such as permalloy and amorphous materials. Effective permeability of soft magnetic material cores. The calculation formula is ;in, This is the demagnetization coefficient. For an aspect ratio of... The demagnetization coefficient of a rotating ellipsoidal magnetic core. It does not depend on the initial permeability of the soft magnetic material It depends on the shape and structure of the magnetic core.

[0093] For slender ellipsoids, the formula for calculating the demagnetization coefficient can be simplified to: , , The length of the magnetic core. The diameter of the magnetic core. The effective permeability of the magnetic core. The larger the magnetic field diameter, the greater the sensitivity of the magnetic field sensor; therefore, a long and thin magnetic core is usually used. Considering both portability and practicality, a length-to-diameter ratio of 50 ≤ 1 is generally chosen for the magnetic core. ≤100, initial permeability of soft magnetic materials ≥50000, at this point the effective permeability of the magnetic core Reached 2500.

[0094] Magnetic sensors made of elongated magnetic core materials have a strong attraction to surrounding magnetic field lines, affecting the distribution of these lines and resulting in a non-uniform distribution. The influence of core-type magnetic sensors on their surrounding magnetic field lines is far greater than that of hollow-core magnetic sensors, essentially altering the surrounding magnetic field strength. Therefore, it is necessary to avoid close-range integration of multiple core-type magnetic sensors. Close-range integration of multiple core-type magnetic sensors inevitably leads to strong signal crosstalk, affecting the accuracy of magnetic signal acquisition. In this embodiment, two horizontal core-type magnetic sensors are installed in a distributed manner, fixedly mounted on a flat polygonal or circular suspension structure, thereby avoiding crosstalk between multiple core-type magnetic sensors.

[0095] In some embodiments of this application, the flight pod structure is a hollow structure, and the diagonal of the polygonal flight pod structure and the diameter of the circular flight pod structure are both greater than a preset size threshold. In other words, the flight pod can adopt a large-size design.

[0096] Furthermore, a first-stage high-frequency damping device is configured between the hollow magnetic sensor and the flight pod structure to suppress local high-frequency vibration noise of the flight pod structure.

[0097] In some embodiments of this application, the suspension cable includes a main suspension cable and n branch cables; n is a positive integer greater than 2. One end of the main suspension cable is connected to the flight platform below the flight platform, and the other end is connected to one end of each branch cable. One end of each branch cable is connected to the main suspension cable, and the other end is connected to different parts of the flight pod structure.

[0098] The length of each branch cable is determined based on the speed of the flight platform, the wind resistance of the flight pod structure, and the weight of the flight pod structure.

[0099] A second-stage vibration damping device is installed at the connection between the flight pod structure and each branch cable to isolate mid-frequency vibration and attitude rotation noise; a third-stage low-frequency vibration damping device is installed at the connection between the main suspension cable and each branch cable to suppress low-frequency displacement velocity changes and attitude changes caused by changes in flight platform speed and airflow, and to suppress low-frequency motion noise of the flight pod structure.

[0100] In other words, flat polygonal or circular airborne magnetic sensor flight pods have a smaller risk surface. Therefore, the pod is not sensitive to short-term environmental changes such as local airflow instability (ripple or end flow) and wind speed changes. As a result, it can achieve high flight stability and ensure that the flight pod maintains a basically horizontal and stable attitude during flight. This reduces the intensity of the induced electromotive force generated by the high-sensitivity magnetic sensor in the geomagnetic field, which reduces the dynamic noise level.

[0101] Polygonal or circular pods are suspended below the helicopter platform by suspension cables, and flight operations are carried out using a soft suspension method to reduce the impact of electromagnetic interference sources on the helicopter platform on the high-sensitivity magnetic sensors.

[0102] The suspension cables consist of branch cables connected to the pod and a main suspension cable connected to the helicopter. To ensure the pod remains horizontally stable throughout flight, the branch suspension cables connected to the pod are designed with different lengths. The length of each branch suspension cable is determined based on the design cruise speed V, the pod's drag F, and the pod's weight G. The pod's drag F is approximately directly proportional to the flight speed V. .in The drag coefficient is related to the structural shape of the flight pod. The larger the drag surface of the pod structure, the larger the drag coefficient. It characterizes the sensitivity relationship between the pod's drag and speed.

[0103] like Figure 4 As shown, the angle between the main suspension cable and the horizontal plane can be calculated based on the pod's wind resistance and weight, and the length of each branch suspension cable can be calculated based on the designed distance between the lower end of the main suspension cable and the pod. For example, the angle between T and the horizontal plane can be calculated by decomposing the forces on the pod into the pod's weight G, the pod's wind resistance F, and the main cable's traction force T, through force analysis.

[0104] In addition to the induced dynamic noise generated by the attitude changes of the sensor pod, the friction between the sensor pod and the atmosphere during flight inevitably generates mid-to-high frequency vibration noise, thus producing mid-to-high frequency induced vibration noise. To eliminate this vibration noise, embodiments of this application employ the following... Figure 5 The three-stage vibration reduction technology shown divides the vibration noise of the sensor into frequency bands and suppresses it step by step.

[0105] The polygonal or circular flight pod structure employs a hollow core design, allowing a large-sized hollow magnetic sensor coil to be installed within it. A first-stage high-frequency vibration damping device is designed between the hollow magnetic sensor coil and the flight pod structure to suppress localized high-frequency vibration noise within the flight pod structure.

[0106] The entire polygonal or circular flight pod structure is designed with a second-stage vibration damping device between it and the branch suspension cables to isolate mid-frequency vibrations and attitude rotation noise.

[0107] A third-stage low-frequency vibration damping device is designed at the lower end of the main suspension cable to suppress low-frequency displacement or attitude changes caused by factors such as changes in the helicopter platform's flight speed and airflow, and to suppress low-frequency motion noise from the sensor pod.

[0108] In some embodiments of this application, the three-component airborne natural field electromagnetic detection system may further include a signal acquisition unit, a pod status auxiliary information measurement unit, and a system real-time status monitoring unit. The signal acquisition unit is used to acquire electromagnetic signals, including natural field electromagnetic signals; the pod status auxiliary information measurement unit is used to acquire flight pod status information in real time; and the system real-time status monitoring unit is used to transmit the system's data acquisition status information and flight pod status information to the flight platform in real time, so that the flight platform can control the flight pod to maintain stability based on the received information.

[0109] In some embodiments of this application, the signal acquisition unit is installed on a flight pod or on a flight platform, and the signal acquisition gain can be matched with the power spectrum of the natural field electromagnetic signal using a frequency-band multi-gain matching signal acquisition method.

[0110] In other words, the high-sensitivity magnetic sensor generates electromagnetic signals much larger than natural electromagnetic signals during flight. In order to simultaneously observe and acquire the weak electromagnetic response signals of the geoelectric medium under strong background electromagnetic field signals, the signal receiver needs to achieve large dynamic range signal acquisition.

[0111] To achieve high dynamic range signal reception, the signal acquisition unit of the airborne natural field electromagnetic detection system employs methods based on the power spectrum distribution characteristics of the natural electromagnetic field signal, such as... Figure 6 The frequency-band multi-gain matched signal acquisition technology shown achieves optimal matching between the signal acquisition gain and the power spectrum of the natural electromagnetic field signal. Since natural field signals in different frequency bands have different signal amplitude ranges, appropriate acquisition circuit gain values ​​can be set for different frequency bands to obtain the maximum receiver signal-to-noise ratio.

[0112] like Figure 6 As shown, the signal acquisition unit can receive broadband natural field signals, perform time-frequency analysis on them, and obtain their frequency domain power spectrum curves and time domain waveform curves. Then, through multi-channel frequency band filtering, it obtains frequency band analog signals, which can be divided into high-frequency, intermediate-frequency, and low-frequency signals. Finally, after multi-channel analog signal processing, it undergoes analog-to-digital conversion (ADC) to obtain the output digital signal. The ADC can include a high-frequency high-gain high-sampling-rate ADC, an intermediate-frequency medium-gain medium-sampling-rate ADC, and a low-frequency low-gain low-sampling-rate ADC. The gain setting value matches the power spectrum intensity of the natural field electromagnetic signal and can be set to an inverse proportional relationship.

[0113] In some embodiments of this application, the pod status auxiliary information measurement unit is installed on the flight pod; the flight pod status information includes at least the flight pod's position coordinates, attitude information, and altitude above the ground.

[0114] In other words, during the flight operation of an airborne electromagnetic field detection equipment system, in order to obtain information such as the sensor pod's positioning coordinates, altitude, and attitude, a GNSS satellite positioning module and an inertial navigation module need to be installed on the pod to form a set of pod status auxiliary information measurement units. The positioning and inertial navigation modules are installed on the structural plane of the polygonal or circular flight pod. Multiple auxiliary information measurement units can be installed on the structural plane of the polygonal or circular flight pod to comprehensively acquire the attitude, displacement, and vibration information of the entire flight pod. The data observed by the pod status auxiliary information measurement units will be stored in real time in the signal acquisition unit for joint data processing.

[0115] In some embodiments of this application, the function of the system real-time status monitoring unit is to send the system data acquisition status information, the positioning and attitude of the flight pod and other dynamic status information to the flight platform in real time, so as to facilitate real-time observation of the working status of the flight pod and the system, so as to control the flight speed and flight altitude in real time and maintain the stability and safety of the flight pod.

[0116] According to the technical solution provided in the embodiments of this application, a high-sensitivity signal observation of the vertical component of the electromagnetic field of the airborne natural field is achieved by using a flat polygonal or circular hollow inductive magnetic sensor. The slender cylindrical magnetic core is installed on the plane of the flat polygonal or circular hollow magnetic sensor flight pod structure in an orthogonal distribution manner, which reduces the crosstalk between the three components of the magnetic sensor without increasing the volume of the entire triaxial magnetic sensor. The flat polygonal or circular design realizes a sensor pod with small volume, low wind resistance, convenient and safe take-off and landing, and low motion noise, which improves the data acquisition quality, flight operation safety and efficiency of the airborne natural field electromagnetic detection system.

[0117] The technical solution provided in this application, by using a hybrid of hollow magnetic sensors and magnetic core magnetic sensors on an aircraft flight pod platform, reduces the crosstalk problem between multi-component magnetic sensors while achieving high sensitivity and low noise signal acquisition, and enhances the flexibility of sensor performance optimization design in terms of sensitivity, noise level, size, and weight.

[0118] Based on a hybrid low-noise magnetic sensor combining hollow and magnetic core types, a three-component orthogonal magnetic sensor device was designed, resulting in a flat-panel aircraft flight pod. This design overcomes the limitations of traditional large-size, low-noise orthogonal three-component hollow magnetic sensors, which suffer from large size, high wind resistance, poor flight attitude stability, and high vibration and dynamic noise. It also overcomes the challenges of small hollow magnetic sensors, such as the difficulty in noise and sensitivity optimization and performance improvement, high flight dynamic noise, difficulty in noise suppression, and the need for rotating suppression measures. This design achieves low wind resistance, safe takeoff and landing, convenient transportation, and easy assembly and disassembly, which is beneficial to the safety and efficiency of field flight operations.

[0119] Meanwhile, a flat polygonal or circular hollow inductive magnetic sensor is used to achieve high-sensitivity signal observation of the vertical component of the airborne natural field electromagnetic field. This technical solution improves the sensitivity and noise level of airborne sensors, optimizes the design and development flexibility and simplicity, and has strong performance redundancy. Simultaneously, a slender cylindrical magnetic core with a large aspect ratio is used to achieve high-sensitivity signal observation of the horizontal component of the airborne natural field electromagnetic field.

[0120] Slender cylindrical magnetic cores are orthogonally distributed and mounted on the flat surface of a polygonal or circular hollow magnetic sensor flight pod, avoiding crosstalk issues that can occur when multiple magnetic core sensors are installed close together. The aerospace orthogonal three-component magnetic sensor is distributed and mounted on a flat flight pod, increasing the distance between each component magnetic sensor without increasing the overall volume of the triaxial magnetic sensor, thus reducing crosstalk between the three components.

[0121] Compared to other types of airborne three-component natural field electromagnetic signal observation sensor devices, this invention is designed based on a hybrid sensor technology of hollow core and magnetic core to realize a flat sensor pod with small size, low wind resistance, convenient and safe take-off and landing, and low motion noise, thereby improving the data acquisition quality, flight operation safety and efficiency of the airborne natural field electromagnetic detection system.

[0122] The overall noise level of an airborne natural field electromagnetic detection system is mainly determined by the sensor's inherent noise level and the dynamic noise of the flight pod. This application proposes a three-stage vibration reduction and frequency-band vibration noise suppression and attitude stabilization technical solution for flat-type flight pods, achieving full-band noise suppression and reducing the sensor's full-band motion noise level.

[0123] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0124] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0125] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A small-volume, highly sensitive, orthogonal three-component airborne electromagnetic detection system for natural fields, characterized in that, The detection system includes a hollow magnetic sensor, a magnetic core magnetic sensor, a flat polygonal or circular flight pod, and suspension cables. The hollow magnetic sensor and the magnetic core magnetic sensor are combined to form an orthogonal three-component magnetic sensor; The flight pod is used to support or fix the hollow magnetic sensor and the magnetic core magnetic sensor, and the flight pod is flexibly suspended below the flight platform by the suspension cable; The orthogonal three-component magnetic sensor is composed of a hollow magnetic sensor and two magnetic core magnetic sensors; the orthogonal three-component magnetic sensor has a flat structure overall. The hollow magnetic sensor is a flat polygonal or circular structure, which is installed in a shape that overlaps with the outer structure of the flight pod; the two magnetic core magnetic sensors are cylindrical or strip-shaped structures, and are both installed horizontally on the plane of the flight pod structure. The two magnetic core type magnetic sensors are orthogonal to each other, and the two magnetic core type magnetic sensors are respectively orthogonal to the hollow type magnetic sensor.

2. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, Two magnetic core-type magnetic sensors are horizontally mounted on different sides of the polygonal flight pod structure; Alternatively, two magnetic core magnetic sensors are horizontally mounted on different central connecting rods of the polygonal flight pod structure; Alternatively, two magnetic core sensors can be horizontally mounted on different central connecting rods of a circular flight pod structure.

3. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, The hollow magnetic sensor includes multiple turns of flexible wire and a low-noise preamplifier. The total length of the multi-turn flexible conductor is less than a preset length threshold to achieve low-noise signal reception.

4. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, The hollow magnetic sensor is used to measure the vertical component of the natural field electromagnetic signal, and the magnetic core magnetic sensor is used to measure the horizontal component of the natural field electromagnetic signal. The orthogonal three-component magnetic sensor acquires orthogonal three-component natural field electromagnetic signals to detect the tipper parameter of the natural field electromagnetic field.

5. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, The flight pod structure is a hollow structure, and the diagonal of the polygonal flight pod structure and the diameter of the circular flight pod structure are both greater than a preset size threshold. A first-stage high-frequency damping device is configured between the hollow magnetic sensor and the flight pod structure to suppress local high-frequency vibration noise of the flight pod structure.

6. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, The suspension cable includes one main suspension cable and n branch cables; n is a positive integer greater than 2; One end of the main suspension cable is connected to the flight platform below the flight platform, and the other end is connected to one end of each branch cable; One end of each branch cable is connected to the main suspension cable, and the other end is connected to different parts of the flight pod structure. The length of each branch cable is determined based on the speed of the flight platform, the wind resistance of the flight pod structure, and the weight of the flight pod structure.

7. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 6, characterized in that, The connection points between the flight pod structure and each branch cable are equipped with a second-stage vibration damping device to isolate mid-frequency vibration and attitude rotation noise. The connection between the main suspension cable and each branch cable is equipped with a third-level low-frequency vibration damping device to suppress low-frequency displacement velocity changes and attitude changes caused by changes in flight platform speed and airflow, and to suppress low-frequency motion noise of the flight pod structure.

8. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 1, characterized in that, The system also includes a signal acquisition unit, a pod status auxiliary information measurement unit, and a system real-time status monitoring unit; The signal acquisition unit is used to acquire electromagnetic signals, including natural field electromagnetic signals. The pod status auxiliary information measurement unit is used to acquire flight pod status information in real time. The system real-time status monitoring unit is used to send the system's data acquisition status information and flight pod status information to the flight platform in real time, so that the flight platform can control the flight pod to maintain stability based on the received information.

9. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 8, characterized in that, The signal acquisition unit is installed on a flight pod or on a flight platform, and uses a frequency-band multi-gain matching signal acquisition method to match the signal acquisition gain with the power spectrum of the natural field electromagnetic signal.

10. The small-volume, high-sensitivity, orthogonal three-component airborne natural field electromagnetic detection system according to claim 8, characterized in that, The pod status auxiliary information measurement unit is installed on the flight pod; The flight pod status information includes at least the flight pod's position coordinates, attitude information, and altitude above the ground.

Images