CN117348093A - Aviation electromagnetic data processing method and system based on ground reference point - Google Patents
Aviation electromagnetic data processing method and system based on ground reference point Download PDFInfo
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Abstract
The invention discloses an aviation electromagnetic data processing method and system based on a ground reference point, comprising the following steps: arranging a transmitting source, and acquiring first response electromagnetic data corresponding to a plurality of air measuring points; selecting a plurality of ground reference points along the direction of the emission source, and acquiring second response electromagnetic data; forward modeling is carried out by adopting the preprocessed first response electromagnetic data, and a difference value between the ground and the air is obtained; loading the difference value into second response electromagnetic data, and obtaining a reference correction value of any air measuring point of the area to be detected by adopting an interpolation method to obtain third response electromagnetic data; presetting an amplitude difference threshold, and comparing the amplitude of the preprocessed first response electromagnetic data with that of the preprocessed third response electromagnetic data to obtain a frequency range of motion noise pollution, wherein the amplitude difference of the frequency range is larger than that of the motion noise pollution corresponding to the amplitude difference threshold; and extracting field value amplitudes of a ground reference point and an air measuring point in a frequency band range polluted by motion noise, and carrying out denoising correction processing by adopting a minimum mean square error algorithm.
Description
Technical Field
The invention relates to the technical field of geophysical exploration, in particular to an aviation electromagnetic data processing method and system based on ground reference points.
Background
The aviation electromagnetic method is one of the geophysical prospecting methods which have been attracting attention in recent years, adopts a ground/air emission mode and an air measurement response magnetic field, and has the advantages of wide detection range, strong terrain adaptability, low detection cost, high efficiency and the like. According to the method, the coil sensor is mounted on a flight platform such as a helicopter and an unmanned aerial vehicle through a cable to perform aerial acquisition measurement, and due to the influence of the measurement acquisition mode and the flight attitude of the flight platform such as the unmanned aerial vehicle, the coil sensor swings, the attitude changes to generate motion noise, acquired data is necessarily influenced by the motion noise of the coil, the motion noise is one of main noise sources of the method, and the data polluted by the motion noise in a low-frequency part is directly shown to be larger than normal data amplitude. Therefore, how to reduce or even eliminate the influence of motion noise on the aviation electromagnetic data is one of the key factors for determining the quality and detection effect of the aviation electromagnetic data.
In the patent publication No.: CN114994777a, name: in the Chinese patent of the ground-air frequency domain electromagnetic motion noise active suppression method, according to the exploration depth range, the frequency band range of the main frequency of the emitted current is calculated by using a skin depth formula; the elastic coefficient of a dynamic noise suppression module of the receiving coil sensor is adjusted, and the natural frequency f of the receiving coil sensor is reduced to enable the natural frequency f of the receiving coil sensor to be not aliased with the transmitting fundamental frequency f 01; the dynamic noise suppression active adjusting module is used for reading the angular speed and the acceleration of the receiving coil sensor in the pitching direction and the rolling direction, adjusting the damping coefficient according to the angular speed and the acceleration, and enabling the acceleration of the receiving coil sensor to be minimum by changing the damping characteristic.
In the patent publication No.: CN115097528A, name: in a chinese patent of an airborne electromagnetic signal observation device and system onboard an unmanned aerial vehicle, it comprises: the cable connecting device comprises an inner frame, an outer frame and a flexible bracket which are connected with each other, wherein a plurality of hanging points are arranged on the surface of the outer frame and are used for connecting cables; the flexible support is arranged below the unmanned aerial vehicle, the flexible support is of a multi-spoke umbrella-shaped structure, and the top ends of the spokes are connected to the hanging points of the outer frame through cables; the outer frame is of a hollow closed structure, and the inside of a pipe of the outer frame is used for installing each electronic unit of the receiver; one or more cable joints are arranged on the surface of the outer frame, and the cable joints are used for connecting sensor output signal cables; the inner frame is used for accommodating the induction type magnetic sensor. The stability of the sensor in flight can be enhanced, and the motion noise can be greatly and remarkably restrained.
In the patent publication No.: CN115356774a, name: in Chinese patent based on coaxial coplanar mutual reference coil group, the semi-aviation electromagnetic detection device and method comprises a measuring coil and a reference coil which are linearly related to additive motion noise, the bandwidths of the reference coil and the measuring coil are consistent and coaxial coplanar, the detection resolution of the reference coil can only distinguish the additive motion noise and can not distinguish the real vertical magnetic field signal, the detection resolution of the measuring coil can simultaneously distinguish the real vertical magnetic field signal and the motion noise, the outer diameter of the reference coil is far smaller than the outer diameter of the measuring coil, and the measuring coil and the reference coil are in hard connection or soft connection. The detection method of the invention only receives the additive motion noise through one coil, the other coil receives the additive motion noise and the real vertical magnetic field signal at the same time, and then the additive motion noise received by the two coils is canceled to obtain the real vertical magnetic field signal. The device and the method simplify the semi-aviation electromagnetic detection measurement system and the method, and improve the consistency of the measurement result and the real result.
In the patent publication No.: CN115510921a, name: in a Chinese patent of a semi-aviation frequency domain electromagnetic detection data noise suppression method based on wavelet denoising and notch fusion, the method comprises the following steps: step 1, performing spectrum analysis on an actual measurement signal containing noise; step 2, the actual measurement signal is processed according to the step 2a, and then the signal obtained by processing is processed according to the step 2 b; and step 3, denoising the signal data processed in the step 2 through a wavelet threshold based on a frequency domain, and filtering other random noise. The invention discloses a novel combined noise suppression method, which combines wavelet de-base denoising with notch processing power frequency interference, can effectively suppress main noise in a semi-aviation electromagnetic detection process, and the processed signal meets the requirement.
The above patent or technology mainly processes aviation electromagnetic motion noise from a hardware or algorithm layer, and can suppress the motion noise to a certain extent, but the above technology cannot thoroughly eliminate the influence of the motion noise due to the randomness of the motion noise.
Therefore, it is highly desirable to provide a method and a system for processing aviation electromagnetic data based on a ground reference point, which are simple in logic, accurate and reliable.
Disclosure of Invention
Aiming at the problems, the invention aims to provide an aviation electromagnetic data processing method and system based on a ground reference point, and the technical scheme adopted by the invention is as follows:
in a first aspect, the present technology provides a ground reference point-based airborne electromagnetic data processing method, comprising the steps of:
arranging a transmitting source on the ground of a region to be detected, carrying a coil sensor on a flight platform to perform uniform flight, and acquiring first response electromagnetic data corresponding to a plurality of aerial measuring points;
selecting a plurality of ground reference points along the direction of the emission source, and acquiring second response electromagnetic data at the ground reference points by using a coil sensor;
preprocessing the first response electromagnetic data and the second response electromagnetic data respectively;
forward modeling is carried out by adopting the preprocessed first response electromagnetic data, and a difference value between the ground and the air is obtained;
loading the difference value into second response electromagnetic data, and obtaining a reference correction value of any air measuring point of the area to be detected by adopting an interpolation method to obtain third response electromagnetic data;
presetting an amplitude difference threshold, comparing the amplitude of the preprocessed first response electromagnetic data with that of the preprocessed third response electromagnetic data, and obtaining a frequency range of motion noise pollution corresponding to which the amplitude difference is larger than the amplitude difference threshold;
and extracting field value amplitudes of a ground reference point and an air measuring point in a frequency band range polluted by motion noise, and carrying out denoising correction processing by adopting a minimum mean square error algorithm.
In a second aspect, the present technology provides a system employing an airborne electromagnetic data processing method based on a ground reference point, comprising:
the first response electromagnetic data acquisition module is used for arranging an emission source on the ground of a region to be detected, carrying a coil sensor on a flight platform for carrying out uniform flight, and acquiring first response electromagnetic data corresponding to a plurality of aerial measuring points;
the second response electromagnetic data acquisition module is used for selecting a plurality of ground reference points along the direction of the emission source and acquiring second response electromagnetic data at the ground reference points by using a coil sensor;
the preprocessing module is connected with the first response electromagnetic data acquisition module and the second response electromagnetic data acquisition module and respectively preprocesses the first response electromagnetic data and the second response electromagnetic data;
the difference value obtaining module is connected with the preprocessing module, acquires preprocessed first response electromagnetic data, performs forward modeling, and obtains a difference value between the ground and the air;
the third response electromagnetic data obtaining module is connected with the difference value obtaining module, loads the difference value into the second response electromagnetic data, and obtains a reference correction value of any aerial measuring point of the area to be detected by adopting an interpolation method to obtain third response electromagnetic data;
the frequency band determining module for motion noise pollution is connected with the third response electromagnetic data solving module and the preprocessing module, an amplitude difference threshold value is preset, amplitude comparison is carried out on the preprocessed first response electromagnetic data and the preprocessed third response electromagnetic data, and a frequency band range of motion noise pollution, of which the amplitude difference is larger than the amplitude difference threshold value, is obtained;
the denoising correction processing module is connected with the frequency band determination module and the preprocessing module for the motion noise pollution, extracts field value amplitudes of a ground reference point and an air measuring point in the frequency band range for the motion noise pollution, and performs denoising correction processing by adopting a minimum mean square error algorithm.
Compared with the prior art, the invention has the following beneficial effects:
the invention skillfully starts from the root cause of the motion noise generation, and corrects the data polluted by the motion noise by collecting the ground reference point data (without being polluted by the motion noise), compared with other methods, the invention can eliminate the influence of the motion noise to the greatest extent and has good effect.
The invention skillfully introduces the minimum mean square error algorithm into the aviation electromagnetic motion noise denoising process, and innovatively improves the super-parameter setting in the minimum mean square error aiming at the motion noise characteristics, so that the super-parameter setting can be dynamically adjusted according to the motion noise characteristics, and the algorithm can meet convergence precision, reduce calculated amount and quickly converge.
In conclusion, the method has the advantages of simple logic, accuracy, reliability and the like, and has high practical value and popularization value in the technical field of geophysical exploration.
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For a clearer description of the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and should not be considered as limiting the scope of protection, and other related drawings may be obtained according to these drawings without the need of inventive effort for a person skilled in the art.
FIG. 1 is a logic flow diagram of the present invention.
Fig. 2 is a schematic acquisition diagram of the present invention.
FIG. 3 is a graph of the constant velocity flight survey point versus reference point of the present invention.
FIG. 4 is a graph of field amplitude at the aerial W1 measurement point according to the present invention.
FIG. 5 is a plot of forward modeling ground, air field value amplitude and difference versus the present invention.
FIG. 6 is a graph showing the amplitude comparison of field values corresponding to the aerial W1 measurement point and the ground G1 measurement point.
Fig. 7 is a graph of mean square error versus time for the present invention.
FIG. 8 is a plot of the amplitude of the dominant frequency of the aerial W1 survey point, the ground G1 survey point, and the final processing results of the present invention.
Description of the embodiments
For the purposes, technical solutions and advantages of the present application, the present invention will be further described with reference to the accompanying drawings and examples, and embodiments of the present invention include, but are not limited to, the following examples. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
In this embodiment, the term "and/or" is merely an association relationship describing the association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone.
The terms first and second and the like in the description and in the claims of the present embodiment are used for distinguishing between different objects and not for describing a particular sequential order of objects. For example, the first target object and the second target object, etc., are used to distinguish between different target objects, and are not used to describe a particular order of target objects.
In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.
In the description of the embodiments of the present application, unless otherwise indicated, the meaning of "a plurality" means two or more. For example, the plurality of processing units refers to two or more processing units; the plurality of systems means two or more systems.
As shown in fig. 1 to 8, the present embodiment provides an airborne electromagnetic data processing method based on a ground reference point, which includes the steps of:
first, data acquisition:
firstly, laying ground emission sources, carrying out uniform-speed flight acquisition data on a design test line through an unmanned aerial vehicle carrying coil sensor, recording related acquisition parameters, and secondly, acquiring a plurality of ground reference point data at certain intervals by adopting the same instrument on the ground position corresponding to the test line. The number of the ground reference points is not less than 5% of the number of the uniform-speed flight measuring points. The layout diagram is shown in fig. 2.
Specifically, according to the topography condition, lay the transmission line source in the flat place of topography, simultaneously according to detecting the degree of depth demand and actual ground resistance, set up suitable transmission dominant frequency and electric current size to the transmission parameters such as record transmission extreme point position, length, transmission dominant frequency and electric current size.
In this embodiment, carry on coil sensor and collection host computer through many rotor unmanned aerial vehicle and carry out data acquisition, many rotor unmanned aerial vehicle pass through the hawser with coil sensor and collection host computer and are connected, for avoiding many rotor unmanned aerial vehicle's electromagnetic noise, coil sensor is greater than 10m with many rotor unmanned aerial vehicle distance, consequently carries hawser length to need be greater than 10m. The uniform speed of the multi-rotor unmanned aerial vehicle is less than 10m/s, flight parameters such as flight height and speed are recorded, and meanwhile, the time of the unmanned aerial vehicle flying into and out of the measuring line is recorded, so that the follow-up processing is facilitated. In this embodiment, the emission source length is 1624m, the emission main frequency is 25Hz, 128Hz, 512Hz, 1200Hz and 6400Hz, and the corresponding current sizes are 5.9A, 5.8A, 5.3A and 4.2A. The flying height is 80m, and the flying speed is 2m/s.
In addition, when the ground reference points collect data, the ground reference points are collected at certain intervals on the corresponding ground positions of the measuring lines, the emission parameters are consistent with those in uniform-speed flight, and the coil sensors and the collecting host are consistent with those in the above. After reaching the ground acquisition point, the coil sensor needs to be horizontally and statically placed on the ground for acquisition, the acquisition time of a single ground acquisition point is longer than 60s, and the acquisition start and end time of the ground acquisition point are recorded, so that the subsequent processing is facilitated. Meanwhile, it is emphasized that the ground reference points must cover the positions of all the measuring lines, and the number of the ground reference points cannot be less than 5% of the number of the measuring points in uniform-speed flight.
In this embodiment, a first mode is adopted to perform ground reference point data acquisition. According to actual conditions, unequal interval collection is adopted, and the collection number is 14, as shown in fig. 3.
Second, data preprocessing, namely data processing of first response electromagnetic data:
in this embodiment, the data preprocessing object includes uniform speed flight data and ground reference point data. The method mainly comprises data format conversion, data arrangement, measurement point coordinate projection, field value calculation, data normalization and the like. The data format conversion is to convert the original data from binary format into ASCII code, including original time sequence data and GPS data. In addition, the data arrangement is to select time sequence data and GPS data which are acquired at a constant speed and correspond to the measuring lines according to the time recorded when the multi-rotor unmanned aerial vehicle flies in the first step; in addition, the time series data and GPS data acquired by the ground reference point are selected according to the time recorded when the ground reference point acquires the data in the first step. In addition, the line coordinate projection in this embodiment is to respectively project the converted GPS coordinates of the uniform flight and the GPS coordinates of the ground reference point together to obtain a relative position diagram of the measurement point and the reference point, as shown in fig. 3.
In this embodiment, the field value calculation is to convert time series data from time domain to frequency domain, and the specific calculation process is as follows:
converting the time series into frequency domain samples using Discrete Fourier Transform (DFT) toAnalysis of (1)>Is a sampling interval, wherein the sampling interval +.>The following conditions must be satisfied:
（1）
where n represents the sequence number of the time domain samples,represents the cut-off frequency, sampling length +.>；
In order to achieve discretization in the fourier transform, there is the following discrete formula:
（2）
wherein,representing the frequency interval; n represents the number of sampling points; />Representing a field value; />A sequence number representing a frequency domain sample; />Representing a time series;
then it is available according to the above formula:
（3）
wherein,representing a set of field signals in the frequency domain; e represents the bottom of the natural logarithm; i is an imaginary unit.
In this embodiment, data normalization refers to subtracting the transmission parameters and gain factors in the field values, and the specific calculation formula is as follows:
（4）
wherein X is the original field value data,for normalized field value data, G is a gain multiple, L is the length of the emission source, and I is the emission current.
Thirdly, reference point data processing, namely data processing of second response electromagnetic data:
in general, the number of ground reference points is far smaller than the number of measurement points acquired in a uniform flight, so that the corresponding number of correction data is needed to be obtained by interpolation according to the ground reference points. Firstly, according to the emission parameters and the flight parameters recorded in the first step, the difference value between the ground and the air is obtained through forward modeling. The forward modeling calculation is too complex, where the field value calculation is given directly as follows:
（5）
wherein,indicating vacuum permeability; />A current representative of the emission source; />Representing the offset distance; />Representing the receiving and transmitting distance of the measuring point relative to the line element; />Representing the length of the emission source; />Representing the ground reflection coefficient; />Representing the vertical direction; />Representing the sampling point positions; />Representing a bessel function of order 1.
In the present embodiment, the values of the air-perpendicular magnetic field are obtained by using the formula (5)And ground perpendicular magnetic field value。
According to the field value of the vertical magnetic field in the airAnd the ground vertical magnetic field value->Obtaining the difference value between the ground and the air ∈>The expression is as follows:
（6）。
as shown in fig. 5, the Bz value curve of the ground and the air perpendicular magnetic field and the difference curve of the two are obtained by forward modeling.
On the basis, the embodiment obtains the reference correction value of the full frequency band in the range of the measuring line/region by interpolation.
Fourth, judging the noise pollution frequency band:
and on the basis of the third step, comparing and analyzing the difference of the data of the air uniform flight and the ground reference point data in amplitude, and judging the frequency range polluted by the motion noise. In general, the direct representation of the signal subjected to the motion noise is that the amplitude of the field value is larger than that of the normal signal, but not all frequency bands are polluted by the motion noise, so that the frequency band range polluted by the motion noise needs to be judged to reduce the subsequent calculation amount.
In the embodiment, a plurality of pairs of uniform speed flight measuring points and ground reference points at the same position are selected, and field value amplitudes of the pairs of uniform speed flight measuring points and ground reference points are drawn in batches. The frequency band with the uniform flight amplitude far larger than the ground reference point amplitude is judged to be the frequency band polluted by the motion noise by comparing the amplitude.
In this embodiment, taking the airborne W1 measurement point and the ground reference point G1 at the same position as an example, as shown in fig. 6, the amplitude of the field value of the airborne W1 measurement point is larger than that of the ground reference point G1 in the low frequency band due to the pollution caused by the motion noise, and as can be seen from fig. 6, the polluted frequency band is approximately within 25Hz to 500 Hz.
Fifth, data denoising correction:
and (3) extracting the field value amplitude of the reference point and corresponding measuring point data in the range according to the noise pollution range judged in the fourth step, taking the measuring point field value amplitude as an input signal, taking the reference point field value amplitude as an expected signal, and adopting an improved minimum mean square error algorithm to carry out denoising correction processing aiming at the motion noise characteristics. Specifically:
first, a filter initial coefficient of default to 0 is defined, and then an input signal (measurement point field value amplitude) and a desired signal (reference point field value amplitude) are input to the filter, respectively.
The output signal of the filter is calculated and the mean square error between the output signal and the desired signal is calculated.
According to the mean square error, the filter coefficient is continuously adjusted so that the mean square error is continuously reduced, and the process can be realized through the following formula:
（7）
wherein,representing a learning rate; />Representing the mean square error between the output signal and the desired signal; />Representing the input signal; />Representing the filter coefficients of the n+1th order; />Representing the filter coefficients of the nth order;
the mean square error between the output signal and the desired signalThe expression of (2) is:
（8）
wherein N represents the number of samples; y (i) represents the actual output value of the ith sample;representing the expected output value of the ith sample. Wherein the mean square error versus time curve is shown in fig. 7.
In this embodiment, the learning rate u is an important super parameter, usually a constant, and a larger learning rate has a faster convergence speed but insufficient convergence accuracy, and a smaller learning rate increases algorithm convergence accuracy, but requires more iterations to converge. Therefore, multiple experiments are often required to determine the optimal learning rate.
Aiming at the characteristics of motion noise, namely high low-frequency pollution and low high-frequency pollution, the embodiment dynamically adjusts the learning rate according to the frequency, has smaller learning rate in a low frequency band (high pollution), improves convergence accuracy, has larger learning rate in a high frequency band (low pollution), and improves convergence speed. The learning rateThe expression of (2) is:
（9）
wherein,representing a scaling factor; />Representing the frequency.
Learning rate of the present embodimentIs controlled to be in the range of 0.1-1. When the mean square error reaches the minimum, the output signal is the signal after removing the motion noise, and the final processing result is shown in fig. 8.
The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention, but all changes made by adopting the design principle of the present invention and performing non-creative work on the basis thereof shall fall within the scope of the present invention.
Claims (7)
1. The aviation electromagnetic data processing method based on the ground reference point is characterized by comprising the following steps of:
arranging a transmitting source on the ground of a region to be detected, carrying a coil sensor on a flight platform to perform uniform flight, and acquiring first response electromagnetic data corresponding to a plurality of aerial measuring points;
selecting a plurality of ground reference points along the direction of the emission source, and acquiring second response electromagnetic data at the ground reference points by using a coil sensor;
preprocessing the first response electromagnetic data and the second response electromagnetic data respectively;
forward modeling is carried out by adopting the preprocessed first response electromagnetic data, and a difference value between the ground and the air is obtained;
loading the difference value into second response electromagnetic data, and obtaining a reference correction value of any air measuring point of the area to be detected by adopting an interpolation method to obtain third response electromagnetic data;
presetting an amplitude difference threshold, comparing the amplitude of the preprocessed first response electromagnetic data with that of the preprocessed third response electromagnetic data, and obtaining a frequency range of motion noise pollution corresponding to which the amplitude difference is larger than the amplitude difference threshold;
and extracting field value amplitudes of a ground reference point and an air measuring point in a frequency band range polluted by motion noise, and carrying out denoising correction processing by adopting a minimum mean square error algorithm.
2. The method for processing airborne electromagnetic data based on ground reference points according to claim 1, wherein the number of ground reference points corresponding to the second response electromagnetic data is not less than 5% of the number of airborne measurement points corresponding to the first response electromagnetic data.
3. The ground reference point-based aviation electromagnetic data processing method according to claim 1, wherein the first response electromagnetic data and the second response electromagnetic data are preprocessed respectively; the preprocessing comprises data format conversion, data arrangement, measurement point coordinate projection, field value calculation and data normalization.
4. The method for processing aviation electromagnetic data based on ground reference points according to claim 1, wherein forward modeling is performed by using the preprocessed first response electromagnetic data, and a difference value between the ground and the air is obtained, comprising:
obtaining the vertical magnetic field value by adopting a field value calculation methodThe expression is as follows:
（5）
wherein,indicating vacuum permeability; />A current representative of the emission source; />Representing the offset distance; />Representing the receiving and transmitting distance of the measuring point relative to the line element; />Representing the length of the emission source; />Representing the ground reflection coefficient; />Representing the vertical direction; />Representing the sampling point positions; />Representing a Bessel function of order 1; e represents a natural logarithmic base;
respectively obtaining the field value of the vertical magnetic field in the air by using the formula (5)And the ground vertical magnetic field value->；
According to the field value of the vertical magnetic field in the airAnd the ground vertical magnetic field value->Obtaining the difference value between the ground and the air ∈>The expression is as follows:
（6）。
5. the method for processing aviation electromagnetic data based on ground reference points according to claim 1, wherein the field value amplitudes of the ground reference points and the air measurement points are extracted in the frequency band range polluted by the motion noise, and the denoising correction is performed by adopting a minimum mean square error algorithm, and the denoising correction by adopting the minimum mean square error algorithm comprises:
the expression of the minimum mean square error algorithm is as follows:
（7）
wherein the method comprises the steps of，Representing a learning rate; />Representing the mean square error between the output signal and the desired signal; />Representing the input signal;representing the filter coefficients of the n+1th order; />Representing the filter coefficients of the nth order;
the mean square error between the output signal and the desired signalThe expression of (2) is:
（8）
wherein N represents the number of samples; y (i) represents the actual output value of the ith sample;representing the expected output value of the ith sample.
6. The ground reference point-based airborne electromagnetic data processing method of claim 5 wherein said learning rateThe expression of (2) is:
（9）
wherein,representing a scaling factor; />Representing the frequency.
7. A system employing the ground reference point-based airborne electromagnetic data processing method of any one of claims 1-6, comprising:
the first response electromagnetic data acquisition module is used for arranging an emission source on the ground of a region to be detected, carrying a coil sensor on a flight platform for carrying out uniform flight, and acquiring first response electromagnetic data corresponding to a plurality of aerial measuring points;
the second response electromagnetic data acquisition module is used for selecting a plurality of ground reference points along the direction of the emission source and acquiring second response electromagnetic data at the ground reference points by using a coil sensor;
the preprocessing module is connected with the first response electromagnetic data acquisition module and the second response electromagnetic data acquisition module and respectively preprocesses the first response electromagnetic data and the second response electromagnetic data;
the difference value obtaining module is connected with the preprocessing module, acquires preprocessed first response electromagnetic data, performs forward modeling, and obtains a difference value between the ground and the air;
the third response electromagnetic data obtaining module is connected with the difference value obtaining module, loads the difference value into the second response electromagnetic data, and obtains a reference correction value of any aerial measuring point of the area to be detected by adopting an interpolation method to obtain third response electromagnetic data;
the frequency band determining module for motion noise pollution is connected with the third response electromagnetic data solving module and the preprocessing module, an amplitude difference threshold value is preset, amplitude comparison is carried out on the preprocessed first response electromagnetic data and the preprocessed third response electromagnetic data, and a frequency band range of motion noise pollution, of which the amplitude difference is larger than the amplitude difference threshold value, is obtained;
the denoising correction processing module is connected with the frequency band determination module and the preprocessing module for the motion noise pollution, extracts field value amplitudes of a ground reference point and an air measuring point in the frequency band range for the motion noise pollution, and performs denoising correction processing by adopting a minimum mean square error algorithm.
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| CN117589890A (en) * | 2024-01-19 | 2024-02-23 | 四川省自然资源勘察设计集团有限公司 | Rock collapse early warning method and system based on acoustic emission characteristics |
| CN117589890B (en) * | 2024-01-19 | 2024-03-26 | 四川省自然资源勘察设计集团有限公司 | Rock collapse early warning method and system based on acoustic emission characteristics |
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