CN111060980A - Distributed sea wave magnetic interference compensation method - Google Patents

Distributed sea wave magnetic interference compensation method Download PDF

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CN111060980A
CN111060980A CN201811208605.4A CN201811208605A CN111060980A CN 111060980 A CN111060980 A CN 111060980A CN 201811208605 A CN201811208605 A CN 201811208605A CN 111060980 A CN111060980 A CN 111060980A
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magnetic field
magnetic
distributed
interference
calculating
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秦杰
王同雷
王春娥
魏克全
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Beijing Automation Control Equipment Institute BACEI
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    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/40—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for measuring magnetic field characteristics of the earth
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/38—Processing data, e.g. for analysis, for interpretation, for correction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
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    • Y02A90/30—Assessment of water resources

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Abstract

The invention discloses a distributed sea wave induction magnetic field interference compensation method, which comprises the following steps of (1) calculating a main magnetic field and a crustal magnetic field; (2) main magnetic field and earth crust magnetic field compensation; (3) eliminating the linear trend; (4) band-pass filtering; (5) calculating the correlation; (6) calculating a transfer function; (7) calculating the magnetic interference of sea waves; (8) and (5) sea wave magnetic interference compensation. The invention has the advantages that: the method can effectively compensate the interference of the environmental magnetic field and improve the detection signal-to-noise ratio of the detection system when being applied to the distributed magnetic anomaly detection system. The method can be applied to compensation of the influence of the interference of the sea wave induction magnetic field on the distributed magnetic anomaly detection system carried on a ground carrier, an air carrier and an underwater carrier. The method is particularly suitable for the application of magnetic anomaly detection of underwater and water surface ferromagnetic targets.

Description

Distributed sea wave magnetic interference compensation method
Technical Field
The invention belongs to a compensation method for sea wave induction magnetic field interference, and particularly relates to a processing method for a magnetic field detection signal in a distributed magnetic anomaly detection system.
Background
The geomagnetic field generally changes regularly and slowly along with time and space, and when a magnetic substance exists, the magnetic field of the substance and the magnetic field induced under the geomagnetic field are superposed on the geomagnetic field, so that the geomagnetic field is abnormal in a certain area. A large amount of metal mineral products are stored in earth land and sea, underwater military equipment such as targets, mines and the like are mainly made of metal materials, and magnetic substances in the metal materials can cause the abnormity of the surrounding geomagnetic field. The magnetic anomaly detection system realizes the detection and positioning of magnetic substances by detecting and identifying the anomaly information of the geomagnetic field, is widely applied in the fields of resource exploration, underwater target detection and the like, and is a key core instrument which is urgently needed by national economic development and national defense construction.
The sea wave induction magnetic field is an induced electromagnetic field generated by the sea water cutting the earth magnetic field, and the magnetic field is very weak and accounts for about ten thousand to one hundred thousand of the total field strength. The wave induced magnetic field interference is mainly caused by seawater flow and is related to factors such as wind speed and wave height, so that the frequency band, amplitude and the like of the wave induced magnetic field are not fixed, and the interference magnetic field mainly represents narrow-band low-frequency large interference or wide-band high-frequency small interference.
Distributed magnetic anomaly detection system adopts novel atomic magnetometer, utilizes small-size unmanned platform such as unmanned aerial vehicle to establish intelligent detection network and carries out the distributed detection, receives the influence that wave induction magnetic field disturbed easily for the SNR of detecting signal reduces, influences performance index such as detection distance, consequently needs to carry out real-time compensation to ocean induction magnetic field interference. The detection signal of the magnetic detection system can be represented by the following formula:
Tmeasuring＝TTarget+TSea wave
Wherein, TMeasuringIs a magnetic sensor measurement; t isTargetGenerating a magnetic anomaly for the detected target; t isSea waveIs the interference of the wave induction magnetic field.
The change rule of the sea wave induction magnetic field is complex, the frequency band covers the frequency band of the target magnetic anomaly signal, and the distributed magnetic detection measurement result is greatly influenced. In order to realize compensation of the interference of the induced magnetic field, a distributed sea wave magnetic interference compensation method is designed.
Disclosure of Invention
The invention aims to provide a distributed wave induction magnetic field interference compensation method, which realizes real-time analysis, processing and compensation of wave induction magnetic interference signals in a multi-platform distributed detection mode, reduces the influence of a wave interference magnetic field on target detection and identification, and improves the detection capability of a distributed magnetic detection system.
The technical scheme of the invention is as follows: a distributed sea wave magnetic interference compensation method comprises the following steps,
(1) calculating a main magnetic field and a crustal magnetic field;
(2) main magnetic field and earth crust magnetic field compensation;
(3) eliminating the linear trend;
(4) band-pass filtering;
(5) calculating the correlation;
(6) calculating a transfer function;
(7) calculating the magnetic interference of sea waves;
(8) and (5) sea wave magnetic interference compensation.
The step (1) comprises the steps of calculating the intensity values B of the main earth magnetic field and the geomagnetic magnetic field on the detection path by using the GPS position information of the detection platform and combining an international reference geomagnetic field model (IGRF) and an earth-crust magnetic field model (NDGC), wherein the calculation formula is as follows:
Figure BDA0001831853000000031
in the formula (I), the compound is shown in the specification,
Figure BDA0001831853000000032
is a Gaussian coefficient; reIs the earth's reference equatorial radius, r is the geocentric distance, λ is the geographic longitude,
Figure BDA0001831853000000033
the weft is left in the center of the earth,
Figure BDA0001831853000000034
in the case of the geographic latitude, the latitude,
Figure BDA0001831853000000035
is a Schmidt quasi-normalized associated Legendre function of order n and m, BSkyA magnetic field in the direction of the sky and the earth, BNorth ChinaA magnetic field in the north-south direction, BEastA magnetic field in the West-east direction, passing through BEast、BNorth ChinaAnd BSkyObtaining the total magnetic field intensity
Figure BDA0001831853000000036
The step (2) comprises eliminating the influence of a geomagnetic main field and a crustal magnetic field, and obtaining a magnetic field detection signal T by distributed magnetic detectionSide 1、TSide 2……TMeasure NSubtracting the geomagnetic main field and the geomagnetic field B at the corresponding positionsGround 1……BGround NAs shown in the following formula,
Bdifference i＝TMeasure i-BGround i(2)
The step (3) comprises eliminating linear trend influence, and the difference obtained in the step (2) can be represented as BDifference i＝k·BGo i+ t (i ═ 1,2 … … N), and B with linear trend eliminated is calculated by the least square methodGo iAs shown in the following formula,
Figure BDA0001831853000000037
Figure BDA0001831853000000038
the step (4) comprises the steps of obtaining the interference of the sea wave induction magnetic field, carrying out band-pass filtering on the result after trend removing, and obtaining a magnetic field signal biAnd the filtering bandwidth is the wave signal frequency band.
The step (5) comprises calculating a correlation function between nodes in the distributed detection network
Figure BDA0001831853000000039
Where Γ (f) is a correlation function,
Figure BDA00018318530000000310
is a signal bi(omega) and bj(ω) a cross-correlation spectrum of (ω),
Figure BDA0001831853000000041
and
Figure BDA0001831853000000042
and selecting two node data with higher correlation in the detection frequency band for the autocorrelation spectrum to perform subsequent processing.
The step (6) comprises calculating a transfer function between the nodes of the distributed detection network
Figure BDA0001831853000000043
In the formula
Figure BDA0001831853000000044
In order to be a cross-correlation spectrum,
Figure BDA0001831853000000045
is an autocorrelation spectrum.
The step (7) comprises the step of solving the sea wave interference magnetic field T by utilizing inverse Fourier transformSea waveThe formula is as follows:
Tsea wave＝F-1(Bi(fl,k)-H(fl,k)·Bj(fl,k)) (4)
Wherein, Bi(ωlK) and Bj(ωlK) are respectively the magnetic field signal biAnd bjThe fourier transform value of (a).
The step (8) comprises the step of obtaining a product by a formula TTarget＝TMeasuring-TSea waveAnd calculating to obtain a target magnetic abnormal signal, and realizing effective compensation of the environmental magnetic interference signal.
The invention has the beneficial effects that: the invention relates to a compensation method for sea wave induction magnetic field interference in distributed magnetic detection, in particular to a method which can effectively compensate environment magnetic field interference and improve the detection signal-to-noise ratio of a detection system when being applied to a distributed magnetic anomaly detection system. The method is suitable for a distributed magnetic anomaly detection system consisting of 2 or more magnetic anomaly detectors or sensors. The method can be applied to the compensation of the influence of the interference of the wave induction magnetic field on the distributed magnetic anomaly detection system carried on a ground carrier, an aerial carrier and an underwater carrier. The method is particularly suitable for the application of magnetic anomaly detection of underwater and water surface ferromagnetic targets.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
A distributed sea wave magnetic interference compensation method comprises the following steps:
(1) main magnetic field and earth-crust magnetic field calculation
Calculating the main earth magnetic field and the earth magnetic field strength value B on a detection path by using the GPS position information of the detection platform and combining an international reference earth magnetic field model (IGRF) and an earth magnetic field model (NDGC), wherein the calculation formula is as follows:
Figure BDA0001831853000000051
in the formula (I), the compound is shown in the specification,
Figure BDA0001831853000000052
is a Gaussian coefficient; reIs the earth's reference equatorial radius; r is the geocentric distance, and λ is the geographic longitude;
Figure BDA0001831853000000053
is the earth core weft remainders;
Figure BDA0001831853000000054
is the geographic latitude;
Figure BDA0001831853000000055
is an n-order m-order schmidt-specific normalized associated legendre function; b isSkyIs a magnetic field in the direction of heaven and earth; b isNorth ChinaA magnetic field in the north-south direction; b isEastIs a magnetic field in the west-east direction. By BEast、BNorth ChinaAnd BSkyObtaining the total magnetic field intensity
Figure BDA0001831853000000056
(2) Main magnetic field and earth-crust magnetic field compensation
Magnetic field detection signal T obtained by distributed magnetic detection and eliminating influence of geomagnetic main field and crustal magnetic fieldSide 1、TSide 2……TMeasure NSubtract the correspondingMain geomagnetic field and geomagnetic field B of positionGround 1……BGround NThe following formula is shown below.
BDifference i＝TMeasure i-BGround i(2)
(3) Eliminating linear trends
Eliminating linear trend influence, the difference value obtained in the step (2) can be represented as BDifference i＝k·BGo i+ t (i ═ 1,2 … … N), and B with linear trend eliminated is calculated by the least square methodGo iThe following formula is shown below.
Figure BDA0001831853000000057
Figure BDA0001831853000000058
(4) Band pass filtering
Obtaining the interference of the sea wave induction magnetic field, carrying out band-pass filtering on the result after trend removing to obtain a magnetic field signal biAnd the filtering bandwidth is the wave signal frequency band.
(5) Correlation calculation
Computing a relevance function between nodes in a distributed probe network
Figure BDA0001831853000000061
Where Γ (f) is a correlation function,
Figure BDA0001831853000000062
is a signal bi(omega) and bj(ω) a cross-correlation spectrum of (ω),
Figure BDA0001831853000000063
and
Figure BDA0001831853000000064
is an autocorrelation spectrum. And selecting two node data with higher correlation in the detection frequency band for subsequent processing.
(6) Transfer function calculation
Computing distributionsMethod for probing transfer function between network nodes
Figure BDA0001831853000000065
In the formula
Figure BDA0001831853000000066
In order to be a cross-correlation spectrum,
Figure BDA0001831853000000067
is an autocorrelation spectrum.
(7) Sea wave magnetic interference calculation
Method for solving sea wave interference magnetic field T by utilizing inverse Fourier transformSea waveThe formula is as follows:
Tsea wave＝F-1(Bi(fl,k)-H(fl,k)·Bj(fl,k)) (4)
Wherein, Bi(ωlK) and Bj(ωlK) are respectively the magnetic field signal biAnd bjThe fourier transform value of (a).
(8) Sea wave magnetic interference compensation
By the formula TTarget＝TMeasuring-TSea waveAnd calculating to obtain a target magnetic abnormal signal, and realizing effective compensation of the environmental magnetic interference signal.

Claims (9)

1. A distributed sea wave magnetic interference compensation method is characterized by comprising the following steps: which comprises the following steps of,
(1) calculating a main magnetic field and a crustal magnetic field;
(2) main magnetic field and earth crust magnetic field compensation;
(3) eliminating the linear trend;
(4) band-pass filtering;
(5) calculating the correlation;
(6) calculating a transfer function;
(7) calculating the magnetic interference of sea waves;
(8) and (5) sea wave magnetic interference compensation.
2. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (1) comprises the steps of calculating the intensity values B of the main earth magnetic field and the geomagnetic magnetic field on the detection path by using the GPS position information of the detection platform and combining an international reference geomagnetic field model (IGRF) and an earth-crust magnetic field model (NDGC), wherein the calculation formula is as follows:
Figure FDA0001831852990000011
in the formula (I), the compound is shown in the specification,
Figure FDA0001831852990000012
is a Gaussian coefficient; reIs the earth's reference equatorial radius, r is the geocentric distance, λ is the geographic longitude,
Figure FDA0001831852990000013
the weft is left in the center of the earth,
Figure FDA0001831852990000014
in the case of the geographic latitude, the latitude,
Figure FDA0001831852990000015
is a Schmidt quasi-normalized associated Legendre function of order n and m, BSkyA magnetic field in the direction of the sky and the earth, BNorth ChinaA magnetic field in the north-south direction, BEastA magnetic field in the West-east direction, passing through BEast、BNorth ChinaAnd BSkyObtaining the total magnetic field intensity
Figure FDA0001831852990000016
3. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (2) comprises eliminating the influence of a geomagnetic main field and a crustal magnetic field, and obtaining a magnetic field detection signal T by distributed magnetic detectionSide 1、TSide 2……TMeasure NSubtracting the geomagnetic main field and the geomagnetic field B at the corresponding positionsGround 1……BGround NAs shown in the following formula,
Bdifference i＝TMeasure i-BGround i(2)
4. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (3) comprises eliminating linear trend influence, and the difference obtained in the step (2) can be represented as BDifference i＝k·BGo i+ t (i ═ 1,2 … … N), and B with linear trend eliminated is calculated by the least square methodGo iAs shown in the following formula,
Figure FDA0001831852990000021
Figure FDA0001831852990000022
5. a distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (4) comprises the steps of obtaining the interference of the sea wave induction magnetic field, carrying out band-pass filtering on the result after trend removing, and obtaining a magnetic field signal biAnd the filtering bandwidth is the wave signal frequency band.
6. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (5) comprises calculating a correlation function between nodes in the distributed detection network
Figure FDA0001831852990000023
Where Γ (f) is a correlation function,
Figure FDA0001831852990000024
is a signal bi(omega) and bj(ω) a cross-correlation spectrum of (ω),
Figure FDA0001831852990000025
and
Figure FDA0001831852990000026
and selecting two node data with higher correlation in the detection frequency band for the autocorrelation spectrum to perform subsequent processing.
7. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (6) comprises calculating a transfer function between the nodes of the distributed detection network
Figure FDA0001831852990000031
In the formula
Figure FDA0001831852990000032
In order to be a cross-correlation spectrum,
Figure FDA0001831852990000033
is an autocorrelation spectrum.
8. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (7) comprises the step of solving the sea wave interference magnetic field T by utilizing inverse Fourier transformSea waveThe formula is as follows:
Tsea wave＝F-1(Bi(fl,k)-H(fl,k)·Bj(fl,k)) (4)
Wherein, Bi(ωlK) and Bj(ωlK) are respectively the magnetic field signal biAnd bjThe fourier transform value of (a).
9. A distributed ocean wave magnetic disturbance compensation method according to claim 1, wherein: the step (8) comprises the step of obtaining a product by a formula TTarget＝TMeasuring-TSea waveAnd calculating to obtain a target magnetic abnormal signal, and realizing effective compensation of the environmental magnetic interference signal.
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CN111856590A (en) * 2020-08-05 2020-10-30 中国海洋大学 Sea wave magnetic interference suppression method for ocean magnetotelluric detection
CN112925030A (en) * 2021-01-26 2021-06-08 重庆大学 Target boundary detection device and method based on underwater magnetic anomaly signals

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
CN111856590A (en) * 2020-08-05 2020-10-30 中国海洋大学 Sea wave magnetic interference suppression method for ocean magnetotelluric detection
CN111856590B (en) * 2020-08-05 2023-03-17 中国海洋大学 Sea wave magnetic interference suppression method for ocean magnetotelluric detection
CN112925030A (en) * 2021-01-26 2021-06-08 重庆大学 Target boundary detection device and method based on underwater magnetic anomaly signals
CN112925030B (en) * 2021-01-26 2024-04-12 重庆大学 Target boundary detection device and method based on underwater magnetic anomaly signals

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Application publication date: 20200424