CN109100809A - Weak magnetic signal noise suppressed and signal extracting device and method under earth magnetism background - Google Patents
Weak magnetic signal noise suppressed and signal extracting device and method under earth magnetism background Download PDFInfo
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- CN109100809A CN109100809A CN201811105285.XA CN201811105285A CN109100809A CN 109100809 A CN109100809 A CN 109100809A CN 201811105285 A CN201811105285 A CN 201811105285A CN 109100809 A CN109100809 A CN 109100809A
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- 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
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/081—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices the magnetic field is produced by the objects or geological structures
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- 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
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- 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
- G01V3/40—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
Abstract
Weak magnetic signal noise suppressed and signal extracting device and method under a kind of earth magnetism ambient field, including magnetic detector, for detecting weak magnetic signal data collecting card, for acquiring the signal of magnetic detector and being transferred to spectrum analyzer；And spectrum analyzer, spectrum analysis and the filtering processing of corresponding signal are carried out for collected signal.The present invention promotes magnetic anomaly signal frequency by improving speed of related movement between detected target and detection sensor, so that magnetic anomaly signal is in higher frequency band, and Geomagnetic signal is near 0Hz frequency, therefore the frequency by promoting echo signal, weak magnetic signal and earth magnetism ambient field are isolated on frequency spectrum, then geomagnetic noise is filtered out using high-pass filter, achievees the purpose that noise suppressed and signal extraction.
Description
Technical field
The present invention relates to weak magnetic detection technology field, especially one kind under earth magnetism ambient field weak magnetic signal noise suppressed with
Method for extracting signal.
Background technique
Weak magnetic Detection Techniques generate the physics of earth's magnetic field abnormal distribution to disturb earth magnetism field distribution with ferromagnetic object
Based on phenomenon, by measuring the distribution of magnetic anomaly signal, the characteristic quantity of magnetic anomaly signal is extracted, and most by certain data processing
Target relevant information is obtained eventually.Compared to detection means such as light, sound, weak magnetic detection is a kind of passive detection technology, is had hidden
Property is good, the advantages such as is not influenced by weather environment, and it is civilian which is now widely used for mineral exploration aviation, navigation, positioning etc., and
The military fields such as target search, battlefield monitoring.
Since when detecting weak magnetic signal, target object magnetic signal is in nanotesla magnitude, and earth's magnetic field signal strength reaches several
Ten micro- special magnitudes, the two differ 3 several magnitudes, therefore noise suppressed to earth magnetism and signal extraction become extremely difficult.
In existing weak magnetic Detection Techniques, the detectivity of detector hardware aspect, example are mainly improved both at home and abroad
Such as three axis magnetometer, fluxgate sensor, magnetic resistance detector, optically pumped magnetometer, superconducting quantum interference device (SQUID).Wherein three axis magnetic strength
Meter is based on faraday electromagnetic induction principle, and investigative range can achieve 10-3—102T, the weak magnetic detection for belonging to a kind of early stage are set
Standby, sensitivity is lower.Fluxgate sensor has the characteristics that noise is low, frequency response is high, temperature performance is good, and measurement range can be with
Reach 10-10—10-3T, sensitivity cover the sub- nT magnitude of small-signal.Magnetic resistance detector is based on resistance under magnetic fields and sends out
The principle for changing, up to pT magnitude on sensitivity theory, the method has resolving power height, fast response time, small in size, power consumption
Low advantage, integrability.Optically pumped magnetometer realizes detection purpose using unstability of the gas under magnetic field, detects sensitive
Degree can reach fT magnitude, and the G-858 caesium optically pumped magnetometer sensitivity of Geometrice company reaches 0.01pT.Superconductive quantum interference
Magnetometer (SQUID) is made using superconductor, sensitivity reaches 10 based on josephson effect theory-15T (fT), is mesh
The preceding highest magnetic detector of sensitivity.Although the sensitivity of current detecting devices hardware aspect is higher and higher, earth magnetism back
The intensity of Jing Chang reaches tens of micro- special magnitudes, how to extract nanotesla, Pi Te off field from overall background and even flies special magnitude magnetic signal
It is maximum difficult point.
Mainly divide following a few classes for the method for inhibiting earth magnetism ambient field to extract weak magnetic signal in the world: (1), passing through multi-pass
Background magnetic field compensation may be implemented in road magnetic detection, the inhibition of earth magnetism ambient field is carried out to signal, but project amount is larger, multichannel
The introducing of detection method causes the increase of electrical signal noise, and multichannel and probe apparatus make higher cost.(2), soft
Part filtering inhibits Noise Method, and this method can carry out the filtering processing of rear end to the data of storage, still after having acquired signal
It can not achieve real-time detection monitoring, the magnetic signal frequency and earth magnetism of timeliness and detected target object lacked to detection result
Signal frequency is close, therefore back end signal filter processing method is ineffective, increases the inhibition difficulty of background magnetic field.(3), hardware
Circuit filtering cut-off method, the method filter out the low frequency signal in earth's magnetic field in circuit design, realize real-time to detection information
Processing.But do not efficiently separate geomagnetic noise signal and detected target magnetic signal, there are also itself to filter for filter circuit
The limitation of wave property does not obtain good inhibitory effect yet.(4), the OBF method based on orthonormal basis, this method are bases
In the baseband signal feature of magnetic signal, by three orthonormal basis come to have the magnetic signal of feature in earth magnetism ambient noise into
Row is effective to be extracted, but this method has considerable advantage for the feature signal extraction under white noise background, and in earth magnetism
Earth magnetism ambient noise is different from white noise off field, weaker to the inhibitory effect of ambient noise.The invention proposes using promotion magnetic
The method of speed of related movement between target and weak magnetic detection separates to increase magnetic signal frequency with low frequency geomagnetic noise,
Have the characteristics that in real time, be easy to analyze.
Summary of the invention
The present invention overcomes above-mentioned the deficiencies in the prior art, proposes weak magnetic signal noise suppressed and letter under a kind of earth magnetism ambient field
Number extraction element and method, are combined based on weak magnetic Detection Techniques and filtering technique, using promoting magnetic target and weak magnetic detects it
Between speed of related movement method to increasing target magnetic signal frequency.
Since Geomagnetic signal is near 0-0.15Hz frequency in detection process, by promoting the frequency of echo signal, make
Echo signal frequency spectrum be in the position (be in 0.15Hz or more) of relative high frequency and isolates weak magnetic signal and earth magnetism on frequency spectrum
Then ambient field filters out geomagnetic noise using high-pass filter, achievees the purpose that noise suppressed and signal extraction.
Basic principle of the invention is based primarily upon the following:
1. magnetic signal detection principle: ferromagnetic object can generate disturbance to surrounding magnetic field, when a detected object passes through
When detection probe, a certain amount of disturbance of magnetic field can be generated to the magnetic field around probe, probe can sense the variation in magnetic field at this time
Intensity, generation electric signal are passed back-end circuit back as detection result and are shown.
2. signal filtering principle: signal filtering is by the operation that specific band frequency filters out in signal, is to inhibit and prevent
One important measures of interference.Be according to the observation a certain random process as a result, being carried out to another random process associated therewith
The probability theory and method of estimation.A kind of technology of useful signal is extracted from containing noisy reception signal.
3. accelerate magnetic disturbance pace of change by increasing the relative moving speed between detected object and detection probe,
It is achieved in mobile to high frequency direction to echo signal frequency spectrum, makes noise and echo signal by improving echo signal frequency spectrum
Frequency spectrum separation, by filtering technique by the signal extraction of needs, to inhibit noise.
Technical solution of the invention is as follows:
Weak magnetic signal noise suppressed and signal extracting device under a kind of earth magnetism ambient field, it is characterized in that: including magnetic detection
Device, for detecting weak magnetic signal；
Data collecting card, for acquiring the signal of magnetic detector and being transferred to spectrum analyzer；And
Spectrum analyzer carries out spectrum analysis and the filtering processing of corresponding signal for collected signal.
The magnetic detector and object under test relative motion.
The object under test is along the x axis with speed V1Movement, the magnetic detector edge-X-direction is with speed V2Fortune
It moves, then the relative velocity V=V between object under test and magnetic detector1+V2。
The X-direction is horizontal direction or vertical direction.
The data collecting card obtains the weak magnetic signal of constant duration, and spectrum analyzer carries out the data acquired back
Fourier's variation, obtains frequency spectrum data, and be filtered to obtain the weak magnetic signal of object under test to data.
Magnetic detector, data collecting card and the spectrum analyzer is sequentially connected and places on a mobile platform.
Weak magnetic signal noise is carried out using weak magnetic signal noise suppressed under the earth magnetism ambient field and signal extracting device
Inhibit the method with signal extraction, it is characterized in that this method includes the following steps:
Step 1) promotes the speed of related movement of object under test and magnetic detector, is carried out by magnetic detector measuring targets
Magnetic detection obtains weak magnetic signal；
The weak magnetic signal of acquisition is transferred to spectrum analyzer and carries out spectrum analysis by step 2) data collecting card, isolates ground
The low-band signal amount and high frequency band signal amount of magnetic noise acoustic jamming；
Step 3) carries out high-pass filtering to high frequency band signal amount, obtains detection echo signal.
The low-band signal amount is 0~0.15Hz, and high frequency band signal amount is 2~5Hz.
Compared with first technology, the present invention is had following technical effect that
(1) by improving the relative velocity between detected target and magnetic detector, accelerate magnetic disturbance pace of change, effectively mention
The frequency of high detected target signal is effectively separated the geomagnetic noise signal of itself and low frequency on frequency spectrum.By to point
Signal from after is filtered the noise suppressed for realizing earth magnetism ambient field；
(2) this method is easily achieved, and can inhibit earth magnetism ambient field noise in real time, increases the sensitivity and in real time of weak magnetic detection
Analysis ability.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of weak magnetic signal noise suppressed and signal extracting device under earth magnetism background of the present invention.
Fig. 2 is the time domain and frequency domain signal diagrams when simulating magnetic detector and detection target relative movement, wherein (a) is magnetic spy
Survey device and the relative velocity for detecting target are time-domain signal corresponding to 20m/s, (b) opposite with detection target for magnetic detector
Speed is frequency-region signal corresponding to 20m/s；(c) speed of related movement for magnetic detector and detection target is 200m/s right
The time-domain signal (d) answered is magnetic detector and the speed of related movement of detection target is frequency-region signal corresponding to 200m/s
In figure: 1- magnetic detector, 2- detecting objects body, 3- data collecting card, 4- spectrum analyzer, 5- mobile platform,
V1Detecting objects body movement speed direction, V2Magnetic detector movement speed direction
Specific embodiment
Below with reference to embodiment and attached drawing, the invention will be further described, but protection model of the invention should not be limited with this
It encloses.
First referring to Fig. 1, Fig. 1 is the structure of weak magnetic signal noise suppressed and signal extracting device under earth magnetism background of the present invention
Schematic diagram, as seen from the figure, the noise suppressed and method for extracting signal of weak magnetic signal under earth magnetism ambient field of the present invention are visited comprising detection
First 1, detected target object 2, data collecting card 3, spectrum analyzer 4, mobile platform 5.By improving detection target and detection
Probe relative velocity in the movement direction, to realize under earth magnetism ambient field the noise suppressed of weak magnetic echo signal and to target
Object signal is effectively extracted.
The step of noise suppressed and method for extracting signal of weak magnetic signal, is as follows under earth magnetism ambient field:
1) detected target is ferromagnetic object, and vertical dimension,postural of the position away from magnetic detector when movement is 100M；
2) when detection starts, detection target is moved along the x axis with 10m/s, and detection probe edge-X-direction is transported with 10m/s
Dynamic, relative velocity 20m/s carries out weak magnetic signal acquisition to target object；Separately detection target is transported along the x axis with 10m/s again
Dynamic, detection probe edge-X-direction is moved with 190m/s, relative velocity 200m/s, carries out weak magnetic signal again to target object
Acquisition；
3) spectrum analysis is carried out for the data-signal that detection probe is passed back, separates the geomagnetic noise interference letter of 0-0.15Hz
Number amount and relative high frequency section 0.15Hz or more detect echo signal amount；
4) high-pass filtering is carried out to the signal after analysis by filtering technique, taking will be high greater than the high-pass filter of 0.3Hz
The detection echo signal of frequency range is separated, and detection echo signal is obtained.
Pass through simulation steps 2), 3) increase detected object and magnetic detector speed of related movement the signals of 10 times of front and backs
Frequency spectrum compares, obtain as shown in Figure 2, it is seen that by it is proposed that increase relative velocity method, when relative velocity is greater than
200m/s can just separate echo signal on frequency spectrum from Geomagnetic signal
5) thus detection target be ferromagnetic object when, moved along the x axis with 0m/s, detection probe edge-X-direction with
200m/s movement, relative velocity 200m/s carry out weak magnetic signal acquisition to target object；Separately detect target along the x axis again
It is moved with 200m/s, detection probe edge-X-direction is moved with 0m/s, relative velocity 200m/s, carries out weak magnetic to target object
Signal acquisition.In this way, echo signal frequency spectrum can be improved, when detection relative velocity is more than 200m/s from the 0- of geomagnetic noise
0.15Hz frequency range separates, and extracts echo signal.
The present invention has the advantages that the noise suppressed under earth magnetism ambient field to weak magnetic signal, can have to echo signal
The advantage of the extraction of effect facilitates the system integration, rapidly and efficiently the characteristics of.
Claims (8)
1. weak magnetic signal noise suppressed and signal extracting device under a kind of earth magnetism ambient field, it is characterised in that: including magnetic detector
(2), for detecting weak magnetic signal；
Data collecting card (3), for acquiring the signal of magnetic detector (2) and being transferred to spectrum analyzer (4)；And
Spectrum analyzer (4) carries out spectrum analysis and the filtering processing of corresponding signal for collected signal.
2. weak magnetic signal noise suppressed and signal extracting device under earth magnetism ambient field according to claim 1, feature exist
In: the magnetic detector (2) and object under test (1) relative motion.
3. weak magnetic signal noise suppressed and signal extracting device under earth magnetism ambient field according to claim 2, feature exist
In: the object under test (1) is along the x axis with speed V1Movement, the magnetic detector (2) edge-X-direction is with speed V2
It moves, then the relative velocity V=V between object under test (1) and magnetic detector (2)1+V2。
4. weak magnetic signal noise suppressed and signal extracting device under earth magnetism ambient field according to claim 3, feature exist
In: the X-direction is horizontal direction or vertical direction.
5. weak magnetic signal noise suppressed and signal extracting device under earth magnetism ambient field according to claim 1, feature exist
Obtain the weak magnetic signal of constant duration in: the data collecting card (3), spectrum analyzer (4) to the data acquired back into
Row Fourier variation, obtains frequency spectrum data, and be filtered to obtain the weak magnetic signal of object under test to data.
6. weak magnetic signal noise suppressed and signal extracting device under earth magnetism ambient field according to claim 1, feature exist
In: magnetic detector (2), data collecting card (3) and the spectrum analyzer (4) is sequentially connected and places on a mobile platform.
7. carrying out weak magnetic letter using weak magnetic signal noise suppressed under earth magnetism ambient field described in claim 1 and signal extracting device
The method of number noise suppressed and signal extraction, it is characterised in that this method includes the following steps:
Step 1) promotes the speed of related movement of object under test (1) and magnetic detector (2), by magnetic detector (2) to determinand
Body (1) carries out magnetic detection, obtains weak magnetic signal；
The weak magnetic signal of acquisition is transferred to spectrum analyzer (4) and carries out spectrum analysis by step 2) data collecting card (3), is isolated
The low-band signal amount and high frequency band signal amount of geomagnetic noise interference；
Step 3) carries out high-pass filtering to high frequency band signal amount, obtains detection echo signal.
8. the method for weak magnetic signal noise suppressed and signal extraction according to claim 7, which is characterized in that described is low
Frequency band signals amount is 0~0.15Hz, and high frequency band signal amount is 2~5Hz.
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| CN201810700401.6A CN108445545A (en) | 2018-06-29 | 2018-06-29 | Weak magnetic signal noise suppressed and signal extracting device and method under earth magnetism background |
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Cited By (3)
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| CN112698411A (en) * | 2021-01-22 | 2021-04-23 | 中国科学院上海光学精密机械研究所 | Dynamic magnetic target magnetic track imaging detection device |
| CN113655529A (en) * | 2021-08-17 | 2021-11-16 | 南京航空航天大学 | Passive magnetic signal optimization extraction and detection method aiming at high sampling rate |
| CN113848589A (en) * | 2021-08-26 | 2021-12-28 | 南京理工大学 | Passive magnetic detection specific target identification method based on discrete Meyer wavelet |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113171098A (en) * | 2021-05-06 | 2021-07-27 | 中国科学院上海光学精密机械研究所 | Detection device and detection method for magnetoencephalography signals in cerebral oscillation |
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| CN113848589A (en) * | 2021-08-26 | 2021-12-28 | 南京理工大学 | Passive magnetic detection specific target identification method based on discrete Meyer wavelet |
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