CN1166942C - Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method - Google Patents
Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method Download PDFInfo
- Publication number
- CN1166942C CN1166942C CNB021169055A CN02116905A CN1166942C CN 1166942 C CN1166942 C CN 1166942C CN B021169055 A CNB021169055 A CN B021169055A CN 02116905 A CN02116905 A CN 02116905A CN 1166942 C CN1166942 C CN 1166942C
- Authority
- CN
- China
- Prior art keywords
- signal
- demodulation
- detection
- excitation
- phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 30
- 230000005284 excitation Effects 0.000 claims abstract description 59
- 238000001514 detection method Methods 0.000 claims abstract description 54
- 230000008569 process Effects 0.000 claims abstract description 14
- 239000004020 conductor Substances 0.000 claims abstract description 12
- 238000004364 calculation method Methods 0.000 claims abstract description 4
- 238000003325 tomography Methods 0.000 claims description 17
- 238000001914 filtration Methods 0.000 claims description 7
- 239000000126 substance Substances 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 8
- 238000012545 processing Methods 0.000 abstract description 5
- 238000010310 metallurgical process Methods 0.000 abstract description 2
- 238000012544 monitoring process Methods 0.000 abstract description 2
- 238000011160 research Methods 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract description 2
- 238000003384 imaging method Methods 0.000 abstract 2
- 238000003780 insertion Methods 0.000 abstract 1
- 230000037431 insertion Effects 0.000 abstract 1
- 238000009826 distribution Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 230000006698 induction Effects 0.000 description 5
- 238000005259 measurement Methods 0.000 description 4
- 230000001360 synchronised effect Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 235000008429 bread Nutrition 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005674 electromagnetic induction Effects 0.000 description 2
- 235000013305 food Nutrition 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005456 ore beneficiation Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
A computer, an excitation signal generator, an excitation signal amplifier, a sensor, a detection signal amplifier, a multiway switch, a multiplier, a filter and an A/D converter in the present invention are orderly connected by conductors, wherein a signal demodulating generator is respectively connected with the computer and the multiplier by conductors; the excitation signal generator is connected with the multiway switch by conductors. The present invention provides a non-contact and non-insertion measuring instrument without harm, so when the instrument is used, the measured signal and magnitude thereof in an electromagnetic chromatographic imaging system complete a task and a process of signal demodulation searched on the basis of phase feedback of the electromagnetic chromatographic imaging system by the excitation, the demodulation, the calculation, the processing, etc. of the measured signals. The instrument can be used for the application fields of detection, control, and monitoring and positioning of foreign materials in metallurgical processes, detection in separation processes of chemical industry, biomedicine research, etc. The instrument has the advantages of accurate data detection and high speed; the detection for all the signals is completed in 200 m.
Description
Technical Field
The invention belongs to the measurement category, and particularly relates to a measurement processing device and a control method for the spatial distribution of electromagnetic substances.
Background
An Electromagnetic Tomography (EMT) technology is a Tomography technology developed in the early nineties of the twentieth century, which is based on a novel process of an Electromagnetic induction principle, and is characterized in that an external alternating excitation magnetic field is adopted to sweep a measured object field with certain magnetic permeability material distribution or electric conductivity material distribution from different observation angles, based on the Electromagnetic induction principle, magnetic permeability materials in the object field can form an induction magnetic field, electric conduction materials can generate electric eddy currents, the induction magnetic field and the electric conduction materials can generate a modulation effect on the original excitation magnetic field, and the induction magnetic field and the electric eddy currents can generate induction potentials with different amplitudes and phases in a detection coil on the boundary of the object field by overlapping the induction magnetic field and the electric conduction materials.
For electromagnetic tomography systems, the modulation of the excitation signal by the object field is reflected in the amplitude and phase variations, which requires that the signal demodulation system has amplitude and phase discrimination functions. Currently, the main methods for demodulating common signals are: digital demodulation and analog demodulation.
The digital demodulation adopts a microprocessor to process a sequence after signal discretization, and uses a digital signal processing algorithm to demodulate the information of the signal, which has high requirements on the conversion speed of an A/D converter, and a processor needs strong data processing and transmission capability. However, the EMT system has high requirements for real-time performance and the tomography technology has high requirements for data information amount, so that the excitation and detection processes have high requirements for data stability, and the software and hardware conditions in the present pure digital signal processing method are not suitable for being used in the signal acquisition and processing unit of the EMT system.
2, analog demodulation, using analog device to decompose the useful information in the tested signal, converting into corresponding DC component through analog average circuit, and collecting by microcomputer system through A/D converter. Currently used analog demodulation methods include switched demodulation, sine wave demodulation, self-multiplication demodulation, and the like.
Square wave demodulation and sine wave demodulation in analog demodulation are phase sensitive multiplication demodulation, which multiply a signal exactly in phase with a detected signal with the detected signal to measure the change of the signal. The phase-sensitive multiplication demodulation requires that the standard signal and the demodulated signal have the same phase, namely the zero-crossing point is completely consistent. If only the amplitude information of the signal is demodulated, the simplest method is to use switch demodulation or self-multiplication demodulation. The switch demodulation effect is similar to full-wave rectification, except that the switch demodulation is accurate, and the full-wave rectification is influenced by the diode conduction voltage and the diode voltage drop, so that the measurement of a precise signal is not facilitated.
In the EMT system, in order to obtain enough information of an object field, the object field is swept by a certain angle by adopting a method of rotating an excitation magnetic field. Due to the modulation of the conductive and magnetic conductive substances in the measured object field and the influence of the distribution of the detection coils, the output signals of different detection coils have different phase differences in different excitation directions and even in the same excitation direction, which brings difficulty to the demodulation of the signals. For example, in a certain fixed magnetic field direction, the magnitude of the phase shift of the detection signal and the excitation signal is related to the position of the detection coil, so that the demodulated reference signal must be used to synchronize with the phase of the detection coil. And the phase information itself carries the object field information and must be one of the bases for image reconstruction. Therefore, demodulation of the detection coil signal in the EMT system requires obtaining both analog and phase information, i.e. real and imaginary information of the signal. It is difficult for a general demodulation method to satisfy such a requirement.
Disclosure of Invention
The invention aims to provide a phase feedback search signal demodulation device and method based on electromagnetic tomography, which are used for solving the problems and meeting the requirements of quick and accurate detection in electromagnetic tomography.
The purpose of the invention is realized as follows: a phase feedback search signal demodulation device based on electromagnetic tomography is disclosed, wherein a computer, an excitation signal generator, an excitation signal amplifier, a sensor, a detection signal amplifier, a multi-way switch, a multiplier, a filter, an A/D converter and the computer are sequentially connected by conductors. The demodulation signal generator is connected with the computer and the multiplier by conductors respectively, and the excitation signal generator is also connected with the multi-way switch by conductors.
A demodulation method of an electromagnetic tomography based phase feedback search signal demodulation device comprises the following steps:
1, starting;
2, controlling the excitation signal generator and the demodulation signal generator to respectively generate and output an excitation signal E and a demodulation signal D;
3, amplifying the excitation signal E, inputting the amplified excitation signal E into a sensor of the electromagnetic tomography system, receiving a detection signal X input by the sensor by a detection signal amplifier, and sending the detection signal X to a multi-path switch;
meanwhile, sending an excitation signal E to the multi-path switch;
4, sequentially gating the excitation signal E and the detection signal X by a multi-way switch;
multiplying the demodulation signal D by the input detection signal X, filtering, performing A/D conversion, and calculating a recording result U;
6, changing the phase theta of the demodulation signal D, repeating the processes 2, 3, 4 and 5, searching the extreme value of U, and recording the theta value of the demodulation signal at the moment, wherein the theta value is the phase to be demodulated;
and 7, controlling the phase of the demodulation signal D, multiplying the demodulation signal D and the detection signal X after synchronization, filtering, performing A/D conversion to obtain a new result U after multiplication, and obtaining the amplitude value of the detection signal after calculation of the new result U.
Because the invention adopts the technical scheme, the invention has the following advantages:
1. in the detection signal demodulation of the EMT system, the detection signal can be completely demodulated, the test data is accurate, the speed is high, and the detection work of the signal can be completed within 200 ms.
2. The method opens up a new field of on-line detection technology for the distribution of the substances by utilizing the electromagnetic property of the substances, is non-contact, non-intervention and harmless measurement, and is easy to form a long-term reliable detection system under the field working condition.
3. The method has wide application field, and can be used in the fields of detection, control, foreign body monitoring and positioning in the metallurgical process, detection in the chemical separation process, biomedical research and the like.
Drawings
FIG. 1 is a schematic block diagram of a demodulation apparatus according to the present invention;
fig. 2 is a flow chart of a demodulation method of the present invention.
In the figure:
1, a computer 2, an excitation signal generator 3, an excitation signal amplifier 4 and a sensor
5, a detection signal amplifier 6, a multi-way switch 7, a multiplier 8 and a filter
9, A/D converter 10, demodulation signal generator
Detailed Description
The following detailed description of the embodiments of the invention is provided in connection with the accompanying drawings:
in fig. 1, a computer 1, an excitation signal generator 2, an excitation signal amplifier 3, a sensor 4, a detection signal amplifier 5, a multiplexer 6, a multiplier 7, a filter 8, and an a/D converter 9 are connected to the computer 1 in this order by conductors. The demodulation signal generator 10 is connected with the computer 1 and the multiplier 7 by conductors respectively, and the excitation signal generator 2 is also connected with the multi-way switch 6 by conductors. Wherein,
1. the computer 1: for generating a control signal C for the excitation signal generator 2EAnd a control signal C of the demodulation signal generator 10DAnd simultaneously, the reading of the output result of the a/D converter 9 is completed.
2. Excitation signal generator 2: electronic components such as AD7008 can be used to generate the excitation signal E for the sensor 4.
3. Driver signal amplifier 3: an operational amplifier LF411 may be employed for amplifying the excitation signal E generated by the excitation signal generator 2 to aELet A beEHas stronger excitation intensity.
4. The sensor 4: the device is used for inducing the measured substance through the action of the magnetic field generated by the excitation signal E and the conductive and magnetic substance.
5. Detection signal amplifier 5: an operational amplifier LF411 may be employed for amplifying the minute detection signal X detected by the sensor 4 into the detection signal X.
6. A multi-way switch 6: a MAX313 model may be used to select the passage of the excitation signal E with the detection signal X, which is equal to the passed signal.
7. The multiplier 7: an optional AD734 model is used to multiply signal X with D and output signal Y.
8. The filter 8: a fourth order active butterworth filter may be selected for filtering Y, with the output result being F.
9. Signal a/D converter 9: the model AD1674 can be used for converting the analog signal of the signal F into a digital signal and outputting a result U to the computer 1.
10. Demodulation signal generator 10: the demodulation circuit can be formed by electronic components such as an AD7008 model and the like and is used for generating a demodulation signal D.
In fig. 2, the implementation flow of the demodulation method of the phase feedback search signal demodulation apparatus based on electromagnetic tomography is described as follows:
1. initially, control program instructions are provided in the computer 1 for controlling the excitation signal generator 2 and the demodulation signal generator 10 to generate and output the excitation signal E and the demodulation signal D, respectively.
2. The computer 1 outputs control program instructions to control the excitation signal generator 2 and the demodulation signal generator 10 to generate the excitation signal E and the demodulation signal D, respectively.
3. The excitation signal generator 2 and the demodulation signal generator 10 receive a control program command input from the computer 1, output an excitation signal E and a demodulation signal D having a frequency of 187.5KHz, an amplitude of 2V, and a phase of 0 to the excitation signal amplifier 2 and the multiplier 7, respectively, and are connected to and transmitted to the excitation signal amplifier 3 and the multiplier 7, respectively.
4. The excitation signal amplifier 3 amplifies the excitation signal E input from the excitation signal generator 2, inputs the amplified excitation signal E to the sensor 4 of the electromagnetic tomography system, receives the amplified detection signal X input from the sensor 4 from the detection signal amplifier 5, and transmits the amplified detection signal X to the multiplexer 6.
At the same time, the demodulation signal generator 10 outputs a demodulation signal D having a frequency of 187.5KHz, an amplitude of 2V, and a phase of 0 to the multiplier 7.
In the process, the driving signal amplifier 3 can adopt an operational amplifier LF411 model, and amplifies the driving signal E into a signal of 5V and 187.5kHz, and the phase is still 0. The sensor 4 outputs a tiny sinusoidal voltage signal under the action of the excitation signal and the object field signal, the frequency is unchanged, the amplitude is between 0 and 2mV, and the phase is changed, wherein the range is between-70 and +70 degrees.
The detection signal amplifier 5 can adopt an operational amplifier LF411 model.
5. The input detection signal X and excitation signal E are gated by the multiplexer 6. The multiplexer 6 is used to complete the selection of the signal. The detection signal X is made equal to the excitation signal E.
In the control process, the computer 1 controls the multi-way switch 6 to enable the multi-way switch to be switched on E; e is the signal generated by the excitation signal generator 2 with amplitude of 2V, frequency of 187.5KHz and phase of 0.
6. After receiving the control program command of the computer 1, the gating signal X with the amplitude of 2V, the frequency of 187.5KHz and the phase of 0 output by the multi-way switch 6 and the demodulation signal D with the frequency of 187.5KHz, the amplitude of 2V and the phase of 0 output by the demodulation signal generator 10 are transmitted to the multiplier 7 for multiplication, then filtering and A/D conversion are carried out, and the result U is calculated and recorded by the computer 1.
The multiplier 7 can be selected from AD734 model to realize analog multiplication of signal X and signal D, the multiplication output result Y is still a sine wave signal, the amplitude phase is determined by X and D, the filter 8 can be selected from a fourth-order active Butterworth filter, the function of the filter is to smooth the input signal to obtain an approximate direct current signal F, and then the A/D converter 9 completes conversion from the analog signal to the digital signal under the control of the computer 1; the a/D converter 9 may be of the AD1674 type.
7. The demodulation signal generator 10 outputs the demodulation signal D with the changed phase θ, and repeats the steps 2, 3, 4, and 5 to find the extreme value of U. The theta value corresponding to the extreme value of U is the phase value to be demodulated in the invention.
The process of finding U is a search process, that is, the extremum of U is found by changing the phase θ of the demodulated signal D. The change in phase value may be searched from 0 to 360 degrees. The phase corresponding to the maximum value of U is the phase θ to be demodulated in the present invention.
When phase demodulation is performed, a correlation coefficient is preset to be 0, namely, a reference signal and a demodulation signal are set to be synchronous, and then the phase difference between the demodulation signal and the reference signal is adjusted according to the difference between a feedback correlation coefficient and the set correlation coefficient until the two signals are synchronous. The phase shift of the demodulated signal relative to the reference signal is then the phase of the signal under test.
The principle of signal correlation is adopted in the process of searching and searching the maximum value, and the point corresponding to the maximum value in the searching and searching process indicates that the similarity of the two signals is maximum.
In the searching and searching process, the phase of the demodulation signal D can be set to be the demodulated theta value, and the multi-way switch 6 is controlled to enable the detection signal X to be gated, namely the detection signal X is equal to the detected signal X; then, the demodulated signal D is multiplied by the newly input detection signal X, and then the filtering, A/D conversion, calculation and recording of the result U are performed.
The details of this step are largely the same as the first few steps. The phase of the demodulation signal for distinguishing the strobe is the same as that of the signal to be measured, so that the amplitude value of the signal to be measured can be obtained. The amplitude value of the measured signal can be obtained by the following formula:
m (t) ═ Acos (ω t + Φ) measured signal
d (t) Acos (ω t + Φ) demodulation signal
Where y (t) is the output of the signal through multiplier 7 and filter 8. From this, the amplitude value of the signal to be measured can be calculated
Thus, the amplitude A of the detected signal X (t) in the electromagnetic tomography system is obtained, and the signal demodulation task and process based on the phase feedback search of the electromagnetic tomography system are completed.
In the invention, the excitation signal is taken as the reference signal of the reference phase, a demodulation signal with the frequency and the phase consistent with the reference signal is preset, the phase of the demodulation signal is controlled to enable the demodulation signal and the detected signal to carry out phase convolution, and the phase correlation is analyzed by the computer 1, so that the phase difference between the reference signal and the detected signal is determined; then the demodulation signal is controlled to be synchronous with the signal to be detected, and the amplitude of the signal to be detected is determined by using multiplication demodulation.
After the amplitude and the phase of the output signal of the EMT sensor 4 are obtained by demodulation through the method, the computer for image reconstruction can calculate the spatial distribution position of the measured substance distributed in the sensor 4 according to the data, thereby completing the distribution position of the measured substance with electric conduction or magnetic conduction characteristics in the space. For example, the invention can be used to distinguish the presence of non-metallic magnetically permeable materials in metal ores during ore beneficiation. The EMT technology can also be used for a nondestructive and non-intrusive detection method, such as the detection of the consumption and distribution condition of steel in a building structure, and can provide scientific basis for the evaluation of the building quality. In the food industry, EMT technology is also used as a means for detecting foreign matter in food. For example, in a bread production line, the invention can be used for quickly detecting metal foreign matters and the like mixed in bread.
Claims (2)
1. A phase feedback search signal demodulation device based on electromagnetic tomography is characterized in that a computer, an excitation signal generator, an excitation signal amplifier, a sensor, a detection signal amplifier, a multi-way switch, a multiplier, a filter, an A/D converter and the computer are sequentially connected through conductors, a demodulation signal generator is respectively connected with the computer and the multiplier through the conductors, and the excitation signal generator is also connected with the multi-way switch through the conductors.
2. The demodulation method of the phase feedback search signal demodulation apparatus based on electromagnetic tomography according to claim 1, comprising the steps of:
1) starting;
2) controlling the excitation signal generator and the demodulation signal generator to respectively generate and output an excitation signal E and a demodulation signal D;
3) the excitation signal E is amplified and input into an electromagnetic tomography system sensor, a detection signal amplifier receives a detection signal X output by the sensor and sends the detection signal X to a multi-way switch:
meanwhile, sending an excitation signal E to the multi-path switch;
4) and sequentially gating the excitation signal E and the detection signal X by a multi-way switch:
5) multiplying the demodulation signal D by the input detection signal X, filtering, A/D converting and calculating a recording result U;
6) changing the phase theta of the demodulation signal D, repeating the processes 2, 3, 4 and 5, searching the extreme value of U, and recording the theta value of the demodulation signal at the moment, wherein the theta value is the phase to be demodulated;
7) and controlling the phase of the demodulation signal D, multiplying the demodulation signal D and the detection signal X after synchronization, filtering and A/D converting to obtain a new result U after multiplication, and obtaining the amplitude value of the detection signal after calculation of the new result U.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021169055A CN1166942C (en) | 2002-04-26 | 2002-04-26 | Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021169055A CN1166942C (en) | 2002-04-26 | 2002-04-26 | Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1380545A CN1380545A (en) | 2002-11-20 |
| CN1166942C true CN1166942C (en) | 2004-09-15 |
Family
ID=4744284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB021169055A Expired - Fee Related CN1166942C (en) | 2002-04-26 | 2002-04-26 | Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1166942C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8177051B2 (en) * | 2007-01-26 | 2012-05-15 | Advanced Imaging Technologies (Proprietary) Limited | Monitoring of conveyor belts |
| CN104991205B (en) * | 2015-07-13 | 2018-01-09 | 杭州永川科技有限公司 | A kind of signal for magnetic induction image high-precision phase measurement encourages harvester and method |
| CN109709496B (en) * | 2017-10-26 | 2021-05-11 | 北京自动化控制设备研究所 | Quantum sensor closed-loop control system and phase error compensation control method |
| CN107991631B (en) * | 2017-11-20 | 2020-10-13 | 哈尔滨工业大学 | Measuring method of magnetic signal measuring device independent of phase |
| CN111458403B (en) * | 2020-03-31 | 2021-06-08 | 湖北工业大学 | Array eddy current detection method and system |
| CN113625353B (en) * | 2021-08-18 | 2022-05-27 | 华北电力大学 | Electric vehicle wireless charging foreign matter detection method and device |
-
2002
- 2002-04-26 CN CNB021169055A patent/CN1166942C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1380545A (en) | 2002-11-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20070242758A1 (en) | Device and Method for Detecting Flaws on Objects or Locating Metallic Objects | |
| CN100337127C (en) | Method and apparatus for visual indication of line location in metal pipe exploration | |
| CN100429515C (en) | Eddy current inspection device based on resistance transducer of gigantic magnetism | |
| Angani et al. | Differential pulsed eddy current sensor for the detection of wall thinning in an insulated stainless steel pipe | |
| JP4863127B2 (en) | Magnetic flaw detection method and magnetic flaw detection apparatus | |
| CN101122580B (en) | Inspection systems and methods of operation | |
| CN103257182A (en) | Pulse vortexing defect quantitative detection method and detection system | |
| CN110057904B (en) | Method and device for quantitatively detecting defects of moving metal component | |
| CA2626886C (en) | S/n ratio measuring method in eddy current testing on internal surface of pipe or tube | |
| CN108872035B (en) | Multichannel abrasive particle detection method and device based on phase division multiplexing technology | |
| CN111043946B (en) | Magnetic field interference noise test system for eddy current displacement sensor | |
| CN1166942C (en) | Electromagnetic chromatographic imaged phase-based feedback search signal demodulating equipment and its method | |
| Zhang et al. | A new signal processing method for the nondestructive testing of a steel wire rope using a small device | |
| CN117607248B (en) | Metal defect detection imaging method based on digital lock-in amplifier | |
| CN102879462B (en) | Metal defect eddy current detection device and probe thereof | |
| CN110703336B (en) | Cable positioning method based on weak magnetic detection technology | |
| CN102520059A (en) | Circuit device based on disturbed magnetic field detection instrument | |
| JP4835995B2 (en) | Magnetic flux leakage flaw detection method and magnetic flux leakage inspection device | |
| Avila et al. | A multi-frequency NDT system for imaging and detection of cracks | |
| CN200975992Y (en) | Strong magnetic resistance sensor based vortex detecting device | |
| CN1414382A (en) | Detector of gas liquid two phase flow split-phase content based on resistance chromatographic imaging and method | |
| US20100045276A1 (en) | Eddy current inspection system | |
| CN210376233U (en) | Orthogonal rotation eddy current detection system | |
| CN114839258B (en) | Automatic measuring method and device for Barkhausen noise with magnetic anisotropy | |
| CN1380546A (en) | Orthogonal signal device of electromagnetic chromatographic imaging system and demodulating method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| C10 | Entry into substantive examination | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |