CN114844776B - Electromagnetic imaging positioning method and device based on time reversal time domain characteristics - Google Patents

Electromagnetic imaging positioning method and device based on time reversal time domain characteristics Download PDF

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CN114844776B
CN114844776B CN202210430587.4A CN202210430587A CN114844776B CN 114844776 B CN114844776 B CN 114844776B CN 202210430587 A CN202210430587 A CN 202210430587A CN 114844776 B CN114844776 B CN 114844776B
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CN114844776A (en
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李欣婕
程梓晗
刘思远
赵德双
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University of Electronic Science and Technology of China
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/06—Management of faults, events, alarms or notifications
    • H04L41/0677—Localisation of faults
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/101—Monitoring; Testing of transmitters for measurement of specific parameters of the transmitter or components thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/15—Performance testing
    • H04B17/17—Detection of non-compliance or faulty performance, e.g. response deviations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/20—Monitoring; Testing of receivers
    • H04B17/29—Performance testing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/08—Testing, supervising or monitoring using real traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
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Abstract

The invention discloses an electromagnetic imaging positioning method and device based on time reversal time domain characteristics, and belongs to the technical field of fault radiation source electromagnetic imaging positioning. The method mainly comprises the following steps: the method comprises the steps that a radiation source emits signals, a time reversal mirror receives the radiation signals, the radiation signals are radiated after time reversal is carried out, sub-array division is carried out on the time reversal mirror, a time domain return electric field at a position of a piece to be detected is recorded, after pretreatment and normalization processing are carried out on the time domain return electric field, a space imaging spectrum is defined, and then the space position of a fault source is found. The method and the device can utilize the return electric field generated by each array element return signal of the time reversal mirror at the radiation source to reach the focusing peak value at the same time under the complex environment of a plurality of scatterers, and carry out super-resolution imaging positioning on the radiation source by the time reversal time domain focusing synchronism and symmetry which can not reach the peak value at the same time at the non-radiation source.

Description

Electromagnetic imaging positioning method and device based on time reversal time domain characteristics
Technical Field
The invention belongs to the technical field of fault radiation source electromagnetic imaging positioning, and particularly relates to an electromagnetic imaging positioning method and device based on time reversal time domain characteristics.
Background
With the continuous development of mobile communication technology, people have higher requirements on communication speed and communication capacity. In order to obtain faster information transmission rate and higher information transmission capacity, the mobile communication base station antenna is developed from a single-frequency single-unit antenna to a multi-frequency multi-beam array antenna which is widely applied nowadays. The base station antenna is used as a transmitting and receiving part of a communication system, and whether the base station antenna operates normally or not determines the performance of the wireless communication system, so that the requirement of the wireless communication on the maintenance of the base station antenna is higher and higher. In the maintenance process of the base station antenna, the requirements on the fault detection precision and efficiency are improved. The electromagnetic imaging positioning detection can ensure that a fault source actively radiated inside the base station antenna can be accurately detected under the condition of not disassembling the base station antenna, secondary damage to the base station antenna is eliminated, and meanwhile, the fault detection process is convenient to operate, so that the method becomes an important research direction for fault detection. The current electromagnetic imaging positioning method for the fault radiation source comprises near-field scanning electromagnetic imaging positioning, sparse source reconstruction electromagnetic imaging positioning, time reversal electromagnetic imaging positioning and the like. Near-field scanning electromagnetic imaging localization is suitable for fault detection in the near-field range but has poor imaging resolution. Sparse source reconstruction electromagnetic imaging positioning needs to be used under a specific electromagnetic scene, and the limiting factors on a fault detection environment are more. The two imaging methods have the problem of poor universality. Time Reversal (TR) has unique advantages in the field of electromagnetic imaging positioning, and can focus electromagnetic waves at a radiation source by utilizing the space-Time synchronous focusing characteristic of the Time reversal technique to realize super-resolution imaging of a radiation target.
Time reversal techniques have unique advantages in the field of electromagnetic imaging, and electromagnetic imaging localization based on time reversal is an important research direction. For example, the chinese patent application with the application number of 202010082926.5 entitled "transmission line and network fault location method based on electromagnetic time reversal transfer function correlation" discloses a fault location method based on time reversal transfer function correlation, which establishes fault signal libraries corresponding to faults occurring at different positions through simulation, and obtains transfer functions corresponding to the fault signal libraries by using a signal filtering method. And calculating a correlation coefficient of the simulation signal transfer function and a transfer function corresponding to an actually detected real fault source, and judging the position of the fault source through the maximum value of the correlation coefficient, but the method can only effectively position the position of a single fault point. In the prior art, "Localization of electromagnetic interference sources using a time-reversal cavity" (IEEE Transactions on Industrial Electronics, vol.68, no.1, pp.654-662, jan.2021), a time-reversal full-wave simulation method is used to image the power distribution in the cavity, and then accurately position the radiation source located in the cavity. Therefore, how to quickly and accurately locate the fault radiation source in a complex environment is one of the key problems that the electromagnetic imaging locating method based on time reversal can be widely applied.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides an electromagnetic imaging positioning method and device based on Time reversal Time domain characteristics, which can utilize the return electric field generated by each array element return signal of a Time Reversal Mirror (TRM) at a radiation source to reach a focusing peak value at the same Time under the complex environment of multiple scatterers, and can carry out super-resolution imaging positioning on the radiation source by using the Time reversal Time domain focusing synchronism and symmetry which can not reach the peak value at the same Time at a non-radiation source.
The technical problem proposed by the invention is solved as follows:
an electromagnetic imaging positioning method based on time reversal time domain characteristics comprises the following steps:
s1.TRM receives fault source signal
K fault source emission signals s of piece to be tested k (r k T), where K is 1. Ltoreq. K.ltoreq.K, t denotes the time,r k the spatial position of the kth fault source is shown, the TRM receives the radiation signal of the fault source, and the signal received by the nth array element is r n (t), wherein N is more than or equal to 1 and less than or equal to N; the arrangement mode of the TRM array is not limited, and the TRM array can be a one-dimensional linear array or a two-dimensional area array and the like.
S2. Time reversal
The TRM array elements carry out time reversal on the received signals to obtain time reversal signals
Figure BDA0003610208550000021
Imaging surface division is carried out on the piece to be measured, and the three-dimensional piece to be measured is divided into a plurality of two-dimensional imaging surfaces which are parallel to each other; each array element sequentially radiates a time reversal signal, and the return electric field of each pixel point on an imaging surface is e n (r, t), wherein r is the position vector of the pixel point of the imaging plane;
s3, carrying out sub-array division on the TRM
The method comprises the following steps of sequentially numbering N array elements of a TRM from 1 to N, dividing the TRM into M sub-arrays, wherein L array elements exist in each sub-array, and M + L = N +1; the mth sub-array is the mth array element to the mth + L-1 array element, and M is more than or equal to 1 and less than or equal to M;
the time domain back electric field generated by each pixel point of the mth sub-array on the imaging surface is as follows:
Figure BDA0003610208550000022
according to the time domain focusing synchronization characteristic of the time reversal technology, the return electric field of the subarray has time domain synchronization at the position of the fault radiation source.
S4, preprocessing a return electric field generated by each pixel point of the sub-array on an imaging surface
Extracting time domain back-transmission electric field y of all sub-arrays at all pixel points of imaging surface m (r, t), the time domain range of the time domain postback electric field is more than or equal to 0 and less than or equal to t end ，t end Sequentially carrying out peak value search on the time domain return electric field of each subarray at each pixel point of the imaging surface for TRM (true target modulation) receiving fault source radiation signal time, searching the first K maximum values of the return electric field, and recording the correspondence of the kth maximum value to the kth maximum valueAt a time t k,m ；
Setting a time threshold value a according to the width of a radiation signal of a fault source, and meeting t when t in a time domain feedback electric field k,m -a≤t≤t k,m And + a, performing zeroing processing on signals of other moments when the time domain signal peak value of each pixel point of the imaging surface of the subarray is unchanged, namely:
Figure BDA0003610208550000031
s5, respectively carrying out normalization processing on return electric fields generated by the preprocessed subarrays at all pixel points on the imaging surface, and carrying out normalization processing on the electric fields in each section of interval in the current interval, so that the brightness of all radiation sources in the imaging surface is uniform, and the influence of the radiation intensity on imaging positioning is eliminated.
The normalization operation is shown by the following equation:
Figure BDA0003610208550000032
wherein, y m (r,t k,m (r)) represents the kth large value of the backtransmission electric field,
Figure BDA0003610208550000033
representing the normalized return electric field;
s6, calculating the spectrum value of each pixel point of the imaging plane
The spectral value of each pixel point on the imaging surface is based on the normalized electric field transmitted back to each pixel point by any subarray. Here, the normalized return electric field from the m-th sub-array to each pixel point of the imaging plane
Figure BDA0003610208550000034
For reference, an imaging spectral function P (r) is defined:
Figure BDA0003610208550000035
wherein i is more than or equal to 1 and less than or equal to M;
according to the time domain focusing synchronism of the time reversal technology, the normalized return electric field of each sub array
Figure BDA0003610208550000036
The simultaneous achievement of the focusing moments at the faulty radiation source represents a good time synchronism, so that at the faulty radiation source a->
Figure BDA0003610208550000037
Figure BDA0003610208550000041
Thereby making->
Figure BDA0003610208550000042
Towards 0, the imaging spectral function may form a spectral peak at the faulty radiation source.
S7, carrying out space search on the spectrum value of the imaging spectrum function P (r)
Setting a spectral value threshold c, wherein the spectral value of the imaging spectral function is greater than or equal to the position r corresponding to the set spectral value threshold s And determining the position of the fault source.
Further, if the signal radiated by the fault source has symmetry, the return electric field at the fault source after TRM time reversal still has symmetry. Extracting the normalized signal at the position where the fault source is determined to be in S7
Figure BDA0003610208550000043
If it is
Figure BDA0003610208550000044
With respect to t = t k,m Symmetry, i.e.: />
Figure BDA0003610208550000045
Wherein, t k,m -a≤t 1 ≤t k,m +a，t k , m -a≤t 2 ≤t k,m + a, and->
Figure BDA0003610208550000046
The S7 positioning is accurate, and the positioning accuracy is further improved.
Based on the fault radiation source electromagnetic imaging positioning method, the invention also provides an electromagnetic imaging positioning device based on time reversal time domain characteristics, which comprises a signal acquisition device and a signal processing device;
the signal acquisition device comprises a time reversal cavity, a to-be-detected piece and a TRM (transmission/reception module), wherein the to-be-detected piece and the TRM are positioned in the time reversal cavity; the signal processing device comprises an analog filter, an analog-to-digital converter, a time reversal processing device and an algorithm positioning device;
the method comprises the steps that a fault source radiation emission signal of a to-be-detected piece is received by a TRM, a signal received by the TRM is filtered by an analog filter, and the analog signal subjected to filtering is discretized by an analog-to-digital converter; the time reversal processing device executes S2 and performs time reversal on the discretization signal; and executing S3-S7 by the algorithm positioning device to judge the position of the fault source.
Furthermore, the to-be-detected piece comprises a dipole antenna and two metal spherical scatterers, the dipole antenna is used as a fault source to radiate signals, and the two metal spherical scatterers are used for increasing the environmental complexity of the to-be-detected piece and changing the signal propagation path.
Further, the time reversal cavity is a closed cavity or a non-closed cavity made of any materials.
Furthermore, the array elements of the TRM may be any type of antenna, the array element spacing is half a wavelength, and the arrangement mode of the array is not limited to a one-dimensional linear array, but also may be a two-dimensional area array, a two-dimensional annular array, etc.
The invention has the beneficial effects that:
(1) The invention uses time reversal technology to fully utilize the multipath information of signal propagation to realize effective imaging of the radiation source in complex environment.
(2) The invention uses the synchronism of the time reversal technology and does not destroy the symmetry of the original radiation signal to carry out the fault source positioning, thereby further improving the positioning accuracy.
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FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a block diagram of the apparatus according to the present invention;
FIG. 3 is a schematic diagram illustrating a structural configuration of a device under test according to an embodiment;
FIG. 4 is a schematic view of a structural configuration of the signal acquisition device according to the embodiment;
FIG. 5 is a waveform diagram of a fault source radiation signal according to an embodiment;
FIG. 6 is a graph of return electric field waveforms generated at a faulty radiation source for each of the subarrays described in the example;
FIG. 7 is a graph of return electric field waveforms generated by the subarrays described in the example at a non-faulty radiation source;
FIG. 8 is a graph of normalized return electric field waveforms for the sub-array at position 1 of the faulty radiation source in the example;
FIG. 9 is a graph of normalized return electric field waveforms for the sub-array at position 1 where the non-faulty radiation source is located in the example embodiment;
FIG. 10 is an electromagnetic imaging scout view of a method according to an embodiment.
Detailed Description
The invention is further described below with reference to the figures and examples.
The embodiment provides an electromagnetic imaging positioning method based on time reversal time domain characteristics, a flow schematic diagram of which is shown in fig. 1, in the embodiment, a to-be-detected piece comprises a dipole antenna and two metal spherical scatterers, the dipole antenna is used as a fault source radiation signal, and the two metal spherical scatterers are used for increasing the environmental complexity of the to-be-detected piece and changing a signal propagation path; TRM is a 1 × 6 one-dimensional uniform linear array, and the array element spacing is half wavelength.
The method comprises the following steps:
s1.TRM receives fault source signal
The fault source of the element to be tested transmits a Gaussian pulse signal s (r) with the central frequency of 1.7GHz d T) is shown in FIG. 5, where t represents time, r d Representing the space position of a fault source, receiving a fault source radiation signal by a TRM, and receiving a signal r by an nth array element n (t), wherein n is more than or equal to 1 and less than or equal to 6;
s2. Time reversal
The TRM array elements carry out time reversal on the received signals to obtain time reversal signals
Figure BDA0003610208550000051
Dividing an imaging surface of the to-be-detected piece, wherein the imaging surface is divided from the to-be-detected piece and comprises a radiation fault source spatial position; sequentially radiating time reversal signals by each array element to obtain a return electric field e of each pixel point on an imaging surface n (r, t), wherein r is the position vector of the pixel point of the imaging plane;
s3, carrying out sub-array division on the TRM
The method comprises the following steps of sequentially numbering 6 array elements of a TRM to be 1-6, dividing the TRM into 4 sub-arrays, and dividing 3 array elements in each sub-array; the mth sub-array is the mth array element to the m +2 array elements, and m is more than or equal to 1 and less than or equal to 4;
the time domain back electric field generated by each pixel point of the mth sub-array on the imaging surface is as follows:
Figure BDA0003610208550000061
fig. 6 is a graph of return electric field waveforms generated at a faulty radiation source for the 1 st to 4 th sub-arrays. FIG. 7 is a graph of return electric field waveforms generated at a non-faulty radiation source for the 1 st to 4 th sub-arrays. According to the time domain focusing synchronization characteristic of the time reversal technology, the return electric field of the subarray has time domain synchronization at the position of the fault radiation source.
S4, preprocessing a return electric field generated by each pixel point of the subarray on an imaging surface
Extracting time domain back transmission electric field y of all subarrays at all pixel points of imaging surface m (r, t) and sequentially performing peak value search, wherein the time domain range of the time domain returning electric field is more than or equal to 0 and less than or equal to t end ，t end Searching the maximum value of the return electric field for the time of receiving the fault source radiation signal by the TRM, wherein the time corresponding to the maximum value is t 1,m ；
According toSetting a time threshold value a =1.65ns for the width of a fault source radiation signal, and meeting t at the moment t in a time domain back-transmission electric field 1,m -a≤t≤t 1,m And + a, performing zeroing processing on signals of other moments when the time domain signal peak value of each pixel point of the imaging surface of the subarray is unchanged, namely:
Figure BDA0003610208550000062
s5, normalization processing is carried out on return electric fields generated by the preprocessed subarrays at all pixel points of the imaging surface, normalization processing is carried out on the electric fields in each section of interval in the interval, the brightness of all radiation sources in the imaging surface is uniform, and the influence of radiation intensity on imaging positioning is eliminated.
The normalization operation is shown by the following equation:
Figure BDA0003610208550000063
wherein, y m (r,t k,m (r)) represents the kth large value of the backtransmission electric field,
Figure BDA0003610208550000064
representing the normalized return electric field;
s6, calculating the spectral value of each pixel point of the imaging surface
The spectral value of each pixel point on the imaging surface is based on the normalized electric field transmitted back to each pixel point by any subarray. Here, the normalized return electric field from the 1 st sub-array to each pixel point on the imaging plane
Figure BDA0003610208550000065
As a basis, an imaging spectral function P (r) is defined: />
Figure BDA0003610208550000071
Wherein i is more than or equal to 1 and less than or equal to 4; the electromagnetic imaging localizer from the imaging spectral function is shown in FIG. 10.
According to the time domain focusing synchronism of the time reversal technology, the normalized return electric field of each sub array
Figure BDA0003610208550000072
The simultaneous achievement of the focusing moments at the faulty radiation source represents a good time synchronism, so that at the faulty radiation source a->
Figure BDA0003610208550000073
Thereby making->
Figure BDA0003610208550000074
Towards 0, the imaging spectral function may form a spectral peak at the faulty radiation source.
S7, carrying out space search on the spectrum value of the imaging spectrum function P (r)
Setting a spectral value threshold c, wherein the spectral value of the imaging spectral function is greater than or equal to the position r corresponding to the set spectral value threshold s And determining the position of the fault source.
Further, if the signal radiated by the fault source has symmetry, the return electric field at the fault source after TRM time reversal still has symmetry. Extracting the normalized signal at the position where the fault source is determined to be in S7
Figure BDA0003610208550000075
If it is
Figure BDA0003610208550000076
With respect to t = t k,m Symmetry, i.e.: />
Figure BDA0003610208550000077
Wherein, t k,m -a≤t 1 ≤t k,m +a，t k,m -a≤t 2 ≤t k,m + a, and->
Figure BDA0003610208550000078
The S7 positioning is accurate, and the positioning accuracy is further improved. S7, the position of the fault source is determinedFirst sub-array normalization signal>
Figure BDA0003610208550000079
The waveform diagram is shown in FIG. 8; the normalized return electric field waveform of the first sub-array at the non-faulty radiation source is shown in fig. 9.
Based on the above fault radiation source electromagnetic imaging positioning method, the present embodiment further provides an electromagnetic imaging positioning apparatus based on time reversal time domain characteristics, a structural block diagram of which is shown in fig. 2, and the electromagnetic imaging positioning apparatus includes a signal acquisition apparatus and a signal processing apparatus;
the schematic structural composition diagram of the signal acquisition device is shown in fig. 4, and the signal acquisition device comprises a time reversal cavity, a to-be-detected part and a TRM, wherein the to-be-detected part and the TRM are positioned in the time reversal cavity; the signal processing device comprises an analog filter, an analog-to-digital converter, a time reversal processing device and an algorithm positioning device; the time reversal processing device and the algorithm positioning device are programs built in a computer.
The method comprises the steps that a fault source radiation emission signal of a to-be-detected piece is received by a TRM, a signal received by the TRM is filtered by an analog filter, and the analog signal subjected to filtering is discretized by an analog-to-digital converter; the time reversal processing device executes S2 and performs time reversal on the discretization signal; and executing S3-S7 by the algorithm positioning device to judge the position of the fault source.
The schematic structural composition diagram of the to-be-measured part is shown in fig. 3, and the to-be-measured part comprises a dipole antenna and two metal spherical scatterers, wherein the dipole antenna is used as a fault source to radiate signals, and the two metal spherical scatterers are used for increasing the environmental complexity of the to-be-measured part and changing a signal propagation path.
The time reversal cavity is a closed cavity or a non-closed cavity made of any materials.
The array elements of the TRM can be any type of antenna, the spacing between the array elements is half wavelength, and the arrangement mode of the array is not limited to a one-dimensional linear array, but also can be a two-dimensional area array, a two-dimensional annular array and the like.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. All such possible equivalents and modifications are deemed to fall within the scope of the invention as defined in the claims.

Claims (6)

1. An electromagnetic imaging positioning method based on time reversal time domain characteristics is characterized by comprising the following steps:
s1.TRM receives fault source signal
K fault source emission signals s of piece to be tested k (r k T), where K is 1. Ltoreq. K.ltoreq.K, t denotes the time r k The spatial position of the kth fault source is shown, the TRM receives the radiation signal of the fault source, and the signal received by the nth array element is r n (t), wherein N is more than or equal to 1 and less than or equal to N;
s2. Time reversal
The TRM array elements perform time reversal on the received signals to obtain time reversal signals
Figure FDA0003610208540000011
Imaging surface division is carried out on the piece to be measured, and the three-dimensional piece to be measured is divided into a plurality of two-dimensional imaging surfaces which are parallel to each other; each array element sequentially radiates a time reversal signal, and the return electric field of each pixel point on an imaging surface is e n (r, t), wherein r is the position vector of the pixel point of the imaging plane;
s3, carrying out sub-array division on the TRM
The method comprises the following steps of sequentially numbering N array elements of a TRM to be 1-N, dividing the TRM into M sub-arrays, wherein L array elements are arranged in each sub-array, and M + L = N +1; the mth sub-array is the mth array element to the mth + L-1 array element, and M is more than or equal to 1 and less than or equal to M;
the time domain back electric field generated by each pixel point of the mth sub-array on the imaging surface is as follows:
Figure FDA0003610208540000012
s4, preprocessing a return electric field generated by each pixel point of the sub-array on an imaging surface
Extracting time domain back-transmission electric field y of all sub-arrays at all pixel points of imaging surface m (r, t), the time domain range of the time domain postback electric field is more than or equal to 0 and less than or equal to t end ，t end For TRM receiving fault source radiation signal time, sequentially carrying out peak value search on the time domain return electric field of each subarray at each pixel point of the imaging surface, searching the first K maximum values of the return electric field, and recording the time t corresponding to the kth maximum value k,m ；
Setting a time threshold a, when the time t in the time domain feedback electric field meets t k,m -a≤t≤t k,m And + a, keeping the time domain signal peak value of each pixel point of the sub-array on the imaging surface unchanged, and carrying out zero-returning processing on signals at other moments, namely:
Figure FDA0003610208540000013
s5, respectively carrying out normalization processing on return electric fields generated by the preprocessed subarrays at each pixel point on the imaging surface, wherein the normalization operation is as follows:
Figure FDA0003610208540000021
wherein, y m (r,t k,m (r)) represents the kth large value of the return electric field,
Figure FDA0003610208540000022
representing the normalized return electric field;
s6, calculating the spectral value of each pixel point of the imaging surface
Normalized return electric field from mth sub-array to each pixel point of imaging surface
Figure FDA0003610208540000023
As a basis, an imaging spectral function P (r) is defined: />
Figure FDA0003610208540000024
Wherein i is more than or equal to 1 and less than or equal to M;
s7, carrying out space search on the spectrum value of the imaging spectrum function P (r)
Setting a spectral value threshold c, wherein the spectral value of the imaging spectral function is greater than or equal to the position r corresponding to the set spectral value threshold c s And determining the position of the fault source.
2. The electromagnetic imaging positioning method based on time-reversal time-domain characteristics according to claim 1, wherein if the signal radiated by the fault source has symmetry, the return electric field at the fault source after TRM time reversal still has symmetry; namely: extracting the normalized signal at the position where the fault source is determined to be in S7
Figure FDA0003610208540000025
If it satisfies
Figure FDA0003610208540000026
Wherein, t k,m -a≤t 1 ≤t k,m +a，t k,m -a≤t 2 ≤t k,m + a, and->
Figure FDA0003610208540000027
Then the
Figure FDA0003610208540000028
With respect to t = t k,m And symmetry shows that S7 is accurately positioned.
3. An electromagnetic imaging positioning device based on time reversal time domain characteristics is characterized by comprising a signal acquisition device and a signal processing device;
the signal acquisition device comprises a time reversal cavity, a to-be-detected piece and a TRM, wherein the to-be-detected piece and the TRM are positioned in the time reversal cavity; the signal processing device comprises an analog filter, an analog-to-digital converter, a time reversal processing device and an algorithm positioning device;
the method comprises the steps that a fault source radiation emission signal of a to-be-detected piece is received by a TRM, a signal received by the TRM is filtered by an analog filter, and the analog signal subjected to filtering is discretized by an analog-to-digital converter; the time reversal processing means performs S2 of the method of claim 1, time-reversing the discretized signal; the algorithm locating device executes S3-S7 of the method of claim 1 to determine the location of the fault source.
4. The electromagnetic imaging positioning device based on time-reversal time-domain characteristics according to claim 3, characterized in that the object to be measured includes a dipole antenna as a fault source radiation signal and two metal spherical scatterers for increasing the environmental complexity of the object to be measured.
5. The electromagnetic imaging positioning apparatus based on time-reversal time-domain characteristics of claim 4, characterized in that the time-reversal cavity is a closed cavity or a non-closed cavity of any material.
6. The electromagnetic imaging positioning apparatus based on time-reversal time-domain characteristics of claim 5, wherein the array element spacing of the TRM is half a wavelength, and the array arrangement mode is a one-dimensional linear array, a two-dimensional planar array or a two-dimensional annular array.
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