CN118377017A - Radar imaging method, device, system and computer equipment - Google Patents
Radar imaging method, device, system and computer equipment Download PDFInfo
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
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- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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Abstract
The application relates to a radar imaging method, a radar imaging device, a radar imaging system and computer equipment. The method comprises the following steps: acquiring initial echo data; dividing initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain a local imaging result corresponding to the sub-echo arrays one by one; and carrying out fusion treatment on all the local imaging results to obtain a final imaging result. The method can solve the problem of excessive hardware resources consumption during radar imaging and improve radar imaging efficiency.
Description
Technical Field
The present application relates to the field of radar imaging technologies, and in particular, to a radar imaging method, apparatus, system, and computer device.
Background
MIMO technology is originally a concept in a control system, researchers introduce MIMO concepts into a communication system in the 70 th century of 20 to improve the quality of experience of users, and formally into the radar field in the beginning of the 21 st century. MIMO radar systems may be considered, in some sense, as a combination of data beam synthesis and synthetic aperture. As the name implies, MIMO radar refers to an antenna array with multiple array elements at both the transmitting end and the receiving end, and the MIMO radar system can obtain an observation channel with far-reaching practical antenna number by selecting orthogonal waveforms between the array elements at the transmitting end or transmitting radar signals by transmitting antenna time-sharing, which makes the MIMO radar obtain a high-resolution target image under the preferential antenna.
In the prior art, three-dimensional imaging based on the MIMO radar consumes a large amount of hardware resources, such as the prior patent CN202011204661.8, and each receiving and transmitting antenna pair needs to be projected into each grid of a set imaging scene by using a back projection algorithm, so that the algorithm has high complexity and is difficult to meet the real-time performance of imaging. In the existing paper Electronic Microwave IMAGING WITH PLANAR Multistatic Arrays, 4DFFT is required to be carried out on echo data in an imaging algorithm, so that the time complexity is high, the memory consumed in the FFT process is huge, a large amount of hardware resources are required to be consumed, and therefore, the memory requirement on hardware is extremely high in practical use.
At present, an effective solution is not proposed for the problem of excessive hardware resources consumed in radar imaging in the prior art.
Disclosure of Invention
Based on the foregoing, it is necessary to provide a radar imaging method, a device, a system and a computer apparatus for solving the above technical problems.
In a first aspect, the present application provides a radar imaging method. The method comprises the following steps:
acquiring initial echo data;
dividing initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain a local imaging result corresponding to the sub-echo arrays one by one;
And carrying out fusion treatment on all the local imaging results to obtain a final imaging result.
In one embodiment, the fusing of all the local imaging results to obtain a final imaging result includes:
And carrying out up-sampling treatment on all the local imaging results to obtain a target local imaging result corresponding to the local imaging result, and carrying out three-dimensional interpolation treatment on the target local imaging result based on an imaging grid to obtain a final imaging result.
In one embodiment, up-sampling all the local imaging results to obtain a target local imaging result corresponding to the local imaging result, including:
determining a preset two-dimensional interval parameter;
And carrying out zero padding on the local imaging result based on the two-dimensional interval parameter, and carrying out two-dimensional low-pass filtering on the zero padded result to obtain the target local imaging result.
In one embodiment, the dividing the initial echo data based on the antenna sparse array arrangement form to obtain at least two sets of sub-echo arrays includes:
Determining a transmitting antenna index of each transmitting antenna and a receiving antenna index of each receiving antenna based on the sparse array arrangement form of the antennas;
Dividing the initial echo data according to an antenna sparse array arrangement form based on the transmitting antenna index and the receiving antenna index to obtain sub-echo arrays, wherein each sub-echo array comprises a group of transmitting antenna data and a group of receiving antenna data.
In one embodiment, imaging processing is performed on all the sub-echo arrays respectively to obtain local imaging results corresponding to the sub-echo arrays one by one, including:
performing frequency domain transformation on the sub-echo array to obtain a frequency domain result of the sub-echo array;
Performing phase compensation processing on the target dimension in the frequency domain result based on the frequency domain result of the sub-echo data to obtain a target frequency domain result of the compensated sub-echo array;
and carrying out non-uniform Fourier transform processing on the target frequency domain result, and carrying out imaging processing on the non-uniform Fourier transform result to obtain a local imaging result.
In one embodiment, performing non-uniform fourier transform processing on a target frequency domain result, and performing imaging processing on the non-uniform fourier transform result to obtain a local imaging result, including:
and carrying out dimension compression processing on the non-uniform Fourier transform result through a preset coordinate mapping relation to obtain a three-dimensional frequency domain result, and carrying out Fourier transform on the three-dimensional frequency domain result to obtain a local imaging result.
In a second aspect, the application further provides a radar imaging device. The device comprises:
The acquisition module is used for acquiring a preset antenna sparse array arrangement form and initial echo data;
The computing module is used for dividing the initial echo data based on the antenna sparse array arrangement form to obtain at least two groups of sub-echo arrays, and respectively carrying out imaging processing on all the sub-echo arrays to obtain local imaging results corresponding to the sub-echo arrays one by one;
And the imaging module is used for carrying out fusion processing on all the local imaging results to obtain a final imaging result.
In a third aspect, the present application also provides a security inspection system, the system comprising: a detection chamber, a scanning device, and an imaging device;
A detection chamber for accommodating an object to be detected;
scanning means for receiving initial echo data reflected from an object to be detected in response to a millimeter wave signal transmitted to the object to be detected;
Imaging means for performing the radar imaging method as described hereinabove based on the initial echo data.
In a fourth aspect, the present application also provides a computer device. The computer device comprises a memory storing a computer program and a processor which when executing the computer program performs the steps of:
acquiring initial echo data;
dividing initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain a local imaging result corresponding to the sub-echo arrays one by one;
And carrying out fusion treatment on all the local imaging results to obtain a final imaging result.
In a fifth aspect, the present application also provides a computer-readable storage medium. The computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of:
acquiring initial echo data;
dividing initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain a local imaging result corresponding to the sub-echo arrays one by one;
And carrying out fusion treatment on all the local imaging results to obtain a final imaging result.
According to the radar imaging method, the radar imaging device, the radar imaging system and the radar imaging computer equipment, the acquired initial echo data are divided based on the arrangement form of the sparse array, imaging processing is respectively carried out on the sub-echo arrays obtained through division, and a local imaging result corresponding to the sub-echo arrays one by one is obtained; and finally, carrying out interpolation processing according to the local imaging result to obtain a final imaging result. According to the method, the initial echo data are split, the radar imaging calculation requiring a large memory is decomposed into a plurality of small memory calculations, and finally, each local imaging result is fused, so that the memory required by the radar imaging calculation is effectively reduced under the condition that the imaging effect is not affected, and the operation time is reduced.
Drawings
FIG. 1 is a diagram of an application environment for a radar imaging method in one embodiment;
FIG. 2 is a flow diagram of a radar imaging method in one embodiment;
FIG. 3 is a schematic diagram of a planar multi-base sparse array arrangement in one embodiment;
FIG. 4 is a flow diagram of two-dimensional upsampling in one embodiment;
FIG. 5 is a schematic diagram of the physical meaning of z a in one embodiment;
FIG. 6 is a schematic diagram of an antenna assembly according to one embodiment;
FIG. 7 is a schematic flow chart of a radar imaging method in a preferred embodiment;
FIG. 8 is a block diagram of a radar imaging device in one embodiment;
Fig. 9 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
The radar imaging method provided by the embodiment of the application can be applied to an application environment shown in fig. 1. Wherein the terminal 102 communicates with the server 104 via a network. The data storage system may store data that the server 104 needs to process. The data storage system may be integrated on the server 104 or may be located on a cloud or other network server. Firstly, acquiring initial echo data; dividing the initial echo data based on the sparse array arrangement form of the antennas to obtain a plurality of groups of sub-echo arrays, respectively performing imaging processing on each sub-echo array to obtain local imaging results corresponding to the sub-echo arrays one by one, and finally performing interpolation processing on all the local imaging results based on the imaging grids to obtain a final imaging result. The terminal 102 may be, but not limited to, various radar scanning devices, and the like. The server 104 may be implemented as a stand-alone server or as a server cluster of multiple servers.
In one embodiment, as shown in fig. 2, a radar imaging method is provided, and the method is applied to the server in fig. 1 for illustration, and includes the following steps:
step S202, acquiring initial echo data.
In practical applications, a signal is usually transmitted to an object to be detected through a transmitting antenna, and then the initial echo signal reflected by the object to be detected is received through a receiving antenna. Preferably, the step frequency signal can be transmitted to the detection object through the transmitting antennas, i.e. only one transmitting antenna is transmitting at the same time, and all receiving antennas are receiving signals at the same time. The initial echo data is the echo signal received by the receiving antenna. Fig. 3 is a schematic diagram of an embodiment of a planar multi-base sparse array antenna, where Tx represents a transmitting antenna, rx represents a receiving antenna, and Rx and Tx are arranged in a delta configuration, further, the interval between antennas needs to satisfy a spatial sampling theorem, or the FOV (Field of View) of the antennas may be limited, so as to satisfy the imaging requirement of the radar, specifically, the determination of the interval between antennas may be derived according to the sampling theorem in the general literature, and may be supplemented with computer simulation verification, and preferably, the interval between transmitting antennas and the interval between receiving antennas are both 4mm. It will be appreciated that the radar imaging method of the present application is not limited to the scenario of the antenna arrangement illustrated in fig. 3, but is applicable to most continuous sparse arrays.
Taking the example of time-division transmission of step frequency signals by the transmitting antenna, the initial echo data s (Tx, rx, k) received by the array is:
Wherein, ,K=2pi f/c, R T is the distance between any one transmitting antenna and the target to be detected, R R is the distance between any one receiving antenna and the target to be detected,Is the reflection coefficient of the object to be detected.
Step S204, dividing the initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain a local imaging result corresponding to the sub-echo arrays one by one.
The preset sparse array arrangement form is an array design of a plurality of antenna units according to actual needs by a user, and it can be understood that the sparse array arrangement form has a wider application range and only needs to meet the spatial sampling theorem or limit the FOV of the antenna.
And dividing the initial echo data based on a sparse array arrangement form to obtain a plurality of groups of sub-echo arrays, wherein the division of the initial echo data is performed based on the geometric positions of the sparse array arrangement, the space Nyquist sampling theorem is required to be satisfied, and if the space Nyquist sampling theorem is not satisfied, the FOV of a receiving and transmitting antenna is required to be controlled. After the initial echo data s (Tx, rx, k) is divided, a set of sub-echo arrays may be denoted as s (x t,yt,xr,yr, k), where x t represents the x-axis coordinate corresponding to the transmitting antenna (in practical application, the index may be reserved only when the computer is stored, that is, the index of the transmitting antenna may be 1,2, 3 … …, for example), y t represents the y-axis coordinate of the transmitting antenna, x r represents the x-axis coordinate of the receiving antenna, y r represents the y-axis coordinate of the receiving antenna, and k represents the frequency of the transmitting signal. In summary, a set of sub-echo arrays s (x t,yt,xr,yr, k) can be understood as a set of sub-echo arrays s (x t,yt,xr,yr, k) where the signal transmitted from the transmitting antenna located at (x t_1,yt_1) passes through the object to be detected, the echo signal reflected by the signal is received by the receiving antenna located at (x r_1,yr_1), and the transmitted signal has multiple frequencies (i.e., k), so that the signal acquired by one receiving antenna can be marked as the form of s (x t,yt,xr,yr, k), where (x t_1,yt_1) is one set of transmitting antennas, and (x r_1,yr_1) is one set of receiving antennas.
After the sub-echo arrays are obtained, imaging processing is performed on all the sub-echo arrays respectively, wherein the imaging processing includes, but is not limited to, a Back-project (BP) algorithm, a wave number domain algorithm and the like, so that local imaging results corresponding to the sub-echo arrays one by one are obtained.
And S206, fusing all the local imaging results to obtain a final imaging result.
The fusion processing method includes, but is not limited to, three-dimensional image interpolation, spatial domain algorithm and the like, so that a final imaging result is obtained. The final imaging result is three-dimensional, and represents the relative position information of the target object to be detected in an imaging coordinate system (the distance information between the target object to be detected and the receiving and transmitting antenna is utilized).
Through steps S202 to S206, based on a preset sparse array arrangement form, the obtained calculation based on the initial echo data requiring a large memory is decomposed into a plurality of times of calculation based on the sub-echo array of a small memory, and finally, each local imaging result is fused to obtain a final imaging result. The final imaging result is similar to the effect of directly imaging based on the original echo data, but the required memory and the calculated amount are greatly reduced, the calculation efficiency is effectively improved, and the requirement on hardware equipment is reduced.
In one embodiment, the method further comprises:
And carrying out up-sampling treatment on all the local imaging results to obtain a target local imaging result corresponding to the local imaging result, and carrying out three-dimensional interpolation treatment on the target local imaging result based on an imaging grid to obtain a final imaging result.
Specifically, the above-described upsampling processing includes, but is not limited to, fourier transform interpolation, time-domain linear interpolation processing, and the like. Because the local imaging results are fused, the imaging resolution is reduced, and therefore, the resolution of the image is converted from low resolution to final imaging resolution by the up-sampling method, namely, the target local imaging result is fused finally, wherein the target local imaging result has higher resolution compared with the local imaging result. Further, in this embodiment, the method for fusing the target local imaging result includes converting the target local imaging result into coordinates, and performing three-dimensional interpolation processing based on an imaging grid to obtain a final imaging result, where the imaging grid Q (x, y, z) is:
wherein I is a sub-picture, p represents the p-th sub-picture, i.e. an index, AndRespectively represent a lower rounding and an upper rounding,,,LResloution (l=x or y or z) represents the resolution after up-sampling. According to the method, the local imaging results of the targets are fused through the three-dimensional linear interpolation method, so that a result with higher precision can be obtained, and the continuity of data can be effectively maintained.
In one embodiment, the method further comprises:
determining a preset two-dimensional interval parameter;
And carrying out zero padding on the local imaging result based on the two-dimensional interval parameter, and carrying out two-dimensional low-pass filtering on the zero padded result to obtain the target local imaging result.
Specifically, fig. 4 is a schematic flow chart of two-dimensional upsampling of a local imaging result in one embodiment. The length and width of the local imaging result may be expressed as x and y, after the local imaging result is obtained, the zero padding is performed at equal intervals according to the two-dimensional interval parameter, that is, the gray rectangle in fig. 4 is the schematic content of partial zero padding, and then the two-dimensional low-pass filtering (not shown in the figure) is performed on the zero padded result, so as to obtain the target local imaging result. According to the embodiment, the resolution of the local imaging results can be effectively improved, the low resolution of each local imaging result is improved to be the final imaging resolution, then fusion is carried out, a foundation is laid for subsequent image fusion, and the final imaging result after final fusion is ensured to have higher resolution.
In one embodiment, the method further comprises:
Determining a transmitting antenna index of each transmitting antenna and a receiving antenna index of each receiving antenna based on the sparse array arrangement form of the antennas;
Dividing the initial echo data according to an antenna sparse array arrangement form based on the transmitting antenna index and the receiving antenna index to obtain sub-echo arrays, wherein each sub-echo array comprises a group of transmitting antenna data and a group of receiving antenna data.
Specifically, the transmitting antenna index of the transmitting antenna and the receiving antenna index of the receiving antenna are generally determined according to the positions of the antenna arrangement, and may be determined by the related personnel according to the actual needs, for example, assuming that in the present application, according to the sparse array arrangement form of the antennas, signals are sequentially transmitted from top to bottom and from left to right, the antenna in the j-th column of the i-th row may be simply referred to as (i, j), i.e. the antenna index of the antenna is referred to as (i, j).
In the conventional calculation method in the prior art, the acquired initial echo data are often stored in the form of a three-dimensional array, which can be expressed as the form s (Tx, rx, k) above, wherein the initial echo data s (Tx, rx, k) only retain the above sequential condition (i.e. from top to bottom and from left to right assumed above) and do not retain the arrangement position condition of the antennas. In the application, the geometric position relation among antennas is considered, namely, the initial echo data is divided according to the transmitting antenna index and the receiving antenna index according to the array arrangement form, so that the data which are recombined according to the antenna arrangement form, namely, the sub-echo array s (x t,yt,xr,yr, k) is obtained, if the index of the subscript of the transmitting antenna is (i, j), the index of the subscript of the receiving antenna is (q, p), the antennas are arranged in an echo mode according to the geometric arrangement, namely, the form of the Cartesian product is (i, j) x (q, p), and the form is s (x t,yt,xr,yr, k). It can be understood that the expressions of different sub-echo arrays can be written as s (x t,yt,xr,yr, k), but the coordinates corresponding to the antennas in the different sub-echo arrays are different, so in practical application, the above expression of s (x t,yt,xr,yr, k) needs to be added with the identification of the corresponding antenna according to the practical situation. According to the method and the device, the obtained initial echo data are divided according to the arrangement mode of the antenna array based on the antenna index, a plurality of sub-echo arrays are obtained, a foundation is laid for follow-up local imaging based on the sub-echo arrays, further, a final imaging result is obtained by fusion based on the local imaging result, the required memory can be effectively reduced, and the calculation efficiency is improved.
In one embodiment, the method further comprises:
performing frequency domain transformation on the sub-echo array to obtain a frequency domain result of the sub-echo array;
Performing phase compensation processing on the target dimension in the frequency domain result based on the frequency domain result of the sub-echo data to obtain a target frequency domain result of the compensated sub-echo array;
and carrying out non-uniform Fourier transform processing on the target frequency domain result, and carrying out imaging processing on the non-uniform Fourier transform result to obtain a local imaging result.
Specifically, the present embodiment is applied to each sub-echo array, that is, the method provided by the present embodiment performs local imaging processing on each sub-echo array to obtain a local imaging result corresponding to the sub-echo data one to one, and taking the application of the present embodiment to one of the sub-echo arrays as an example: firstly, carrying out four-dimensional Fourier transform processing on a sub-echo array to obtain a frequency domain result of the sub-echo array:
where, referring to the explanation above, s (x t,yt,xr,yr, k) is the form of the data of s (Tx, rx, k) after being arranged according to the antenna geometry, that is, the above sub-echo array, F 4D represents 4D-FFT (Fast Fourier Transform), k xt represents the corresponding wave number domain after fourier transforming the x-dimension of the transmitting antenna, and similarly, k yt represents the corresponding wave number domain after fourier transforming the y-dimension of the transmitting antenna, k xr represents the corresponding wave number domain after fourier transforming the x-dimension of the receiving antenna, k yr represents the corresponding wave number domain after fourier transforming the y-dimension of the receiving antenna, and k is the total wave number domain in space, and as will be understood by those skilled in the art, the formula is 4pi (fc+Δf)/c, where fc is the carrier frequency, Δf is the step frequency, and c is the speed of light. The frequency domain result of the sub-echo array can be obtained by an analysis method:
Wherein, Respectively representing two-dimensional Fourier transform of transmitting antennas and two-dimensional Fourier transform of receiving antennas which are arranged at equal intervals in a certain antenna arrangement direction (such as along an x-axis direction or along a y-axis direction) according to actual antenna arrangement conditions, wherein the two-dimensional Fourier transform can be integrated and solved by adopting a stationary phase method, and a specific analysis form is as follows:
wherein S is as above The above formula is the frequency domain result of the sub-echo array, z a is the distance from the plane of the antenna array to the region of the imaged object, that is, the object dimension described above, fig. 5 is a schematic diagram of the physical meaning of z a in an embodiment, in which the hexagon in the figure represents the object to be detected, and the figure also includes the plane 51 of the antenna and the region 52 of the object to be detected, and the straight line distance between 51 and 52 is z a.
After the frequency domain result of the sub-echo array is obtained, performing phase compensation processing on the target dimension z a in the frequency domain result, namely, performing phase compensation processing on the above formula: if compensation processing is not performed, the imaging algorithm fails due to additional phase errors, and the subsequent algorithm cannot be normally developed. The compensation phase of the structure can be:
The target frequency domain result of the compensated sub-echo array is obtained by the method that:
Since the fourier transform basis in the above formula has a Non-uniform characteristic in the z direction and cannot be realized by using the FFT method, NUFFT (Non-Uniform Fast Fourier Transform, non-uniform fourier transform) is adopted instead of the conventional FFT for calculation in the present application, and the Non-uniform fourier transform result is:
Finally, an imaging process is performed, including but not limited to three-dimensional linear interpolation, fourier transform interpolation, etc. The application respectively carries out imaging processing on each sub-echo array to obtain a corresponding local imaging result, and the imaging efficiency is effectively improved by imaging the sub-echo array through the wave number domain algorithm, which is different from the original BP algorithm imaging.
In one embodiment, the method further comprises:
and carrying out dimension compression processing on the non-uniform Fourier transform result through a preset coordinate mapping relation to obtain a three-dimensional frequency domain result, and carrying out Fourier transform on the three-dimensional frequency domain result to obtain a local imaging result.
Specifically, in this embodiment, a coordinate mapping method is adopted to perform a dimension compression process on the non-uniform fourier transform result, and map the original 5D data into 3D data, where the dimension compression method specifically includes:
And finally obtaining kx, ky and k, wherein kx is a space wave number domain corresponding to the newly constructed x dimension, ky is a space wave number domain corresponding to the newly constructed y dimension, and k is a total space wave number domain. And then carrying out Fourier transform operation to obtain the local imaging result. According to the embodiment, the memory required by imaging calculation is reduced, and the calculation efficiency is improved.
The present embodiment also provides a preferred embodiment of a radar imaging method.
Fig. 6 is a schematic diagram of an antenna combination form in an embodiment, in which there are two sets of green and red transmitting antennas Tx and two sets of blue and yellow receiving antennas Rx, according to the arrangement combination of the two sets of transmitting antennas and the two sets of receiving antennas, four combination forms can be obtained, that is, in this embodiment, four sets of sub-echo arrays can be obtained according to the arrangement combination of the transmitting antennas and the receiving antennas.
In the prior art, the original imaging method is imaging based on a line of antennas, which results in a very large memory for storing data. For example, assuming that the number of transmitting antennas per row is NumTx and the number of receiving antennas per column is NumRx, according to a general imaging method, a memory space greater than or equal to NumRxX × NumTxX × NumTxY × NumRxY is required in consideration of the process of imaging calculation. In the present application, the initial echo data is split, as shown in fig. 6, all green transmitting antennas are grouped, all red transmitting antennas are grouped, all blue receiving antennas are grouped, and all yellow receiving antennas are grouped, so that four combination forms exist, namely four sub-echo arrays are obtained, the four combination forms are respectively imaged locally to obtain local imaging results, and finally fusion is performed, so that the required memory is reduced, namely the required memory in the present application is: numTx/2× NumRx/2× NumTx × NumRx, it can be seen that in this embodiment, the memory required by the method of the present application is reduced by four times, and it is further known that if more transmitting antennas and receiving antennas are used in practical application, the present application can save more memory.
Fig. 7 is a schematic flow chart of a radar imaging method in a preferred embodiment.
Firstly, initial echo data s (Tx, rx, k) is acquired, then, according to a preset sparse array arrangement form of antennas, the geometric position relation of the receiving and transmitting antennas is introduced, the geometric position relation is represented by the number of rows and the number of columns of the receiving and transmitting antennas, and the array combination is carried out based on a plurality of groups of receiving and transmitting antennas, so that the initial echo data are recombined, and a plurality of groups of sub-echo arrays s (x t,yt,xr,yr, k) are obtained. Each group of sub-echo arrays at least comprises a group of transmitting antennas and a group of receiving antennas.
Imaging is carried out on each group of sub-echo arrays respectively to obtain a local imaging result which corresponds to each group of sub-echo arrays one by one, imaging is completed through a wave number domain algorithm in the embodiment, and the method specifically comprises the steps of carrying out four-dimensional Fourier transform on the sub-echo arrays to obtain a frequency domain result of the sub-echo arrays, constructing a compensation item aiming at a target dimension in the frequency domain result, carrying out phase compensation processing to obtain a compensated target frequency domain result, carrying out non-uniform Fourier transform processing on the target frequency domain result, carrying out dimension compression processing on a non-uniform Fourier transform structure through a coordinate mapping method, converting 5D data into 3D data, and carrying out FFT calculation of two dimensions to obtain the local imaging result.
Considering that in this embodiment, a plurality of local imaging results are fused to obtain a final imaging result, which may result in a lower resolution of a final imaging structure, in this embodiment, a time-domain two-dimensional upsampling operation is performed on each local imaging result, that is, two-dimensional equidistant zero padding is performed on pixel points in the local imaging result, and then two-dimensional low-pass filtering is performed to obtain a target local imaging result. Considering that the image imaging areas corresponding to different combinations of the antennas have deviation, in this embodiment, each local imaging result is converted into a coordinate form by an image interpolation method so as to facilitate three-dimensional interpolation, then each local imaging result is interpolated into a final imaging grid, and finally each target local imaging result is fused by three-dimensional linear interpolation, and all acquired initial echo data are traversed to obtain a final imaging result.
It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
Based on the same inventive concept, the embodiment of the application also provides a radar imaging device for realizing the radar imaging method. The implementation of the solution provided by the device is similar to the implementation described in the above method, so the specific limitation in one or more embodiments of the radar imaging device provided below may be referred to the limitation of the radar imaging method hereinabove, and will not be repeated here.
In one embodiment, as shown in fig. 8, there is provided a radar imaging apparatus including: an acquisition module 81, a calculation module 82 and an imaging module 83, wherein:
The acquisition module is used for acquiring a preset antenna sparse array arrangement form and initial echo data;
The computing module is used for dividing the initial echo data based on the antenna sparse array arrangement form to obtain at least two groups of sub-echo arrays, and respectively carrying out imaging processing on all the sub-echo arrays to obtain local imaging results corresponding to the sub-echo arrays one by one;
And the imaging module is used for carrying out fusion processing on all the local imaging results to obtain a final imaging result.
Specifically, the acquisition module acquires a preset antenna sparse array arrangement form and initial echo data, the calculation module divides the initial echo data based on the antenna sparse array arrangement form to obtain a plurality of groups of sub-echo arrays, imaging processing is respectively carried out on all the sub-echo arrays to obtain local imaging results corresponding to the sub-echo arrays one by one, the local imaging results are finally sent to the imaging module, and the imaging module fuses all the local imaging results to obtain a final imaging result.
The respective modules in the radar imaging apparatus described above may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a security inspection system is provided that includes a detection chamber, a scanning device, and an imaging device;
A detection chamber for accommodating an object to be detected;
scanning means for receiving initial echo data reflected from an object to be detected in response to a millimeter wave signal transmitted to the object to be detected;
Imaging means for performing the radar imaging method as described above based on the initial echo data.
Specifically, millimeter wave imaging can detect various dangerous articles hidden under clothes of a human body by measuring the difference of millimeter wave electromagnetic characteristics between the human body and an object, and has certain resolving power for hidden articles of different materials, such as metal cutters, plastic handguns, liquid explosives and the like, and security scanning of contraband is carried out on people flow dense scenes such as railway stations, airports and the like in common terms.
In this embodiment, the detection chamber is configured to accommodate an object to be detected, and the scanning device transmits a millimeter wave signal to the object to be detected and receives initial echo data reflected from the object to be detected. Imaging is then completed by the imaging device based on the initial echo data.
In one embodiment, a computer device is provided, which may be a server, and the internal structure of which may be as shown in fig. 9. The computer device includes a processor, a memory, and a network interface connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The database of the computer device is for storing data related to radar imaging. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a radar imaging method.
It will be appreciated by persons skilled in the art that the architecture shown in fig. 9 is merely a block diagram of some of the architecture relevant to the present inventive arrangements and is not limiting as to the computer device to which the present inventive arrangements are applicable, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.
In one embodiment, a computer readable storage medium is provided having a computer program stored thereon, which when executed by a processor implements a radar imaging method as described above.
The user information (including but not limited to user equipment information, user personal information, etc.) and the data (including but not limited to data for analysis, stored data, presented data, etc.) related to the present application are information and data authorized by the user or sufficiently authorized by each party.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magneto-resistive random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (PHASE CHANGE Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in various forms such as static Random access memory (Static Random Access Memory, SRAM) or Dynamic Random access memory (Dynamic Random AccessMemory, DRAM), and the like. The databases referred to in the embodiments provided herein may include at least one of a relational database and a non-relational database. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processor referred to in the embodiments provided in the present application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, or the like, but is not limited thereto.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the application and are described in detail herein without thereby limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of the application should be assessed as that of the appended claims.
Claims (10)
1. A radar imaging method, the method comprising:
acquiring initial echo data;
Dividing the initial echo data based on a preset sparse array arrangement form of the antenna to obtain at least two groups of sub-echo arrays, and respectively performing imaging processing on all the sub-echo arrays to obtain local imaging results corresponding to the sub-echo arrays one by one;
And carrying out fusion treatment on all the local imaging results to obtain a final imaging result.
2. The method of claim 1, wherein the fusing all the local imaging results to obtain a final imaging result comprises:
And carrying out up-sampling treatment on all the local imaging results to obtain a target local imaging result corresponding to the local imaging result, and carrying out three-dimensional interpolation treatment on the target local imaging result based on a preset imaging grid to obtain the final imaging result.
3. The method according to claim 2, wherein the up-sampling all the local imaging results to obtain a target local imaging result corresponding to the local imaging result includes:
determining a preset two-dimensional interval parameter;
And carrying out zero padding on the local imaging result based on the two-dimensional interval parameter, and carrying out two-dimensional low-pass filtering on the zero padded result to obtain the target local imaging result.
4. The method of claim 1, wherein the dividing the initial echo data based on the preset sparse array arrangement of the antennas to obtain at least two sets of sub-echo arrays comprises:
Determining a transmitting antenna index of each transmitting antenna and a receiving antenna index of each receiving antenna based on the sparse array arrangement form of the antennas;
Dividing the initial echo data according to the antenna sparse array arrangement form based on the transmitting antenna index and the receiving antenna index to obtain sub-echo arrays, wherein each sub-echo array comprises a group of transmitting antenna data and a group of receiving antenna data.
5. The method according to claim 1, wherein the imaging processing is performed on all the sub-echo arrays respectively to obtain local imaging results corresponding to the sub-echo arrays one to one, and the method comprises:
performing frequency domain transformation on the sub-echo array to obtain a frequency domain result of the sub-echo array;
performing phase compensation processing on a target dimension in the frequency domain result based on the frequency domain result of the sub-echo array to obtain a compensated target frequency domain result of the sub-echo array;
and carrying out non-uniform Fourier transform processing on the target frequency domain result, and carrying out imaging processing on the non-uniform Fourier transform result to obtain the local imaging result.
6. The method of claim 5, wherein said performing a non-uniform fourier transform on said target frequency domain result and performing an imaging process on said non-uniform fourier transform result to obtain said local imaging result comprises:
And carrying out dimension compression processing on the non-uniform Fourier transform result through a preset coordinate mapping relation to obtain a three-dimensional frequency domain result, and carrying out Fourier transform on the three-dimensional frequency domain result to obtain the local imaging result.
7. A radar imaging apparatus, the apparatus comprising:
The acquisition module is used for acquiring a preset antenna sparse array arrangement form and initial echo data;
the calculation module is used for dividing the initial echo data based on the antenna sparse array arrangement form to obtain at least two groups of sub-echo arrays, and respectively carrying out imaging processing on all the sub-echo arrays to obtain local imaging results corresponding to the sub-echo arrays one by one;
And the imaging module is used for carrying out fusion processing on all the local imaging results to obtain a final imaging result.
8. A security inspection system, wherein the system comprises a detection room, a scanning device and an imaging device;
the detection chamber is used for accommodating an object to be detected;
The scanning device is used for responding to millimeter wave signals emitted to the object to be detected and receiving initial echo data reflected from the object to be detected;
the imaging device for performing the radar imaging method according to any one of claims 1 to 6 based on the initial echo data.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any one of claims 1 to 6 when the computer program is executed.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any one of claims 1 to 6.
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