MIMO-SAR Fast Imaging Method, Device, Equipment and Medium

Abstract

The present disclosure provides a fast imaging method for MIMO-SAR, including: collecting the scattered echo signals of a target object based on a MIMO transmit-receive linear array; modifying the functional representation form of the scattered echo signals to strip the variable related to the wave number in the functional representation form; introducing a Fourier transform pair related to the wave number in the modified scattered echo signals, performing a fast inverse Fourier transform in the wave number domain to obtain the time-domain signal of the target object; reconstructing the objective function of the target object based on the time-domain signal, and performing imaging processing on the target object based on the objective function. This method solves the problem that the traditional back-projection algorithm takes time for integration in the wave number dimension. The present disclosure also provides a fast imaging device, an electronic device and a storage medium for MIMO-SAR.

Description

Technical Field

[0001] The present disclosure relates to the technical field of radar imaging, and in particular, to a MIMO-SAR fast imaging method, apparatus, electronic device, and medium. Background Art

[0002] MIMO radar imaging methods can be simply divided into two categories: time-domain coherent imaging algorithms and frequency-domain imaging algorithms. The most representative time-domain coherent imaging algorithm is the Back Projection (BP) algorithm. This algorithm obtains the reconstructed image through multi-dimensional integration of the array aperture and wavenumber dimensions. Its physical meaning is clear, the imaging accuracy is high, and the operation is simple. However, the multiple integral calculation burden is heavy and time-consuming, and its application possibility in real-time imaging scenarios is very small. Commonly used frequency-domain imaging algorithms include MIMO-RMA (Range Migration Algorithm) and MIMO-PSM algorithm (Phase Shift Migration), etc. Although the RMA operation speed is relatively fast, the slot interpolation therein has a great impact on both the imaging quality and time. PSM has an integration process in one dimension and is slower than MIMO-RMA. The characteristic of this algorithm is to perform a fast Fourier transform in the azimuth direction to improve the imaging speed. However, in order to perform a fast Fourier transform in the azimuth direction, the sampling interval in the azimuth direction needs to satisfy the Nyquist sampling law to avoid aliasing in image reconstruction, which requires a very high sparsity of the MIMO array. Summary of the Invention

[0003] In view of the above problems, the present disclosure provides a MIMO-SAR fast imaging method to solve the problem of long time consumption of existing algorithms for MIMO radar imaging.

[0004] The first aspect of the present disclosure provides a MIMO-SAR fast imaging method, including: collecting the scattered echo signal of a target object based on a MIMO transmit-receive linear array; modifying the function representation form of the scattered echo signal to strip the variable about the wavenumber in the function representation form; introducing a Fourier transform pair about the wavenumber into the modified scattered echo signal, performing a fast inverse Fourier transform in the wavenumber domain to obtain the time-domain signal of the target object; reconstructing the objective function of the target object based on the time-domain signal, and performing imaging processing on the target object based on the objective function.

[0005] Optionally, the formula for modifying the function representation form of the scattered echo signal is expressed as:

[0006] sS(x t ,x r ,y l ,k i) = ∫∫∫ dxdydz · O(x, y, z) · exp(-jk i R m )

[0007] = ∫∫∫ dxdydz · O(x, y, z) · exp(-jk0R m ) · exp[-j(i - 1)ΔkR m )

[0008] Wherein, in the MIMO - SAR imaging scenario, it is assumed that the plane where the MIMO transmit - receive antenna array is located is at z = 0, and sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x - axis coordinate of the transmit antenna in the MIMO transmit - receive antenna array, x r represents the x - axis coordinate of the receive antenna in the MIMO transmit - receive antenna array, y l represents the y - axis coordinate of the MIMO transmit - receive antenna array, k i represents the wave number corresponding to the broadband signal with different transmit frequencies transmitted by the MIMO transmit - receive antenna array, O(x, y, z) represents the objective function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wave number, k i = k0+(i - 1)Δk, Δk represents the wave - number domain sampling interval, and R m represents the sum of the distances from the receive antenna and the transmit antenna to the target object.

[0009] Optionally, the formula for introducing the Fourier transform pair of wave numbers into the modified scattered echo signal is expressed as:

[0010] R n =(n - 1)ΔR

[0011]

[0012] Wherein, R n represents the Fourier transform pair of the wave number k i , ΔR represents the sampling interval of the Fourier transform pair, sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x - axis coordinate of the transmit antenna in the MIMO transmit - receive antenna array, x r represents the x - axis coordinate of the receive antenna in the MIMO transmit - receive antenna array, y l represents the y - axis coordinate of the MIMO transmit - receive antenna array, ki represents the wavenumber corresponding to the broadband signal with different transmission frequencies transmitted by the MIMO transceiver array, O(x, y, z) represents the objective function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wavenumber, k i = k0 + (i - 1)Δk, where Δk represents the wavenumber domain sampling interval, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, R n is used to approximate R m , n represents a maximum value such that R n is closest to R m , represents the phase error.

[0013] Optionally, performing the fast inverse Fourier transform in the wavenumber domain, the obtained time-domain signal formula of the target object is expressed as:

[0014]

[0015] where, ss(x t , x r , y l , n k ) represents the time-domain signal, N k represents the number of sampling points of the scattered echo signal, δ(n k ) is defined to be 1 if and only if n = n k , and the function value is 0 for other values of n.

[0016] Optionally, the method further includes: determining the upsampling rate of the fast inverse Fourier transform, padding zeros to the scattered echo signal in the beam domain when performing the fast inverse Fourier transform; performing conditional constraints during the fast inverse Fourier transform such that

[0017]

[0018]

[0019] where, M represents the upsampling rate, B k represents the beam domain bandwidth, MN k represents the number of sampling points of the fast inverse Fourier transform.

[0020] Optionally, the objective function for reconstructing the target object based on the time-domain signal includes: reconstructing the objective function of the target object and compensating for the phase error caused by the Fourier transform pair introducing the wavenumber.

[0021] Optionally, the formula of the objective function for phase error compensation is expressed as:

[0022] O(x, y, z)

[0023] ≈∫∫∫dx t dx r dy l ·ss(x t ,x r ,y l ,n k )exp(jk0R m )C(x t ,x r ,y l ,n)

[0024]

[0025] Among them, O(x, y, z) represents the target function, ss(x t ,x r ,y l ,n k ) represents the time-domain signal, x t represents the x-axis coordinate of the transmitting antenna in the MIMO transmit-receive wire array, x r represents the x-axis coordinate of the receiving antenna in the MIMO transmit-receive wire array, y l represents the y-axis coordinate of the MIMO transmit-receive wire array, k0 represents the minimum wavenumber, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, C(x t ,x r ,y l ,n) represents the compensation term of the phase error, R n represents the Fourier transform pair, n represents a maximum value such that R n is closest to R m ,Δk represents the wavenumber domain sampling interval, N k represents the number of sampling points of the scattered echo signal.

[0026] The second aspect of the present disclosure provides a MIMO-SAR fast imaging device, including: a signal acquisition module for acquiring the scattered echo signal of the target object based on the MIMO transmit-receive wire array; a signal modification module for modifying the functional representation form of the scattered echo signal and stripping the variable about the wavenumber in the functional representation form; a signal transformation module for introducing the Fourier transform pair about the wavenumber into the modified scattered echo signal and performing an inverse fast Fourier transform in the wavenumber domain to obtain the time-domain signal of the target object; a signal reconstruction module for reconstructing the target function of the target object based on the time-domain signal and performing imaging processing on the target object based on the target function.

[0027] The third aspect of the present disclosure provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the computer program, each step in the MIMO-SAR fast imaging method described in any one of the first aspects is implemented.

[0028] The fourth aspect of the present disclosure provides a computer-readable storage medium, on which a computer program is stored, wherein when the computer program is executed by a processor, each step in the MIMO-SAR fast imaging method described in any one of the first aspects is implemented.

[0029] At least one of the above technical solutions adopted in the embodiments of the present disclosure can achieve the following beneficial effects:

[0030] The present disclosure provides a MIMO-SAR fast imaging method. Compared with the traditional back-projection algorithm, the integration in the wavenumber dimension is cancelled, and the imaging speed is significantly improved; compared with the frequency-domain imaging algorithm, there are no particularly strict requirements for the array arrangement, and the applicable scenarios are wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more fully understand the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0032] Figure 1 Schematically shows a MIMO-SAR imaging scenario provided by an embodiment of the present disclosure;

[0033] Figure 2 Schematically shows a schematic diagram of a MIMO-SAR fast imaging method provided by an embodiment of the present disclosure;

[0034] Figure 3 Schematically shows a MIMO linear array arrangement provided by an embodiment of the present disclosure;

[0035] Figure 4A Schematically shows a schematic diagram of a multi-target 3-D scene provided by an embodiment of the present disclosure;

[0036] Figure 4B Schematically shows a multi-target BPA 3-D simulation result provided by an embodiment of the present disclosure;

[0037] Figure 4C Schematically shows a multi-target MIMO-SAR fast imaging method 3-D simulation result provided by an embodiment of the present disclosure;

[0038] Figure 4D Schematically shows an XY cross-sectional view of a multi-target BPA simulation result provided by an embodiment of the present disclosure;

[0039] Figure 4E Schematically shows the XY cross-sectional view of the simulation results of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure;

[0040] Figure 4F Schematically shows the XZ cross-sectional view of the simulation results of a multi-target BPA provided by an embodiment of the present disclosure;

[0041] Figure 4G Schematically shows the XZ cross-sectional view of the simulation results of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure;

[0042] Figure 4H Schematically shows the comparison diagram of the one-dimensional azimuth contour diagrams of a multi-target BPA and a MIMO-SAR fast imaging method provided by an embodiment of the present disclosure at y = 0m and z = 0.7m;

[0043] Figure 4I Schematically shows the comparison diagram of the one-dimensional azimuth contour diagrams of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure along x = 0m and z = 0.7m.

[0044] Figure 5 Schematically shows the structural block diagram of a MIMO-SAR fast imaging device provided by an embodiment of the present disclosure;

[0045] Figure 6 Schematically shows the structural block diagram of an electronic device provided by an embodiment of the present disclosure; Detailed implementation manners

[0046] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0047] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0048] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0049] Some block diagrams and / or flowcharts are shown in the accompanying drawings. It should be understood that some blocks or combinations of blocks in the block diagrams and / or flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when executed by the processor, these instructions can create a device for implementing the functions / operations illustrated in these block diagrams and / or flowcharts.

[0050] Therefore, the technology of the present disclosure can be implemented in the form of hardware and / or software (including firmware, microcode, etc.). Additionally, the technology of the present disclosure can take the form of a computer program product on a computer-readable medium storing instructions, which can be used by or in conjunction with an instruction execution system. In the context of the present disclosure, a computer-readable medium can be any medium that can contain, store, transmit, propagate, or transport instructions. For example, a computer-readable medium can include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, components, or propagation media. Specific examples of computer-readable media include: magnetic storage devices, such as magnetic tapes or hard disk drives (HDDs); optical storage devices, such as compact discs (CD-ROMs); memories, such as random access memories (RAMs) or flash memories; and / or wired / wireless communication links.

[0051] Figure 1 Schematically shows a MIMO-SAR imaging scenario provided by an embodiment of the present disclosure.

[0052] As Figure 1 shown, it is assumed that the plane where the MIMO array is located is at z = 0, the transmitting antenna is located at (x t , y l , z = 0), and the receiving antenna is located at (x r , y l , z = 0). The array has the transmitting antenna in the middle and the receiving antenna in the middle, and the transceiver units are evenly arranged. The excitation frequency is a stepped-frequency signal, k i is the wave number corresponding to different transmitting frequencies of the broadband signal, and k0 is the minimum wave number. The following embodiments will all be described by taking the imaging scenario as shown Figure 1 as an example.

[0053] Figure 2 Schematically shows a schematic diagram of a MIMO-SAR fast imaging method provided by an embodiment of the present disclosure.

[0054] As shown Figure 2 in the figure, a MIMO-SAR fast imaging method provided by an embodiment of the present disclosure includes S210 to S240.

[0055] S210, acquiring the scattered echo signal of the target object based on the MIMO transmit-receive array. In the MIMO-SAR system, the scattered echo at each acquisition position can be expressed as:

[0056] sS(x t , x r , y l , k i ) = ∫∫∫O(x, y, z)·exp[-jk i (R T + R R )]dxdydz

[0057] where R T , R n are the distances from the transmitting antenna and the receiving antenna to the target point respectively, and can be expressed as

[0058]

[0059]

[0060] The array adopts the form of N xt transmissions and N xr receives, the scanning path length is N y , the stepped-frequency signal has a total of N k sampling points; the echo is uniformly sampled in the wavenumber domain, where k0 is the wavenumber corresponding to the starting frequency, the sampling interval is Δk, and k i = k0 + (i - 1)Δk.

[0061]

[0062] where f0 is the initial frequency, Δf is the sampling frequency interval, and the wavenumber domain bandwidth B k = (N k - 1)Δk.

[0063] S220, modifying the functional representation form of the scattered echo signal and stripping the variable related to the wavenumber in the functional representation form.

[0064] The formula for modifying the functional representation form of the scattered echo signal is expressed as:

[0065] sS(x t , x r , y l , k i) = ∫∫∫ dxdydz·O(x, y, z)·exp(-jk i R m )

[0066] = ∫∫∫ dxdydz·O(x, y, z)·exp(-jk0R m )·exp[-j(i - 1)ΔkR m )

[0067] Wherein, in the MIMO - SAR imaging scenario, it is assumed that the plane where the MIMO transmit - receive antenna array is located is at z = 0, and sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x - axis coordinate of the transmitting antenna in the MIMO transmit - receive antenna array, x r represents the x - axis coordinate of the receiving antenna in the MIMO transmit - receive antenna array, y l represents the y - axis coordinate of the MIMO transmit - receive antenna array, k i represents the wavenumber corresponding to the broadband signal with different transmission frequencies transmitted by the MIMO transmit - receive antenna array, O(x, y, z) represents the target function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wavenumber, k i = k0+(i - 1)Δk, Δk represents the wavenumber domain sampling interval, and R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object. Among them, k i has a total of N k sampling points.

[0068] In the above - mentioned function representation of the modified scattered echo signal, the variable part of k i in the echo signal is stripped out to facilitate writing it in the form of a Fourier transform.

[0069] S230, in the modified scattered echo signal, a Fourier transform pair with respect to the wavenumber is introduced, and an inverse fast Fourier transform is performed in the wavenumber domain to obtain the time - domain signal of the target object.

[0070] The Fourier transform pair of k i is expressed as:

[0071] R n = (n - 1)ΔR

[0072] The formula for introducing a Fourier transform pair with respect to the wavenumber in the modified scattered echo signal is expressed as:

[0073]

[0074] Wherein, Rn Denote the wave number as k i of the Fourier transform pair, ΔR represents the sampling interval of the Fourier transform pair, sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x-axis coordinate of the transmitting antenna in the MIMO transmit-receive array, x r represents the x-axis coordinate of the receiving antenna in the MIMO transmit-receive array, y l represents the y-axis coordinate of the MIMO transmit-receive array, k i represents the wave number corresponding to the broadband signal transmitted at different transmission frequencies by the MIMO transmit-receive array, O(x, y, z) represents the objective function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wave number, k i = k0+(i - 1)Δk, Δk represents the sampling interval in the wave number domain, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, R n is used to approximate R m , n represents a maximum value such that R n is closest to R m , represents the phase error.

[0075] In the above formula, the purpose of performing this transformation is to integrate the pair of Fourier transform of k i and R n together, facilitating the subsequent calculation of the inverse Fourier transform. Among them, using R n to approximate R m results in an error term.

[0076]

[0077] The formula for calculating the objective function of traditional BP is

[0078] O(x, y, z)=∫∫∫∫sS(x r , x r , y l , k i )exp[jk i (R T +R R )]dx t dx r dy l dk i

[0079] According to this formula, the implementation operation is essentially a four-dimensional coherent accumulation.

[0080] In this embodiment, a one-dimensional inverse fast Fourier transform is performed in the wavenumber domain, and the time-domain signal of the target object is obtained and expressed as:

[0081]

[0082] where ss(x t , x r , y l , n k ) represents the time-domain signal, N k represents the number of sampling points of the scattered echo signal, and δ(n k ) is defined as having a value of 1 if and only if n = n k , and the function value is 0 for other values of n.

[0083] It can be seen that after introducing the Fourier transform pair, performing a one-dimensional inverse fast Fourier transform in the wavenumber domain, the time-domain signal of the target object cancels the coherent accumulation in the k i dimension. Specifically, it can be seen from the formula that there is no variable related to k i on the right side of the formula.

[0084] Furthermore, in order to reduce the error, in this embodiment, it is necessary to determine the IFFT upsampling rate M, that is, to determine the number of sampling points and the sampling interval ΔR of the IFFT. At this time, the number of IFFT sampling points is MN k , and when performing IFFT, it is necessary to pad zeros at the end of the wavenumber dimension data, and the number of padded zeros is (M - 1)N k . The time-domain signal after padding zeros is expressed as:

[0085]

[0086] To avoid the influence of the phase error term , it is necessary to make the magnitude of |R m - R n | be small enough compared to the minimum wavelength λ min = 2π / (k0 + k max ), that is, |R m - R n | << λ min . Thus, there is

[0087]

[0088]

[0089] S240, reconstruct the objective function of the target object based on the time-domain signal, and perform imaging processing of the target object based on the objective function.

[0090] For a one-dimensional linear inverse scattering problem, the objective function can be reconstructed as

[0091] O(x, y, z)

[0092] ≈∫∫∫ss(x t , x r , y l , n k )exp(jk0R m )dx t dx r dy l

[0093] To further improve the accuracy of the reconstructed image, the phase error can be compensated by the following formula:

[0094]

[0095] The objective function formula for phase error compensation is expressed as:

[0096] O(x, y, z)

[0097] ≈∫∫∫dx t dx r dy l ·ss(x t , x r , y l , n k )exp(jk0R m )C(x t , x r , y l , n)

[0098] where O(x, y, z) represents the objective function, ss(x t , x r , y l , n k ) represents the time-domain signal, x t represents the x-axis coordinate of the transmitting antenna in the MIMO transmit-receive wire array, x r represents the x-axis coordinate of the receiving antenna in the MIMO transmit-receive wire array, y l represents the y-axis coordinate of the MIMO transmit-receive wire array, k0 represents the minimum wavenumber, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, C(x t , x r , y l , n) represents the compensation term for the phase error, R n represents the Fourier transform pair, n represents a maximum value such that R n is closest to R m , Δk represents the wavenumber domain sampling interval, N kIndicates the number of sampling points of the scattered echo signal.

[0099] Compared with the traditional BP algorithm, in this embodiment, the weighted accumulation of the original echo signal in four dimensions only needs to be coherently accumulated in three dimensions: the transmit dimension, the receive dimension, and the scan dimension after IFFT and rounding. Especially for the case of too many wavenumber sampling points, the improvement of the operation speed of this algorithm is more obvious, solving the problem of time-consuming integration in the wavenumber dimension of the traditional back-projection algorithm.

[0100] Wavenumber domain algorithms such as RMA and PSM have certain requirements for the transceiver element spacing of the MIMO array and need to satisfy the Nyquist sampling law. Otherwise, the reconstructed image will have a defocus phenomenon and may not be applicable to arrays with a certain degree of sparsity. This embodiment also solves the problem of strict requirements for array spacing in traditional RMA and PSM algorithms.

[0101] Figure 3 Schematically shows a MIMO linear array setting provided by an embodiment of the present disclosure.

[0102] In the MIMO linear array as Figure 3 shown, the simulation parameters are set as shown in Table 1:

[0103] Table 1 Instance simulation parameter settings

[0104]

[0105] Under the conditions of this MIMO linear array setting, this embodiment provides a multi-dimensional comparison diagram of the BPA algorithm and the MIMO-SAR fast imaging algorithm provided by an embodiment of the present disclosure. For a multi-target 3-D scene as Figure 4A shown, Figure 4B a multi-target BPA 3-D simulation result is given; Figure 4C shows a 3-D simulation result of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure; Figure 4D Schematically shows an XY sectional view of a multi-target BPA simulation result provided by an embodiment of the present disclosure; Figure 4E Schematically shows an XY sectional view of a simulation result of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure; Figure 4F Schematically shows an XZ sectional view of a multi-target BPA simulation result provided by an embodiment of the present disclosure; Figure 4G Schematically shows an XZ sectional view of a simulation result of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure; Figure 4H Schematically shows a comparison diagram of the one-dimensional azimuth contour of a multi-target BPA and a MIMO-SAR fast imaging method at y = 0m and z = 0.7m provided by an embodiment of the present disclosure;Figure 4I Schematically shows a comparison diagram of one-dimensional azimuth profiles along x = 0 m and z = 0.7 m of a multi-target MIMO-SAR fast imaging method provided by an embodiment of the present disclosure. It can be seen that the multi-target MIMO-SAR fast imaging method provided by the embodiment of the present disclosure can ensure the imaging accuracy on the basis of reducing the calculation dimension.

[0106] Figure 5 Schematically shows a structural block diagram of a MIMO-SAR fast imaging device provided by an embodiment of the present disclosure.

[0107] As Figure 5 shown, an embodiment of the present disclosure provides a MIMO-SAR fast imaging device, including: a signal acquisition module 510, a signal modification module 520, a signal transformation module 530, and a signal reconstruction module 540.

[0108] The signal acquisition module 510 is configured to acquire the scattered echo signal of the target object based on the MIMO transmit-receive line array.

[0109] The signal modification module 520 is configured to modify the functional representation form of the scattered echo signal and strip the variable about the wave number in the functional representation form.

[0110] The signal transformation module 530 is configured to introduce a Fourier transform pair about the wave number into the modified scattered echo signal, perform a fast inverse Fourier transform in the wave number domain, and obtain the time-domain signal of the target object.

[0111] The signal reconstruction module 540 is configured to reconstruct the objective function of the target object based on the time-domain signal and perform imaging processing on the target object based on the objective function.

[0112] It can be understood that the signal acquisition module 510, the signal modification module 520, the signal transformation module 530, and the signal reconstruction module 540 can be implemented in one module, or any one of them can be split into multiple modules. Or, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present invention, at least one of the signal acquisition module 510, the signal modification module 520, the signal transformation module 530, and the signal reconstruction module 540 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on chip, a system on a substrate, a system in a package, an application specific integrated circuit (ASIC), or can be implemented in any other reasonable way of integrating or packaging circuits, etc., in hardware or firmware, or in an appropriate combination of software, hardware, and firmware. Or, at least one of the signal acquisition module 510, the signal modification module 520, the signal transformation module 530, and the signal reconstruction module 540 can be at least partially implemented as a computer program module, and when the program is run on a computer, it can execute the functions of the corresponding module.

[0113] Figure 6 The block diagram of a kind of electronic device provided by an embodiment of the present disclosure is schematically shown.

[0114] As Figure 6 shown, the electronic device described in this embodiment includes: The electronic device 600 includes a processor 610 and a computer-readable storage medium 620. The electronic device 600 can execute the method described above with reference to Figure 2 to implement the detection of specific operations.

[0115] Specifically, the processor 610 can include, for example, a general microprocessor, an instruction set processor, and / or a related chipset, and / or a dedicated microprocessor (such as an application specific integrated circuit (ASIC)), etc. The processor 610 can also include on-board memory for caching purposes. The processor 610 can be a single processing unit or multiple processing units for executing different actions of the method flow according to an embodiment of the present disclosure described with reference to Figure 1 above.

[0116] The computer-readable storage medium 620 can be, for example, any medium capable of containing, storing, transmitting, propagating, or transporting instructions. For example, the readable storage medium can include, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, component, or propagation medium. Specific examples of the readable storage medium include: magnetic storage devices, such as magnetic tapes or hard disk drives (HDDs); optical storage devices, such as compact discs (CD-ROMs); memories, such as random access memories (RAMs) or flash memories; and / or wired / wireless communication links.

[0117] The computer-readable storage medium 620 may include a computer program 621, and the computer program 621 may include code / computer-executable instructions which, when executed by the processor 610, cause the processor 610 to execute, for example, the method flows described above in connection with Figure 1 and any variations thereof.

[0118] The computer program 621 may be configured to have computer program code including, for example, computer program modules. For example, in an exemplary embodiment, the code in the computer program 621 may include one or more program modules, such as including 621A, module 621B,.... It should be noted that the way of dividing the modules and the number of them are not fixed, and those skilled in the art may use appropriate program modules or combinations of program modules according to the actual situation. When these combinations of program modules are executed by the processor 610, the processor 610 can execute, for example, the method flows described above in connection with Figure 2 and any variations thereof.

[0119] According to an embodiment of the present invention, at least one of the signal acquisition module 510, the signal modification module 520, the signal transformation module 530, and the signal reconstruction module 540 may be implemented as a computer program module described with reference to Figure 6 which, when executed by the processor 310, can implement the corresponding operations described above.

[0120] The present disclosure also provides a computer-readable medium, which may be included in the device / apparatus / system described in the above embodiments; or may exist alone without being assembled into the device / apparatus / system. The above computer-readable medium carries one or more programs which, when the one or more programs are executed, implement the method according to the embodiments of the present disclosure.

[0121] Those skilled in the art can understand that the features recited in the various embodiments and / or claims of the present disclosure can be combined or combined in a variety of ways, even if such combinations or combinations are not explicitly recited in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features recited in the various embodiments and / or claims of the present disclosure can be combined and combined in a variety of ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0122] Although the present disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Accordingly, the scope of the present disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A MIMO-SAR fast imaging method, characterized in that, Including: Collecting the scattered echo signals of the target object based on the MIMO transmit-receive line array; Modifying the functional representation form of the scattered echo signals, and stripping the variable related to the wave number in the functional representation form; Introducing a Fourier transform pair related to the wave number into the modified scattered echo signals, and performing an inverse fast Fourier transform in the wave number domain to obtain the time domain signals of the target object; Reconstructing the objective function of the target object based on the time domain signals, and performing imaging processing of the target object based on the objective function.

2. The method according to claim 1, characterized in that, The formula for modifying the functional representation form of the scattered echo signals is: sS(x t , x r , y l , k i ) = ∫∫∫ dxdydz · O(x, y, z) · exp(-jk i R m ) = ∫∫∫dxdydz·O(x, y, z)·exp(-jk0R m )·exp[-j(i - 1)ΔkR m ​ Among them, in the MIMO-SAR imaging scenario, it is assumed that the plane where the MIMO transmit-receive antenna array is located is at z = 0, sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x-axis coordinate of the transmit antenna in the MIMO transmit-receive antenna array, x r represents the x-axis coordinate of the receive antenna in the MIMO transmit-receive antenna array, y l represents the y-axis coordinate of the MIMO transmit-receive antenna array, k i represents the wave number corresponding to the broadband signal with different transmit frequencies transmitted by the MIMO transmit-receive antenna array, O(x, y, z) represents the objective function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wave number, k i = k0 + (i - 1)Δk, Δk represents the wave number domain sampling interval, R m represents the sum of the distances from the receive antenna and the transmit antenna to the target object.

3. The method according to claim 1, characterized in that, The formula for introducing a Fourier transform pair related to the wave number into the modified scattered echo signals is: R n = (n - 1)ΔR wherein, R n represents the Fourier transform pair of the wave number k i , ΔR represents the sampling interval of the Fourier transform pair, sS(x t , x r , y l , k i ) represents the scattered echo signal, x t represents the x-axis coordinate of the transmitting antenna in the MIMO transmit-receive line array, x r represents the x-axis coordinate of the receiving antenna in the MIMO transmit-receive line array, y l represents the y-axis coordinate of the MIMO transmit-receive line array, k i represents the wave number corresponding to the broadband signal with different transmission frequencies transmitted by the MIMO transmit-receive line array, O(x, y, z) represents the objective function, (x, y, z) represents the coordinates of the target object, k0 represents the minimum wave number, k i = k0 + (i - 1)Δk, Δk represents the sampling interval in the wave number domain, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, R n is used to approximate R m , n represents a maximum value such that R n is closest to R m , represents the phase error.

4. The method according to claim 3, characterized in that, The formula for performing an inverse fast Fourier transform in the wave number domain to obtain the time domain signals of the target object is: where, ss(x t , x r , y l , n k ) represents the time-domain signal, N k represents the number of sampling points of the scattered echo signal, δ(n k ) is defined as being equal to 1 if and only if n = n k , and being equal to 0 for other values of n.

5. The method according to claim 4, characterized in that, The method further includes: Determining the upsampling rate of the inverse fast Fourier transform, and padding zeros to the scattered echo signals in the beam domain when performing the inverse fast Fourier transform; Performing conditional constraints during the inverse fast Fourier transform to make where M represents the upsampling rate, and B k represents the beam domain bandwidth, and MN k represents the number of sampling points of the fast inverse Fourier transform.

6. The method according to claim 1, characterized in that, The reconstructing the objective function of the target object based on the time domain signals includes: Reconstructing the objective function of the target object, and compensating for the phase error caused by introducing the Fourier transform pair related to the wave number.

7. The method according to claim 6, characterized in that, The formula for the objective function for performing phase error compensation is: O(x, y, z) ≈∫∫∫dx t dx r dy l ·ss(x t ,x r ,y l ,n k )exp(jk0R m )C(x t ,x r ,y l ,n) Among them, O(x, y, z) represents the objective function, ss(x t , x r , y l , n k ) represents the time-domain signal, x t represents the x-axis coordinate of the transmitting antenna in the MIMO transceiver antenna array, x r represents the x-axis coordinate of the receiving antenna in the MIMO transceiver antenna array, y l represents the y-axis coordinate of the MIMO transceiver antenna array, k0 represents the minimum wavenumber, R m represents the sum of the distances from the receiving antenna and the transmitting antenna to the target object, C(x t , x r , y l , n) represents the compensation term of the phase error, R n represents the Fourier transform pair, n represents a maximum value such that R n is closest to R m , Δk represents the wavenumber domain sampling interval, N k represents the number of sampling points of the scattered echo signal.

8. A MIMO-SAR fast imaging device, characterized in that, Including: A signal acquisition module for collecting the scattered echo signals of the target object based on the MIMO transmit-receive line array; A signal modification module for modifying the functional representation form of the scattered echo signals, and stripping the variable related to the wave number in the functional representation form; A signal transformation module for introducing a Fourier transform pair related to the wave number into the modified scattered echo signals, and performing an inverse fast Fourier transform in the wave number domain to obtain the time domain signals of the target object; A signal reconstruction module for reconstructing the objective function of the target object based on the time domain signals, and performing imaging processing of the target object based on the objective function.

9. An electronic device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the computer program, each step in the MIMO-SAR fast imaging method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, having a computer program stored thereon, characterized in that When the computer program is executed by the processor, each step in the MIMO-SAR fast imaging method according to any one of claims 1 to 7 is implemented.

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