Method, device and medium for generating target situation in line-of-sight and non-line-of-sight measurement in multipath environment

Abstract

The present invention discloses a method, device and medium for generating target situation in line-of-sight and non-line-of-sight measurement in a multipath environment, which can be applied to the field of radar target situation generation technology. The present invention addresses the problem that the existing non-line-of-sight target measurement method only considers non-line-of-sight scenarios and cannot be applied to more complex scenarios. Based on the electromagnetic wave propagation characteristics in a typical corner scenario where line-of-sight targets and non-line-of-sight targets coexist, the present invention establishes the background clutter and target position in the scene as an optimization problem with low rank, sparse and group sparse joint constraints, and adopts an iterative optimization method based on proximal gradient to obtain the optimization result of the optimization problem, and obtains the line-of-sight and non-line-of-sight measurement target situation. The present invention suppresses clutter while achieving high-precision reconstruction of line-of-sight target and non-line-of-sight target images. The present invention can efficiently and accurately achieve line-of-sight and non-line-of-sight target situation generation at a low signal-to-noise ratio.

Description

Technical Field

[0001] The present application relates to the field of radar measurement technology, and in particular to a method, device and medium for generating target situation in line-of-sight and non-line-of-sight measurement in a multipath environment. Background Art

[0002] Non-line-of-sight target measurement technology (NLOS-TM) can accurately locate, track and image hidden targets outside the line of sight by capturing multipath signals formed by diffraction from building edges and reflection from walls. This technology greatly expands the measurement range of traditional radar systems and brings revolutionary progress to fields such as monitoring and autonomous driving.

[0003] Many research institutions at home and abroad have conducted research on target detection technology based on the use of multipath signals and have produced rich research results. Some researchers have conducted experiments using X-band radars and found that electromagnetic waves can reach the target through multiple reflections from buildings, ultimately forming rich multipath echoes. Based on experimental analysis of multipath phenomena, researchers have also proposed a variety of algorithms for using multipath signals to achieve target situation generation, including methods based on matched subspace filters, methods based on arrival time, and methods based on grid matching.

[0004] Despite the great progress made in the field of NLOS-TM, there are still several issues that remain unsolved in previous works. One of the main challenges of NLOS-TM is the matching problem between the theoretical multipath propagation model and the actual situation. Existing methods only consider the presence of non-line-of-sight targets in the radar's surveillance area. However, these methods fail once the line-of-sight targets enter the radar beam. The reasons are: on the one hand, the superposition of line-of-sight and non-line-of-sight target echoes increases the complexity of multipath signal modeling. On the other hand, since the signal strength from the line-of-sight target is usually much higher than that from the non-line-of-sight target, the non-line-of-sight signal may be masked by the stronger line-of-sight signal during the target measurement process.

[0005] Another issue worth paying attention to in NLOS-TD is clutter suppression. Since NLOS-TD needs to extract extremely weak target signals from multipath echoes, these weak signals are often masked by strong clutter, so it is difficult to effectively utilize multipath echoes. Although existing moving target indication methods such as two-pulse cancellation and mean cancellation can achieve clutter suppression, they also reduce the signal-to-noise ratio of target echoes. Therefore, it is of great practical significance to study a target situation generation method suitable for line-of-sight and non-line-of-sight measurement in complex multipath environments. Summary of the invention

[0006] To solve the above technical problems, the present application proposes a method, device and medium for generating target situation in a multipath environment line-of-sight and non-line-of-sight measurement, which can achieve line-of-sight and non-line-of-sight joint target position measurement and situation generation while suppressing scene clutter.

[0007] The first aspect of the present application provides a method for generating a target situation for line-of-sight and non-line-of-sight measurement in a multipath environment, the method comprising the following steps:

[0008] Step 1, constructing a multipath echo signal model in a scenario where non-line-of-sight targets and line-of-sight targets coexist based on background clutter signals, line-of-sight-non-line-of-sight target echo signals and noise;

[0009] The line-of-sight-non-line-of-sight target echo signal includes a line-of-sight target echo signal of a target located in a line-of-sight area and a non-line-of-sight target echo signal of a target located in a non-line-of-sight area;

[0010] Step 2: Based on the constructed multipath echo signal model, the background clutter signal and the target position are constructed into a target measurement optimization model with low rank, sparse and group sparse joint constraints;

[0011] Among them, the constraint condition of the target measurement optimization model is that the approximation error between the echo signal calculated based on the multipath echo signal model and the echo signal measurement data is within the allowable range;

[0012] Step 3, the proximal gradient method is used to iteratively solve the target measurement optimization model to obtain the target situation generation image of the line-of-sight target and the non-line-of-sight target, that is, the target reconstructed image of the target position.

[0013] This application is first based on the electromagnetic wave propagation characteristics in scenes where line-of-sight targets and non-line-of-sight targets coexist (such as typical corner scenes). Then the background clutter and target position in the scene are established as a low-rank, sparse and group-sparse joint constraint optimization problem to build a target measurement optimization model; finally, the target measurement optimization model is iterated based on the proximal gradient method to achieve high-precision reconstruction of line-of-sight targets and non-line-of-sight target images while suppressing clutter. This application can efficiently and accurately achieve line-of-sight and non-line-of-sight target situation generation at low signal-to-noise ratio.

[0014] Furthermore, the multipath echo signal model in step 1 is specifically:

[0015]

[0016] in, , , , Respectively The dimensions of the line-of-sight-non-line-of-sight target echo signal, clutter signal, target echo signal and noise in a transmission cycle are ,in, is the number of radar units, is the frequency point number.

[0017] Furthermore, step 1 includes:

[0018] The imaging space is divided into equal-sized grids, define Indicates The first emission cycle The reflectivity coefficient of the grid is When there is a target in the grid, its value corresponds to the reflectivity coefficient of the target; otherwise ;

[0019] Based on dictionary matrix and Reflection coefficient The reflectivity coefficient vector Acquire line-of-sight and non-line-of-sight target echo signals The matrix-vector form of is:

[0020]

[0021] in, , Respectively The echo signals of non-line-of-sight targets and line-of-sight targets in each transmission cycle are: They are the dictionary matrix and reflectivity coefficient vector of non-line-of-sight targets respectively; They are the dictionary matrix and reflectivity coefficient vector of the sight range target, the dictionary matrix Each element of is:

[0022]

[0023] in, For complex fields, element index , is an imaginary unit, For the The frequency of the frequency point, The time delay for the target, Indicates the radar channel number.

[0024] Furthermore, in step 2, based on the downsampling matrix For the measured data ( ) and the observation matrix are downsampled, and the target measurement optimization model after downsampling is:

[0025] ;

[0026] Among them, the downsampling matrix , is the expected dimension after downsampling, is the clutter signal matrix after downsampling, , Represent the reflection coefficient matrices of the line-of-sight target and the non-line-of-sight target respectively, represents the number of non-line-of-sight target propagation paths, is the dictionary matrix of the downsampled sight range target, is the dictionary matrix of the downsampled non-line-of-sight target, with parameters and are two regularization factors, is the preset threshold, symbol express norm, represents the low-rank norm, and Respectively and Norm.

[0027] Furthermore, step 3 specifically includes:

[0028] Construct the objective function of the Lagrangian form of the target measurement optimization model:

[0029]

[0030] in, is the measured data of the echo signal after downsampling, is a positive value used to balance the fidelity term and the regularization term.

[0031] Furthermore, in step 3, the proximal gradient method is used to iteratively solve the target measurement optimization model, specifically including:

[0032] Estimation of the downsampled clutter signal matrix using the alternating multiplier method And the reflection coefficient matrix and , the Lagrangian objective function It can be broken down into the following three sub-problems:

[0033]

[0034] Among them, the subscript is the current iteration number, For the The clutter signal matrix after downsampling at the iteration is based on the subproblem <1> The solution result is, For the The reflection coefficient matrix of the sight target at the iteration is based on the subproblem <2> The solution result is:

[0035] Solve the three sub-problems in turn. <1> Using singular value soft threshold method, sub-problem <2> and <3> Adopting gradient iteration method;

[0036] Finally, the reflection coefficient matrix of the obtained line-of-sight target and non-line-of-sight target is , After matrixing, images of line-of-sight targets and non-line-of-sight targets can be obtained.

[0037] A second aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to execute the method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement as described in the present application.

[0038] A third aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, the program being executed by a processor to execute the method for generating a target situation in a multipath environment line-of-sight and non-line-of-sight measurement as described in the present application.

[0039] The technical solution provided by this application brings at least the following beneficial effects:

[0040] The method of the present invention has the following advantages:

[0041] (1) A multipath propagation model is established, which takes into account the direct echo from the line-of-sight target and the multipath echo from the non-line-of-sight target. This model can solve the problem of radar target situation generation in the context of compressed sensing, thereby facilitating fast data acquisition and efficient data storage;

[0042] (2) An optimization model for target localization and clutter suppression combined with low-rank sparse regularization is constructed. By using the proximal forward-backward splitting technique, the target localization and clutter suppression problems can be effectively solved with fast convergence speed.

[0043] (3) This application can be applied to fields such as autonomous driving and disaster relief. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0045] Figure 1 A flow chart of a method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement provided in an embodiment of the present application;

[0046] Figure 2A schematic diagram of electromagnetic wave propagation in a corner scenario where a non-line-of-sight (NLOS) target and a line-of-sight (LOS) target coexist in an embodiment of the present application;

[0047] Figure 3 A schematic diagram of a scenario in which LOS and NLOS targets coexist in an embodiment of the application;

[0048] Figure 4 It is a schematic diagram for comparing the electromagnetic simulation results in the application embodiment, wherein: Figure 4 (a) and (c) are the multi-dictionary fusion reconstruction results of LOS target and NLOS target obtained by the existing methods, respectively. Figure 4 (b) and (d) are target situation generation images of the LOS target and NLOS target respectively reconstructed by the method proposed in the embodiment of the present application.

[0049] Figure 5 A schematic diagram of the structure of an electronic device provided for an application embodiment. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions of the embodiments of the present application will be described in detail and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described with reference to the drawings are exemplary and are intended to be used to explain the present application, and cannot be understood as limiting the present application.

[0051] The embodiment of the present application provides a method for generating target situation in line-of-sight and non-line-of-sight measurement in a multipath environment, which is used to solve the problem that the existing non-line-of-sight target measurement method only considers non-line-of-sight scenarios and cannot be applied to more complex scenarios, so as to achieve efficient and accurate line-of-sight and non-line-of-sight target situation generation under low signal-to-noise ratio.

[0052] See also Figure 1 The present application provides a method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement, which is applied to a scenario where non-line-of-sight targets and line-of-sight targets coexist, and includes the following steps:

[0053] Step S1, constructing a multipath echo signal model in a scenario where non-line-of-sight targets and line-of-sight targets coexist based on background clutter signals, line-of-sight-non-line-of-sight target echo signals and noise;

[0054] The line-of-sight-non-line-of-sight target echo signal includes a line-of-sight target echo signal of a target located in a line-of-sight area and a non-line-of-sight target echo signal of a target located in a non-line-of-sight area;

[0055] Step S2, based on the constructed multipath echo signal model, the background clutter signal and the target position are constructed into a target measurement optimization model with low rank, sparse and group sparse joint constraints;

[0056] Among them, the constraint condition of the target measurement optimization model is that the approximation error between the echo signal calculated based on the multipath echo signal model and the echo signal measurement data is within the allowable range;

[0057] In step S3, the target measurement optimization model is iteratively solved using the proximal gradient method to obtain target reconstruction images (i.e., target situation generation images) of the target positions of the line-of-sight target and the non-line-of-sight target, so as to reconstruct high-precision line-of-sight target and non-line-of-sight target images while suppressing clutter.

[0058] In one embodiment, the scenario where non-line-of-sight targets and line-of-sight targets coexist may be: Figure 2 The typical corner scene shown in the figure includes two buildings, namely Building 1 and Building 2. The radar is deployed on one side of Building 1. The wall close to the radar is defined as Wall 1. The two walls opposite to Building 1 and Building 2 are defined as Wall 2 and Wall 3 respectively. The turning point of Building 1 is defined as C. The corresponding non-line-of-sight area (NLOS area) and line-of-sight area (LOS area) are as follows: Figure 2 As shown, the area between wall 2 and wall 3 is the NLOS area, and there are several targets in the NLOS area, namely, non-line-of-sight targets (NLOS targets), such as Figure 2 Target-II in the LOS region, and there are several targets, namely, line-of-sight targets (LOS targets), such as Figure 2 Target-I in. Among them, Figure 2 Path-D in the figure represents the direct-view path, and Path-1 and Path-2 represent the two reflection paths of target-II (NLOS target).

[0059] Consider Figure 2 The scene shown in the figure has LOS targets, and NLOS targets. Assume that each transmitter transmits The pulse repetition interval (PRI) is , number of cycles is recorded as slow time. The radar unit is equivalent to Among them, The first cycle The radar channel The echo signal of a frequency point It can be expressed as:

[0060] (1)

[0061] in, , , is the frequency point number, is the scene clutter signal, that is, the background clutter signal, is the target echo signal, For noise.

[0062] Since the clutter signal remains unchanged during the observation time, it can be expressed as:

[0063] (2)

[0064] in, represents the number of reflection paths formed by buildings and other reflectors, is the reflection coefficient, and The paths The path loss factor and time delay, is the natural base, is an imaginary unit, For the The frequency of a frequency point.

[0065] Considering that there are both LOS targets and NLOS targets in the measurement area, the target echo signal can be expressed as a combination of the LOS target and the NLOS target echo signal, expressed as:

[0066] (3)

[0067] in, , Respectively The first cycle The radar channel The echo signals of LOS targets and NLOS targets at different frequencies.

[0068] Using the direct line of sight path, targets located in the line of sight area can be observed, such as Figure 2 The target shown is -I. Therefore, The echo signal of a LOS target can be specifically expressed as:

[0069] (4)

[0070] in, For the The frequency of the frequency point, for The index of the LOS target, For LOS target The reflection coefficient, and LOS targets The path loss factor and time delay.

[0071] For NLOS targets that are blocked by buildings and located in the radar blind area, the traditional line-of-sight detection method fails due to the obstruction of the line-of-sight path. However, the multipath signal generated by the reflection of the building wall can be used to observe non-line-of-sight targets. Based on the multipath propagation characteristics of electromagnetic waves, the NLOS target echo signal can be reconstructed as:

[0072] (5)

[0073] in, represents the number of NLOS target propagation paths, for The index of the NLOS target, For LOS target On the path The reflection coefficient, and LOS targets On the path The path loss factor and time delay.

[0074] Will channels and The measured data of each frequency point (also called measured data) is superimposed in vector form , so the echo signal model can be rewritten as:

[0075] (6)

[0076] in, is the echo signal vector, is the background clutter signal vector, is the target echo signal vector, is the noise vector, and the dimensions of the three vectors are .

[0077] In order to obtain LOS and NLOS target situation generation images, it is necessary to establish a representation relationship between the target echo and the imaging space. To this end, the imaging space is first divided into (It can be set based on the actual scene requirements) grids of equal size. Indicates The reflectivity coefficient of the grid is When there is a target in the grid, its value corresponds to the reflectivity coefficient of the target. Otherwise, Therefore, the In the cycle The target echo signals of each channel can be expressed in matrix-vector form, which can be expressed as:

[0078] (7)

[0079] in, For the The reflectivity coefficient vector of the period, is a dictionary matrix, each element of which is:

[0080] (8)

[0081] in, is a complex field, .

[0082] Since the direct round-trip path of the LOS target usually produces a stronger signal than the multipath signal, the embodiment of the present application normalizes the complex amplitude corresponding to the NLOS target relative to the LOS target during processing to prevent over-parameterization. It can be expressed as:

[0083] (9)

[0084] in, Indicates that the direct view path is The path loss factor at each pixel is: For the The path in The path loss factor at each pixel point. Therefore, the echo signal of the NLOS target is represented as the sum of the delays and weights of the transmission signals corresponding to all possible propagation paths, expressed as:

[0085] (10)

[0086] in, For the The echo signal vector of the NLOS target with a period, represents the path weight matrix, .

[0087] For ease of expression, the path weight matrix can be Merge to target scatter vector middle, Therefore, the modified echo signal vector of the NLOS target can be rewritten as follows:

[0088] (11)

[0089] in, is the dictionary matrix of NLOS targets, For NLOS targets The reflectivity coefficient vector of the period, and , ,symbol Indicates transpose.

[0090] In one embodiment, due to the sparsity of LOS targets and the group sparsity between different sub-images formed by NLOS targets, in step S2, the target measurement problem is expressed as the following optimization problem:

[0091] (12)

[0092] in, and Respectively and Norm. Parameters and As a regularization factor, it is used to control the sparsity of the reconstructed image. is the preset threshold.

[0093] Assumptions express The measured data of the period, each column represents channels and Correspondingly, the background clutter signal, target echo signal and noise can be expressed as , as well as Therefore, the echo signal model can be expressed as:

[0094] (13)

[0095] In order to reduce the echo correlation, the data matrix (i.e. the measured data ) and the observation matrix are downsampled. Assume that the downsampled target echo signal is expressed as:

[0096] (14)

[0097] in, is the downsampling matrix, , Represent the reflection coefficient matrices of LOS target and NLOS target respectively, , . is the dictionary matrix of the downsampled sight range target, is the dictionary matrix of the downsampled non-line-of-sight target. Since the time delay of the wall clutter to each channel is consistent and satisfies the low-rank characteristic in space, the optimization problem shown in formula (12) can be rewritten as:

[0098] (15)

[0099] Formula (15) is the target measurement optimization model constructed in this embodiment, and the corresponding constraint term is the difference between the echo signal calculated based on the multipath echo signal model and the echo signal measurement data: The square of the norm is within the allowable range, that is, the difference between the calculated echo signal and the echo signal measurement data The square of the norm does not exceed the preset threshold The optimization model can be iteratively solved using the proximal gradient method, and the target positions of the LOS target and the NLOS target can be obtained based on the solution results, and the target situation generation image can be reconstructed. for Norm.

[0100] in, , of The norm is calculated as follows:

[0101] (16)

[0102] Based on formula (15), the corresponding Lagrangian objective function can be obtained as:

[0103] (17)

[0104] in, is a positive value used to balance the fidelity term and the regularization term. represents the low-rank norm.

[0105] In one embodiment, based on the objective function shown in formula (17), the specific solution process of the constructed target measurement optimization model is:

[0106] Clutter estimation using the alternating method of multipliers (ADMM) And the target matrix and . The Lagrangian form of the problem can be decomposed into the following form:

[0107] (18)

[0108] <1> Sub-questions:

[0109] The subproblem above can be rewritten as:

[0110] (19)

[0111] in, , the singular value soft threshold method is used to solve the rank minimization relaxation problem in the above formula. And the solution of formula (19) is used as , that is, The stationary clutter signal matrix at the iteration is: is the current iteration number.

[0112] <2> , Sub-questions:

[0113] <2-1> For The sub-problem can be calculated using the gradient iteration method, as shown in the following formula:

[0114] (20)

[0115] in, For the The reflection coefficient matrix of the sight-range target at the iteration, that is, the reflection coefficient matrix of the sight-range target after the current update, can be obtained based on the solution result of formula (20).

[0116] in Defined as:

[0117] (twenty one)

[0118] In the above formula satisfy For the above formula The norm is solved using the soft threshold method.

[0119] <2-2> For The sub-problem can also be calculated using the gradient iteration method, as shown in the following formula:

[0120] (twenty two)

[0121] in, For the The reflection coefficient matrix of the non-line-of-sight target at the iteration, that is, the reflection coefficient matrix of the non-line-of-sight target after the current update, can be obtained based on the solution result of formula (22).

[0122] The auxiliary variables It is expressed as:

[0123] (twenty three)

[0124] in, It is the reflection coefficient matrix of the non-line-of-sight target at the current iteration.

[0125] To ensure convergence, the parameter satisfy .symbol represents the conjugate transpose. The norm is solved using the row soft thresholding method.

[0126] Finally, the reflection coefficient matrices of the LOS and NLOS targets are solved. , After matrixing, images of LOS targets and NLOS targets can be obtained.

[0127] The reconstruction performance of the target situation generation image of the multipath environment line-of-sight-non-line-of-sight measurement target situation generation method provided by the embodiment of the present application is further verified through simulation verification. Figure 3 As shown in the figure, it consists of two 2m×6m buildings, with a relative dielectric constant ε of 8 and a conductivity σ of 0.1S / m. The two targets move in the range of (3.0, 1.0)m to (5.0, 1.0)m and (2.5, 4.0)m to (4.5, 6.0)m respectively. A 2-transmit 4-receive MIMO array is used for target detection. The transmitting antennas are placed at (1, 1)m and (1, 1.4)m, and the receiving antennas are placed at an equal interval of 0.1m. The center frequency is used. =1.5GHz, a stepped frequency signal with bandwidth B=1GHz is used as the transmitting signal.

[0128] The multi-imaging dictionary fusion results are as follows Figure 4 As shown in (a) and (c), this is the method proposed in the literature “Multiple targets localization behind L-shaped corner via UWB radar, IEEE Trans. Veh. Technol, vol. 70, no.4, pp. 3087-3100, Apr. 2021.” It can be found that due to problems such as grating lobes and imaging expansion, the performance of this method is poor, and ghost interference will occur around the wall. Figure 4 (b) and (d) are the target situation generation images of the LOS target and the NLOS target reconstructed by the method proposed in the embodiment of the present application. The method proposed in the present application can effectively realize the positioning of the LOS target and the NLOS target. And compared with the multi-imaging dictionary fusion method, the method proposed in the present application can effectively suppress background clutter while measuring the LOS target and the NLOS target.

[0129] Figure 5A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include: a memory, a processor, and a computer program stored in the memory and executable on the processor; when the processor executes the program, the method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement provided in the above embodiment is implemented.

[0130] Furthermore, the electronic device further comprises:

[0131] A communication interface for communication between the memory and the processor;

[0132] Memory is used to store computer programs that can be run on the processor.

[0133] The memory may include high-speed random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage. If the memory, processor and communication interface are implemented independently, the communication interface, memory and processor can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0134] Optionally, in a specific implementation, if the memory, processor and communication interface are integrated on a chip, the memory, processor and communication interface can communicate with each other through an internal interface. The processor may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0135] This embodiment also provides a computer-readable storage medium, in which at least one computer program is stored. The at least one computer program is loaded and executed by a processor of a computer device to implement the method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement provided in this embodiment.

[0136] In a possible implementation, the computer-readable storage medium may be a read-only memory, a random access memory, a read-only optical disk, a magnetic tape, an optical data storage device, and the like.

[0137] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0138] Any process or method description described in a flowchart or otherwise in this specification may be understood to represent a module, fragment or portion of code that includes one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0139] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0140] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for generating target situation in line-of-sight and non-line-of-sight measurement in a multipath environment, characterized in that: The following steps are involved: Step 1, constructing a multipath echo signal model in a scenario where non-line-of-sight targets and line-of-sight targets coexist based on background clutter signals, line-of-sight-non-line-of-sight target echo signals and noise; The line-of-sight-non-line-of-sight target echo signal includes a line-of-sight target echo signal of a target located in a line-of-sight area and a non-line-of-sight target echo signal of a target located in a non-line-of-sight area; Step 2: Based on the constructed multipath echo signal model, the background clutter signal is constructed as a target measurement optimization model with low rank, sparse and group sparse joint constraints; Among them, the constraint condition of the target measurement optimization model is that the approximation error between the echo signal calculated based on the multipath echo signal model and the echo signal measurement data is within the allowable range; Step 3, using the proximal gradient method to iteratively solve the target measurement optimization model to obtain target situation generation images of the line-of-sight target and the non-line-of-sight target; in, The multipath echo signal model in step 1 is specifically: Among them, y k , ξ k are the echo signal, background clutter signal, line-of-sight-non-line-of-sight target echo signal and noise in the kth transmission cycle, and their dimensions are all MN×1, where M is the number of radar units and N is the number of frequency points; Step 1 also includes: dividing the imaging space into Q equal-sized grids along the azimuth and distance directions, defining s k (q) represents the reflectivity coefficient of the qth grid in the kth emission cycle. When there is a target in the qth grid, its value corresponds to the reflectivity coefficient of the target; otherwise, s k (q) = 0; Based on dictionary matrix and Q reflection coefficients s k (q) is the reflectivity coefficient vector Acquire line-of-sight and non-line-of-sight target echo signals The matrix-vector form of is: in, are the non-line-of-sight target echo signal and line-of-sight target echo signal in the kth transmission cycle, respectively, NLOS , are the dictionary matrix and reflectivity coefficient vector of non-line-of-sight targets respectively; Ψ LOS , They are the dictionary matrix and reflectivity coefficient vector of the sight range target, the dictionary matrix Each element of is: Ψ(i',q)=exp(-j2πf n t m,q ),n=i'modN, in, is a complex field, element index i'=0,…,MN-1, j is an imaginary unit, f n is the frequency of the nth frequency point, τ m,q is the time delay of the target, and m is the radar channel number. In step 2, the measured data and the observation matrix are downsampled based on the downsampling matrix Φ, and the target measurement optimization model after downsampling is: Among them, the downsampling matrix K' is the expected dimension after downsampling, is the background clutter signal matrix after downsampling, They represent the reflection coefficient matrices of the line-of-sight target and the non-line-of-sight target respectively, R represents the number of propagation paths of the non-line-of-sight target, is the dictionary matrix of the downsampled sight range target, is the dictionary matrix of the downsampled non-line-of-sight target, parameters λ1 and λ2 are two regularization factors, ∈ is the preset threshold, and the symbol ||·|| F represents the F-norm, ||·|| * represents the low-rank norm, ||·||1 and ||·|| 2,1 Represent l1 and l 2,1 Norm.

2. The method for generating target situation in a multipath environment line-of-sight-non-line-of-sight measurement as claimed in claim 1, characterized in that: Step 3 specifically includes: Construct the objective function of the Lagrangian form of the target measurement optimization model: in, is the measured data of the downsampled echo signal, γ is a preset positive value used to balance the fidelity term and the regularization term, and the symbol ||·|| F represents the F-norm, ||·|| * represents the low-rank norm, ||·||1 and ||·|| 2,1 Represent l1 and l 2,1 Norm.

3. The method for generating target situation in a multipath environment line-of-sight-non-line-of-sight measurement as claimed in claim 2, characterized in that: In step 3, the proximal gradient method is used to iteratively solve the target measurement optimization model, specifically including: Estimate the downsampled background clutter signal matrix Y using the alternating multiplier method w , and the estimated reflection coefficient matrix and The objective function in Lagrangian form It can be broken down into the following three sub-problems: Among them, the subscript i is the current iteration number, is the downsampled background clutter signal matrix at the i+1th iteration, which is based on the subproblem <1> The solution result is, is the reflection coefficient matrix of the sight target at the i+1th iteration, based on the subproblem <2> The solution result is: Solve the three sub-problems in turn. <1> Using singular value soft threshold method, sub-problem <2> and <3> Adopting gradient iteration method; Finally, the reflection coefficient matrix of the obtained line-of-sight target and non-line-of-sight target is After matrixing, images of line-of-sight targets and non-line-of-sight targets can be obtained.

4. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement as described in any one of claims 1 to 3.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the method for generating a target situation in a multipath environment line-of-sight-non-line-of-sight measurement as claimed in any one of claims 1 to 3.

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