Rapid null pattern synthesis method

Abstract

The fast null directional diagram synthesis method is suitable for suppression of interference of an aerial carrier radar to a target object, the radar comprises array plane coordinates, and the method comprises the steps that S101, an array plane steering vector model # imgabs0 # is determined according to the array plane coordinates, S102, an optimization model P1 is constructed according to the array plane steering vector model and array element excitation w0 pointed by a current main wave beam of the radar, and the optimization model P2 is constructed according to the array element excitation w0 pointed by the current main wave beam of the radar; determining a target function according to the optimization model P1; and S103, determining an optimal weight value wopt according to the target function. While the precision and the accuracy are met, the calculation time consumption can be shortened, and the hardware cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of radar detection, and in particular relates to a fast null pattern synthesis method. Background Art

[0002] In a complex electromagnetic environment, the existing radar system is easily interfered by the target equipment. When the target is not in the direction of the radar detection main beam, the side lobe of the directional pattern is set to zero to increase the radar's low interception and anti-interference capabilities. However, when the array is large and the number of array elements is large, The complexity of the level is difficult to meet the real-time requirements, and when designing the receiving pattern, the array element excitation can realize amplitude and phase weighting. Therefore, the optimization model is usually a convex optimization problem, and the analytical solution can be directly given. The complexity of the matrix inversion method using LU decomposition is about It is also difficult to meet the real-time requirements when the array is large. Although the existing method derives an analytical expression without matrix inversion, it can only achieve the null sink design of two angle sampling points at most, and the null sink width is narrow, which is inefficient. Summary of the invention

[0003] In view of this, the fast null pattern synthesis method of the present invention solves the technical problem that the existing method causes low radar utilization efficiency.

[0004] A fast null pattern synthesis method is suitable for suppressing interference of a carrier radar to a target object. The radar includes array coordinates. The method includes:

[0005] S101: Determine the array guidance vector model according to the array coordinates

[0006] S102: constructing an optimization model P1 according to the array steering vector model and the array element excitation w0 pointed to by the current main beam of the radar, and determining an objective function according to the optimization model P1;

[0007] S103: Determine the optimal weight value w according to the objective function op t .

[0008] Beneficial Effects

[0009] The present invention is designed to be applicable to the phase-only weight at the transmitting end (only the phase of the array element excitation is adjustable), and can also be designed to be applicable to the amplitude-phase weight at the receiving end (both the amplitude and the phase of the array element excitation are adjustable). Through the use of this method, the null pattern weight can be quickly calculated during radar detection to reduce the radiation power in a specific direction, or to suppress the echo signal in the interference direction, thereby improving the low interception and anti-interference performance of the existing radar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 is the uniform square matrix coordinate of 500×500 array elements;

[0012] Figure 2 The directional pattern null obtained by the traditional phase-only weighting method;

[0013] Figure 3 This is the directional pattern null obtained by the method of the present invention. DETAILED DESCRIPTION

[0014] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0015] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0016] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0017] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and only show the components related to the present disclosure rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0018] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, one skilled in the art will appreciate that aspects may be practiced without these specific details.

[0019] Forming a null on the transmit pattern can reduce the radar's radiation power in a specific direction and prevent the radar signal from being intercepted by electronic reconnaissance equipment; forming a null on the receive pattern can prevent the entry of sidelobe interference signals and achieve spatial filtering. In actual combat scenarios, since the number and position of the target's electronic warfare equipment are unknown and changing, this requires that the pattern nulling algorithm should have the ability to adjust the number, position and width of the null in real time. When designing the transmit pattern, in order to ensure detection power, the array element excitation usually only uses phase-only constraints, which results in the design model being a non-convex optimization problem. The complexity of existing solutions in solving such problems is approximately N is the number of array elements, T is the number of algorithm iterations, and the utilization efficiency is low. The present invention makes improvements based on this problem.

[0020] like Figures 1 to 3 The fast null pattern synthesis method shown is suitable for suppressing interference of aircraft radar to target objects. Preferably, it is suitable for large-scale arrays. The radar includes array coordinates. The method includes

[0021] S101: Determine the array guidance vector model according to the array coordinates Specifically, the guided vector model It is expressed as:

[0022] Where N is the number of array elements; and θ are the azimuth and elevation angles respectively; is the array element directivity diagram of the nth array element; f0 is the radar carrier frequency, (x n ,y n ,z n ) is the coordinate of the nth array element, and c is the speed of light.

[0023] S102: construct an optimization model P1 according to the array steering vector model and the array element excitation w0 pointed to by the current main beam of the radar, and determine the objective function according to the optimization model P1. Specifically,

[0024] The optimization model P1 is expressed as:

[0025] In the formula, is the elevation angle and azimuth angle of the null area; |w(n)|=1 is the "phase-only" constraint, which is used to ensure that the array element works in a saturated state and is suitable for the design of the transmission pattern; ||w|| 2 =N is used to constrain the total excitation energy, which can be weighted by amplitude and phase, and is suitable for receiving pattern design; the first term of the objective function in the optimization model To form the null, the second term (1-λ)||w-w0|| 2 It is used to ensure that the characteristics of other areas of the directional pattern after the null is generated are consistent with the original directional pattern. The parameter λ is used to weigh the null depth and the overall directional pattern performance; w is the weight;

[0026] by As the objective function

[0027] S103: Determine the optimal weight value w according to the objective function opt , specifically:

[0028] The objective function is relaxed to a bilinear quadratic polynomial optimization model P2, expressed as: The purpose is to reduce the complexity of the problem

[0029]

[0030] Where b = (1-λ)w0; μ is the matrix When the bilinear variables in the optimization model are alternately solved, the quadratic problem is relaxed into a linear problem, and the complexity is reduced. The specific solution method is implemented in the following sub-steps; w is the real part operation; k For the optimization variable after w relaxation, k is a natural positive integer 1 or 2;

[0031] Determine the optimal weight w based on the quadratic polynomial optimization model P2 opt ,For example,

[0032] S401: Set t=0, initialize bilinear variables (t) represents the tth iteration, is the first-dimensional array element excitation when k=1, is the second-dimensional array element excitation when k=2;

[0033] S402: Optimize the bilinear quadratic polynomial optimization model P2, where the first dimension array element excitation is fixed Solving the second dimension of array element excitation It is expressed as:

[0034] j is the imaginary unit; ∠ is the operation for finding the complex phase angle; is the second vector; The second solution of the bilinear quadratic polynomial optimization model P2;

[0035] Or, fixed second dimension element excitation Solving the first-dimensional array element excitation It is expressed as:

[0036] is the first vector; is the first solution of the bilinear quadratic polynomial optimization model P2, where

[0037]

[0038] S403: The second solution and the first solution are respectively brought into the objective function of the bilinear quadratic polynomial optimization model P2, and the objective function value y is obtained. 1 and the objective function value y 2 , according to the objective function value y 1 and the objective function value y 2 Determine the optimal weight w opt ;

[0039] S404: objective function value y 1 and the objective function value y 2 Respectively expressed as:

[0040]

[0041] S405: According to the objective function value y 1 and the objective function value y 2 The relative size of the bilinear variable Update to meet:

[0042]

[0043] S406: Iterate steps S402-S405 until the algorithm converges or reaches the maximum number of iterations, and compare y at the last iteration. 1 and 2 The size of the optimal weight w opt , expressed as:

[0044]

[0045] Compared with the traditional method, the present invention iteratively solves the most complex calculation process steps S402-S405, wherein: and The calculation is based on the priority of the brackets in the calculation formula, and its calculation complexity is Considering the number of algorithm iterations T, the overall complexity of the algorithm proposed in this invention is It is linearly related to the number of array elements N. Both T and K are much smaller than N. Therefore, the algorithm efficiency is high, and the present invention reduces the overall complexity of the algorithm from Downgrade to It can shorten the calculation time and reduce the hardware cost while meeting the requirements of precision and accuracy.

[0046] Example

[0047] Step 1, based on Figure 1 Given uniform square matrix coordinates, construct a two-dimensional steering vector model:

[0048] Among them, the number of array elements N = 2500; and θ are the azimuth and elevation angles respectively; is the array element directivity diagram of the nth array element; f0 is the radar carrier frequency, (x n ,y n ,z n ) is the coordinate of the nth array element.

[0049] Step 2: Construct an optimization model based on the array steering vector model and the array element excitation w0 in the current beam pointing direction:

[0050]

[0051] st |w(n)|=1,n=1,…,N or ‖w|| 2 =N.

[0052] Assume the beam points to (0°, 0°), then w0 = 1 N ; Assume that the two nulls point to (-26°, 0°) and (55°, 0°) respectively, and the angle range of null 1 is θ k ∈[-0.5°,0.5°], the angle region of the null 2 ​​is θ k ∈[-0.5°,0.5°]; parameter λ=0.9.

[0053] Step 3: Relax the optimization model in step 2 and construct the following bilinear quadratic polynomial optimization model:

[0054]

[0055] st |w k (n)|=1,n=1,...,Nk=1,2 or||w k || 2 =N,k=1,2

[0056] Where b = (1-λ)w0; μ is the matrix The optimization model is solved in the following sub-steps.

[0057] Step 3.1, let t = 0, initialize the bilinear variables (t) represents the tth iteration.

[0058] Step 3.2, for the optimization problem in step 3, when fixed Solution hour, The solution is

[0059]

[0060] When the fixed solution hour, The solution is

[0061] in,

[0062]

[0063] Step 3.3: Substitute the value calculated in step 3.2 into and Substitute the following two equations and calculate their values.

[0064]

[0065] Step 3.4, compare y 1 The size of and is updated according to the following formula

[0066]

[0067] Step 3.5, iterate steps 3.2-3.4 until the algorithm converges or reaches the maximum number of iterations, and compare y at the last iteration 1 and 2 The size of the optimized weight is finally output according to the following formula:

[0068]

[0069] The effectiveness of the present invention is illustrated by simulation results below. Figure 2 The existing phase-only design method is based on Figure 1 The null pattern of the array design, Figure 3 The null-steering pattern obtained by the present invention includes a phase-only weighted design and an amplitude-phase weighted design. Figure 3It can be seen that the radiation pattern forms nulls in the preset directions of (-26°, 0°) and (55°, 0°), and the null depth is better than the existing solution, about -70dB. Figure 2 The complexity of the design scheme adopted is The number of algorithm iterations of the present invention is The complexity of the proposed method is better than that of the existing solutions, and its advantages are:

[0070] 1) The complexity of the algorithm of the present invention is It is linearly related to the number of array elements, where T is the number of algorithm iterations and K is the total number of sampling points in the null angle area. Both T and K are much smaller than N, so it has higher algorithm efficiency and better real-time performance.

[0071] 2) The method proposed in the present invention only needs to change one of the calculation steps when switching between phase-only weighting and amplitude-phase weighting design, and has good compatibility. When phase-only weighting is used, it is suitable for the design of transmitting pattern nulling, which can reduce the probability of radar signals being intercepted by reconnaissance receivers in a specific direction; when amplitude-phase weighting is used, it is suitable for the design of receiving pattern nulling, which can suppress interference in a specific direction.

[0072] 3) The design model proposed in the present invention optimizes the Euclidean distance between the array excitation and the given excitation w0, so that the overall shape of the directional pattern after the null is generated still maintains the characteristics of the original w0 directional pattern (such as low sidelobe characteristics).

[0073] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A fast null pattern synthesis method, suitable for suppressing interference of a carrier radar to a target object, the radar including a front coordinate, characterized in that: The methods include: S101: Determine the array guidance vector model according to the array coordinates S102: constructing an optimization model P1 according to the array steering vector model and the array element excitation w0 pointed to by the current main beam of the radar, and determining an objective function according to the optimization model P1; S103: Determine the optimal weight value w according to the objective function opt .

2. The fast null pattern synthesis method according to claim 1, characterized in that: Steering vector model in S101 It is expressed as: Where N is the number of array elements; and θ are the azimuth and elevation angles respectively; is the array element directivity diagram of the nth array element; f0 is the radar carrier frequency, (x n ,y n ,z n ) is the coordinate of the nth array element, and c is the speed of light.

3. The fast null pattern synthesis method according to claim 2, characterized in that: S102 includes: The optimization model P1 is expressed as: In the formula, is the elevation angle and azimuth angle of the null region; |w(n)|=1 is the "phase only" constraint; ||w|| 2 = N is used to constrain the total excitation energy, which can be weighted by amplitude and phase; the first term of the objective function in the optimization model To form the null, the second term (1-λ)||w-w0|| 2 It is used to ensure that the characteristics of other areas of the directional pattern after the null is generated are consistent with the original directional pattern. The parameter λ is used to weigh the null depth and the overall directional pattern performance; w is the weight; by as the objective function.

4. The fast null pattern synthesis method according to claim 3, characterized in that: S103 includes: The objective function is relaxed into a bilinear quadratic polynomial optimization model P2, expressed as: Where b = (1-λ)w0; μ is the matrix The maximum eigenvalue of , R is the real part operation; w k For the optimization variable after w relaxation, k is a natural positive integer 1 or 2; Determine the optimal weight value w according to the quadratic polynomial optimization model P2 opt .

5. The fast null pattern synthesis method according to claim 4, characterized in that: Determine the optimal weight value w according to the quadratic polynomial optimization model P2 opt include, S401: Set the number of iterations t=0, initialize the bilinear variables is the first-dimensional array element excitation when k=1, is the second-dimensional array element excitation when k=2; S402: Optimizing the bilinear quadratic polynomial optimization model P2, wherein the first-dimensional array element excitation is fixed Solving the second dimension of array element excitation It is expressed as: j is the imaginary unit; ∠ is the operation for finding the complex phase angle; is the second vector; The second solution of the bilinear quadratic polynomial optimization model P2; Or, fixed second dimension element excitation Solving the first-dimensional array element excitation It is expressed as: is the first vector; is the first solution of the bilinear quadratic polynomial optimization model P2, where S403: The second solution and the first solution are respectively brought into the objective function of the bilinear quadratic polynomial optimization model P2, and the objective function value y is obtained. 1 and the objective function value y 2 , according to the objective function value y 1 and the objective function value y 2 Determine the optimal weight w opt .

6. The fast null pattern synthesis method according to claim 5, characterized in that: According to the objective function value y 1 and the objective function value y 2 Determine the optimal weight w opt include, S404: objective function value y 1 and the objective function value y 2 Respectively expressed as: S405: According to the objective function value y 1 and the objective function value y 2 The relative size of the bilinear variable Update to meet: S406: Iterate steps S402-S405 until the algorithm converges or reaches the maximum number of iterations, and compare y at the last iteration. 1 and 2 The size of the optimal weight w opt , expressed as:

Images