A broadband space-time anti-interference method for reconstructing direction vector

Abstract

A broadband space-time anti-jamming method for reconstructing the direction vector, and its implementation steps are as follows: (1) Establish a space-time uniform linear array model; (2) Divide the entire target signal frequency band into I frequency sub-bands, and reconstruct the desired signal direction vector c for each frequency sub-band i ; (3) According to the reconstructed sub-band direction vector c i , further construct the constraint matrix C; (4) Establish the linear constraint minimum variance criterion expression of the broadband signal space-time anti-jamming filtering algorithm; (5) Use the Lagrange multiplier method to solve the optimal weight expression as w opt ; (6) The array beam synthesis outputs the received signal after anti-jamming. The present invention can achieve the suppression of broadband interference signals, maintain the flatness of the in-band array gain of the broadband desired signal, and has the advantages of small degrees of freedom consumption and simple algorithm. The present invention can be applied to fields such as broadband satellite communication

Description

Technical Field

[0001] The invention relates to the field of satellite communications, and in particular to utilizing a space-time array to achieve suppression of broadband interference signals and distortion-free reception of broadband desired signals. Background Art

[0002] With the development of information technology and the change of demand, in the field of satellite communications, broadband signal systems are the inevitable direction of future development. The use of array antennas and beamforming algorithms with space-time two-dimensional structures can effectively suppress broadband interference. However, traditional space-time anti-interference technology either uses single-frequency point constraints and directly applies narrowband anti-interference methods to space-time two-dimensional structures, which will result in uneven gain within the desired signal band; or uses full-band multi-frequency point constraints, resulting in excessive consumption of degrees of freedom, limiting the number of interference suppression and interference suppression capabilities. To this end, the present invention proposes a broadband space-time anti-interference method for reconstructing directional vectors. Summary of the invention

[0003] The problem to be solved by the present invention is: the problem of gain fluctuation in the desired signal band and excessive degree of freedom consumption caused by the traditional space-time anti-interference method when receiving a broadband desired signal. The method for solving the technical problem is a broadband space-time anti-interference method for reconstructing a direction vector, and the implementation steps are:

[0004] (1) Establish a space-time uniform linear array model. M array elements are arranged into a uniform linear array. The first array element of the linear array is located at the origin of the coordinate system. The array element spacing is d. The expected signal incident angle is θ. 0 , the broadband incident desired signal at the origin of the coordinate is s(t). The time delay between adjacent array elements is τ. Each array element channel is connected to an N-order transverse filter, and the system sampling period is T s The signal after the nth-order delay of the mth array element is expressed as x m,n (kT s ), where m = 0, ..., M-1, n = 0, ..., N-1, k is the sampling sequence, k = 0, 1, ..., K-1. The space-time array receives the signal vector X(kT s )for

[0005] X(kT s )=[X 0 X 1 ...X N-1 ] T

[0006] Among them, the sequence number 0, 1, ..., N-1 represents the space-time order, the symbol "T" represents the transpose, X n The expression is

[0007] X n =[x 0,n (kTs ) x 1,n (kT s )…x M-1,n (kT s )] T

[0008] Define the desired signal space-time direction vector a(θ 0 ,ω), which can be calculated by known parameters, and the calculation formula is:

[0009]

[0010] Where ω is the intermediate frequency of the incident signal. The weight w is the column vector to be solved, expressed as

[0011] w=[w 0,0 w 1,0 …w M-1,0 w 0,1 w 1,1 …w M-1,1 …w 0,N-1 w 1,N-1 …w M-1,N-1 ] T

[0012] It is a column vector of MN dimension.

[0013] (2) Reconstruct the desired signal direction vector. The specific steps are as follows:

[0014] In the first step, the entire desired signal frequency band is divided into I frequency sub-bands;

[0015] The second step is to select J frequency values ​​ω at equal intervals in the i-th frequency subband. i,j , j = 0, 1, ..., J-1, and calculate the direction vector a (θ 0 ,ω i,j ), reconstruct the desired signal direction vector in the i-th frequency subband as

[0016]

[0017] (3) According to the reconstructed subband direction vector c i , further construct the constraint matrix C, the expression of C is

[0018] C=[c 0 c 1 …c I-1 ]

[0019] Among them, the dimension of C is MN×I.

[0020] (4) After the space-time steering vector is reconstructed, the linearly constrained minimum variance criterion expression of the broadband signal space-time anti-interference filtering algorithm is established:

[0021]

[0022] The symbol “H” indicates taking the conjugate transpose, and the constraint response vector g is

[0023] g=[1 1…1]

[0024] It is a row vector of dimension 1×I.

[0025] (5) Using the Lagrange multiplier method, the optimal weight expression is solved as w opt

[0026]

[0027] in,

[0028]

[0029] μ 2 =C H R -1 C

[0030] All of them can be calculated matrices, so as to finally obtain the optimal weight expression w opt .

[0031] (6) The output signal of the array after anti-interference is expressed as

[0032]

[0033] The beneficial effect of the present invention is that it can suppress broadband interference signals, keep the in-band array gain of broadband desired signals flat, and has the advantages of low degree of freedom consumption and simple algorithm. The present invention can be applied to the fields of broadband satellite communications and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the geometric structure of a uniform linear array;

[0035] Figure 2 It is a schematic diagram of the space-time anti-interference beam synthesis structure;

[0036] Figure 3 The present invention is a flowchart of a broadband space-time anti-interference method for reconstructing a directional vector. DETAILED DESCRIPTION

[0037] First, a space-time array receiving signal model is established, and the receiving signal bandwidth is divided into multiple frequency sub-bands. Each frequency sub-band uses multiple frequency points to reconstruct the space-time direction vector, and then the new space-time direction vector is constrained, and finally the optimal weight vector solution is solved. The overall steps are as follows: Figure 3 As shown, the specific implementation steps are:

[0038] (1) Establish a space-time uniform linear array model. M array elements are arranged into a uniform linear array. The first array element of the linear array is located at the origin of the coordinate system. The array element spacing is d. The expected signal incident angle is θ. 0 , the broadband incident desired signal at the origin of the coordinate is s(t). The time delay between adjacent array elements is τ. Each array element channel is connected to an N-order transverse filter, and the system sampling period is T s The signal after the nth-order delay of the mth array element is expressed as x m,n (kT s ), where m = 0, ..., M-1, n = 0, ..., N-1, k is the sampling sequence, k = 0, 1, ..., K-1. The space-time array receives the signal vector X(kT s )for

[0039] X(kT s )=[X 0 X 1 …X N-1 ] T

[0040] Among them, the sequence number 0, 1, ..., N-1 represents the space-time order, the symbol "T" represents the transposition, X n The expression is

[0041] X n =[x 0,n (kT s ) x 1,n (kT s )…x M-1,n (kT s )] T

[0042] Define the desired signal space-time direction vector a(θ 0 ,ω), which can be calculated by known parameters, and the calculation formula is:

[0043]

[0044] Where ω is the intermediate frequency of the incident signal. The weight w is the column vector to be solved, expressed as

[0045] w=[w 0,0 w 1,0 …w M-1,0 w 0,1 w 1,1…w M-1,1 …w 0,N-1 w 1,N-1 …w M-1,N-1 ] T

[0046] It is a column vector of MN dimension.

[0047] (2) Reconstruct the desired signal direction vector. The specific steps are as follows:

[0048] In the first step, the entire desired signal frequency band is divided into I frequency sub-bands;

[0049] The second step is to select J frequency values ​​ω at equal intervals in the i-th frequency subband. i,j , j = 0, 1, ..., J-1, and calculate the direction vector a (θ 0 ,ω i,j ), reconstruct the desired signal direction vector in the i-th frequency subband as

[0050]

[0051] (3) According to the reconstructed subband direction vector c i , further construct the constraint matrix C, the expression of C is

[0052] C=[c 0 c 1 …c I-1 ]

[0053] Among them, the dimension of C is MN×I.

[0054] (4) After the space-time steering vector is reconstructed, the linearly constrained minimum variance criterion expression of the broadband signal space-time anti-interference filtering algorithm is established:

[0055]

[0056] The symbol “H” indicates taking the conjugate transpose, and the constraint response vector g is

[0057] g=[1 1…1]

[0058] It is a row vector of dimension 1×I.

[0059] (5) Using the Lagrange multiplier method, the optimal weight expression is solved as w opt

[0060]

[0061] in,

[0062]

[0063] μ2 =C H R -1 C

[0064] All of them can be calculated matrices, so as to finally obtain the optimal weight expression w opt .

[0065] (6) The output signal of the array after anti-interference is expressed as

[0066]

[0067] The beneficial effect of the present invention is that it can suppress broadband interference signals, keep the in-band array gain of broadband desired signals flat, and has the advantages of low degree of freedom consumption and simple algorithm. The present invention can be applied to the fields of broadband satellite communications and the like.

Claims

1. A broadband space-time anti-interference method for reconstructing a direction vector, the implementation steps of which are: (1) Establish a space-time uniform linear array model; M array elements are arranged into a uniform linear array, the first array element of the linear array is located at the origin of the coordinate system, the array element spacing is d, the expected signal incident angle is θ0, and the broadband incident expected signal at the origin of the coordinate system is s(t); the time delay between adjacent array elements is τ; each array element channel is connected to an N-order transverse filter, and the system sampling period is T s ; The signal after the nth-order delay of the mth array element is represented by x m,n (kT s ), where m = 0, ..., M-1, n = 0, ..., N-1, k is the sampling sequence, k = 0, 1, ..., K-1; the space-time array receives the signal vector X(kT s )for X(kT s )=[X0 X1 ... X N-1 ] T in, The sequence number 0, 1, ..., N-1 represents the space-time order, the symbol "T" represents the transpose, X n The expression is X n =[x 0,n (kT s ) x 1,n (kT s ) … x M-1,n (kT s )] T Define the desired signal space-time direction vector a(θ0,ω), which can be calculated using known parameters. The calculation formula is: Among them, ω is the center frequency of the desired signal; the weight w is the column vector to be solved, expressed as in=[in 0,0 In 1,0 …In M-1,0 In 0,1 In 1,1 …In M-1,1 …In 0,N-1 In 1,N-1 …In M-1,N-1 ] T It is a column vector of MN dimension; (2) Reconstruct the desired signal direction vector. The specific steps are as follows: In the first step, the entire target signal frequency band is divided into I frequency sub-bands; The second step is to select J frequency values ​​ω at equal intervals in the i-th frequency subband. i,j , j = 0, 1, ..., J-1, and calculate the direction vector a (θ0, ω i,j ), reconstruct the desired signal direction vector in the i-th frequency subband as (3) According to the reconstructed subband direction vector c i , further construct the constraint matrix C, the expression of C is C=[c0 c1 … c I-1 ] Among them, the dimension of C is MN×I; (4) After the space-time steering vector is reconstructed, the linearly constrained minimum variance criterion expression of the broadband signal space-time anti-interference filtering algorithm is established: The symbol "H" indicates taking the conjugate transpose, and the constraint response vector g is g＝[1 1 … 1] It is a row vector of dimension 1×I; (5) Using the Lagrange multiplier method, the optimal weight expression is solved as w opt in, μ2=C H R -1 C All of them can be calculated matrices, so as to finally obtain the optimal weight expression w opt ; (6) The output signal of the array after anti-interference is expressed as

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