Split array beamforming directional method based on planar array

Abstract

The application provides a split array beam forming orientation method based on a plane array, which comprises the following steps: first, constructing a plane array by using row arrays and column arrays with the same dimension; then, selecting one row array element and one column array element in the plane array to form four groups of array elements; and finally, jointly solving the azimuth angle and the elevation angle in the plane array split array beam forming by using the phase difference between the signals received by the four groups of array elements and the position relationship of the array elements, so as to realize the orientation of the target beam signal. Therefore, in the case that the array elements are easily affected by the environment, the application only introduces part of the array elements for beam forming orientation, so that the error caused by the array elements can be greatly reduced, and the beam orientation precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of target orientation technology, and particularly relates to a beamforming orientation method based on a split array of planar arrays. Background Technology

[0002] Currently, split array beamforming is mostly used in the field of linear arrays. When applied to area arrays and cylindrical arrays, split array beamforming often requires solving for the azimuth or elevation angle separately. Moreover, the beamforming method is relatively complex. In addition, during the detection process, some array elements may be greatly affected by the environment. In this case, using all array elements for beamforming will introduce a large error. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a planar array-based split-array beamforming directionality method, which enables the beam signal's elevation angle θ and azimuth angle to be directed after freely selecting array elements. Simultaneously, a simple solution is performed.

[0004] A beamforming direction-oriented method based on a split array planar array includes the following steps:

[0005] By overlapping and combining row and column matrices of the same dimension from the middle, a planar matrix is ​​obtained;

[0006] Choose any row from the plane array direction, and divide its array elements evenly into y-orders. 左 y 右 Two groups; randomly select one column from the planar array direction, and uniformly divide the array elements on it into z groups. 上 z 下 Two groups;

[0007] The beam signal is received using four sets of array elements, and y is obtained based on the received beam signal. 左 y 右 Phase difference of the beam signals received by the two array elements and z 上 z 下 Phase difference of the beam signals received by the two array elements

[0008] Based on phase difference and phase difference Obtain the elevation angle θ and azimuth angle of the beam signal

[0009] Furthermore, phase difference and phase difference The method for obtaining it is as follows:

[0010] The beam signals y received by the four array elements 左 (n), y 右 (n), z上 (n), z 下 (n) Perform quadrature demodulation, low-pass filtering and downsampling in sequence, where n = 0, 1, 2...N, and N represents the number of sampling points;

[0011] For the beam signals of each sequence received by each array element in each group after downsampling, the beam signals of each sequence are combined into a total beam signal of one sequence by summing the beam signals received at the same time.

[0012] The total beam signals corresponding to the four array elements are subjected to discrete Fourier transform to obtain Y. 左 (f), Y 右 (f), Z 上 (f), Z 下 (f);

[0013] Get Y 左 (f), Y 右 (f) Mapping relationship, Z 上 (f), Z 下 (f) The mapping relationship is as follows:

[0014]

[0015]

[0016] Where * denotes conjugate, Y(f) represents the Fourier transform of the beam signal in the row direction, |Y(f)| represents the magnitude of the Fourier transform of the beam signal in the row direction, Z(f) represents the Fourier transform of the beam signal in the column direction; |Z(f)| represents the magnitude of the Fourier transform of the beam signal in the column direction.

[0017] The phase difference is obtained based on the mapping relationship. and phase difference

[0018]

[0019]

[0020] Where Im[·] represents the imaginary part and Re[·] represents the real part.

[0021] Furthermore, based on the phase difference and phase difference Obtain the elevation angle θ and azimuth angle of the beam signal Specifically:

[0022] Obtaining phase difference And pitch angle θ, azimuth angle The first mapping relationship is as follows:

[0023]

[0024] Where d is the element spacing, f0 is the frequency of the beam signal, and c is the speed of sound in water;

[0025] Obtaining phase difference And pitch angle θ, azimuth angle The second mapping relationship is as follows:

[0026]

[0027] In phase difference and phase difference Given the conditions, combine the first and second mapping relationships to obtain the elevation angle θ and azimuth angle of the beam signal.

[0028] Furthermore, the method for obtaining the first mapping relationship is as follows:

[0029] Assuming the planar array has a dimension of 6×6, the signal s received by the i-th element of the currently selected row is... i (t) is:

[0030]

[0031] Where m is the row number of the i-th element in the planar array, and n is the column number of the i-th element in the planar array. The relative time delay between the received signals when the array elements in the m-th row containing the i-th array element are divided into left and right groups is given. Let be the relative time delay between the received signals when the nth column of array elements containing the i-th array element is divided into upper and lower groups of array elements, and we have:

[0032]

[0033]

[0034] Based on the signals s received by each array element i (t), obtain array element y 左 y 右 The received beam signal is as follows:

[0035]

[0036]

[0037] Where A is the array element y 左 The amplitude of the received beam signal, B is the array element y 右The amplitude of the received beam signal, α is the amplitude of the array element y. 左 The phase of the received beam signal, β is the phase of the array element y 右 The phase of the received beam signal, and has:

[0038]

[0039] Among them, u m relative time delay The cosine value, and v m relative time delay The sine value, and

[0040] Meanwhile, the calculation methods for phase α and phase β are as follows:

[0041]

[0042] General Array y 左 y 右 The first mapping relationship is obtained by subtracting the received beam signals.

[0043] Furthermore, the 4×6 row and column arrays are overlapped and combined from the middle to obtain a planar array containing 32 array elements.

[0044] Choose any row from the 2nd to the 5th row of the planar array, and divide its array elements evenly into y-orders. 左 y 右 Two groups, each with 3 array elements; randomly select one column from the 2nd to 5th columns of the planar array direction, and evenly divide the array elements on it into z groups. 上 z 下 Two groups, each with 3 array elements.

[0045] Beneficial effects:

[0046] 1. This invention provides a beamforming direction-oriented method for split array beamforming based on a planar array. First, a planar array is constructed using row and column arrays of the same dimension. Then, one row and one column of array elements are selected from the planar array to form four sets of array elements. The azimuth and elevation angles are jointly solved in the split array beamforming process by using the phase difference between the received signals of the four sets of array elements and the positional relationship of the array elements to achieve the directionality of the target beam signal. It can be seen that when the array elements are susceptible to environmental influences, this invention introduces only a portion of the array elements for beamforming direction-oriented beamforming, which can greatly reduce the error caused by the array elements and improve the beam orientation accuracy.

[0047] 2. This invention provides a beamforming orientation method based on a split array planar array. Beamforming orientation can be achieved by selecting one row of array elements and one column of array elements in the planar array. When the candidate array elements are malfunctioning, another row or another column of array elements can be directly switched to re-perform beamforming orientation. The degree of freedom in array element selection is greatly increased, and the stability of beamforming orientation is also improved.

[0048] 3. This invention provides a beamforming direction method for a split array based on a planar array, which derives the phase difference based on the positional relationship of the array elements. With pitch angle θ and azimuth angle The mapping relationship is then used to simultaneously calculate the pitch angle θ and azimuth angle. The beamforming method is relatively simple. Attached Figure Description

[0049] Figure 1 A flowchart of a beamforming orientation method based on a split array of a planar array provided by the present invention;

[0050] Figure 2 This is a schematic diagram of a planar array provided by the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0052] like Figure 1 As shown, a beamforming direction-oriented method based on a split array planar array includes the following steps:

[0053] S1: Overlap and combine row and column matrices of the same dimension from the middle to obtain a planar matrix;

[0054] like Figure 2 As shown, a 4×6 row array and a column array are overlapped and combined from the middle to obtain a planar array containing 32 array elements (the four corners of the planar array are one less array element).

[0055] S2: Select any row from the plane array direction and divide its array elements evenly into y-orders. 左 y 右 Two groups; randomly select one column from the planar array direction, and uniformly divide the array elements on it into z groups. 上 z 下 Two groups;

[0056] like Figure 2 As shown, select any row from the 2nd to the 5th row of the planar array, and divide the array elements on it evenly into y-columns. 左 y 右Two groups, each with 3 array elements; randomly select one column from the 2nd to 5th columns of the planar array direction, and evenly divide the array elements on it into z groups. 上 z 下 Two groups, each with 3 array elements.

[0057] S3: The beam signal is received using four array elements, and y is obtained based on the received beam signal. 左 y 右 Phase difference of the beam signals received by the two array elements and z 上 z 下 Phase difference of the beam signals received by the two array elements Specifically as follows:

[0058] The beam signals y received by the four array elements 左 (n), y 右 (n), z 上 (n), z 下 (n) Perform quadrature demodulation, low-pass filtering and downsampling in sequence, where n = 0, 1, 2...N, and N represents the number of sampling points;

[0059] For the beam signals of each sequence received by each array element in each group after downsampling, the beam signals of each sequence are combined into a total beam signal of one sequence by summing the beam signals received at the same time.

[0060] The total beam signals corresponding to the four array elements are subjected to discrete Fourier transform to obtain Y. 左 (f), Y 右 (f), Z 上 (f), Z 下 (f);

[0061] Get Y 左 (f), Y 右 (f) Mapping relationship, Z 上 (f), Z 下 (f) The mapping relationship is as follows:

[0062]

[0063]

[0064] Where * denotes conjugate, Y(f) represents the Fourier transform of the beam signal in the row direction, |Y(f)| represents the magnitude of the Fourier transform of the beam signal in the row direction, Z(f) represents the Fourier transform of the beam signal in the column direction; |Z(f)| represents the magnitude of the Fourier transform of the beam signal in the column direction.

[0065] The phase difference between the left and right sets of array elements is obtained based on the mapping relationship. Phase difference between the upper and lower array elements

[0066]

[0067]

[0068] Where Im[·] represents the imaginary part and Re[·] represents the real part.

[0069] S4: Based on phase difference and phase difference Obtain the elevation angle θ and azimuth angle of the beam signal like Figure 2 As shown, the yz plane is a 32-element planar array, and θ is the elevation angle formed by the incident wave direction and the planar array. The azimuth angle formed by the incident wave direction and the planar array;

[0070] according to Figure 2 Assuming that the array elements in the 3rd row and 3rd column are used for beamforming direction, the elevation angle θ and azimuth angle are respectively... The specific derivation of the method for obtaining it is as follows:

[0071] y from 1 to 3 左 The left beam y is obtained by summing the outputs of the array elements. 左 (n), y from 4 to 6 右 The right beam y is obtained by summing the outputs of the array elements. 右 (n); z from 1 to 3 上 The left beam z is obtained by summing the outputs of the array elements. 上 (n), z from 4 to 6 下 The right beam z is obtained by summing the outputs of the array elements. 下 (n); y 左 (n), y 右 (n), z 上 (n), z 下 The relative time delay and signal incident angle azimuth between (n) The relationship between pitch angle θ and the angle of elevation.

[0072] Taking the center of the array as the reference point, and assuming the input is a single-frequency signal cos(2πf0t), and the dimension of the array is 6×6, then the signal s received by the i-th (1≤i≤6) element in the currently selected row is... i (t) is:

[0073]

[0074] Where f0 is the frequency of the beam signal, m is the row number of the i-th element in the planar array, and n is the column number of the i-th element in the planar array. The relative time delay between the received signals when the array elements in the m-th row containing the i-th array element are divided into left and right groups is given. Let be the relative time delay between the received signals when the nth column of array elements containing the i-th array element is divided into upper and lower groups of array elements, and we have:

[0075]

[0076]

[0077] Where d is the element spacing (the distance between the centers of two elements), which can be taken as half the wavelength of the beam signal, and c is the speed of sound in water;

[0078] Based on the signals s received by each array element i (t), obtain array element y 左 The received beam signal is as follows:

[0079]

[0080] Among them, u m relative time delay The cosine value, and v m relative time delay The sine value, and

[0081] Rewrite the above equation in the form of a single-frequency signal:

[0082]

[0083] Where A is the array element y 左 The amplitude of the received beam signal, α is the amplitude of the array element y. 左 The phase of the received beam signal, and has:

[0084]

[0085] Similarly, we can obtain y 右 The received beam signal is as follows:

[0086]

[0087] Where B is the array element y 右 The amplitude of the received beam signal, β is the array element y 右 The phase of the received beam signal, and has:

[0088]

[0089] General Array y 左 y 右 The received beam signals are subtracted to obtain the first mapping relationship as follows:

[0090]

[0091] Similarly, the second mapping relationship can be obtained as follows:

[0092]

[0093] Substituting the results of formulas (3) and (4) into formulas (9) and (10) respectively, and solving formulas (9) and (10) simultaneously, the elevation angle θ and azimuth angle for obtaining the beam signal can be obtained. To achieve the orientation of the target beam.

[0094] In summary, this invention optimizes linear array beamforming, allowing for more flexible selection of array elements on the surface array for split array beamforming, and then jointly solving for azimuth and elevation angles during the split array beamforming process.

[0095] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A beamforming direction-oriented method based on a split-array planar array, characterized in that, Includes the following steps: By overlapping and combining row and column matrices of the same dimension from the middle, a planar matrix is ​​obtained; Choose any row from the plane array direction, and divide its array elements evenly into y-orders. 左 y 右 Two groups; randomly select one column from the planar array direction, and uniformly divide the array elements on it into z groups. 上 z 下 Two groups; The beam signal is received using four sets of array elements, and y is obtained based on the received beam signal. 左 y 右 Phase difference of the beam signals received by the two array elements and z 上 z 下 Phase difference of the beam signals received by the two array elements Based on phase difference and phase difference Obtain the elevation angle θ and azimuth angle of the beam signal 2. The beamforming direction method based on a split array using a planar array as described in claim 1, characterized in that, Phase difference and phase difference The method for obtaining it is as follows: The beam signals y received by the four array elements 左 (n), y 右 (n), z 上 (n), z 下 (n) Perform quadrature demodulation, low-pass filtering and downsampling in sequence, where n = 0, 1, 2...N, and N represents the number of sampling points; For the beam signals of each sequence received by each array element in each group after downsampling, the beam signals of each sequence are combined into a total beam signal of one sequence by summing the beam signals received at the same time. The total beam signals corresponding to the four array elements are subjected to discrete Fourier transform to obtain Y. 左 (f), Y 右 (f), Z 上 (f), Z 下 (f); Get Y 左 (f), Y 右 (f) Mapping relationship, Z 上 (f), Z 下 (f) The mapping relationship is as follows: Where * denotes conjugate, Y(f) represents the Fourier transform of the beam signal in the row direction, |Y(f)| represents the magnitude of the Fourier transform of the beam signal in the row direction, Z(f) represents the Fourier transform of the beam signal in the column direction; |Z(f)| represents the magnitude of the Fourier transform of the beam signal in the column direction. The phase difference is obtained based on the mapping relationship. and phase difference Where Im[·] represents the imaginary part and Re[·] represents the real part.

3. The beamforming direction method based on a split array using a planar array as described in claim 1, characterized in that, Based on phase difference and phase difference Obtain the elevation angle θ and azimuth angle of the beam signal Specifically: Obtaining phase difference And pitch angle θ, azimuth angle The first mapping relationship is as follows: Where d is the element spacing, f0 is the frequency of the beam signal, and c is the speed of sound in water; Obtaining phase difference And pitch angle θ, azimuth angle The second mapping relationship is as follows: In phase difference and phase difference Given the conditions, combine the first and second mapping relationships to obtain the elevation angle θ and azimuth angle of the beam signal.

4. The beamforming direction method based on a split array using a planar array as described in claim 3, characterized in that, The method for obtaining the first mapping relationship is as follows: Assuming the planar array has a dimension of 6×6, the signal s received by the i-th element of the currently selected row is... i (t) is: Where m is the row number of the i-th element in the planar array, and n is the column number of the i-th element in the planar array. The relative time delay between the received signals when the array elements in the m-th row containing the i-th array element are divided into left and right groups is given. Let be the relative time delay between the received signals when the nth column of array elements containing the i-th array element is divided into upper and lower groups of array elements, and we have: Based on the signals s received by each array element i (t), obtain array element y 左 y 右 The received beam signal is as follows: Where A is the array element y 左 The amplitude of the received beam signal, B is the array element y 右 The amplitude of the received beam signal, α is the amplitude of the array element y. 左 The phase of the received beam signal, β is the phase of the array element y 右 The phase of the received beam signal, and has: Among them, u m relative time delay The cosine value, and v m relative time delay The sine value, and Meanwhile, the calculation methods for phase α and phase β are as follows: General Array y 左 y 右 The first mapping relationship is obtained by subtracting the received beam signals.

5. A beamforming direction method based on a split array using a planar array as described in any one of claims 1 to 4, characterized in that, By overlapping and combining 4×6 row and column arrays from the middle, a planar array containing 32 array elements is obtained. Choose any row from the 2nd to the 5th row of the planar array, and divide its array elements evenly into y-orders. 左 y 右 Two groups, each with 3 array elements; randomly select one column from the 2nd to 5th columns of the planar array direction, and evenly divide the array elements on it into z groups. 上 z 下 Two groups, each with 3 array elements.

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