CN-119310553-B - Near field strong interference suppression method based on spherical wave deconvolution beam forming positioning

CN119310553BCN 119310553 BCN119310553 BCN 119310553BCN-119310553-B

Abstract

The invention discloses a near field strong interference suppression method based on spherical wave deconvolution beam forming and positioning, which comprises the steps of carrying out fine grid division on a towed line array near field scanning area, carrying out spherical wave focusing beam forming and two-dimensional deconvolution beam forming on distance and angle under the condition of unknown sound source positions in the near field scanning area, calculating distribution entropy characteristics of deconvolution beam forming results in angle dimension, carrying out interference positioning of associated targets by utilizing a preset threshold, constructing an array flow pattern matrix A l of each near field target and generating a covariance matrix A, calculating an orthogonal complementary space projection matrix of the covariance matrix A, acting the orthogonal complementary space projection matrix on an array element domain covariance matrix C to carry out near field interference suppression, and carrying out deconvolution beam forming calculation on the covariance matrix for suppressing near field interference by using a far field plane wave model to obtain a passive detection result of near field strong interference suppression. The invention can realize near field interference positioning and interference suppression under the condition of unknown interference position.

Inventors

WANG XUECHENG
Jiang Xihai
LUO BIN
WANG XIAOLIN
ZHU XIAN

Assignees

中国船舶集团有限公司第七一五研究所

Dates

Publication Date: 20260512
Application Date: 20241018

Claims (10)

1. A near field strong interference suppression method based on spherical wave deconvolution beam forming positioning, characterized in that the method comprises: carrying out fine grid division on a towed line array near field scanning area; performing spherical wave focusing beam forming and two-dimensional deconvolution beam forming about distance-angle under the condition of unknown sound source position in a near-field scanning area; calculating the distribution entropy characteristics of deconvolution beam forming results in the angle dimension, and carrying out interference positioning of the associated targets by utilizing a preset threshold; constructing an array flow pattern matrix A l of each near-field target and generating a covariance matrix A of the array flow pattern matrix; calculating an orthogonal complement space projection matrix of the covariance matrix A, and acting the projection matrix on the array element domain covariance matrix C to perform near field interference suppression; Deconvolution beam forming calculation is carried out on the array element domain covariance matrix C for inhibiting near field interference by using a far field plane wave model, and a passive detection result for inhibiting near field strong interference is obtained.
2. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 1, wherein the fine meshing of the towed linear array near field scanning area comprises: Coarse division is carried out on the far field and the near field of the towed linear array, so that a towed linear array near field scanning area is obtained; And carrying out fine grid division on the towed linear array near field scanning area based on the required near field estimation resolution.
3. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 2, wherein the coarse division of the far field and the near field of the towed linear array adopts a towed linear array focusing distance division method, and the method comprises the following steps: Assuming that the target is far-field plane waves, obtaining signal magnitudes SL (R) after array gain at different focusing distances according to spherical wave beam forming in a scanning area R= [ R 1 ,r 2 ,...,r n ], and calculating signal Loss Loss (R) = SL-SL (R) caused by focusing, wherein SL is the signal magnitude obtained according to plane wave beam forming; Comparing the signal Loss (R), r=1, 2,..n with the allowable signal Loss amount sigma, when the Loss (R) is equal to or greater than sigma and the signal Loss is min (Loss (R) -sigma), the corresponding R is the focusing distance when the signal Loss is closest to sigma, and the distance between the far and near fields of the towed linear array is recorded as R m =r.
4. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 1, wherein the spherical wave focusing beam forming algorithm is expressed as: , Wherein P' (r, θ) is a spatial spectrum when a focusing distance is r and a focusing direction is θ, c is a wave velocity, d is an array element distance of a linear array, M is an array element number of the linear array, r is a focusing distance, θ is a focusing direction, X 0 is a distance difference between an acoustic signal and a reference acoustic channel, j is an imaginary number, f is a signal frequency, a (r, θ) is a driving vector, τ is an arrival time delay of a signal with the focusing distance of r and the focusing direction of θ in each acoustic channel, T is a transpose, and x= [ X 1 (f),x 2 (f),...,x M (f) ], which represents a result of Fourier transform of an array element domain signal at a frequency f.
5. The near-field strong interference suppression method based on spherical wave deconvolution beamforming localization of claim 4, wherein said two-dimensional deconvolution beamforming with respect to distance-angle in case of unknown sound source location in the near-field scan region comprises: calculating a scattering function of the sound source at 90 degrees along with the focusing distance r: , Wherein rs is the distance from the sound source to each array element of the towed linear array, rr is the distance from the scanning point to each array element of the towed linear array, and a is the reciprocal of the distance from the sound source to each array element of the towed linear array; calculating a deconvolution beam forming result P 1 according to the spatial spectrum P' (r, theta) and a scattering function PSF (r, 90 °); The spatial spectrum distribution at the center distance of P 1 is taken as deconvolution spatial spectrum P deconv at the distance r, and the distance dimension is scanned, so that a two-dimensional deconvolution beam forming result P deconv (r, theta) is obtained.
6. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning according to claim 1, wherein the calculating the distribution entropy characteristic of deconvolution beam forming result in the angle dimension and utilizing the preset threshold to perform the interference positioning of the associated target comprises the following steps: Performing angle dimension slicing θ= { θ 1 ,θ 2 ,...,θ k ,.. } on a two-dimensional deconvolution beamforming result P deconv (r, θ), wherein k is a slice index, and calculating distribution entropy Entropy (θ k ) of the P deconv (r, θ) angle dimension slice; Judging whether the distribution entropy Entropy (theta k ) is not larger than a threshold TEntropy for setting the distribution entropy, if yes, extracting a distance r k corresponding to the maximum value of a theta k slice in P deconv (r, theta), and recognizing that near field interference exists at the scanning grid (r k ,θ k ).
7. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 1, wherein the orthogonal complement space projection matrix calculation formula of the covariance matrix a of the array flow pattern matrix is: P=I-A T (AA T ) -1 A, wherein T is the transpose and I is the identity matrix.
8. The near-field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 1, wherein the calculation formula of the projection matrix P acting on the array element domain covariance matrix C is C=PC.
9. The near-field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 1, wherein deconvolution beam forming calculation of the array element domain covariance matrix C for suppressing near-field interference by using a far-field plane wave model comprises: calculating a far-field planar beam forming result ISCBF by using the array element domain covariance matrix C of near-field interference suppression; The far field deconvolution beamforming scattering function PSF (r, 90 °) and the far field plane beamforming result ISCBF are used as inputs to the RL deconvolution algorithm to obtain deconvolution beamforming result ISDBF after near field interference is suppressed.
10. The near field strong interference suppression method based on spherical wave deconvolution beam forming positioning of claim 9, wherein the RL deconvolution algorithm is formulated as: , where i is the number of iterations, r is the scanning distance range, θ is the scanning angle, And (3) obtaining a distance angle two-dimensional spatial spectrum estimation result obtained by deconvolution iteration calculation for the ith time, wherein P (r, theta) is a distance angle two-dimensional spatial spectrum estimation obtained by conventional beam forming.

Description

Near field strong interference suppression method based on spherical wave deconvolution beam forming positioning Technical Field The invention belongs to the field of towed passive target detection of a towed linear array, and particularly relates to a near-field strong interference suppression method based on spherical wave deconvolution beam forming positioning. Background With the development of vibration reduction and noise reduction technology, the target noise level, especially the high-frequency noise level, is drastically reduced, but the low-frequency noise is difficult to reduce. The towed line array is suitable for underwater sound target detection due to the advantages of large aperture, low detection frequency, small interference noise caused by the ship and the like. The near field interference has a larger influence on the target detection performance when the large-aperture towed line array is detected, especially when the directions of the interested target and the near field strong interference are relatively close. The current common near-field interference suppression method generally utilizes a method of combining inverse beam forming with adaptive filtering to realize interference cancellation, however, the position of an interference target is unknown or the position estimation is inaccurate, and better interference suppression performance is difficult to realize. Disclosure of Invention The invention aims to provide a large-aperture towed linear array near field strong interference suppression method based on spherical wave deconvolution beam forming positioning, which realizes accurate positioning of near field interference, suppresses near field interference and improves target detection performance. In order to achieve the above purpose, the present invention provides the following technical solutions: a near field strong interference suppression method based on spherical wave deconvolution beam forming positioning, the method comprising: carrying out fine grid division on a towed line array near field scanning area; performing spherical wave focusing beam forming and two-dimensional deconvolution beam forming about distance-angle under the condition of unknown sound source position in a near-field scanning area; calculating the distribution entropy characteristics of deconvolution beam forming results in the angle dimension, and carrying out interference positioning of the associated targets by utilizing a preset threshold; constructing an array flow pattern matrix A l of each near-field target and generating a covariance matrix A of the array flow pattern matrix; calculating an orthogonal complement space projection matrix of the covariance matrix A, and acting the projection matrix on the array element domain covariance matrix C to perform near field interference suppression; and deconvolution beam forming calculation is carried out on the covariance matrix for restraining the near-field interference by using the far-field plane wave model, so that a passive detection result for restraining the near-field strong interference is obtained. Preferably, the fine meshing of the towed linear array near field scanning area includes: Coarse division is carried out on the far field and the near field of the towed linear array, so that a towed linear array near field scanning area is obtained; And carrying out fine grid division on the towed linear array near field scanning area based on the required near field estimation resolution. Preferably, the coarse division of the far field and the near field of the towed line array adopts a towed line array focusing distance division method, which comprises the following steps: Assuming that the target is far-field plane waves, obtaining signal magnitudes SL (R) after array gain at different focusing distances according to spherical wave beam forming in a scanning area R= [ R 1,r2,...,rn ], and calculating signal Loss Loss (R) = SL-SL (R) caused by focusing, wherein SL is the signal magnitude obtained according to plane wave beam forming; Comparing the signal Loss (R), r=1, 2,..n with the allowable signal Loss amount sigma, when the Loss (R) is equal to or greater than sigma and the signal Loss is min (Loss (R) -sigma), the corresponding R is the focusing distance when the signal Loss is closest to sigma, and the distance between the far and near fields of the towed linear array is recorded as R m =r. Preferably, the spherical wave focusing beam forming algorithm is expressed as: , Wherein P' (r, θ) is a spatial spectrum when a focusing distance is r and a focusing direction is θ, c is a wave velocity, d is an array element distance of a linear array, M is an array element number of the linear array, r is a focusing distance, θ is a focusing direction, X 0 is a distance difference between an acoustic signal and a reference acoustic channel, j is an imaginary number, f is a signal frequency, a (r, θ) is a driving vector, τ is an arrival time dela