A towed array passive localization method based on wideband matrix filtering

Abstract

The application discloses a towed array passive positioning method based on wideband matrix filtering, calculates a sound field propagation matrix by using a two-dimensional parabolic equation model, obtains different distance sound source-receiver system propagation matrices through matrix multiplication operation, extracts matrix coefficients from different distance system propagation matrices according to sound source depth and horizontal array element positions, and forms a new sparse system propagation matrix. The sparse system propagation matrix is processed to form a wideband matrix filter set, finally, the horizontal array receiving signal is processed by using the wideband matrix filter set, energy normalization is performed on different distance processing results, a wideband distance-depth ambiguity diagram is formed, and target depth and distance estimation results are obtained. The application can effectively improve the target position resolution of the towed array wideband signal passive positioning, reduce the sidelobe intensity in the two-dimensional ambiguity diagram, and greatly reduce the energy outside the main lobe, and has important value for improving the target positioning performance in the actual environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater target acoustic positioning, and particularly relates to a towed array passive positioning method based on wideband matrix filtering. BACKGROUND

[0002] Underwater acoustic target passive positioning is based on the underwater acoustic propagation characteristics of target radiation noise, an associated model of target-sound channel-receiving array is constructed, and different acoustic positioning methods are formed according to the matching of the model prediction results and the actual underwater acoustic environment, such as the matching field positioning method based on sound pressure matching, the matching mode positioning method based on normal mode, the matching beam positioning method based on different beam incident energy, etc. The matching field positioning method has been greatly developed with the improvement of the accuracy of the underwater sound field prediction model, and has become a main method of underwater acoustic target acoustic positioning. The towed array underwater passive positioning is an important direction and problem of underwater acoustics, and due to the large horizontal correlation radius of the sound field, it is difficult for the horizontal array acoustic matching positioning technology to obtain high main lobe intensity and high resolution. SUMMARY

[0003] The application provides a towed array passive positioning method based on wideband matrix filtering, which improves the target positioning resolution, improves the target main lobe intensity, and reduces the main lobe outside the background energy intensity in all aspects while maintaining good environmental adaptability.

[0004] The technical solution of the application is to provide a towed array passive positioning method based on wideband matrix filtering, and the method steps are as follows,

[0005] Step 1, calculating the sound field propagation matrix by using a two-dimensional parabolic equation model;

[0006] Step 2, obtaining the propagation matrix of the sound source-receiver system at different distances through matrix multiplication operation;

[0007] Step 3, extracting matrix coefficients from the different distance system propagation matrix according to the sound source depth and the horizontal array element position to form a new sparse system propagation matrix;

[0008] Step 4, processing the sparse system propagation matrix, using the least square estimation method, and increasing the diagonal load factor to form a wideband matrix filter set;

[0009] Step 5, processing the horizontal array receiving signal by using the wideband matrix filter set, energy normalizing the processing results at different distances, forming a wideband distance-depth ambiguity diagram, and obtaining the target depth and distance estimation results.

[0010] As a preferred, in step 1, the recursive solution matrix equation of the two-dimensional parabolic equation model can be expressed in the following form:

[0011]

[0012] where R l , S l is the matrix of marine environmental parameters, U N is the vector of sound pressure at different distances, and the matrix T(f, r+dr) is the propagation matrix at distance level r+dr at different frequencies, and dr is the distance grid interval.

[0013] As a preference, in step 2, the system propagation matrix at different distances of the receiving array needs to contain the product of all propagation matrices at the entire transmission distance:

[0014] PM(f, M*dr) = T(f, M*dr)T(f, (M-1)*dr)…T(f, m*dr)…T(f, 2*dr)T(f, 1*dr)

[0015] where the matrix PM(f, M*dr) is the system propagation matrix at different frequencies and different distances.

[0016] As a preference, in step 3, assuming that the sound source is located at a distance of m*dr and the receiving array is located at a depth of N0*dz and at a distance of (M1~M2)*dr, the system propagation matrix satisfies:

[0017]

[0018] where P zs (f, (1:N)*dz) is the initial sound field vector, N is the number of depth grids of the sound source, and dz is the depth grid interval.

[0019] As a preference, in step 4, the least square estimation is used, and a diagonal loading factor is added to obtain the depth ambiguity estimation results at different frequencies and distances:

[0020]

[0021] In the formula, the symbol (·) T represents the conjugate transpose of the complex matrix, and δ is the diagonal loading factor, which can be adjusted according to different signal-to-noise ratios. The lower the signal-to-noise ratio, the larger the diagonal loading factor.

[0022] As a preference, in step 5, the depth ambiguity results at different distances are energy-balanced and normalized in the following manner:

[0023]

[0024] As a preference, in step 5, the broadband two-dimensional ambiguity results can be obtained through broadband energy incoherent superposition:

[0025]

[0026] Compared with the prior art, the present application has the following advantages:

[0027] The towed array passive positioning method based on wideband matrix filtering can effectively improve the target position resolution of towed array wideband signal passive positioning, reduce the side lobe intensity in the two-dimensional ambiguity diagram, and greatly reduce the energy outside the main lobe. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The implementation process diagram of the present application.

[0029] Figure 2 The ocean waveguide parameter diagram.

[0030] Figure 3 The sound source positioning results obtained by using the conventional matching processor and the method of the present application.

[0031] Figure 4 The depth-intensity results at the sound source distance calculated by using the conventional matching processor and the method of the present application.

[0032] Figure 5 The distance-intensity results at the sound source depth calculated by using the conventional matching processor and the method of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described in combination with the specific embodiments and the accompanying drawings:

[0034] Referring to Figure 1 The implementation process diagram shown in the figure, the present application relates to a towed array passive positioning method based on wideband matrix filtering, which adopts a high-order parabolic equation model to calculate the sound field propagation matrix. Then, the system propagation matrix is obtained through multiplication operation. According to the sound source depth and the horizontal array element position, the matrix coefficients are extracted from the system propagation matrix at different distances to form a new sparse system propagation matrix. Subsequently, the least square estimation method is used, and a diagonal load factor is added to form a wideband matrix filter set. Subsequently, the horizontal array received signal is processed by using the wideband matrix filter set, the energy normalization is performed on the processing results at different distances, and finally the wideband distance-depth ambiguity diagram is formed to obtain the target positioning result.

[0035] Among them,

[0036] In the case that the ocean environmental parameters slowly change in the horizontal direction, the two-dimensional parabolic equation model recursive solution matrix equation can be written in the following form from the most intuitive point of view:

[0037]

[0038] where R l l is the matrix of marine environmental parameters, U N is the vector of sound pressure at different distances, and the matrix T(f,r+dr) is the propagation matrix at distance level r+dr at different frequencies, and dr is the distance grid interval.

[0039] And the system transfer matrix at different distances of the receiving array needs to include the product of all step propagation matrices on the entire transmission distance:

[0040] PM(f,M*dr)=T(f,M*dr)T(f,(M-1)*dr)…T(f,m*dr)…T(f,2*dr)T(f,1*dr)

[0041] where the matrix PM(f,M*dr) is the system propagation matrix at different frequencies and different distances.

[0042] Assuming that the sound source is located at a distance of m*dr, the receiving array is located at a depth of N0*dz and at a distance of (M1~M2)*dr, the system propagation matrix is the matrix connecting the sound source and the receiving position, and when the sound pressure on the receiving array is known, the sound source position can be estimated by the inverse matrix, which satisfies:

[0043]

[0044] where P zs (f,(1:N)*dz) is the initial sound field vector, N is the number of depth grid of the sound source, and dz is the depth grid interval.

[0045] (4) Using least squares estimation and adding a diagonal loading factor to the matrix, the depth ambiguity estimation results at different frequencies and distances can be obtained:

[0046]

[0047] In the above formula, the symbol (·) T represents the conjugate transpose of the complex matrix, and δ is the diagonal loading factor, which can be adjusted according to different signal-to-noise ratios. The lower the signal-to-noise ratio, the larger the diagonal loading factor.

[0048] Further, according to the seabed depth, the depth ambiguity results at different distances are energy balanced and normalized:

[0049]

[0050] Then, in order to obtain the wideband gain, the ambiguity functions obtained at different frequencies are non-coherently superimposed in wideband energy, and the wideband two-dimensional ambiguity result can be obtained:

[0051] ​

[0052] Referring to Figure 2 The ocean waveguide parameter diagram shown in the figure shows the ocean geoacoustic parameters and sound source information. The broadband sound source frequency range is 200Hz-250Hz, and 11 frequency points are selected, namely 200Hz, 205Hz, 210Hz, 215Hz, 220Hz, 225Hz, 230Hz, 235Hz, 240Hz, 245Hz, and 250Hz. The horizontal array is a 100-element array, the array element spacing is 5m, and the water entry depth is 40m. The sound source depth is 50m, and the distance is 7km.

[0053] Figure 3 The sound source positioning results obtained by using the conventional matching processor and the method are given, and it can be seen that the target positions in the calculation results of the method are more concentrated, proving that the depth-distance resolution is high, and the number of high-intensity noise points is greatly reduced, and the side lobe intensity outside the main lobe is reduced.

[0054] Further, referring to Figure 4 and Figure 5 , Figure 4 The depth-intensity results at the sound source distance calculated by using the above two methods are given, and it can be seen that the main lobe width of the target depth in the calculation results of the method is narrower, the resolution is higher, and the side lobe intensity is lower. Figure 5 The distance-intensity results at the sound source depth calculated by using the above two methods are given, and it can be seen that the main lobe width of the target distance in the calculation results of the method is narrower, the resolution is higher, and the side lobe intensity is lower.

[0055] It can be seen that the towed array passive positioning method based on the broadband matrix filtering of the present application can effectively improve the target position resolution of the towed array broadband signal passive positioning, reduce the side lobe intensity in the two-dimensional ambiguity diagram, and greatly reduce the energy outside the main lobe, which has important value for improving the performance of target positioning in the actual environment.

[0056] The above only describes the preferred embodiments of the present application, but cannot be understood as limiting the claims. Any equivalent process transformation made by using the present application specification is included in the patent protection range of the present application.

Claims

1. A towed array passive localization method based on broadband matrix filtering, characterized in that: The method steps are as follows, Step 1, the sound field propagation matrix is calculated by using a two-dimensional parabolic equation model; Step 2, the sound source-receiver system propagation matrix at different distances is obtained by matrix multiplication operation; Step 3, according to the sound source depth and horizontal array element position, the matrix coefficients are extracted from the different distance system propagation matrix to form a new sparse system propagation matrix; Step 4, the sparse system propagation matrix is processed, the least square estimation method is used, and the diagonal load factor is added to form a wideband matrix filter set; Step 5, the wideband matrix filter set is used to process the horizontal array receiving signal, the energy normalization is performed on the different distance processing results, the wideband range-depth ambiguity diagram is formed, and the target depth and distance estimation results are obtained.

2. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 1, the recursive solution of the two-dimensional parabolic equation model matrix equation is expressed in the following form: where R l is the matrix of the marine environmental parameters, U l is the vector of the sound pressure at different distances, and the matrix T(f, r+dr) is the propagation matrix at distance level r+dr at different frequencies, and dr is the distance grid interval. N ​ 3. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 2, the system propagation matrix at different distances of the distance receiving array needs to include the product of all propagation matrices in the entire transmission distance: PM(f, M*dr) = T(f, M*dr) T(f, (M-1)*dr)…T(f, m*dr)…T(f, 2*dr) T(f, 1*dr) Wherein, the matrix PM(f, M*dr) is the system propagation matrix at different frequencies and different distances.

4. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 3, it is assumed that the sound source is located at a distance of m*dr, the receiving array is located at a depth of N0*dz, and the system propagation matrix satisfies: where P zs (f, (1 :N)*dz) is the initial sound field vector, N is the number of depth grid of sound source, and dz is the depth grid interval.

5. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 4, the least square estimation is used, and the diagonal load factor of the matrix is added to obtain the depth ambiguity estimation results at different frequencies and distances: The symbol (·) in the formula T δ represents the conjugate transpose of a complex matrix, and δ is the diagonal loading factor.

6. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 5, the depth ambiguity results at different distances are energy balanced and normalized in the following way:

7. The broadband matrix filtering based towed array passive localization method of claim 1, wherein: In step 5, the wideband two-dimensional ambiguity result is obtained by wideband energy incoherent superposition:

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