Azimuth history plot display method combining frequency shading and broadband frequency signatures

Abstract

The application belongs to the technical field of underwater acoustic array signal processing, and discloses a bearing history diagram display method combining frequency coloring and wideband frequency characteristics, which separately processes the array receiving signal in multiple time periods, performs bearing estimation by using frequency domain beam forming to obtain a frequency bearing matrix, sets a color mapping matrix to map the frequency information of the wideband signal into RGB three primary colors, normalizes the wideband target bearing spectrum to the interval of 0-255, allocates different three primary color values to the wideband target bearing estimation output according to the mapping value proportion of RGB, and outputs the color wideband target bearing estimation of different time periods in parallel to obtain an improved bearing history diagram. The computer numerical simulation result shows that the bearing history diagram display method combining frequency coloring and wideband frequency characteristics can enhance the display effect of the bearing history diagram, effectively identifies the target trajectory, solves the problem of inaccurate human observation in the prior art, and improves the passive detection capability of the sonar.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic array signal processing technology, and particularly relates to a method for displaying azimuth history diagrams that combine frequency coloring and broadband frequency characteristics. Background Technology

[0002] In passive sonar systems, broadband signals offer numerous advantages over narrowband signals, such as higher information content, stronger anti-interference capabilities, lower correlation with background noise, and higher resolution. These advantages are highly beneficial for target detection, feature extraction, and parameter estimation. Broadband beamforming is performed on the broadband signal received by the array to obtain a broadband beamout, i.e., a frequency-azimuth matrix. Broadband integration then yields a broadband azimuth estimate, which, when output in parallel according to time, provides a traditional azimuth-time history map.

[0003] Wax et al. were among the first to propose using the incoherent subspace method for broadband azimuth estimation (see "Spatio-temporal spectral analysis by eigenstructure methods" published in IEEE Transactions on Acoustics, Speech, and Signal Processing, 1984, 32(4):817-827). This method first divides the received broadband signal into several sub-bands using Discrete Fourier Transform (DFT), then estimates the data in each sub-band using narrowband DOA technology, and finally averages the results of each sub-band to obtain the broadband azimuth spectrum. The azimuth time history is then output using intensity coloring. This method is simple to operate and easy to implement in engineering. However, when the signal-to-noise ratio is low and the target azimuth is relatively close, the similar colors of the target trajectories cause mutual masking, resulting in poor estimation performance. Since the colors in the traditional azimuth time history map only represent intensity information, other broadband signal azimuth estimation methods also suffer from this problem.

[0004] Current research on traditional orientation time history diagrams mainly includes: Liu Xionghou, Wang Cong, Sun Chao, Yang Yixin, Zhuo Jie. A broadband energy detection method based on frequency coloring processing [P]. Shaanxi Province: CN110208810B, 2022-08-19. (hereinafter referred to as Invention 1); Wang Cong, Liu Xionghou, Sun Chao, et al. A broadband energy detection method for passive sonar based on frequency coloring [J]. Journal of Harbin Engineering University, 2021, 42(4):456-462. (hereinafter referred to as Reference 1)

[0005] Invention 1 and Reference 1 address the shortcomings of traditional azimuth time history maps by proposing a frequency-colored passive sonar broadband energy detection method. This method introduces the three primary colors of light (RGB) into passive sonar broadband energy detection, mapping the beam output of the processed broadband signal to different primary color values ​​according to frequency. Finally, a colored azimuth time history map (BTR) is output in parallel according to time, which improves the target resolution and detection capabilities of passive sonar broadband energy detection (CED) to some extent. However, its designed color mapping matrix has defects and cannot accurately reflect the frequency characteristics of the broadband signal. In addition, the primary colors output by this method have the potential for color value overflow.

[0006] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0007] (1) When the signal-to-noise ratio is low and the target is close, the broadband orientation estimation method using the incoherent subspace method has poor estimation performance because the target trajectories are similar in color and the trajectories overlap.

[0008] (2) Since the color of the traditional azimuth time history map only represents intensity information, other broadband signal azimuth estimation methods also have the problem of poor estimation performance.

[0009] (3) The color mapping matrix designed by the existing passive sonar broadband energy detection method has defects. It cannot accurately reflect the frequency characteristics of the broadband signal, and the output three primary colors have the potential risk of color value overflow. Summary of the Invention

[0010] To overcome the problems existing in related technologies, the present invention discloses an embodiment of a method for displaying azimuth history maps combining frequency coloring and broadband frequency features, the technical solution of which is as follows:

[0011] This invention is implemented as follows: a method for displaying azimuth history maps combining frequency coloring and broadband frequency characteristics, comprising the following steps:

[0012] S1, the received signal from the array is divided into multiple time periods for separate processing, and the time domain signal is converted to the frequency domain by fast Fourier transform. Beamforming is performed on each sub-band signal at different azimuth positions to obtain the frequency azimuth matrix.

[0013] S2, create a color mapping matrix, and use matrix-vector operations to obtain red, green and blue color matrices respectively between the frequency orientation matrix and the color value mapping matrix;

[0014] S3, sum the frequency azimuth matrix along the frequency dimension to obtain the broadband beam output vector, and normalize the obtained broadband target azimuth estimation result to the 0~255 range.

[0015] S4, sum the red, green and blue color matrices along the frequency dimension to obtain the broadband beam output vectors of red, green and blue in sequence, and normalize them to obtain different color coefficients;

[0016] S5. Multiply the result obtained in step S3 by the corresponding red, green and blue color coefficients obtained in step S4 to obtain the output color values ​​of the three primary colors in each direction.

[0017] S6 stacks the output color values ​​of the three primary colors to obtain a color broadband target azimuth estimate; outputs the color broadband target azimuth estimates of different time periods in parallel to obtain an improved azimuth history map.

[0018] In step S1, azimuth estimation is performed on each segment of the time-domain signal using frequency-domain beamforming to obtain a frequency-azimuth matrix, including:

[0019] (1) Perform FFT operation on the time domain signal of each array element to obtain the frequency domain signal of each array element;

[0020] (2) Divide the frequency domain signal into K sub-bands;

[0021] (3) Perform phase compensation on the frequency domain signal of each sub-band. The compensation vector is:

[0022] W(f, θ) = [1 e -i2πfdsinθ / c e -i2πf 2dsinθ / c ... e -i2πf(M-1)dsinθ / c ]

[0023]

[0024]

[0025] In the formula, W(f, θ) is the weighted vector of the design, f is the frequency, θ is the scanning angle, i represents the imaginary number, d is the element spacing, c is the underwater sound speed, M is the number of elements, n is the azimuth scanning sequence number, and N is the number of azimuth scanning grids.

[0026] (4) Multiply the frequency domain signal of each array element with the compensation vector, and then take the square of the modulus of the signal to obtain the energy of the frequency domain beamforming.

[0027] (5) Save the beamforming vector of each sub-band to form a frequency azimuth matrix with dimension K×N. The element in the i-th row and j-th column is denoted as p. i，j .

[0028] In step S2, creating the color mapping matrix includes:

[0029] (1) The dimension of the matrix is ​​K×3, where K is the number of sub-bands divided in step S1. Let all matrix elements be zero.

[0030] (2) The vector in the i-th row of the color mapping matrix is ​​denoted as (wr i wg i wb i Let i = 1, 2, ..., K, and each column of the matrix represent red, green, and blue mapping values, respectively. The values ​​are assigned according to the following rules:

[0031]

[0032] In the formula, K is the number of sub-bands. This is the floor symbol.

[0033] In step S2, the elements of the red, green, and blue color matrices are calculated according to the following rules:

[0034]

[0035] In the formula, r i，j The initial color value for red is g. i，j The initial color value for green is b. i，j p is the initial color value for blue. i，j For the element in the i-th row and j-th column of the frequency azimuth matrix, wr i For red mapping values, wg i For green mapping values, wb i The blue mapping value is represented by i and j, which indicate the i-th row and j-th column in the matrix. K is the number of sub-bands, and N is the number of azimuth scan grids.

[0036] In step S3, the broadband beam output vector is:

[0037] P = [P1, P2, ..., P] N ],

[0038] In the formula, P represents the omnidirectional broadband beam output, P1, P2…P N For the broadband beam output vector result, P j For the beam output in the j-th azimuth direction, p i，j Let K be the element in the i-th row and j-th column of the frequency azimuth matrix, K be the number of sub-bands, and N be the number of azimuth scan grids.

[0039] Furthermore, the broadband beam output vector results are P1, P2…P N The broadband beam output vector results are processed as follows: The minimum and maximum values ​​are found, with the minimum value corresponding to a grayscale value of 0 and the maximum value corresponding to a grayscale value of 255. Other values ​​are linearly distributed between 0 and 255. The result is P. j ′, j=1,2…N, are called the gray values ​​of the broadband beam output vector, where N is the number of azimuth scanning grids.

[0040] In step S4, the output vectors of the red, green, and blue broadband beams are respectively:

[0041] R = [R1, R2, ..., R] N ]

[0042] G = [G1, G2, ..., G] N ]

[0043] B = [B1, B2, ..., B] N ]

[0044] In the formula, R1, R2…R N Let G1, G2…G be the output vector of the red broadband beam. N The green broadband beam output vectors, B1, B2…B N is the blue broadband beam output vector, and N is the number of azimuth scan grids.

[0045] The elements in the vector are:

[0046]

[0047] In the formula, R j ′ represents an element in the secondary red broadband beam output vector, G j ′ represents an element in the secondary green broadband beam output vector, B j ′ represents an element in the secondary blue broadband beam output vector, r i，j For the elements in the red matrix, g i，j b is an element in the green matrix. i，j The elements in the blue matrix are K, N, and j. K represents the number of sub-bands, N represents the number of azimuth scan grids, and j represents the azimuth index number.

[0048] In step S4, based on the broadband beam output vectors of red, green, and blue, the red, green, and blue color coefficients for the j-th azimuth are calculated as follows:

[0049]

[0050] In the formula, R j ′ represents an element in the secondary red broadband beam output vector, G j ′ represents an element in the secondary green broadband beam output vector, B j ′ represents an element in the secondary blue broadband beam output vector, N is the number of azimuth scan grids, max is the maximum value operation, and j is the azimuth index number.

[0051] In step S5, the output color values ​​of the three primary colors are as follows:

[0052] R j "=P j ′×a r， j

[0053] G j "=P j ′×a g，j j = 1, 2, ..., N

[0054] B j "=P j ′×a b，j

[0055] In the formula, P j ′ represents the grayscale value of the broadband beam output vector, R j "G represents the final red broadband beam output vector." j "B" represents the final green broadband beam output vector. j " is the final blue broadband beam output vector, N is the number of azimuth scan grids, and j is the azimuth index number.

[0056] Another object of the present invention is to provide a location history map display system combining frequency coloring and broadband frequency characteristics, the system being used to control the location history map display method combining frequency coloring and broadband frequency characteristics, the system comprising:

[0057] The azimuth estimation module is used to divide the array received signal into multiple time periods, and perform azimuth estimation on each time-domain signal using frequency-domain beamforming to obtain a frequency azimuth matrix.

[0058] The color matrix construction module is used to create color mapping matrices. It operates on the frequency orientation matrix and the color value mapping matrix according to certain rules to obtain three color matrices: red, green, and blue.

[0059] The target azimuth estimation module is used to sum the frequency azimuth matrix along the frequency dimension to obtain the broadband beam output vector, and to normalize the broadband target azimuth estimation results to the 0-255 range.

[0060] The color coefficient calculation module is used to sum the red, green, and blue color matrices along the frequency dimension to obtain the broadband beam output vectors of red, green, and blue in sequence, and normalize them to obtain different color coefficients.

[0061] The three primary color output color value calculation module is used to multiply the results obtained by the target orientation estimation module by the corresponding red, green and blue color coefficients to obtain the three primary color output color values ​​for each orientation.

[0062] The orientation history map display module is used to stack the output color values ​​of the three primary colors to obtain color broadband target orientation estimates for different time periods, and then output them in parallel to obtain an improved orientation history map.

[0063] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows: This invention provides a method for displaying a azimuth history map that combines frequency coloring and broadband frequency characteristics. By dividing the array-received signal into multiple time periods for separate processing, azimuth estimation is performed using frequency-domain beamforming to obtain a frequency azimuth matrix. A color mapping matrix is ​​set to map the frequency information of the broadband signal to the RGB primary colors. The broadband target azimuth spectrum is normalized to the 0-255 range. Different primary color values ​​are assigned to the broadband target azimuth estimation output according to the RGB mapping value ratio. Finally, the color broadband target azimuth estimates from different time periods are output side-by-side to obtain an improved azimuth history map. This invention utilizes the frequency information of the broadband signal and accurately maps its characteristics to the three primary colors of light to colorize the traditional azimuth history map. When the frequency characteristics of broadband targets with similar azimuths differ, the improved azimuth history map of this invention can identify the target's azimuth based on the difference in displayed colors, improving the passive detection capability of sonar.

[0064] This invention maps the frequency characteristics of broadband signals to the three primary colors of light and incorporates them into a traditional azimuth history map for display. When broadband targets are located close to each other and their frequency characteristics differ, this method enhances the display effect, effectively identifies the target trajectory, solves the inaccuracies of previous manual observations, and improves the passive detection capability of sonar. Computer numerical simulation results show that, under the above conditions, the azimuth history map display method of this invention can effectively improve the display effect of the azimuth history map. Attached Figure Description

[0065] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0066] Figure 1 This is a flowchart of the method for displaying the azimuth history map of joint frequency coloring and broadband frequency features provided in an embodiment of the present invention;

[0067] Figure 2 This is a schematic diagram of the method for displaying the azimuth history diagram of joint frequency coloring and broadband frequency features provided in an embodiment of the present invention.

[0068] Figure 3(a) is the azimuth history diagram output after conventional processing when two targets, one strong and one weak (1° is the strong target with a signal-to-noise ratio of 10dB and 3° is the weak target with a signal-to-noise ratio of 5dB), are under the simulation conditions provided by the embodiment of the present invention.

[0069] Figure 3(b) is the azimuth history diagram output after coloring the frequency characteristics of the targets using the method of the present invention when two targets, one strong and one weak (1° is the strong target with a signal-to-noise ratio of 10dB and 3° is the weak target with a signal-to-noise ratio of 5dB), are under the simulation conditions provided by the embodiment of the present invention.

[0070] Figure 4(a) is the azimuth history diagram output after conventional processing when two targets have equal intensity (azimuth of 1° and 3° respectively) under the simulation conditions provided by the embodiment of the present invention.

[0071] Figure 4(b) is the azimuth history diagram output after coloring the frequency characteristics of the targets using the method of the present invention when the two targets have the same intensity (azimuth of 1° and 3° respectively) under the simulation conditions provided by the embodiment of the present invention. Detailed Implementation

[0072] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0073] Examples, such as Figure 1 As shown, the method for displaying the azimuth history map of joint frequency coloring and broadband frequency features provided in this embodiment of the invention includes the following steps:

[0074] S101, the array received signal is divided into multiple time periods for separate processing, and the azimuth estimation is performed using frequency domain beamforming to obtain the frequency azimuth matrix;

[0075] S102, Set the color mapping matrix to map the frequency information of the broadband signal to the three primary colors of RGB; normalize the broadband target azimuth spectrum to the range of 0 to 255;

[0076] S103 assigns different primary color values ​​to the broadband target azimuth estimation output according to the RGB mapping value ratio; the color broadband target azimuth estimates of different time periods are output in parallel to obtain an improved azimuth history map.

[0077] As a preferred embodiment, such as Figure 2 As shown, the method for displaying the azimuth history map of joint frequency coloring and broadband frequency features provided in this embodiment of the invention specifically includes the following steps:

[0078] Step 101): Divide the array-received signal into multiple time periods;

[0079] Step 102): Perform frequency domain beamforming on each time domain signal to estimate the azimuth and obtain the frequency azimuth matrix.

[0080] Step 103), create a color mapping matrix;

[0081] Step 104) The frequency orientation matrix and the color value mapping matrix are operated according to certain rules to obtain three color matrices: red, green and blue.

[0082] Step 105): Summate the frequency azimuth matrix obtained in step 102) along the frequency dimension to obtain the broadband beam output vector.

[0083] Step 106): Summing the red, green, and blue color matrices obtained in step 104) along the frequency dimension to obtain the broadband beam output vectors of red, green, and blue in sequence, and normalizing them according to certain rules to obtain different color coefficients.

[0084] Step 107): Normalize the broadband target azimuth estimation result obtained in step 105 to the range of 0 to 255.

[0085] Step 108): Multiply the result obtained in step 107) by the corresponding red, green and blue color coefficients respectively to obtain the output color values ​​of the three primary colors in each direction;

[0086] Step 109): Stack the three primary color output values ​​obtained in step 108) to obtain a color broadband target orientation estimate;

[0087] Step 110): The color broadband target azimuth estimates for different time periods are output in parallel to obtain the improved azimuth history map.

[0088] In a preferred embodiment, step 102 of the present invention specifically includes:

[0089] Step 102-1): Perform FFT operation on the time domain signal of each array element to obtain the frequency domain signal of each array element;

[0090] Step 102-2): Divide the frequency domain signal into K sub-bands;

[0091] Step 102-3): Perform phase compensation on the frequency domain signal of each sub-band. The compensation vector is:

[0092] W(f, θ) = [1 e -i2πfdsinθ / c e -i2πf 2dsinθ / c ... e -i2πf(M-1)dsinθ / c ]

[0093]

[0094]

[0095] In the formula, W(f, θ) is the weighted vector of the design, f is the frequency, θ is the scanning angle, t represents the imaginary number, d is the element spacing, c is the underwater sound speed, M is the number of elements, n is the azimuth scanning sequence number, and N is the number of azimuth scanning grids.

[0096] Step 102-4): Multiply the frequency domain signal of each array element with the compensation vector, and then take the square of the modulus of the signal to obtain the energy of the frequency domain beamforming.

[0097] Step 102-5): Save the beamforming vector of each sub-band to form a frequency azimuth matrix with dimension K×N. The element in the i-th row and j-th column is denoted as p. i，j .

[0098] In a preferred embodiment, step 103 of the present invention specifically includes:

[0099] Step 103-1): Create a color mapping matrix with dimensions K×3, where K is the number of sub-bands divided in step 102-2), and set all matrix elements to zero.

[0100] Step 103-2), the vector in the i-th row of the color mapping matrix is ​​denoted as (wr i wg i wb i Let i = 1, 2, ..., K, and each column of the matrix represent red, green, and blue mapping values, respectively. The values ​​are assigned according to the following rules:

[0101]

[0102] In the formula, K is the number of sub-bands. Using a rounding down sign, the color mapping matrix designed in this invention can uniformly divide the frequency band, with the mapping color ratio of low frequency, mid frequency, and high frequency being 1:1:1.

[0103] In a preferred embodiment, step 104 of the present invention specifically includes:

[0104] The elements of the red, green, and blue color matrices are obtained by performing operations according to the following rules:

[0105]

[0106] In the formula, r i，j The initial color value for red is g. i，j The initial color value for green is b. i，j p is the initial color value for blue. i，j For the element in the i-th row and j-th column of the frequency azimuth matrix, wr i For red mapping values, wg i For green mapping values, wb i The blue mapping value is represented by i and j, which indicate the i-th row and j-th column in the matrix. K is the number of sub-bands, and N is the number of azimuth scan grids.

[0107] In a preferred embodiment, step 105 of the present invention specifically includes:

[0108] The broadband beam output vector is:

[0109] P = [P1, P2, ..., P] N ],

[0110] In the formula, P represents the omnidirectional broadband beam output, P1, P2…P N For the broadband beam output vector result, P j For the beam output in the j-th azimuth direction, p i，j Let K be the element in the i-th row and j-th column of the frequency azimuth matrix, K be the number of sub-bands, and N be the number of azimuth scan grids.

[0111] In a preferred embodiment, step 106 of the present invention specifically includes:

[0112] Step 106-1), the output vectors of the red, green, and blue broadband beams are respectively:

[0113] R = [R1, R2, ..., R] N ]

[0114] G = [G1, G2, ..., G] N ]

[0115] B = [B1, B2, ..., B] N ]

[0116] In the formula, R1, R2…R N Let G1, G2…G be the output vector of the red broadband beam. N The green broadband beam output vectors, B1, B2…B N is the blue broadband beam output vector, and N is the number of azimuth scan grids;

[0117] The elements in the vector are:

[0118]

[0119] In the formula, R j ′ represents an element in the secondary red broadband beam output vector, G j ′ represents an element in the secondary green broadband beam output vector, B j ′ represents an element in the secondary blue broadband beam output vector, r i，j For the elements in the red matrix, g i，j b is an element in the green matrix. i，j The elements in the blue matrix are K, N, and j. K represents the number of sub-bands, N represents the number of azimuth scan grids, and j represents the azimuth index number.

[0120] Step 106-2): Based on the result obtained in step 106-1), calculate the red, green, and blue color coefficients for the j-th orientation as follows:

[0121]

[0122] In the formula, R j ′ represents an element in the secondary red broadband beam output vector, G j ′ represents an element in the secondary green broadband beam output vector, B j ′ represents an element in the secondary blue broadband beam output vector, N is the number of azimuth scan grids, max is the maximum value operation, and j is the azimuth index number.

[0123] In a preferred embodiment, step 107 of the present invention specifically includes:

[0124] The broadband beam output vector results are: P1, P2, P3…P N The following steps will be taken to address this:

[0125] Find the minimum and maximum values, set the gray level of the minimum value to 0, the gray level of the maximum value to 255, and let the other values ​​be linearly distributed between 0 and 255. The result is P. j , j = 1, 2…N, are called the grayscale values ​​of the broadband beam output vector, where N is the number of azimuth scan grids. This invention fuses the target frequency information into the traditional broadband energy detection results through operations such as normalization.

[0126] In a preferred embodiment, step 108 of the present invention specifically includes:

[0127] The output color values ​​of the three primary colors are as follows:

[0128] R j "=P j ′×a r，j

[0129] G j "=P j ′×a g，j j = 1, 2, ..., N

[0130] B j "=P j ′×a b,j

[0131] In the formula, P j ′ represents the grayscale value of the broadband beam output vector, R j "G represents the final red broadband beam output vector." j "B" represents the final green broadband beam output vector. j " is the final blue broadband beam output vector, N is the number of azimuth scan grids, and j is the azimuth index number.

[0132] The azimuth history map display system for joint frequency coloring and broadband frequency characteristics provided in this embodiment of the invention includes:

[0133] The azimuth estimation module is used to divide the array received signal into multiple time periods, and perform azimuth estimation on each time-domain signal using frequency-domain beamforming to obtain a frequency azimuth matrix.

[0134] The color matrix construction module is used to create color mapping matrices. It operates on the frequency orientation matrix and the color value mapping matrix according to certain rules to obtain three color matrices: red, green, and blue.

[0135] The target azimuth estimation module is used to sum the frequency azimuth matrix along the frequency dimension to obtain the broadband beam output vector, and to normalize the broadband target azimuth estimation results to the 0-255 range.

[0136] The color coefficient calculation module is used to sum the red, green, and blue color matrices along the frequency dimension to obtain the broadband beam output vectors of red, green, and blue in sequence, and normalize them to obtain different color coefficients.

[0137] The three primary color output color value calculation module is used to multiply the results obtained by the target orientation estimation module by the corresponding red, green and blue color coefficients to obtain the three primary color output color values ​​for each orientation.

[0138] The orientation history map display module is used to stack the output color values ​​of the three primary colors to obtain color broadband target orientation estimates for different time periods, and then output them in parallel to obtain an improved orientation history map.

[0139] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0140] The information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of the present invention. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0141] Those skilled in the art will understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the functions described above can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments.

[0142] According to embodiments of this application, the present invention also provides a computer device comprising: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor executes the computer program to implement the steps in any of the above-described method embodiments.

[0143] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the steps described in the various method embodiments above.

[0144] This invention also provides an information data processing terminal, which, when executed on an electronic device, provides a user input interface to implement the steps described in the above method embodiments. The information data processing terminal is not limited to mobile phones, computers, or switches.

[0145] This invention also provides a server that, when executed on an electronic device, provides a user input interface to implement the steps described in the above method embodiments.

[0146] This invention also provides a computer program product that, when run on an electronic device, enables the electronic device to implement the steps described in the various method embodiments above.

[0147] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying the computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0148] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0149] To further demonstrate the positive effects of the above embodiments, the present invention conducts the following experiments based on the above technical solutions.

[0150] The effectiveness of the method of the present invention is verified by using computer simulation for numerical simulation.

[0151] Assume the underwater sound wave propagation speed is 1500 m / s. The receiving array is a 64-element uniform linear array with a base frequency of 800 Hz, a sampling frequency of 8 kHz, an azimuth scanning range of [-20°, 20°], a scanning interval of 0.1°, and a broadband signal bandwidth of 200–800 Hz, which is divided into 77 sub-bands. The simulated signal used contains information about two broadband targets.

[0152] Simulations were performed using conventional beamforming (CBF) methods:

[0153] Target 1 has a broadband frequency characteristic of 600–800 Hz, a target radiated noise intensity of 10 dB, an in-band signal-to-noise ratio of 10 dB, and an angle of 1°; Target 2 has a broadband frequency characteristic of 200–800 Hz, a target radiated noise intensity of 5 dB, an in-band signal-to-noise ratio of 5 dB, and an angle of 3°.

[0154] according to Figure 2The process was simulated to obtain the processing results of the traditional method and the orientation history diagram of the present invention. As can be seen from the output results in Figures 3(a) and 3(b), the traditional method, due to the close proximity of the two simulated targets, results in similar trajectory colors, making it impossible to distinguish the orientations of the two targets in Figure 3(a). In contrast, the present invention's method shows the strong target at 1° as a high-frequency band, displayed as blue in Figure 3(b), and the weak target at 3° as a full-bandwidth target, displayed as white. Due to its lower energy, the display brightness is also lower. The two targets can be distinguished by their colors. Therefore, the present invention can utilize the frequency characteristics of broadband signals, using different colors to represent the frequency differences of broadband signals, enhancing the display effect and improving detection capabilities.

[0155] For comparison, two targets of equal intensity were set. Target 1 has a broadband frequency characteristic of 200–400 Hz, a target intensity of 10 dB, an in-band signal-to-noise ratio of 10 dB, and an angle of 1°. Target 2 has a broadband frequency characteristic of 200–600 Hz, a target intensity of 10 dB, an in-band signal-to-noise ratio of 10 dB, and an angle of 3°. As shown in Figures 4(a) and 4(b), the traditional method cannot distinguish the azimuth of two close targets. The target at 1° contains a low-frequency band and is displayed in red, while the target at 3° contains a mid-to-low frequency band and is displayed in a color close to yellow. The two targets can be distinguished by their colors. From the results in Figures 4(a) and 4(b), it can be seen that the azimuth history map display of this invention utilizes the frequency characteristics of the signal. The improved azimuth history map display method of this invention demonstrates its effectiveness and advantages through comparison.

[0156] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for displaying azimuth history maps combining frequency coloring and broadband frequency characteristics, characterized in that, The method includes the following steps: S1, the received signal from the array is divided into multiple time periods for separate processing, and the time domain signal is converted to the frequency domain by fast Fourier transform. Beamforming is performed on each sub-band signal at different azimuth positions to obtain the frequency azimuth matrix. S2, create a color mapping matrix, and use matrix-vector operations to obtain red, green and blue color matrices respectively between the frequency orientation matrix and the color value mapping matrix; S3, sum the frequency azimuth matrix along the frequency dimension to obtain the broadband beam output vector, and normalize the obtained broadband target azimuth estimation result to the 0~255 range. S4, sum the red, green and blue color matrices along the frequency dimension to obtain the broadband beam output vectors of red, green and blue in sequence, and normalize them to obtain different color coefficients; S5. Multiply the result obtained in step S3 by the corresponding red, green and blue color coefficients obtained in step S4 to obtain the output color values ​​of the three primary colors in each direction. S6 stacks the output color values ​​of the three primary colors to obtain a color broadband target azimuth estimate; outputs the color broadband target azimuth estimates of different time periods in parallel to obtain an improved azimuth history map. In step S1, azimuth estimation is performed on each segment of the time-domain signal using frequency-domain beamforming to obtain the frequency-azimuth matrix, which includes: (1) Perform FFT operation on the time domain signal of each array element to obtain the frequency domain signal of each array element; (2) Divide the frequency domain signal into K sub-bands; (3) Perform phase compensation on the frequency domain signal of each sub-band. The compensation vector is: W(f,θ)=[1 e -i2πfdsinθ / c e -i2πf2dsinθ / c ... e -i2πf(M-1)dsinθ / c ] ； ； In the formula, W(f,θ) is the weighted vector of the design, f is the frequency, θ is the scanning angle, i represents the imaginary number, d is the element spacing, c is the underwater sound speed, M is the number of elements, n is the azimuth scanning sequence number, and N is the number of azimuth scanning grids. (4) Multiply the frequency domain signal of each array element with the compensation vector, and then take the square of the modulus of the signal to obtain the energy of the frequency domain beamforming. (5) Save the beamforming vector of each sub-band to form a frequency azimuth matrix with dimension K×N. The element in the i-th row and j-th column is denoted as p. i,j； In step S2, creating the color mapping matrix includes: (1) The dimension of the matrix is ​​K×3, where K is the number of sub-bands divided in step S1. Let all matrix elements be zero. (2) The vector in the i-th row of the color mapping matrix is ​​denoted as (wr i ,wg i wb i (i=1,2…K), where each column of the matrix represents the red, green, and blue mapping values, and the values ​​are assigned according to the following rules: ； In the formula, K is the sub-band number, and is the floor sign; In step S2, the elements in the red, green, and blue color matrices are calculated according to the following rules: ； In the formula, r i,j The initial color value for red is g. i,j The initial color value for green is b. i,j p is the initial color value for blue. i,j For the element in the i-th row and j-th column of the frequency azimuth matrix, wr i For red mapping values, wg i For green mapping values, wb i The blue mapping value is represented by i,j, which indicates the i-th row and j-th column in the matrix. K is the number of sub-bands, and N is the number of azimuth scan grids.

2. The method for displaying azimuth history maps based on joint frequency coloring and broadband frequency characteristics according to claim 1, characterized in that, In step S3, the broadband beam output vector is: ； In the formula, P represents the omnidirectional broadband beam output, P1, P2…PN represents the broadband beam output vector result, and P…PN…PN…PN…PN…PN…PN…PN…P ... j For the beam output in the j-th azimuth direction, p i,j Let K be the element in the i-th row and j-th column of the frequency azimuth matrix, K be the number of sub-bands, and N be the number of azimuth scan grids.

3. The method for displaying the azimuth history map of combined frequency coloring and broadband frequency characteristics according to claim 2, characterized in that, The broadband beam output vector results are P1, P2…P N The broadband beam output vector results are processed as follows: The minimum and maximum values ​​are found, with the minimum value corresponding to a grayscale value of 0 and the maximum value corresponding to a grayscale value of 255. Other values ​​are linearly distributed between 0 and 255. The result is P. j′ ,j=1,2…N, are called the gray values ​​of the broadband beam output vector, where N is the number of azimuth scan grids.

4. The method for displaying azimuth history maps based on joint frequency coloring and broadband frequency characteristics according to claim 1, characterized in that, In step S4, the output vectors of the red, green, and blue broadband beams are respectively: R=[R1,R2…R N ]; G=[G1,G2…G N ]; B=[B1,B2…B N ]; In the formula, R1, R2…R N Let G1, G2…G be the output vector of the red broadband beam. N The green broadband beam output vectors, B1, B2…B N is the blue broadband beam output vector, and N is the number of azimuth scan grids; The elements in the vector are: ； In the formula, R j′ G represents an element in the secondary red broadband beam output vector. j′ B is an element in the secondary green broadband beam output vector. j′ r is an element in the secondary blue broadband beam output vector. i,j For the elements in the red matrix, g i,j b is an element in the green matrix. i,j The elements in the blue matrix are K, N, and j. K represents the number of sub-bands, N represents the number of azimuth scan grids, and j represents the azimuth index number.

5. The method for displaying the azimuth history map of combined frequency coloring and broadband frequency characteristics according to claim 1, characterized in that, In step S4, based on the broadband beam output vectors of red, green, and blue, the red, green, and blue color coefficients for the j-th azimuth are calculated as follows: ； In the formula, R j′ G represents an element in the secondary red broadband beam output vector. j′ B is an element in the secondary green broadband beam output vector. j′ is an element in the secondary blue broadband beam output vector, N is the number of azimuth scan grids, max is the maximum value operation, and j is the azimuth index number.

6. The method for displaying azimuth history maps based on joint frequency coloring and broadband frequency characteristics according to claim 1, characterized in that, In step S5, the output color values ​​of the three primary colors are as follows: R j″ =P j′ ×a r,j； G j″ =Pj′×a g,j ,j=1,2…N; Bj″=P j′ ×a b,j； In the formula, P j′ R represents the grayscale value of the broadband beam output vector. j″ G is the final red broadband beam output vector. j″ B is the final green broadband beam output vector. j″ The final blue broadband beam output vector is denoted by N, where N is the number of azimuth scan grids and j is the azimuth index number.

7. A location history map display system combining frequency coloring and broadband frequency characteristics, characterized in that, This system is used to control the azimuth history plot display method of joint frequency coloring and broadband frequency characteristics as described in any one of claims 1 to 6. The system comprises: The azimuth estimation module is used to divide the array received signal into multiple time periods, and perform azimuth estimation on each time-domain signal using frequency-domain beamforming to obtain a frequency azimuth matrix. The color matrix construction module is used to create color mapping matrices. It operates on the frequency orientation matrix and the color value mapping matrix according to certain rules to obtain three color matrices: red, green, and blue. The target azimuth estimation module is used to sum the frequency azimuth matrix along the frequency dimension to obtain the broadband beam output vector, and to normalize the broadband target azimuth estimation results to the 0-255 range. The color coefficient calculation module is used to sum the red, green, and blue color matrices along the frequency dimension to obtain the broadband beam output vectors of red, green, and blue in sequence, and then normalize them to obtain different color coefficients. The three primary color output color value calculation module is used to multiply the results obtained by the target orientation estimation module by the corresponding red, green and blue color coefficients to obtain the three primary color output color values ​​for each orientation. The orientation history map display module is used to stack the output color values ​​of the three primary colors to obtain color broadband target orientation estimates for different time periods, and then output them in parallel to obtain an improved orientation history map.

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