A reverberation beam domain time domain signal simulation method based on sound field calculation

Abstract

The application provides a reverberation beam domain time domain signal simulation method based on a sound field calculation, comprising the following steps: establishing a sea battle field simulation situation, obtaining simulation situation information, and including a reverberation calculation direction; querying environmental database information according to the reverberation calculation direction, and obtaining marine environmental parameters of a target sea area after grid processing; selecting a sound field model, generating a sound ray reaching structure based on the marine environmental parameters by using a physical modeling method; generating a reverberation level result of each direction based on the sound ray reaching structure and in combination with a reverberation level calculation model; performing energy level signal level conversion according to the reverberation level calculation result of each direction, performing sound field calculation by grid division of the marine environment, calling a reverberation model to calculate the reverberation level in layers, and performing energy level signal level conversion; and compared with a conventional method, the calculation efficiency can be effectively improved, the problems of low simulation efficiency and the inability to reflect dynamic changes of a combat environment can be solved, and the authenticity of a reverberation background of an active sonar is enhanced.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic signal processing and simulation, and in particular to a method for simulating reverberant beam-domain time-domain signals based on sound field calculation. Background Technology

[0002] Underwater acoustic reverberation is one of the main sources of interference in active sonar systems. It is generated by the scattering of sound waves on the sea surface, seabed, and in water bodies. Simulating the reverberation signal of active sonar in combat detection scenarios is of great significance for underwater acoustic target detection and live-fire exercises.

[0003] Existing reverberation simulation methods are mainly divided into two categories: one is the scattering element superposition method, such as the spatial partitioning-scattering element superposition method, the transceiver separate monostatic interface scattering model, and the element scattering theory method. This type of method divides the ocean into discrete scatterers and calculates the reverberant echo signals formed by all scatterers, superimposing them to form the total reverberant signal. This type of method is relatively universal and has the basic characteristics of reverberant signals, but it cannot reflect the environmental changes in actual combat scenarios. The other type is the acoustic spatial modeling method, which simulates the emission, propagation, reflection, refraction, and attenuation of sound waves in water by constructing a simulation environment (including seawater temperature, depth, current velocity, seabed topography, sea surface waves, etc.). It processes and identifies the received echo signals and extracts reverberation information. This type of method has high simulation accuracy and can reflect the environmental changes in actual combat scenarios, but the computational load is huge, making it difficult to calculate the reverberation signal of active sonar in real time. Existing methods are difficult to balance between computational efficiency and simulation accuracy, especially in dynamic marine environments where it is difficult to generate high-fidelity reverberation signals in real time. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes a reverberant beam domain time domain signal simulation method based on sound field calculation.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for simulating reverberant beam-domain time-domain signals based on sound field calculation, comprising: Establish a simulated battlefield situation at sea and obtain simulated situation information, including reverberation calculation bearing; Based on the reverberation calculation orientation, environmental database information is queried, and marine environmental parameters of the target sea area are obtained after gridding. Select a sound field model and, based on the aforementioned marine environmental parameters, use a physical modeling method to generate the ray arrival structure; Based on the sound arrival structure and combined with the reverberation level calculation model, the reverberation level results for each direction are generated. Based on the reverberation level calculation results from each direction, energy level signal level conversion is performed to realize the simulation calculation of the reverberant beam domain time domain signal.

[0006] Preferably, the physical modeling method includes a ray model.

[0007] Preferably, the marine environment is divided into grids, and the marine environment parameters of the corresponding points are queried using the current status of the platform target. All calculation parameters required by the ray model are input to generate the ray arrival structure, which includes the number of rays, ray amplitude, ray delay and intrinsic ray incident angle.

[0008] Preferably, the reverberation level calculation model generates a distance sequence and a reverberation energy level sequence that corresponds one-to-one with the sequence. The two are combined to form a reverberation energy level curve that varies with distance. The reverberation level calculation model includes a sea surface reverberation model, a seabed reverberation model, and a volume reverberation model.

[0009] Preferably, the simulation situation information also includes the platform target motion situation and equipment operating parameters.

[0010] Preferably, the marine environmental parameters include sound velocity profile, seabed sediment type, and seabed topography.

[0011] Preferably, the intrinsic sound ray information at different receiving depths corresponding to the sampling distance in the sound propagation calculation results is obtained, and the receiving depth is iterated. According to different receiving depths, the corresponding reverberation intensity is calculated. Specifically, when the receiving depth is the sea surface, it corresponds to sea surface reverberation; when the receiving depth is the seabed, it corresponds to seabed reverberation; and other depths correspond to volumetric reverberation. The intrinsic sound ray is iterated, and the scattering intensity model corresponding to the reverberation type is called to calculate the sea surface reverberation, seabed reverberation, or volumetric reverberation intensity respectively. The calculation results are injected into a unified time window. Finally, the reverberation intensities of each type are superimposed and synthesized according to the unified time window to obtain the total reverberation intensity time decay curve.

[0012] Preferably, during the reverberation level energy level signal level conversion, a single-frame time sequence corresponding to the equipment is generated according to the sampling frequency, and the energy level curve is converted into a signal level time sampling sequence using numerical methods. The final result is generated by convolving it with the transmission signal time sequence with Doppler.

[0013] In a second aspect, the present invention provides an electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the reverberation beam domain time-domain signal simulation method based on sound field calculation.

[0014] Thirdly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the reverberant beam-domain time-domain signal simulation method based on sound field calculation.

[0015] Compared with existing technologies, the beneficial effects of this invention include: by dividing the marine environment into grids, performing sound field calculations, calling the reverberation model to calculate the reverberation level in layers, and performing energy level-signal level conversion, the computational efficiency can be effectively improved compared with conventional methods. Through the above calculation method, the problems of low simulation efficiency and inability to reflect the dynamic changes of the combat environment can be solved, and the realism of the reverberation background of active sonar can be enhanced. Attached Figure Description

[0016] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 A flowchart for reverberant beam domain time-domain signal simulation based on sound field calculation; Figure 2 A schematic diagram of a gridded marine environment; Figure 3 A comparison chart of calculated reverberation levels at the seabed; Figure 4 A comparison diagram of energy levels in CW reverberation simulation signals; Figure 5 A comparison diagram of energy levels in LFM reverberation simulation signals; Figure 6 The results show the autocorrelation characteristics of the reverberation signal in LFM simulation. Figure 7 The LFM simulation results show the reverberation signal spectrum. Figure 8 The results of time-frequency analysis of the LFM simulation reverberation signal; Figure 9 The results of the instantaneous probability distribution of the reverberation signal in LFM simulation; Figure 10 The time-domain waveform of the LFM simulation reverberation signal; Figure 11 The results of LFM simulation of reverberation signal envelope distribution; Figure 12 This is a azimuth-distance diagram of a full-beam reverberant signal in LFM simulation. Detailed Implementation

[0017] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0018] Example 1, referring to Figures 1-12 As an embodiment of the present invention, a method for simulating reverberant beam-domain time-domain signals based on sound field calculation is provided, comprising: S100: Reverberation level calculation considering dynamic environmental effects Traditional ray reverberation models divide the seabed into numerous interconnected rectangular scattering bodies using a grid, but they do not account for the influence of topographic relief. To improve this reverberation calculation model and enable reverberation level calculation under dynamically changing environments, topographic data (elevation data of each grid point) is used as input parameters for calculation. Figure 2 As shown, after meshing in the calculation orientation, the first mesh layer is the sea surface reverberation calculation layer. The seabed layer is no longer simply the bottom layer, but rather the mesh points where the seabed (thick black solid line) is located are taken as the calculation layer. The middle layer is the volumetric reverberation calculation layer. Specifically, the following steps are included: (1) Perform input parameter validation and calculation result initialization; (2) Obtain the intrinsic acoustic ray information at different receiving depths corresponding to the sampling distance in the acoustic propagation calculation results; (3) The receiving depth is cycled, and the corresponding reverberation intensity is calculated according to the different receiving depths. Among them, the receiving depth at the sea surface corresponds to sea surface reverberation, the receiving depth at the seabed corresponds to seabed reverberation, and the other depths correspond to volumetric reverberation; (4) The intrinsic sound rays are looped, and the scattering intensity model corresponding to the reverberation type is called to calculate the reverberation intensity of the sea surface, seabed, or volumetric reverberation respectively, and the calculation results are injected into a unified time window. Among them, the sea surface scattering model adopts the Chapman and Harris empirical fitting model, and the sea surface scattering intensity is... for: (1) (2) in, The glancing angle of the incident sound ray, in degrees; This is a sea surface roughness parameter, which is related to wind speed frequency; Wind speed, in kN; This refers to the frequency, measured in Hz.

[0019] The volumetric reverberation model adopts the deep-water scattering layer model with fish swarm distribution and swim bladders established by Love and Andreeva. In the volumetric backscattering model, the volumetric backscattering intensity is used to represent the volumetric backscattering intensity, which is taken as a constant value. .

[0020] The seabed scattering model adopts the Lambert scattering model, and the seabed scattering intensity is... for: (3) in, The angle of attack of the incident sound ray is expressed in degrees.

[0021] (5) By superimposing and synthesizing the reverberation intensities of various types according to a unified time window, the total reverberation intensity time decay curve can be obtained. The conversion formula between reverberation time and distance is as follows: The reverberation time is denoted as T, where T is the two-way reverberation time in seconds; c0 is the reference speed of sound in meters per second; and R is the converted distance in kilometers.

[0022] S200: Verification of the impact of dynamic environment on reverberation level The change in reverberation level with dynamic environment is mainly reflected in seabed reverberation, that is, the influence of topographic undulation on seabed reverberation is significant. The optimized algorithm and the traditional algorithm are compared to demonstrate that the optimized algorithm can reflect the influence of dynamic environment on reverberation level calculation.

[0023] In a sea area with undulating topography, under identical conditions such as calculation point location, calculation azimuth, and emission source level, calculate the seabed reverberation level at 20km using both the traditional algorithm and the optimized algorithm. Figure 3 As shown in the results, the traditional algorithm cannot reflect the impact of terrain undulation on the reverberation level, while the optimized algorithm clearly shows the appearance of an energy peak, indicating the presence of a slope at the corresponding distance, which causes fluctuations in the reverberation level. The results demonstrate that the optimized algorithm can reflect the changes in reverberation level with the dynamic environment.

[0024] S300: Reverberation Energy Level Signal Level Conversion Method The conversion of reverberation energy level to signal level requires two elements: first, the transmission conditions, i.e., the relevant parameters of the active sonar transmitted signal; and second, the environmental conditions, i.e., the energy distribution of reverberation after signal transmission. The specific implementation steps are as follows: S301: Generate a reverberation calculation time sampling sequence based on the sampling frequency. For the reverberation energy level curve (distance sequence) and energy sequence Interpolation calculation, and superposition of random phases: (4) Where interp1 is the interpolation calculation function, and the random phase is... The calculation is as follows: (5) rand is a uniform distribution of 0-1.

[0025] S302: Energy to amplitude calculation, generating reverberation amplitude signal : (6) S303: Generates the corresponding time-domain sequence of the transmitted signal based on the transmitted signal format (CW, LFM, etc.) and parameters. ; S304: Calculate the bearing based on the platform's heading, speed, and reverberation. Corresponding reverberation Doppler : (7) in, For platform speed, The center frequency of the transmitted signal. For the platform's course, Calculate the direction for reverberation.

[0026] S305: Superimpose Doppler information onto the time-domain sequence of the transmitted signal: By superimposing the Doppler frequency shift onto the transmitted sequence through complex exponential modulation, the simulated signal has frequency spread and shift characteristics.

[0027] (8) in, This is the time sampling sequence of the transmitted pulse.

[0028] S306: Transmit the reverberation amplitude signal Time-domain sequence of transmitted signals and superimposed Doppler signals Perform convolution (or frequency domain multiplication) to finally obtain the reverberant beam domain time-domain signal in the calculated azimuth. : (9) Here, conv represents the convolution operation.

[0029] S400: Verification of Basic Characteristics of Reverberant Beam-Domain and Time-Domain Signals To investigate the reliability of this simulation technology, a simulation scenario was constructed to verify the basic characteristics of the simulated reverberant beam domain time-domain signal results. The sonar-mounted platform was set to move in a straight-line motion with a heading of 60° and a speed of 4 knots. Using the active sonar simulation parameter table, the reverberant beam domain time-domain signal was obtained through the aforementioned simulation calculations. Taking the first beam as an example, the following characteristics were verified.

[0030] Active Sonar Simulation Parameter Table S401: Energy level invariance The power spectrum of the simulated reverberation beam-domain time-domain signal after matched filtering is calculated and compared with the original reverberation level. Figure 4 This is a comparison chart of the reverberation levels of CW transmitted signals. Figure 5 The image shows a comparison of reverberation levels for LFM transmitted signals. As can be seen from the image, the reverberation energy curve remains essentially unchanged after the energy level is converted to the signal level, demonstrating energy level invariance. Furthermore, the self-convolution operation of a single-frequency signal is similar to a smoothing window process, which to some extent eliminates the influence of terrain on reverberation. Therefore, the simulation effect of broadband FM signal reverberation is better than that of single-frequency signal reverberation.

[0031] S402: Time-related characteristics Extensive experiments have demonstrated that reverberation possesses autocorrelation characteristics. Taking any two beams, autocorrelation processing is performed on the simulated reverberation beam-domain and time-domain signals of the 1st and 16th beams. The results are as follows: Figure 6 As shown in the results, there is a maximum peak at 0 time delay, and the simulation results satisfy the time correlation characteristics.

[0032] S403: Spectral Characteristics In platform motion scenarios, the reverberation signal spectrum exhibits the Doppler effect, and the simulated signal spectrum results are as follows: Figure 7 As shown, the gray dashed lines correspond to the upper and lower frequency limits of the original transmitted signal. The results show that the simulated signal exhibits frequency spread and frequency shift, which satisfies the reverberation spectrum characteristics.

[0033] S404: Time-Frequency Characteristics Based on the spectral characteristics, the time-frequency results of the simulated reverberation signal are further analyzed using the short-time Fourier transform method, such as... Figure 8 As shown in the results, the simulated reverberation signal exhibits the characteristic of energy decay over time, and the frequency corresponds to the transmitted signal with random expansion, satisfying the reverberation time-frequency characteristics.

[0034] S405: Instantaneous Value Distribution Characteristics Extensive experiments have demonstrated that the instantaneous reverberation value distribution follows a normal distribution. The simulated LFM reverberation time-domain waveform is shown after downsampling, as follows: Figure 10 We can see that the energy decay trend is consistent with reality; we select the corresponding signal to perform amplitude histogram statistics, and then overlay the fitted normal distribution curve, as shown below. Figure 9 As shown in the results, the instantaneous value distribution fits well, and the simulation results satisfy the characteristics of the reverberation instantaneous value distribution.

[0035] S406: Envelope Distribution Characteristics Extensive experiments have demonstrated that the reverberation envelope distribution approximates the Rayleigh distribution. The aforementioned LFM simulation reverberation time-domain signal was processed using a Hilbert transform to obtain the envelope data, and amplitude histogram statistics were performed on it. The fitted Rayleigh distribution curve was then superimposed, as shown below. Figure 11 As shown in the results, the envelope distribution fits well, and the simulation results satisfy the characteristics of the reverberation envelope distribution.

[0036] S407: Azimuth and Distance Map The first 10 seconds (7.5 km) of the reverberant full-beam time-domain signal are extracted for azimuth-range map calculation. This involves performing matched filtering on the original signal at each azimuth. The matched filtering algorithm is as follows: (10) Where fliplr is the flip operation and H is the conjugate operation. This refers to the reverberation signals from various directions. This is the sequence of transmitted signals. This is the result of the matched filtering.

[0037] The result of the orientation and distance map processing is as follows Figure 12 As shown in the figure, the reverberation signal in each direction shows a decay trend, and due to the influence of terrain, the existence of reverberation bands can be clearly seen. Moreover, different directions have different peaks, which proves that the reverberation signal simulated by this invention can reflect the dynamic changes of the combat environment and has important significance for the realization of actual combat simulation.

[0038] This embodiment also provides an electronic device, including: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the reverberant beam domain time domain signal simulation method based on sound field calculation are implemented.

[0039] This embodiment also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of a reverberant beam-domain time-domain signal simulation method based on sound field calculation.

[0040] The storage medium proposed in this embodiment and the method for simulating reverberant beam domain time-domain signals based on sound field calculation proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0041] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0042] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for simulating reverberant beam-domain time-domain signals based on sound field calculation, characterized in that, include: Establish a simulated battlefield situation at sea and obtain simulated situation information, including reverberation calculation bearing; Based on the reverberation calculation orientation, environmental database information is queried, and marine environmental parameters of the target sea area are obtained after gridding. Select a sound field model and, based on the aforementioned marine environmental parameters, use a physical modeling method to generate the ray arrival structure; Based on the sound arrival structure and combined with the reverberation level calculation model, the reverberation level results for each direction are generated. Based on the reverberation level calculation results from each direction, energy level signal level conversion is performed to realize the simulation calculation of the reverberant beam domain time domain signal.

2. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The physical modeling method includes ray modeling.

3. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The marine environment is divided into grids, and the marine environment parameters of the corresponding points are queried using the current status of the platform target. All calculation parameters required by the ray model are input to generate the ray arrival structure, which includes the number of rays, ray amplitude, ray delay and intrinsic ray incident angle.

4. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The reverberation level calculation model generates a distance sequence and a reverberation energy level sequence that corresponds one-to-one with the sequence. The two are combined to form a reverberation energy level curve that varies with distance. The reverberation level calculation model includes a sea surface reverberation model, a seabed reverberation model, and a volume reverberation model.

5. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The simulated situation information also includes the platform target's motion status and equipment operating parameters.

6. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The marine environmental parameters include sound velocity profile, seabed sediment type, and seabed topography.

7. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, The intrinsic sound ray information at different receiving depths corresponding to the sampling distance in the sound propagation calculation results is obtained. The receiving depth is iterated, and the corresponding reverberation intensity is calculated according to different receiving depths. Specifically, the receiving depth at the sea surface corresponds to sea surface reverberation, the receiving depth at the seabed corresponds to seabed reverberation, and the other depths correspond to volumetric reverberation. The intrinsic sound rays are iterated, and the scattering intensity model corresponding to the reverberation type is called to calculate the sea surface reverberation, seabed reverberation, or volumetric reverberation intensity respectively. The calculation results are injected into a unified time window. Finally, the reverberation intensities of each type are superimposed and synthesized according to the unified time window to obtain the total reverberation intensity time decay curve.

8. The method for simulating reverberant beam-domain time-domain signals based on sound field calculation according to claim 1, characterized in that, During the reverberation level-energy level-signal level conversion, a single-frame time sequence corresponding to the equipment is generated based on the sampling frequency. The energy level curve is then converted into a signal level time sampling sequence using numerical methods. Finally, the result is generated by convolving the signal with the Doppler-enhanced transmission signal time sequence.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the reverberation beam domain time-domain signal simulation method based on sound field calculation as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the reverberant beam-domain time-domain signal simulation method based on sound field calculation as described in any one of claims 1 to 8.

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