Moving target sound scattering signal modeling method based on segmented path updating in waveguide

Abstract

The invention belongs to the field of underwater acoustic signal simulation, and particularly relates to a moving target acoustic scattering signal modeling method based on segmented path updating in a waveguide. Comprising the following steps: constructing a sound source emission signal, and discretizing the sound source emission signal; setting a motion path of the motion target, and discretizing the motion path of the motion target; calculating a channel impulse response function at each discretized position of the sound source and the moving target; calculating a signal excited by the sound source to the moving target; discretizing a signal, excited to the moving target, of the sound source; calculating a channel impulse response function at each discretized position of the receiving hydrophone and the moving target; a received signal at the receiving hydrophone is calculated. According to the method, a more accurate moving target received signal simulation result can be generated, and the limitation that an existing Bellhop model cannot calculate received signal simulation under target movement is eliminated.

Description

Technical Field

[0001] The present invention belongs to the field of underwater acoustic signal simulation, and particularly relates to a method for modeling acoustic scattering signals of moving targets based on segmented path updating in a waveguide. Background Art

[0002] In the field of acoustic communication, the simulation of received signals in a waveguide is a key research topic. A waveguide refers to the path of sound waves propagating in an ocean medium. Due to the inhomogeneity of the medium and the complexity of the boundary conditions, the propagation characteristics of sound waves become very complex. Therefore, accurately simulating and predicting the signal propagation behavior in a waveguide is crucial for designing efficient communication systems, acoustic detection devices, and other related applications. To achieve this goal, numerical simulation tools are usually used to calculate the sound field distribution and signal reception characteristics in a waveguide. Among them, Bellhop is a widely used simulation tool.

[0003] Bellhop is an acoustic propagation model based on ray theory and is widely used in the field of ocean acoustics to simulate the propagation path of sound waves and received signals in a complex ocean environment. Its basic principle is to regard the propagation of sound waves as a process of a series of rays. By tracking the reflection, refraction, and attenuation behaviors of these rays in different media, the distribution of the sound field and the characteristics of the received signal are predicted. The advantage of Bellhop is its high computational efficiency, which can quickly simulate the propagation of sound waves in a large-scale ocean environment. This makes it particularly suitable for application scenarios with high real-time requirements, such as acoustic monitoring and communication.

[0004] However, the traditional Bellhop model mainly simulates the received signals of stationary targets, that is, it is assumed that the positions of the sound source and the receiver remain unchanged throughout the simulation process. This assumption is reasonable in many practical applications, but it is insufficient in scenarios involving moving targets. The presence of a moving target will cause the Doppler effect to occur, which will in turn affect the frequency of the received signal. The conventional Bellhop model has not been optimized for these dynamic changes, so it may not provide accurate prediction results when dealing with the simulation of received signals of moving targets.

[0005] Therefore, in view of the above disadvantages, the present invention proposes a method for simulating moving target signals based on a segmented path-updated channel of Bellhop, enabling it to simulate the received signals of moving targets. This improvement can dynamically update the channel. Through these improvements, the acoustic characteristics of moving targets can be more accurately reflected, providing more reliable simulation results for related applications. Summary of the Invention

[0006] The objective of the present invention is to overcome the limitations of the existing Bellhop model in simulating the received signals of moving targets, and to propose an innovative method for simulating the received signals of moving targets. This method discretizes the trajectory of the moving target and calculates each segment of the channel after path discretization. Then, it performs a convolution operation on the transmitted signal and each segment of the channel, and updates the channel information segment by segment, thereby generating a more accurate simulation result of the received signals of the moving target.

[0007] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0008] A method for modeling the acoustic scattering signals of moving targets based on segmented path update in a waveguide provided by the present invention specifically includes the following steps:

[0009] (1) Construct the transmitted signal of the sound source and discretize the transmitted signal of the sound source;

[0010] (2) Set the moving path of the moving target and discretize the moving path of the moving target;

[0011] (3) Calculate the channel impulse response function at each discretized position between the sound source and the moving target;

[0012] (4) Calculate the signal excited from the sound source to the moving target: Convolve the discretized transmitted signal of the sound source with the channel impulse response function at each discretized position between the sound source and the moving target, and splice the signal segments obtained after convolution from the sound source excited to the moving target on the absolute time axis to obtain the signal excited from the sound source to the moving target;

[0013] (5) Discretize the signal excited from the sound source to the moving target;

[0014] (6) Calculate the channel impulse response function at each discretized position between the receiving hydrophone and the moving target;

[0015] (7) Calculate the received signal at the receiving hydrophone: Convolve the discretized signal excited from the sound source to the moving target with the channel impulse response function at each discretized position between the receiving hydrophone and the moving target, and splice the signal segments of the receiving hydrophone obtained after convolution on the absolute time axis to obtain the received signal at the receiving hydrophone.

[0016] Further, in step (1), let SL be the transmitted sound source level, then the transmitted signal of the sound source is:

[0017] S s =A s cos(2πf s t) (1)

[0018] f s is the transmission frequency of the signal, t is the time width of the transmitted signal, As is the amplitude of the transmitted signal:

[0019]

[0020] The sound source transmits a signal S s is segmented into transmitted signal segments of the moving target on different segmented paths according to Δt, and each transmitted signal segment is denoted as S s(m) :

[0021]

[0022] where m ∈ [1, n] is a segment in the total path segmentation, and n is the number of segments of the total path.

[0023] Further, the specific operation steps of step (2) are as follows:

[0024] In the direction of the transceiver connection line, the distance D between the sound source and the receiving hydrophone sr , the distance D between the sound source and the moving target st , the distance D between the moving target and the receiving hydrophone tr ; The moving target starts to move from one side of the transceiver connection line, and the starting position of the movement is x l , passes through the transceiver connection line and gradually moves to the other side of the transceiver connection line, and the ending position of the movement is x r , and the position of the moving target at each moment of movement is x t(m) , and the time difference between adjacent moment positions is Δt.

[0025] Further, the specific operation steps of step (3) are as follows:

[0026] According to the distance D between the sound source and the moving target in the direction of the transceiver connection line st and the position x of the moving target at each moment t(m) calculate the horizontal distance R between the sound source and the moving target at different positions st(m) , and according to R st(m) calculate the channel impulse response function h st(m) (t) between the sound source and the moving target at different positions.

[0027] Further, the specific operation steps of step (4) are as follows:

[0028] The transmitted signal S s is segmented into transmitted signal segments S of the moving target located on different segmented trajectories according to Δt s(m) Convolve the channel impulse response h st(m) (t) between the moving target at different positions and the sound source and superimpose them to obtain the signal S t1 received by the moving target radiated by the sound source:

[0029]

[0030] Furthermore, the specific operation steps of step (5) are as follows:

[0031] Discretize the signal from the sound source excited at the moving target according to Δt, discretize it into the sound source excitation signals received when the moving target moves to different positions, and each signal segment is denoted as S t1(m) :

[0032]

[0033] Furthermore, it is characterized in that the specific operation steps of step (6) are as follows:

[0034] According to the distance D between the moving target and the receiving hydrophone in the direction of the transceiver connection line tr and the position x of the moving target at each moment t(m) calculate the horizontal distance R between the receiving hydrophone and the moving target at different positions tr(m) , and then calculate the channel h between the receiving hydrophone and the moving target at different positions tr(m) (t).

[0035] Furthermore, the specific operation steps of step (7) are as follows:

[0036] Convolve the discretized signal from the sound source excited at the moving target S t1(m) with the channel impulse response h between the moving target at different positions and the receiving hydrophone tr(m) (t) and superimpose them to obtain the received signal S of the receiving hydrophone tr .

[0037] The beneficial effects of the present invention are as follows:

[0038] Aiming at the deficiencies of the existing Bellhop model, the present invention proposes an innovative simulation method for the received signal of a moving target. The proposed method discretizes the trajectory of the moving target, calculates each segment of the channel after path discretization. Then, convolves the transmitted signal with each segment of the channel, updates the channel information segment by segment, so as to generate a more accurate simulation result of the received signal of the moving target. It gets rid of the limitation that the existing Bellhop model cannot calculate the simulation of the received signal under the movement of the target. Description of the Drawings

[0039] Figure 1 is the implementation flowchart of the present invention;

[0040] Figure 2 is the side view of the simulation model of the received signal of the hydrophone when the target crosses the transceiver connection line under waveguide conditions;

[0041] Figure 3 It is the top view of the simulation model of the received signal of the hydrophone when the target crosses the transceiver connection line under waveguide conditions;

[0042] Figure 4 It is the curve graph of the signal frequency change from the sound source excitation to the target during the process of the target crossing the transceiver connection line obtained according to the theoretical Doppler calculation formula;

[0043] Figure 5 It is the time-domain waveform graph of the signal from the sound source excitation to the target during the process of the target crossing the transceiver connection line simulated according to the present invention;

[0044] Figure 6 It is the time-frequency analysis graph of the signal from the sound source excitation to the target during the process of the target crossing the transceiver connection line simulated according to the present invention;

[0045] Figure 7 It is the curve graph of the signal frequency change of the received hydrophone during the process of the target crossing the transceiver connection line obtained according to the theoretical Doppler calculation formula;

[0046] Figure 8 It is the time-domain waveform graph of the signal received by the hydrophone during the process of the target crossing the transceiver connection line simulated according to the present invention;

[0047] Figure 9 It is the time-frequency analysis graph of the signal received by the hydrophone during the process of the target crossing the transceiver connection line simulated according to the present invention. Specific embodiments

[0048] The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and implementation steps.

[0049] A method for modeling the acoustic scattering signal of a moving target based on segmented path update in a waveguide provided by the present invention includes the following steps:

[0050] (1) Discretization of the target motion trajectory;

[0051] The motion path of the moving target crossing the transceiver-separated sonar system is discretized. The continuous motion process of the moving target is segmented according to a preset time interval to obtain the positions of the moving target at different time points.

[0052] (2) Discretization of the sound source emission signal;

[0053] The sound source emission signal is discretized. The purpose is to clarify which segment of the emission signal is excited on the target at this time at different time points of the target motion.

[0054] (3) Calculate the channel impulse response function of the sound source and each discrete position of the moving target;

[0055] Calculate the channel impulse response function at different positions after discretizing the sound source and the moving target through the Bellhop model, and obtain the channels through which different segments of the discretized transmitted signal are transmitted to different positions where the target moves at different time points.

[0056] (4) Calculate the signal from the sound source excitation to the moving target;

[0057] Convolve the discretized transmitted signal of the sound source with the channel impulse response functions of the sound source and the discretized target moving to different positions calculated in step (3) respectively, to obtain the received signal segments of the transmitted signal segments acting on the moving target through the corresponding channels when the target moves to different positions. Piece together the signals calculated above on the absolute time axis to obtain the signal excited by the sound source received by the moving target throughout its entire movement trajectory.

[0058] (5) Discretize the signal from the sound source excitation to the moving target;

[0059] Perform discretization processing on the signal from the sound source excitation to the moving target. The purpose is to clarify which segment of the signal radiated by the moving target is excited on the receiving hydrophone at different time points during the movement of the target.

[0060] (6) Calculate the channel impulse response function between each discretized position of the moving target and the receiving hydrophone;

[0061] Calculate the channel impulse response function between different discretized positions of the moving target and the receiving hydrophone through the Bellhop model. Obtain the channels through which different segments of the discretized signal radiated by the moving target are transmitted to the receiving hydrophone at different time points.

[0062] (7) Calculate the received signal at the receiving hydrophone;

[0063] Convolve the discretized signal radiated by the moving target with the channel impulse response functions of the receiving hydrophone and the discretized target moving to different positions calculated in step (6) respectively, to obtain the received signal segments of the signal radiated by the target acting on the receiving hydrophone through the corresponding channels when the target moves to different positions. Piece together the signals calculated above on the absolute time axis to obtain the signal received by the receiving hydrophone throughout the entire movement trajectory of the moving target.

[0064] Figure 1 It is a flowchart of a simulation method for a moving target signal of a channel with segmented path update based on Bellhop in a waveguide, and its specific implementation steps are as follows:

[0065] (1) Construct the transmitted signal of the sound source and discretize the transmitted signal of the sound source;

[0066] SL is the emission sound source level, and the sound source emits a signal as follows:

[0067] S s = A s cos(2πf s t) (1)

[0068] f s is the emission frequency of the signal, t is the time width of the emission signal, and A s is the amplitude of the emission signal:

[0069]

[0070] The emission signal S s is segmented into emission signal segments of the moving target on different segmented paths according to Δt. Each emission signal segment is denoted as S s(m) :

[0071]

[0072] where m ∈ [1, n] is a segment in the total path segmentation, and n is the number of segments of the total path.

[0073] (2) Set the moving path of the moving target and discretize the moving path of the moving target;

[0074] In the direction of the transceiver connection line, the distance D sr between the sound source and the receiving hydrophone, the distance D st between the sound source and the moving target, and the distance D tr between the moving target and the receiving hydrophone. The moving target starts to move from one side of the transceiver connection line, the starting moving position is x l , passes through the transceiver connection line and gradually moves to the other side of the transceiver connection line, the ending moving position is x r , and the position of the moving target at each moment of movement is x t(m) , and the time difference between adjacent moment positions is Δt;

[0075] (3) Calculate the channel impulse response function at each discretized position of the sound source and the moving target;

[0076] According to the distance D st between the sound source and the moving target in the direction of the transceiver connection line and the position x t(m) of the moving target at each moment, the horizontal distance R st(m) between the sound source and the moving target at different positions can be calculated. According to R st(m) , the channel impulse response function h st(m) (t) at different positions where the sound source and the moving target move to can be calculated;

[0077] (4) Calculate the signal excited by the sound source to the moving target;

[0078] Transmitted signal S s Segmented according to Δt into transmitted signal segments S when the target is on different segmented trajectories s(m) Convolve the channel impulse response h between the target's motion to different positions and the sound source st(m) (t) and superimpose to obtain the signal S received at the moving target radiated by the sound source t1 :

[0079]

[0080] (5) Discretize the signal from the sound source excited to the moving target;

[0081] Discretize the signal from the sound source excited to the moving target according to Δt into the sound source excitation signals received at different positions of the moving target, and each signal segment is denoted as S t1(m) :

[0082]

[0083] (6) Calculate the channel impulse response function between the discretized positions of the moving target and the receiving hydrophone;

[0084] According to the distance D between the moving target and the receiving hydrophone in the transceiver connection direction tr and the position x of the moving target at each moment t(m) Calculate the horizontal distance R between the receiving hydrophone and the moving target at different positions tr(m) , and further calculate the channel h between the receiving hydrophone and the moving target at different positions tr(m) (t).

[0085] (7) Calculate the received signal at the receiving hydrophone;

[0086] Convolve the discretized signal from the sound source excited to the moving target S t1(m) with the channel impulse response h between the target's motion to different positions and the receiving hydrophone tr(m) (t) and superimpose to obtain the received signal S at the receiving hydrophone tr .

[0087] As Figure 2 shown, it is a side view of the simulation model of the received signal of the hydrophone when the target crosses the transceiver connection line under waveguide conditions. In the figure, H is the sea depth, H s is the depth of the sound source from the sea surface, H t is the depth of the moving target from the sea surface, H r is the depth of the receiving hydrophone from the sea surface, D st is the horizontal distance from the sound source to the moving target, D tris the horizontal distance from the moving target to the receiving hydrophone, D sr is the horizontal distance from the sound source to the receiving hydrophone, h sr h(t) is the channel transfer function from the sound source to the receiving hydrophone sr(m) h(t) is the channel transfer function between the sound source and the moving target when they move to the m-th segment of the segmented path tr(m) h(t) is the channel transfer function between the receiving hydrophone and the moving target when the moving target moves to the m-th segment of the segmented path, where m ∈ [1, n], and n is the number of divisions of the moving path of the moving target

[0088] As Figure 3 shown, it is a top view of the simulation model of the signal received by the hydrophone when the target crosses the transceiver connection line under waveguide conditions. x t(m) is the position of the target at different positions

[0089] As Figure 4 shown, it is a curve graph of the frequency change of the signal from the sound source excitation to the target during the process of the target crossing the transceiver connection line obtained according to the theoretical Doppler calculation formula

[0090] As Figure 5 shown, it is a time-domain waveform graph of the signal from the sound source excitation to the target during the process of the target crossing the transceiver connection line simulated according to the present invention

[0091] As Figure 6 shown, it is a time-frequency analysis graph of the signal from the sound source excitation to the target during the process of the target crossing the transceiver connection line simulated according to the present invention. It can be seen from the figure that the simulated time-frequency graph of the signal coincides with Figure 4 the predicted frequency change graph of the signal at the target according to the theoretical Doppler calculation formula in

[0092] As Figure 7 shown, it is a curve graph of the frequency change of the signal received by the receiving hydrophone during the process of the target crossing the transceiver connection line obtained according to the theoretical Doppler calculation formula

[0093] As Figure 8 shown, it is a time-domain waveform graph of the signal received by the receiving hydrophone during the process of the target crossing the transceiver connection line simulated according to the present invention

[0094] As Figure 9 shown, it is a time-frequency analysis graph of the signal received by the receiving hydrophone during the process of the target crossing the transceiver connection line simulated according to the present invention. It can be seen from the figure that the simulated time-frequency graph of the signal coincides with Figure 7 the predicted frequency change graph of the signal received by the receiving hydrophone according to the theoretical Doppler calculation formula in

[0095] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for modeling acoustic scattering signals of moving targets in waveguides based on segmented path updating, characterized in that: The following steps are involved: (1) constructing a sound source emission signal and discretizing the sound source emission signal; (2) Setting a moving target motion path and discretizing the moving target motion path; (3) Calculate the channel impulse response function at each discretized position of the sound source and the moving target; (4) Calculating the signal from the sound source to the moving target: convolve the discretized sound source emission signal with the channel impulse response function at each discretized position of the corresponding sound source and the moving target, and splice the signal fragments from the sound source to the moving target obtained after the convolution on the absolute time axis to obtain the signal from the sound source to the moving target; (5) Discretize the signal from the sound source to the moving target; (6) Calculate the channel impulse response function at each discretized position of the receiving hydrophone and the moving target; (7) Calculate the received signal at the receiving hydrophone: Convolve the signal from the discretized sound source to the moving target with the channel impulse response function at each discretized position of the corresponding receiving hydrophone and the moving target, and splice the received hydrophone signal segments obtained after the convolution on the absolute time axis to obtain the received signal at the receiving hydrophone.

2. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: In step (1), let SL be the emission sound source level, then the emission signal of the sound source is: S s =A s cos(2πf s t) (1) f s is the transmission frequency of the signal, t is the time width of the transmission signal, A s is the amplitude of the transmitted signal: The sound source emits a signal S s According to Δt segmentation, the moving target is divided into transmission signal segments on different segment paths. Each transmission signal segment is represented by S s(m) : Among them, m∈[1,n] is a segment in the total path segmentation, and n is the number of segments of the total path.

3. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (2) are as follows: In the direction of the transmission and reception line, the distance between the sound source and the receiving hydrophone is D sr , the distance D between the sound source and the moving target st , the distance D between the moving target and the receiving hydrophone tr ; The moving target starts to move from one side of the sending and receiving line, and the starting moving position is x l , cross the transmission and reception line and gradually move to the other side of the transmission and reception line, and the end movement position is x r , the position of the moving target at each moment is x t(m) , the time difference between adjacent time positions is Δt.

4. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (3) are as follows: According to the distance D between the sound source and the moving target in the direction of the transmission and reception line st and the position x of the moving target at each moment t(m) Calculate the horizontal distance R between the sound source and the moving target at different positions st(m) , according to R st(m) The channel impulse response function h of the sound source and the moving target moving to different positions is calculated st(m) (t).

5. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (4) are as follows: Transmit signal S s According to Δt segment cutting, the target is located on different segmented trajectories when the transmission signal segment S s(m) The channel impulse response h between the convolution target moving to different positions and the sound source st(m) (t) and superimposed to obtain the signal S radiated by the sound source received at the moving target t1 :

6. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (5) are as follows: The signal from the sound source to the moving target is discretized according to Δt, and is discretized into the sound source excitation signal received by the moving target when it moves to different positions. Each signal segment is represented by S t1(m) :

7. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (6) are as follows: According to the distance D between the moving target and the receiving hydrophone in the direction of the transmitting and receiving line tr and the position x of the moving target at each moment t(m) The horizontal distance R between the receiving hydrophone and the moving target at different positions is calculated. tr(m) , and then calculate the channel h when the receiving hydrophone and the moving target move to different positions tr(m) (t).

8. The method for modeling moving target acoustic scattering signals in a waveguide based on segmented path updating according to claim 1, characterized in that: The specific steps of step (7) are as follows: The discretized sound source is excited to the moving target signal S t1(m) The channel impulse response h between the convolution target moving to different positions and the receiving hydrophone tr(m) (t) and superimposed, we can get the receiving signal S of the receiving hydrophone tr .

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