Method for modeling moving target acoustic scattering signals in waveguides based on piecewise path updates

Abstract

The application belongs to the field of underwater acoustic signal simulation, and particularly relates to a waveguide motion target acoustic scattering signal modeling method based on segmented path updating. The method comprises the following steps: constructing an acoustic source emission signal, and discretizing the acoustic source emission signal; setting a motion target motion path, and discretizing the motion target motion path; calculating a channel impulse response function of the acoustic source and the discretized positions of the motion target; calculating a signal from the acoustic source excitation to the motion target; discretizing the signal from the acoustic source excitation to the motion target; calculating a channel impulse response function of a receiving hydrophone and the discretized positions of the motion target; and calculating a receiving signal at the receiving hydrophone. The application can generate more accurate motion target receiving signal simulation results, and gets rid of the limitation that the existing Bellhop model cannot calculate the receiving signal simulation under target motion.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic signal simulation, specifically relating to a method for modeling acoustic scattering signals of moving targets in waveguides based on segmented path updates. Background Technology

[0002] In the field of acoustic communication, the simulation of received signals in waveguides is a crucial research topic. A waveguide refers to the path through which sound waves propagate in a marine medium. Due to the inhomogeneity of the medium and the complexity of boundary conditions, the propagation characteristics of sound waves become extremely complex. Therefore, accurately simulating and predicting signal propagation behavior in waveguides is essential for designing efficient communication systems, acoustic detection equipment, and other related applications. To achieve this goal, numerical simulation tools are typically used to calculate the sound field distribution and signal reception characteristics in waveguides. Bellhop is a widely used simulation tool among these.

[0003] Bellhop is an acoustic propagation model based on ray theory, widely used in marine acoustics to simulate the propagation path of sound waves and the characteristics of received signals in complex marine environments. Its basic principle is to treat the propagation of sound waves as a series of rays, and by tracking the reflection, refraction, and attenuation behavior of these rays in different media, it predicts the distribution of the sound field and the characteristics of the received signal. Bellhop's advantage lies in its high computational efficiency, enabling rapid simulation of sound wave propagation in a wide range of marine environments. This makes it particularly suitable for applications with high real-time requirements, such as acoustic monitoring and communication.

[0004] However, traditional Bellhop models primarily simulate signals received from stationary targets, assuming that the positions of the sound source and receiver remain constant throughout the simulation. While this assumption is reasonable in many practical applications, it proves insufficient in scenarios involving moving targets. The presence of moving targets leads to the Doppler effect, which in turn affects the frequency of the received signal. Conventional Bellhop models are not optimized for these dynamic changes and therefore may not provide accurate predictions when simulating signals received from moving targets.

[0005] Therefore, to address the aforementioned shortcomings, this invention proposes a Bellhop-based segmented path update channel simulation method for moving target signals, enabling it to simulate the received signals of moving targets. This improvement allows for dynamic channel updates. 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 purpose of this invention is to overcome the limitations of existing Bellhop models in simulating moving target signal reception and to propose an innovative method for simulating moving target signal reception. This method discretizes the trajectory of the moving target and calculates the channel for each discretized channel segment. Then, it convolves the transmitted signal with each channel segment, updating the channel information segment by segment, thereby generating more accurate simulation results for moving target signal reception.

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

[0008] This invention provides a method for modeling acoustic scattering signals of moving targets in waveguides based on piecewise path updates, which specifically includes the following steps:

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

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

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

[0012] (4) Calculate the signal excited by 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 sound source and the moving target, and splice the convolved signal segments excited by the sound source to the moving target on the absolute time axis to obtain the signal excited by the sound source to the moving target.

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

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

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

[0016] Furthermore, in step (1), assuming SL is the sound source level, the sound source emission signal is:

[0017] S s =A s cos(2πf s t) (1)

[0018] f s Let A be the signal transmission frequency, t be the transmission duration of the signal, and A be the signal width.s The amplitude of the transmitted signal:

[0019]

[0020] The sound source emits a signal S s The signal is segmented according to Δt, and the transmitted signal is divided into segments along different segments of the moving target's path. Each segment is represented as S. s(m) :

[0021]

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

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

[0024] In the direction of the transmit / receive connection, the distance D between the sound source and the receiving hydrophone sr Distance D between the sound source and the moving target st Distance D between the moving target and the receiving hydrophone tr The moving target starts moving from one side of the transmit / receive connection, with an initial position of x. l It gradually moves across the transmit / receive connection to the other side of the connection, and terminates at position x. r The position of the moving target at each moment of its motion is x. t(m) The time difference between adjacent positions is Δt.

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

[0026] Based on the distance D between the sound source and the moving target along the line connecting the transmitter and receiver st The position x of the moving target at each moment t(m) The horizontal distance R between the sound source and the moving target at different positions was calculated. st(m) According to R st(m) The channel impulse response function h of the sound source and the moving target at different positions was calculated. st(m) (t).

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

[0028] Transmit signal S s The motion is divided into segments according to Δt, and the transmitted signal segments S are located on different segments of the target's trajectory. s(m) The channel impulse response h between the convolutional target and the sound source at different positions is as follows: st(m) (t) are then superimposed to obtain the signal S received at the moving target by the radiation from the sound source. t1 :

[0029]

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

[0031] The signal excited by the sound source to the moving target is discretized according to Δt, resulting in the sound source excitation signal received by the moving target at different positions. Each signal segment is represented as S. t1(m) :

[0032]

[0033] Furthermore, the specific operation steps of step (6) are as follows:

[0034] Based on the distance D between the moving target and the receiving hydrophone along the transmitting and receiving line. tr 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 was calculated. tr(m) Then, the channel h is calculated when the receiving hydrophone and the moving target move to different positions. tr(m) (t).

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

[0036] The discretized sound source excites the signal S at the moving target. t1(m) The channel impulse response h between the convolutional target at different positions and the receiving hydrophone tr(m) (t) and superimposed, the received signal S of the hydrophone can be obtained. tr .

[0037] The beneficial effects of this invention are:

[0038] This invention addresses the shortcomings of existing Bellhop models by proposing an innovative method for simulating received signals from moving targets. The proposed method discretizes the trajectory of the moving target and calculates the channel for each segment of the discretized path. Then, it convolves the transmitted signal with each channel segment, updating the channel information segment by segment, thereby generating more accurate simulation results for received signals from moving targets. This overcomes the limitation of existing Bellhop models in simulating received signals under moving targets. Attached Figure Description

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

[0040] Figure 2 This is a side view of a simulation model of a hydrophone receiving signals under waveguide conditions where a target crosses a transceiver connection.

[0041] Figure 3 This is a top view of a simulation model of a hydrophone receiving signals when a target crosses a transceiver line under waveguide conditions.

[0042] Figure 4 The curve of signal frequency change from sound source excitation to target during the target crossing the transmit / receive connection is obtained based on the theoretical Doppler calculation formula.

[0043] Figure 5 The present invention provides a simulation of the time-domain waveform of the signal excited by the sound source to the target during the target's crossing of the transceiver connection.

[0044] Figure 6 The above is a time-frequency analysis diagram of the signal excited by the sound source to the target during the target crossing the transceiver connection, obtained by simulation according to the present invention.

[0045] Figure 7 The curve of frequency change of the received signal by the hydrophone during the target crossing the transceiver line is obtained based on the theoretical Doppler calculation formula.

[0046] Figure 8 The present invention provides a simulation of the time-domain waveform of the hydrophone received signal during the target's crossing of the transceiver connection.

[0047] Figure 9 The above is a time-frequency analysis diagram of the received signal from the hydrophone during the target's crossing of the transceiver line, obtained by simulation according to the present invention. Detailed Implementation

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

[0049] This invention provides a method for modeling acoustic scattering signals of moving targets in waveguides based on piecewise path updates, comprising the following steps:

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

[0051] The movement path of a moving target traversing a split-transmitter sonar system is discretized. The continuous movement of the moving target is segmented according to a preset time interval to obtain the position of the moving target at different time points.

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

[0053] The sound source's emitted signal is discretized. The purpose is to identify which segment of the emitted signal is exciting the target at different points in time during the target's motion.

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

[0055] By using the Bellhop model to calculate the channel impulse response function at different locations after the sound source and moving target are discretized, the channel through which different segments of the discretized transmitted signal are transmitted to different locations of the target at different time points is obtained.

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

[0057] The discretized sound source emission signal is convolved with the sound source and the channel impulse response function of the discretized target at different positions calculated in step (3) to obtain the received signal segment of the emission signal segment acting on the moving target through the corresponding channel when the target moves to different positions. The above calculated signals are spliced ​​together on the absolute time axis to obtain the signal excited by the sound source received by the moving target throughout the entire motion trajectory.

[0058] (5) Discretize the signal excited by the sound source to the moving target;

[0059] The signal excited by the sound source to the moving target is discretized. The purpose is to identify which segment of the moving target's radiated signal excites the receiving hydrophone at different points in time during the target's motion.

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

[0061] The channel impulse response function between the discretized moving target and the receiving hydrophone at different locations was calculated using the Bellhop model. This yielded the channel traversed by different segments of the discretized moving target's radiated signal as they reached the receiving hydrophone at different time points.

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

[0063] The discretized moving target radiation signal is convolved with the channel impulse response function of the discretized target at different positions by the receiving hydrophone calculated in step (6), respectively, to obtain the received signal segment of the target radiation signal segment through the corresponding channel when the target moves to different positions. The above calculated signals are spliced ​​on the absolute time axis to obtain the signal received by the receiving hydrophone throughout the entire motion trajectory of the moving target.

[0064] Figure 1 The flowchart shows a simulation method for a segmented path update channel for moving target signals in a waveguide based on Bellhop. The specific implementation steps are as follows:

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

[0066] SL represents the sound source level, and the sound source emits the following signal:

[0067] S s =A s cos(2πf s t) (1)

[0068] f s Let A be the signal transmission frequency, t be the transmission duration of the signal, and A be the signal width. s The amplitude of the transmitted signal:

[0069]

[0070] Transmit signal S s The signal is segmented according to Δt, and the transmitted signal is divided into segments along different segments of the moving target's path. Each segment is represented as S. s(m) :

[0071]

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

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

[0074] In the direction of the transmit / receive connection, the distance D between the sound source and the receiving hydrophone sr Distance D between the sound source and the moving target st Distance D between the moving target and the receiving hydrophone tr The moving target starts moving from one side of the transmit / receive connection, with an initial position of x. l It gradually moves across the transmit / receive connection to the other side of the connection, and terminates at position x. r The position of the moving target at each moment of its motion is x. t(m) The time difference between adjacent positions is Δt;

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

[0076] Based on the distance D between the sound source and the moving target along the line connecting the transmitter and receiver st The position x of the moving target at each moment t(m) The horizontal distance R between the sound source and the moving target at different positions can be calculated. st(m) According to R st(m) The channel impulse response function h at different positions of the sound source and the moving target can be calculated. st(m) (t);

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

[0078] Transmit signal S s The motion is divided into segments according to Δt, and the transmitted signal segments S are located on different segments of the target's trajectory. s(m) The channel impulse response h between the convolutional target and the sound source at different positions is as follows: st(m) (t) and superimposed, we can obtain the signal S received at the moving target by the radiation radiated by the sound source. t1 :

[0079]

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

[0081] The signal excited by the sound source to the moving target is discretized according to Δt, resulting in the sound source excitation signal received by the moving target at different positions. Each signal segment is represented as S. t1(m) :

[0082]

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

[0084] Based on the distance D between the moving target and the receiving hydrophone along the transmitting and receiving line. tr 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 was calculated. tr(m) Then, the channel h is calculated when the receiving hydrophone and the moving target move to different positions. tr(m) (t).

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

[0086] The discretized sound source excites the signal S at the moving target. t1(m) The channel impulse response h between the convolutional target at different positions and the receiving hydrophone tr(m) (t) and superimposed, the received signal S of the hydrophone can be obtained. tr .

[0087] like Figure 2 The image shown is a side view of a simulation model of a hydrophone receiving signals under waveguide conditions where a target traverses a transceiver connection. In the figure, H represents the sea depth, H... s The depth of the sound source from the sea surface, H t For the moving target's distance from the sea surface, H r To receive the hydrophone's distance from the sea surface, D st D is the horizontal distance from the sound source to the moving target. trD represents the horizontal distance from the moving target to the receiving hydrophone. sr h is the horizontal distance from the sound source to the receiving hydrophone. sr (t) is the channel transmission function from the sound source to the receiving hydrophone, h sr(m) (t) represents the channel transmission function between the sound source and the moving target as they move to the m-th segment of the segmented path, h tr(m) (t) is the channel transmission function between the moving target and the receiving hydrophone when the moving target moves to the m-th segment of the segmented path, where m∈[1,n] and n is the number of segments of the moving target's movement path.

[0088] like Figure 3 The image shown is a top view of a simulation model of a hydrophone receiving signals under waveguide conditions where a target crosses a transceiver connection. t(m) The target moves to different positions.

[0089] like Figure 4 The figure shown is a curve of the frequency change of the signal excited by the sound source to the target during the target crossing the transmitter-receiver connection, obtained according to the theoretical Doppler calculation formula.

[0090] like Figure 5 The figure shown is a time-domain waveform of the signal excited by the sound source to the target during the target crossing the transmit / receive connection, obtained by simulation according to the present invention.

[0091] like Figure 6 The figure shows a time-frequency analysis diagram of the signal excited by the sound source to the target during the target's crossing of the transceiver line, obtained through simulation according to the present invention. It can be seen from the figure that the simulated time-frequency diagram is consistent with... Figure 4 The signal frequency variation at the target location predicted by the theoretical Doppler calculation formula matches perfectly, demonstrating the effectiveness of the invention.

[0092] like Figure 7 The figure shown is a curve of the frequency change of the received signal by the hydrophone during the target crossing the transceiver line, obtained according to the theoretical Doppler calculation formula.

[0093] like Figure 8 The figure shown is a time-domain waveform diagram of the received signal from the hydrophone during the target crossing the transceiver line, obtained by simulation according to the present invention.

[0094] like Figure 9 The figure shows a time-frequency analysis diagram of the received signal from the hydrophone during the target's crossing of the transceiver line, obtained through simulation according to the present invention. It can be seen from the figure that the simulated time-frequency diagram is consistent with... Figure 7 The frequency variation of the received signal from the hydrophone, predicted according to the theoretical Doppler calculation formula, matches perfectly. This proves the effectiveness of the invention.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for modeling a moving target acoustic scattering signal in a waveguide based on piecewise path updates, the method comprising: The method comprises the following steps: (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) calculating a channel impulse response function of the sound source and the discretized positions of the moving target; (4) calculating a signal from the sound source to the moving target: convolving the discretized sound source emission signal and the channel impulse response function corresponding to the discretized positions of the sound source and the moving target, splicing the signal segments from the sound source to the moving target obtained after the convolution on an absolute time axis, and obtaining a signal from the sound source to the moving target; (5) discretizing the signal from the sound source to the moving target; (6) calculating a channel impulse response function of a receiving hydrophone and the discretized positions of the moving target; (7) calculating a receiving signal at the receiving hydrophone: convolving the discretized signal from the sound source to the moving target and the channel impulse response function corresponding to the discretized positions of the receiving hydrophone and the moving target, splicing the receiving hydrophone signal segments obtained after the convolution on an absolute time axis, and obtaining a receiving signal at the receiving hydrophone.

2. The method of claim 1, wherein, In step (1), let SL be a transmitting sound source level, and the sound source emission signal is: S s = A s cos(2πf s t) (1) f s is the frequency of the transmitted signal, t is the time duration of the transmitted signal, A s is the amplitude of the transmitted signal: The sound source emits a signal S s The signal emitted by the moving target in different segment paths is cut into pieces according to Δt segmentation, and each piece of emitted signal is represented as S s(m) : Wherein, m [1, n] is a segment in the total path segmentation, and n is the number of total path segmentation.

3. The method of claim 1, wherein, The specific operation steps of step (2) are as follows: In the direction of the transmitting-receiving line, the distance between the sound source and the receiving hydrophone is D sr , the distance between the sound source and the moving target is D st , the distance between the moving target and the receiving hydrophone is D tr ; the moving target starts to move from one side of the transmitting-receiving line, the initial moving position is x l , gradually moves across the transmitting-receiving line to the other side of the transmitting-receiving line, and the final moving position is x r , the position of the moving target at each moment is x t(m) , and the time difference between the adjacent moment positions is Δt.

4. The method of claim 1, wherein, The specific operation 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 transmitting-receiving line st and the position x of the moving target at each moment t(m) The horizontal distance R between the sound source and the moving target moving to different positions is calculated st(m) According to R st(m) The channel impulse response function h st(m) (t) of the sound source and the moving target moving to different positions is calculated.

5. The method of claim 1, wherein, The specific operation steps of step (4) are as follows: The transmitted signal S s The transmitted signal S is cut into segments S according to the Δt segmentation s(m) The channel impulse response h between the sound source and the moving target at different positions is convolved st(m) (t) and superimposed to obtain the received signal S radiated by the sound source at the moving target t1 : 。 6. The method of claim 1, wherein, The specific operation steps of step (5) are as follows: The signal of the sound source excitation at the moving target is discretized by Δt, discretized as the sound source excitation signal received by the moving target moving to different positions, and each signal segment is represented as S t1(m) : 。 7. The method of claim 1, wherein, The specific operation 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-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 moving to different positions is calculated tr(m) , and the channel h tr(m) (t) between the receiving hydrophone and the moving target moving to different positions is calculated.

8. The method of claim 1, wherein, The specific operation steps of step (7) are as follows: The discretized sound source excitation at the moving target location signal S t1(m) Convolve the target motion to different locations with the channel impulse response h between the receiving hydrophone tr(m) (t) and superimpose, the receiving hydrophone receives the signal S tr .

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