Multi-channel underwater acoustic signal transmitting and measuring system and signal processing method

Abstract

The invention relates to the technical field of underwater acoustic engineering and ocean exploration, in particular to a multi-channel underwater acoustic signal transmitting and measuring system and a signal processing method, which are used for solving the problems that the existing multi-channel underwater acoustic signal processing generally depends on fixed threshold detection or simple time sequence alignment, and the signal processing efficiency is low. The problem that residual vibration, local noise abrupt change or multipath reverberation is easily misjudged as an effective first arrival signal in a complex underwater environment due to the fact that the influence of the physical response characteristic of a transducer on emission time calibration is not considered and effective verification on whether a candidate arrival structure accords with a sound wave propagation physical rule is lacked is solved. According to the invention, a multi-channel energy time sequence and hydrophone space geometrical relationship is fused through an underwater sound propagation initial physical judgment module, a judgment mechanism is constructed based on distance-time consistency of sound propagation, and self-consistent verification is realized by combining a cross-channel arrival sequence and sound velocity constraint. And the accuracy, the robustness and the physical interpretability of the judgment of the effective launching time of the underwater sound are obviously improved.

Description

Technical Field

[0001] This invention relates to the fields of underwater acoustic engineering and marine exploration technology, and more specifically, to a multi-channel underwater acoustic signal transmission and measurement system and signal processing method. Background Technology

[0002] With the increasing demand for marine resource development, underwater security, and scientific research, underwater acoustic technology is becoming increasingly important as a key means of underwater information acquisition and transmission. Traditional single-channel or multi-channel underwater acoustic systems suffer from problems such as small coverage, weak resolution, and poor anti-interference, making it difficult to meet the needs of high precision, high efficiency, and multi-tasking in complex marine environments. Although multi-channel underwater acoustic array technology can achieve beamforming and multi-target tracking, existing systems generally suffer from insufficient synchronization accuracy between channels, weak transmit waveform control capabilities, low integration, and reliance on external equipment for data processing, resulting in beam pointing deviation, limited environmental adaptability, and difficulties in field deployment.

[0003] Reference patent application CN118041459A discloses a multi-channel joint processing method and underwater acoustic communication system for deep-sea acoustic communication. The method includes: at the transmitting end, a single transmitting transducer transmits a single-carrier signal underwater; at the receiving end, a hydrophone array receives the signal, and a signal processing device demodulates the received signal to baseband to obtain multi-channel baseband data; equalizes the multi-channel data based on PTR-DFE to obtain initial symbol estimates; constructs an initial observation matrix using the PTR-DFE-equalized symbols, iteratively jointly estimates the channels and symbols of the multi-channels, and outputs the converged symbols for decoding; this invention fully utilizes the gain of multi-channel reception, iteratively updates symbols, channels, and noise based on multi-channel observations, and completes maximum likelihood estimation of symbols while approximating the maximum a posteriori estimation of channels and noise, achieving a lower bit error rate; constructing an initial observation matrix using PTR-DFE-equalized symbols ensures convergence; However, existing multi-channel underwater acoustic signal processing typically relies on fixed threshold detection or simple timing alignment, without considering the impact of transducer physical response characteristics on transmission time calibration. It also lacks effective verification of whether candidate arriving structures conform to the physical laws of sound wave propagation. This leads to the easy misjudgment of residual vibrations, sudden changes in local noise, or multipath reverberation as valid first arrival signals in complex underwater environments, resulting in transmission time estimation errors, main path misjudgments, and multi-channel timing mismatches. As a result, it is difficult to meet the requirements of high-precision underwater acoustic synchronization, positioning, and channel modeling.

[0004] To address the aforementioned problems, this invention proposes a multi-channel underwater acoustic signal transmission and measurement system and signal processing method. Summary of the Invention

[0005] The purpose of this invention is to address the problem that existing multi-channel underwater acoustic signal processing typically relies on fixed threshold detection or simple timing alignment, without considering the impact of transducer physical response characteristics on transmission time calibration, and lacks effective verification of whether candidate arriving structures conform to the physical laws of sound wave propagation. This leads to the easy misjudgment of residual vibrations, sudden changes in local noise, or multipath reverberation as valid first arrival signals in complex underwater environments, resulting in transmission time estimation errors, main path misjudgments, and multi-channel timing mismatches, making it difficult to meet the requirements of high-precision underwater acoustic synchronization, positioning, and channel modeling.

[0006] The objective of this invention is achieved through the following technical solution: A multi-channel underwater acoustic signal transmission and measurement system, comprising: The underwater acoustic emission physical modeling module extracts and quantifies the actual physical response characteristics of the transducer based on the theoretical start time of the preset underwater acoustic emission signal and the synchronously acquired electrical signal feedback from the transducer drive end, and generates a set of emission timing constraint parameters based on the theoretical start time. The underwater acoustic propagation preprocessing module determines the residual vibration time range based on the duration of the transducer's residual vibration attenuation and removes data segments from the received signals of each channel that fall within the residual vibration time range. The underwater acoustic propagation initiation physical determination module determines the first propagation-related structure in the multi-channel received signal after after-resonance removal, based on the correlation between the cross-channel arrival order of significant energy structures and the spatial position of the hydrophone, and takes its earliest appearance time as the effective underwater acoustic transmission time. The underwater acoustic path topology verification module uses the effective underwater acoustic transmission time as a benchmark to extract candidate arriving structures from the received signals of each channel after residual vibration elimination. Based on the causal relationship between their cross-channel arrival order and the number of reflections and arrival time, it eliminates physically infeasible candidate structures. The multi-channel main path selection module calculates the cross-channel time consistency based on the arrival times of candidate multi-paths that satisfy the propagation topology constraints in each channel, selects the path with the highest consistency as the main propagation path, and outputs its arrival time.

[0007] In a preferred embodiment of the present invention, the underwater acoustic propagation preprocessing module determines the residual vibration time range based on the duration of transducer residual vibration attenuation, and the process of removing data segments from the received signals of each channel that fall within the residual vibration time range includes: Obtain the transmission end time provided by the transmission controller, obtain the pre-calibrated and stored residual vibration attenuation duration, take the transmission end time as the start time of the residual vibration time range, and take the sum of the transmission end time and the residual vibration attenuation duration as the end time. The residual vibration time range is a closed interval including the start time and the end time. For each receiving channel, traverse all sampling points, remove sampling points whose timestamps are not less than the start time and not greater than the end time, and output the received signal of each receiving channel after removing the sampling points within the residual vibration time range.

[0008] In a preferred embodiment of the present invention, the process by which the underwater acoustic propagation initiation physical determination module analyzes the correlation between the cross-channel arrival order of significant energy structures and the spatial position of the hydrophone in the multi-channel received signal after residual vibration elimination includes: After removing residual vibrations, the multi-channel received signal is obtained, and the spatial coordinates of each hydrophone are obtained. For each hydrophone channel, the energy output value is calculated. For each hydrophone channel, the moment when the energy output value first exceeds the preset threshold is recorded as the moment when the significant energy structure appears. A hydrophone is randomly selected as the reference hydrophone, and the Euclidean distance from each hydrophone to the reference hydrophone is calculated. All hydrophones are sorted in ascending order of Euclidean distance. The significant energy structures of hydrophones whose appearance time is earlier than the appearance time of all hydrophones closer to them, and whose advance time is greater than the corresponding distance difference divided by the speed of sound in water, are excluded. The remaining significant energy structures and their appearance times are output.

[0009] In a preferred embodiment of the present invention, the process by which the underwater acoustic propagation initiation physical determination module determines the first propagation-related structure and uses its earliest occurrence time as the effective underwater acoustic emission time includes: Obtain a set of significant energy structures that satisfy the physical consistency between distance sorting and occurrence time; obtain the spatial position and sound speed in water for each hydrophone; calculate the Euclidean distance from each hydrophone to the reference hydrophone based on the spatial position of the hydrophone; sort the set of significant energy structures from earliest to latest occurrence time; and perform corresponding processing operations on each significant energy structure in the sort. If a hydrophone has a significant energy structure and its occurrence time is between the structure occurrence time and the upper limit of the response time, the count is incremented by one. When there are at least two hydrophones that meet the conditions, the current structure is designated as the first propagation-related structure and the traversal is terminated. Finally, the earliest occurrence time of this structure in all channels is taken as the effective underwater acoustic emission time.

[0010] In a preferred embodiment of the present invention, the underwater acoustic path topology verification module processes the received signals of each channel after residual vibration removal, based on the effective underwater acoustic transmission time. The effective underwater acoustic transmission time and signal sampling rate are obtained, and the sum of the maximum propagation delay and safety margin is obtained as the duration of the analysis window. For each hydrophone channel, the received signal after residual vibration is removed from the corresponding channel is read. Based on the effective underwater acoustic transmission time, the signal start recording time, and the signal sampling rate, the sample start index of the effective underwater acoustic transmission time in the received signal is calculated. Based on the analysis window duration and the signal sampling rate, the number of samples to be truncated is calculated. Starting from the sample start index, a continuous number of signal samples are truncated. If the signal length is insufficient, zeros are padded to the end to the specified number of samples. The truncated and zero-padded signal is used as the processing result of the current channel, and the processing results of all channels are output.

[0011] In a preferred embodiment of the present invention, the process by which the underwater acoustic path topology verification module extracts candidate arriving structures from the received signals of each channel after residual vibration elimination includes: After removing residual vibrations, obtain the marked start events in the received signals of each channel. Sort all start events in ascending order of occurrence time, obtain the maximum allowable time difference of arrival, initialize the candidate arrival structure list, and traverse from the first start event. Starting from the occurrence time of the current start event, establish a time window with a duration equal to the maximum allowable time difference of arrival. Within the window, each hydrophone channel retains only the earliest occurrence start event. If the retained start events come from at least two hydrophone channels, then each hydrophone channel and its corresponding earliest occurrence time form a candidate arrival structure and add it to the candidate arrival structure list. Move the traversal position to the first start event after the end time of the time window, repeat the traversal until all start events have been processed, and output the candidate arrival structure list.

[0012] In a preferred embodiment of the present invention, the underwater acoustic path topology verification module, based on the causal relationship between its cross-channel arrival order and the number of reflections and arrival time, eliminates physically infeasible candidate structures through the following process: Initialize the list of physically feasible structures, obtain the first candidate arrival structure from the candidate arrival structure sequence, and when there are unprocessed candidate arrival structures, extract the start event, path type marker, and required number of reflections for each channel from the current candidate arrival structure, obtain the straight-line distance from the corresponding hydrophone to the sound source, and verify the three causal rules: First, in all direct path start events, if the straight-line distance between any two hydrophones is less than that between the other, then the occurrence time of the former is no greater than that of the latter. Second, the number of reflections required should not exceed the maximum number of reflections supported by the environment; Third, if both direct and reflected path initiation events exist simultaneously, the occurrence time of each reflected path initiation event is greater than the occurrence time of all direct path initiation events. If all three rules are met, the current candidate arrival structure is added to the list of physically feasible structures, the next candidate arrival structure is obtained, and the list of physically feasible structures is output.

[0013] As a preferred embodiment of the present invention, a multi-channel underwater acoustic signal processing method includes the following steps: Step 1: Based on the theoretical start time of the preset underwater acoustic emission signal and the synchronously acquired electrical signal feedback from the transducer drive end, extract and quantify the actual physical response characteristics of the transducer, and generate a set of emission timing constraint parameters based on the theoretical start time. Step 2: Determine the residual vibration time range based on the duration of the transducer's residual vibration attenuation, and remove data segments from the received signals of each channel that fall within the residual vibration time range; Step 3: In the multi-channel received signal after after-resonance removal, the first propagation-related structure is determined based on the correlation between the cross-channel arrival order of significant energy structures and the spatial position of the hydrophone, and its earliest occurrence time is taken as the effective underwater acoustic transmission time. Step 4: Based on the effective transmission time of underwater acoustics, extract candidate arriving structures from the received signals of each channel after residual vibration elimination. Based on the causal relationship between their cross-channel arrival order and the number of reflections and arrival time, eliminate physically infeasible candidate structures. Step 5: Based on the arrival times of candidate multipaths that satisfy the propagation topology constraints in each channel, calculate the cross-channel time consistency, select the path with the highest consistency as the main propagation path, and output its arrival time.

[0014] Compared with the prior art, the advantages of this invention are: (1) In this invention, the multi-channel energy timing and hydrophone spatial geometry relationship are integrated by the underwater acoustic propagation initiation physical determination module. Based on the distance-time consistency of sound propagation, a discrimination mechanism is constructed. After eliminating residual vibration interference, the sensitivity to weak first arrival signals is enhanced by weighted historical energy detection. Self-consistent verification is achieved by combining cross-channel arrival order and sound speed constraints, which significantly improves the accuracy, robustness and physical interpretability of underwater acoustic effective emission time determination. (2) In this invention, the underwater acoustic path topology verification module uses the high-precision effective underwater acoustic emission time as a benchmark, and combines the propagation physical constraints such as distance-time causality, upper limit of reflection times and direct reflection path timing logic to systematically screen the candidate arrival structures of multiple channels, effectively eliminating physically infeasible events caused by noise, reverberation or false detection. The verification rules based on the spatial geometry and sound speed propagation model significantly improve the reliability of identification and physical interpretability, providing high-quality input with clear structure and consistent timing for multipath modeling, environmental inversion and target localization. Attached Figure Description

[0015] Figure 1This is a system block diagram of the present invention; Figure 2 This is a flowchart of the steps in the multi-channel underwater acoustic signal processing method of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Example 1: As Figure 1 As shown, the present invention proposes a multi-channel underwater acoustic signal transmission and measurement system, comprising: The underwater acoustic emission physical modeling module extracts and quantifies the actual physical response characteristics of the transducer based on the theoretical start time of the preset underwater acoustic emission signal and the synchronously acquired electrical signal feedback from the transducer drive end. These characteristics include the oscillation delay time, sound pressure build-up time, and residual vibration attenuation duration. The module generates a set of emission timing constraint parameters based on the theoretical start time, including the oscillation delay time, sound pressure build-up time, and residual vibration attenuation duration. The underwater acoustic emission physical modeling module, based on the preset theoretical start time of the underwater acoustic emission signal and the synchronously acquired transducer drive terminal electrical signal feedback, extracts and quantifies the actual physical response characteristics of the transducer, and generates a set of emission timing constraint parameters based on the theoretical start time. The process includes: The theoretical start time of the preset underwater acoustic emission signal is obtained. In the synchronously acquired electrical signal envelope of the transducer drive end, the sampling point where the amplitude first leaves the peak-to-peak range of the background noise and continues to rise is taken as the amplitude rise start time. The oscillation delay time is the difference between the amplitude rise start time and the theoretical start time. The sampling point where the rise ends and the difference between adjacent peaks in the subsequent periodic oscillation does not exceed the peak-to-peak value of the background noise is taken as the stable oscillation start time. The sound pressure establishment time is the difference between the stable oscillation start time and the theoretical start time. The termination time of the preset underwater acoustic transmission signal is obtained. The sampling point where the amplitude attenuation first falls back to the peak-to-peak range of the background noise and remains there is taken as the final silence start time. The duration of residual vibration attenuation is the difference between the final silence start time and the signal termination time. The output is a set of transmission timing constraint parameters consisting of the oscillation delay time, the sound pressure set-up time, and the duration of residual vibration attenuation. The underwater acoustic emission physical modeling module is based on the theoretical start time and the synchronously acquired drive-end electrical signal. It uses the background noise adaptive criterion to accurately extract the start-up delay, sound pressure build-up and residual vibration decay time, and fully characterize the transient response characteristics of the transducer. It does not require additional sound field measurement, has high precision, strong robustness and good engineering applicability. The generated timing constraint parameters can directly support system optimization such as communication waveform design, sonar scheduling and multi-channel synchronization.

[0018] The underwater acoustic propagation preprocessing module determines the residual vibration time range based on the duration of the transducer's residual vibration attenuation and removes data segments from the received signals of each channel that fall within the residual vibration time range. The underwater acoustic propagation preprocessing module determines the residual vibration time range based on the transducer's residual vibration attenuation duration, and the process of removing data segments from the received signals of each channel that fall within the residual vibration time range includes: The system obtains the transmission end time provided by the transmission controller, obtains the pre-calibrated and stored residual vibration attenuation duration, takes the transmission end time as the start time of the residual vibration time range, and takes the sum of the transmission end time and the residual vibration attenuation duration as the end time. The residual vibration time range is a closed interval including the start time and the end time. All receiving channel sampling data are based on the same time reference as the transmission controller. For each receiving channel, all sampling points are traversed, and sampling points with timestamps not less than the start time and not greater than the end time are removed. The system outputs the received signal of each receiving channel after removing sampling points within the residual vibration time range. By utilizing the calibrated residual vibration attenuation duration and a unified time reference, the underwater acoustic propagation preprocessing module accurately defines and eliminates data intervals contaminated by transducer residual vibration in each receiving channel, effectively eliminating the interference of residual vibration at the transmitting end on subsequent propagation signal analysis. This method is simple to implement, has low computational overhead, and requires no complex filtering or modeling, yet it can significantly improve the purity and timing accuracy of the received signal, providing a high-quality data foundation for tasks such as underwater acoustic channel estimation, target echo detection, and multi-channel joint processing.

[0019] The underwater acoustic propagation initiation physical determination module determines the first propagation-related structure in the multi-channel received signal after after-resonance removal, based on the correlation between the cross-channel arrival order of significant energy structures and the spatial position of the hydrophone, and takes its earliest appearance time as the effective underwater acoustic transmission time. The process by which the underwater acoustic propagation initiation physics determination module analyzes the correlation between the cross-channel arrival order of significant energy structures and the spatial location of the hydrophone in the multi-channel received signal after afterreverberation rejection includes: Obtain the multi-channel received signal after after-vibration rejection, acquire the spatial coordinates of each hydrophone, and calculate the energy output value for each hydrophone channel: ,in Let be the amplitude of the received signal of the i-th hydrophone channel at time t. For the i-th hydrophone channel at time... Instantaneous energy, Used as an integer index to iterate through a series of discrete time points traversing backward from the current moment. The basic time interval used for system sampling. The range of historical time to be backtracked is determined by using a fixed non-negative integer. To fix the non-negative weighting coefficients, they are arranged in non-increasing order from most recent to oldest time. A fixed real number greater than zero is used to apply a nonlinear transformation to the accumulated result. Let t be the energy output value of the i-th hydrophone channel. For each hydrophone channel, record the moment when the energy output value first exceeds the preset threshold as the moment when the significant energy structure appears. Select any hydrophone as the reference hydrophone, calculate the Euclidean distance from each hydrophone to the reference hydrophone, sort all hydrophones in ascending order of Euclidean distance, exclude the significant energy structure of hydrophones whose appearance time is earlier than the appearance time of all hydrophones closer to them, and whose advance time is greater than the corresponding distance difference divided by the speed of sound in water, and output the remaining significant energy structure and its appearance time. The process by which the underwater acoustic propagation initiation physics determination module identifies the first propagation-related structure and uses its earliest occurrence time as the effective underwater acoustic emission time includes: Obtain the set of significant energy structures that satisfy the physical consistency between distance sorting and occurrence time; obtain the spatial location and sound speed in water for each hydrophone; calculate the Euclidean distance from each hydrophone to the reference hydrophone based on the spatial location of the hydrophone; sort the set of significant energy structures from earliest to latest occurrence time; and perform corresponding processing operations for each significant energy structure in the sort: determine the hydrophone where the structure is located, and initialize the number of hydrophones that meet the conditions to zero. For each hydrophone, if its distance to the reference hydrophone is greater than the distance between the current structure's hydrophone and the reference hydrophone, the maximum propagation delay is obtained by dividing the distance difference by the speed of sound in water, and the upper limit of the response time is obtained by adding the time when the structure appears. If the hydrophone has a significant energy structure and its appearance time is between the time when the structure appears and the upper limit of the response time, the count is incremented by one. When there are at least two hydrophones that meet the conditions, the current structure is designated as the first propagation-related structure and the traversal is terminated. Finally, the earliest appearance time of this structure in all channels is taken as the effective underwater acoustic emission time. By integrating multi-channel energy timing characteristics with the spatial geometry of hydrophones through a physical determination module for the initiation of underwater acoustic propagation, a discrimination mechanism based on the physical laws of acoustic propagation (distance-time consistency) is constructed. This mechanism effectively distinguishes real underwater acoustic propagation signals from local interference or noise abrupt changes. After eliminating residual vibration contamination, weighted historical energy detection is used to enhance the sensitivity to weak first-arrival signals. Self-consistent verification is achieved through cross-channel arrival order and sound velocity constraints, significantly improving the accuracy, robustness, and physical interpretability of determining the effective emission time of underwater acoustics. This lays a reliable timing benchmark for applications such as high-precision synchronization, positioning, and channel inversion.

[0020] Example 2: The technical solution of this embodiment of the invention differs from that of Example 1 in that: like Figure 1 As shown, the underwater acoustic path topology verification module extracts candidate arriving structures from the received signals of each channel after residual vibration is eliminated, based on the effective underwater acoustic transmission time. Based on the causal relationship between the arrival order across channels and the number of reflections and the arrival time, physically infeasible candidate structures are eliminated. The underwater acoustic path topology verification module, based on the effective underwater acoustic transmission time, processes the received signals of each channel after residual vibration removal, including the following steps: The effective underwater acoustic transmission time and signal sampling rate are obtained, and the sum of the maximum propagation delay and safety margin is obtained as the duration of the analysis window. For each hydrophone channel, the received signal after residual vibration is removed from the corresponding channel is read. Based on the effective underwater acoustic transmission time, the signal start recording time, and the signal sampling rate, the sample start index of the effective underwater acoustic transmission time in the received signal is calculated. Based on the analysis window duration and the signal sampling rate, the number of samples to be truncated is calculated. Starting from the sample start index, a number of consecutive signal samples are truncated. If the signal length is insufficient, zeros are padded to the end to the specified number of samples. The truncated and padded signal is used as the processing result of the current channel. The processing results of all channels are output. The process by which the underwater acoustic path topology verification module extracts candidate arriving structures from the received signals of each channel after residual vibration elimination includes: After removing residual vibrations, obtain the marked start events in the received signals of each channel. Each start event includes the occurrence time and the hydrophone channel number. Sort all start events in ascending order of occurrence time, obtain the maximum allowable time difference of arrival, initialize the candidate arrival structure list, and traverse from the first start event. Starting from the occurrence time of the current start event, establish a time window with a duration equal to the maximum allowable time difference of arrival. Within the window, each hydrophone channel retains only the earliest occurrence start event. If the retained start events come from at least two hydrophone channels, then each hydrophone channel and its corresponding earliest occurrence time form a candidate arrival structure and add it to the candidate arrival structure list. Move the traversal position to the first start event after the end time of the time window, repeat the traversal until all start events have been processed, and output the candidate arrival structure list. The underwater acoustic path topology verification module, based on the causal relationship between its cross-channel arrival order and the number of reflections and arrival time, eliminates physically infeasible candidate structures through the following process: Initialize the list of physically feasible structures, obtain the first candidate arrival structure from the candidate arrival structure sequence, and when there are unprocessed candidate arrival structures, extract the start event, path type marker, and required number of reflections for each channel from the current candidate arrival structure, obtain the straight-line distance from the corresponding hydrophone to the sound source, and verify the three causal rules: First, in all direct path start events, if the straight-line distance between any two hydrophones is less than that between the other, then the occurrence time of the former is no greater than that of the latter. Second, the number of reflections required should not exceed the maximum number of reflections supported by the environment; Third, if both direct and reflected path initiation events exist simultaneously, the occurrence time of each reflected path initiation event is greater than the occurrence time of all direct path initiation events. If all three rules are satisfied, the current candidate arrival structure is added to the list of physically feasible structures, the next candidate arrival structure is obtained, and the list of physically feasible structures is output. The theoretical expression of the verification logic is described by the following formula: ,in This indicates the structure reached by the k-th candidate. This indicates the multi-channel received signal after afterimage removal. This indicates whether the k-th candidate arrival structure satisfies the three causal rules; if any rule is violated, then... , This indicates whether the observed signal has an initiation event at the predicted time point, given that the k-th candidate arrival structure is valid. This is a normalization constant; By using the underwater acoustic path topology verification module as a benchmark based on the high-precision effective underwater acoustic emission time, and combining propagation physical constraints (such as distance-time causality, upper limit of reflection times, and direct / reflection path timing logic), a systematic screening of multi-channel candidate arrival structures is performed, effectively eliminating physically infeasible events caused by noise, reverberation, or false detections. By constructing verification rules based on spatial geometry and sound speed propagation models, not only is the reliability and physical interpretability of arrival structure identification improved, but also high-quality inputs with clear structure and consistent timing are provided for subsequent multipath modeling, environmental inversion, and target localization, which have strong robustness, low false alarm rate, and good engineering feasibility.

[0021] The multi-channel main path selection module calculates the cross-channel time consistency based on the arrival times of candidate multi-paths that satisfy the propagation topology constraints in each channel, selects the path with the highest consistency as the main propagation path, and outputs its arrival time. The multi-channel main path selection module calculates the cross-channel time consistency based on the arrival times of candidate multi-paths that satisfy the propagation topology constraints in each channel, selects the path with the highest consistency as the main propagation path, and outputs its arrival time. The process includes: The first candidate propagation path is obtained from the candidate propagation path sequence. The consistency index of the record is initialized to positive infinity. The arrival time sequence of the main propagation path is empty. When there is an unprocessed path, the arrival time of each receiving channel of the current path is obtained. All different receiving channel pairs are traversed. The absolute value of the difference between the arrival times of each pair is accumulated and counted. If the number of channel pairs is greater than zero, the consistency index is calculated as the accumulated value divided by the number. Otherwise, it is set to positive infinity. If the current consistency index is less than the consistency index of the record, the record index and the arrival time sequence of the main propagation path are updated. Then the next candidate propagation path is obtained. After processing, the arrival time sequence of the main propagation path is output. By quantifying the time-of-arrival consistency of each candidate propagation path across multiple channels through a multi-channel master path optimization module, and aiming to minimize cross-channel time difference, the method automatically selects the master path that best conforms to the physical propagation law, effectively suppressing abnormal paths caused by multipath interference, local noise, or detection bias. The method is computationally simple, requires no prior environmental information, and can robustly identify the dominant propagation component by relying solely on time alignment characteristics, providing a reliable and low-jitter time-of-arrival reference for applications such as active sonar ranging, underwater acoustic communication synchronization, and high-precision positioning.

[0022] Example 3: The technical solution of this embodiment of the invention differs from that of Example 1 and Example 2 in that: like Figure 2 As shown, a multi-channel underwater acoustic signal processing method includes the following steps: Step 1: Based on the theoretical start time of the preset underwater acoustic emission signal and the synchronously acquired electrical signal feedback from the transducer drive end, extract and quantify the actual physical response characteristics of the transducer, and generate a set of emission timing constraint parameters based on the theoretical start time. Step 2: Determine the residual vibration time range based on the duration of the transducer's residual vibration attenuation, and remove data segments from the received signals of each channel that fall within the residual vibration time range; Step 3: In the multi-channel received signal after after-resonance removal, the first propagation-related structure is determined based on the correlation between the cross-channel arrival order of significant energy structures and the spatial position of the hydrophone, and its earliest occurrence time is taken as the effective underwater acoustic transmission time. Step 4: Based on the effective transmission time of underwater acoustics, extract candidate arriving structures from the received signals of each channel after residual vibration elimination. Based on the causal relationship between their cross-channel arrival order and the number of reflections and arrival time, eliminate physically infeasible candidate structures. Step 5: Based on the arrival times of candidate multipaths that satisfy the propagation topology constraints in each channel, calculate the cross-channel time consistency, select the path with the highest consistency as the main propagation path, and output its arrival time. This multi-channel underwater acoustic signal processing method constructs a high-precision time-series estimation framework driven by physical constraints across the entire link through five collaborative steps: transmission response modeling, aftershock removal, first-arrival physical determination, path topology verification, and main path consistency optimization. Without requiring prior environmental information, it effectively suppresses aftershocks, noise, and spurious multipath interference, significantly improving the accuracy, robustness, and timing consistency of the effective underwater acoustic transmission time and the main path arrival time, providing reliable technical support for applications such as underwater acoustic communication, detection, and positioning.

[0023] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. A multi-channel underwater acoustic signal transmitting and measuring system, characterized in that, The method comprises the following steps: An underwater acoustic emission physical modeling module extracts and quantifies the actual physical response characteristics of the transducer based on the theoretical starting time of the preset underwater acoustic emission signal and the feedback of the synchronously collected electric signal at the driving end of the transducer, and generates a set of emission timing constraint parameters based on the theoretical starting time; An underwater acoustic propagation preprocessing module determines the residual vibration time range according to the residual vibration decay duration, and eliminates the data segments in the residual vibration time range in the received signals of each channel; An underwater acoustic propagation starting physical judgment module determines the first propagation-related structure in the multi-channel received signals after residual vibration elimination according to the correlation between the cross-channel arrival order of the significant energy structure and the spatial position of the hydrophone, and takes the earliest occurrence time of the structure as the effective underwater acoustic emission time; An underwater acoustic path topology verification module extracts candidate arrival structures in the received signals of each channel after residual vibration elimination based on the effective underwater acoustic emission time, and eliminates the candidate structures that are physically infeasible based on the causal relationship between the cross-channel arrival order and the reflection number and arrival time; A multi-channel main path optimization module calculates the cross-channel time consistency based on the arrival time of the candidate multi-path that meets the propagation topology constraint, selects the path with the highest consistency as the main propagation path, and outputs the arrival time of the path.

2. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 1, characterized in that, The process of the underwater acoustic emission physical modeling module based on the theoretical starting time of the preset underwater acoustic emission signal and the feedback of the synchronously collected electric signal at the driving end of the transducer, extracting and quantifying the actual physical response characteristics of the transducer, and generating a set of emission timing constraint parameters based on the theoretical starting time comprises: Obtain the theoretical starting time of the preset underwater acoustic emission signal, locate the sampling point where the amplitude first leaves the peak-to-peak value range of the background noise and continuously rises in the envelope of the synchronously collected electric signal at the driving end of the transducer as the amplitude rise starting time, the vibration delay time is the difference between the amplitude rise starting time and the theoretical starting time, locate the sampling point where the rising ends and the difference between the adjacent peak values in the subsequent periodic oscillation does not exceed the peak-to-peak value of the background noise as the stable oscillation starting time, and the sound pressure build-up time is the difference between the stable oscillation starting time and the theoretical starting time; Obtain the termination time of the preset underwater acoustic emission signal, locate the sampling point where the amplitude first falls back to the peak-to-peak value range of the background noise and continuously maintains as the final silence starting time, the residual vibration decay duration is the difference between the final silence starting time and the signal termination time, and the emission timing constraint parameter set composed of the vibration delay time, the sound pressure build-up time and the residual vibration decay duration is output.

3. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 1, characterized in that, The process of the underwater acoustic propagation preprocessing module determining the residual vibration time range according to the residual vibration decay duration and eliminating the data segments in the residual vibration time range in the received signals of each channel comprises: The water acoustic propagation starting physical judgment module comprises the following steps: acquiring a transmission end time provided by a transmission controller, acquiring a pre-labeled and stored residual vibration decay duration, taking the transmission end time as a residual vibration time range start time, taking a sum of the residual vibration decay duration and the transmission end time as an end time, taking the residual vibration time range as a closed interval containing the start time and the end time, removing, for each receiving channel, all sampling points with a time stamp not less than the start time and not greater than the end time, and outputting a receiving signal of each receiving channel after removing the sampling points in the residual vibration time range.

4. The multi-channel underwater acoustic signal transmitting and measuring system according to claim 1, characterized in that, The process of the water acoustic propagation starting physical judgment module analyzing the correlation between the cross-channel arrival order of the significant energy structure and the spatial position of the hydrophone in the multi-channel receiving signal after the residual vibration removal comprises the following steps: The process of the water acoustic propagation starting physical judgment module analyzing the correlation between the cross-channel arrival order of the significant energy structure and the spatial position of the hydrophone in the multi-channel receiving signal after the residual vibration removal comprises the following steps:

5. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 4, characterized in that, The process of the water acoustic propagation starting physical judgment module determining the first propagation-related structure and taking the earliest occurrence time of the first propagation-related structure as the water acoustic effective transmission time comprises the following steps: The process of the water acoustic propagation starting physical judgment module determining the first propagation-related structure and taking the earliest occurrence time of the first propagation-related structure as the water acoustic effective transmission time comprises the following steps: The process of the water acoustic path topology verification module taking the water acoustic effective transmission time as a reference and processing each channel receiving signal after the residual vibration removal comprises the following steps:

6. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 1, characterized in that, The process of the water acoustic path topology verification module taking the water acoustic effective transmission time as a reference and processing each channel receiving signal after the residual vibration removal comprises the following steps: ​ 7. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 6, characterized in that, The process of extracting candidate arrival structures from the received signals of each channel after the residual vibration is removed by the underwater acoustic path topology verification module includes: Obtaining the marked starting events in the received signals of each channel after the residual vibration is removed, arranging all the starting events in ascending order of occurrence time, obtaining the maximum allowed arrival time difference, initializing the candidate arrival structure list, starting from the first starting event, taking the occurrence time of the current starting event as the starting point, establishing a time window with a duration of the maximum allowed arrival time difference, in the window, only the earliest occurring starting event is retained for each hydrophone channel, if the retained starting event comes from no less than two hydrophone channels, a candidate arrival structure is formed by each hydrophone channel and the corresponding earliest occurrence time, and is added to the candidate arrival structure list, the traversal position is moved to the first starting event after the end time of the time window, and the traversal is repeated until all the starting events are processed, and the candidate arrival structure list is output.

8. A multi-channel underwater acoustic signal transmitting and measuring system according to claim 7, characterized in that, The process of eliminating physically infeasible candidate structures based on the causal relationship between the cross-channel arrival order and the reflection number and the arrival time of the underwater acoustic path topology verification module includes: Initializing the physically feasible structure list, obtaining the first candidate arrival structure from the candidate arrival structure sequence, when there is an unprocessed candidate arrival structure, extracting the starting event of each channel, path type label and required reflection number from the current candidate arrival structure, obtaining the straight-line distance from the corresponding hydrophone to the sound source, verifying three causal rules: First, in all direct path starting events, if the straight-line distance of any two hydrophones is less than the other, the occurrence time of the former is not greater than that of the latter; Second, the required reflection number does not exceed the maximum reflection number supported by the environment; Third, if there are direct and reflected path starting events at the same time, the occurrence time of each reflected path starting event is greater than that of all direct path starting events; If the three rules are met, the current candidate arrival structure is added to the physically feasible structure list, the next candidate arrival structure is obtained, and the physically feasible structure list is output.

9. The multi-channel underwater acoustic signal transmitting and measuring system according to claim 1, characterized in that, The process of calculating the cross-channel time consistency based on the arrival time of the candidate multi-path satisfying the propagation topology constraint, selecting the path with the highest consistency as the main propagation path and outputting the arrival time of the main propagation path by the multi-channel main path optimization module includes: Obtaining the first candidate propagation path from the candidate propagation path sequence, initializing the recorded consistency index to positive infinity, and the main propagation path arrival time sequence is empty, when there is an unprocessed path, obtaining the arrival time of each receiving channel of the current path, traversing all different receiving channel pairs, accumulating the absolute value of the difference between each pair of arrival times and counting, if the number of channel pairs is greater than zero, the consistency index is calculated as the accumulated value divided by the number, otherwise it is set to positive infinity, if the current consistency index is less than the recorded consistency index, the recorded index and the main propagation path arrival time sequence are updated, then the next candidate propagation path is obtained, and after the processing is completed, the main propagation path arrival time sequence is output.

10. A method for processing multi-channel underwater acoustic signals, applied to a multi-channel underwater acoustic signal transmitting and measuring system as claimed in any one of claims 1-9, characterized in that, The process includes the following steps: Step one: Based on the theoretical starting time of the preset underwater acoustic emission signal and the feedback of the transducer driving end electric signal collected synchronously, the actual physical response characteristics of the transducer are extracted and quantified, and the emission timing constraint parameter set with the theoretical starting time as the reference is generated; Step two: According to the residual vibration decay duration of the transducer, the residual vibration time range is determined, and the data segments in the receiving signals of each channel located in the residual vibration time range are removed; Step three: In the multi-channel receiving signal after residual vibration removal, according to the correlation between the cross-channel arrival order of the significant energy structure and the spatial position of the hydrophone, the first propagation related structure is determined, and the earliest occurrence time thereof is taken as the effective underwater acoustic emission time; Step four: Taking the effective underwater acoustic emission time as the reference, the candidate arrival structure is extracted in each channel receiving signal after residual vibration removal, and based on the causality relationship between the cross-channel arrival order and the reflection number and the arrival time, the physically unfeasible candidate structure is removed; Step five: Based on the arrival time of the candidate multi-path satisfying the propagation topology constraint in each channel, the cross-channel time consistency is calculated, the path with the highest consistency is selected as the main propagation path, and the arrival time thereof is output.

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