Ship water area depth detection method and system

Abstract

The invention relates to the technical field of ship water area depth detection, and discloses a ship water area depth detection method and system, which captures an echo signal by introducing an energy threshold, and further judges the time multiple relationship and the specific energy relationship between potential main echoes and potential secondary echoes to determine the water area depth of a ship. The problem of depth misjudgment caused by weak real underwater echo signals of a traditional sonar system in a complex water area environment is effectively solved. Compared with the traditional identification logic which only depends on'the first arrival and the strongest energy ', the method provided by the invention can more accurately identify the real bottom echo, even if the energy is very weak, thereby avoiding the situation that the secondary echo is misjudged as the real water bottom echo, remarkably improving the accuracy and reliability of water depth detection, and improving the accuracy and reliability of water depth detection. Especially in challenging environments such as organism attached to a ship body or soft sludge at the water bottom, more reliable depth information guarantee is provided for ship navigation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship water depth detection, and in particular to a ship water depth detection method and system. BACKGROUND

[0002] The safety of ship navigation is highly dependent on accurate water depth information. At present, the ship generally adopts sonar technology to detect water depth, emits a sound wave pulse to the underwater through the sonar transducer on the ship bottom, receives the main echo reflected from the bottom, measures the round trip time of the sound wave and calculates the water depth combined with the sound speed in water.

[0003] However, in actual navigation, various complex factors may cause the traditional depth detection system to misjudge. For example, when the ship sails in the tropical or subtropical waters for a long time, if the antifouling coating of the ship body fails, marine organisms may be attached to the surface of the sonar transducer, forming a rough and uneven biological film. When the sound wave pulse passes through this layer of attachment, the complex structure will cause obvious absorption and scattering of the sound wave, resulting in a significant reduction of the effective sound energy actually entering the water.

[0004] The superposition of various factors causes the ship depth detection system to continuously output a set of values that appear to be continuous but actually have no regular changes between the true depth value and an error depth value about twice the true depth value. The uncertainty of such values makes it difficult for the crew to determine which reading displayed on the screen is reliable, and in the shallow water channel where accurate operation of the ship is required, such unreliable depth information will pose a huge risk to navigation safety. SUMMARY

[0005] The present application provides a ship water depth detection method and system, aiming to solve the problem that the existing ship depth detection system is inaccurate and unreliable due to signal attenuation and multipath effect in complex water environment, and even outputs an error depth value, thereby affecting the safety of navigation.

[0006] In a first aspect, to solve the above technical problems, the present application provides a ship water depth detection method, comprising: obtaining an echo signal sequence, the echo signal sequence being captured by applying an energy threshold lower than the energy threshold; identifying a potential main echo in the echo signal sequence, and obtaining the arrival time of the potential main echo; searching for a potential secondary echo in the echo signal sequence according to the arrival time, and judging whether the potential main echo and the potential secondary echo satisfy a time multiple relationship and a specific energy relationship, the specific energy relationship being that the energy of the potential main echo is weaker than the energy of the potential secondary echo; If yes, it is confirmed that the potential primary echo is a real water bottom primary echo, and a real water depth is calculated based on the arrival time of the real water bottom primary echo; If no, a specific warning information is sent out.

[0007] Preferably, the searching for potential secondary echoes and judging whether the time multiple relationship and the specific energy relationship are satisfied between the potential primary echo and the potential secondary echoes according to the arrival time, the specific energy relationship being that the energy of the potential primary echo is weaker than that of the potential secondary echoes, comprises: searching for the potential secondary echoes and potential tertiary echoes in the echo signal sequence; judging whether the time multiple relationship and the specific energy relationship are satisfied between the potential primary echo, the potential secondary echoes and the potential tertiary echoes; checking the waveform stability of the potential secondary echoes and the potential tertiary echoes; If the time multiple relationship, the specific energy relationship and the waveform stability are stably satisfied between the potential primary echo, the potential secondary echoes and the potential tertiary echoes, it is confirmed that the potential primary echo is the real water bottom primary echo.

[0008] Preferably, the confirming that the potential primary echo is the real water bottom primary echo if the time multiple relationship, the specific energy relationship and the waveform stability are stably satisfied between the potential primary echo, the potential secondary echoes and the potential tertiary echoes, comprises: adjusting the similarity threshold and the continuous period number requirement of the waveform stability checking according to the ship navigation speed and the water depth change rate; smoothing the waveform features of the continuously captured potential secondary echoes and potential tertiary echoes to obtain smoothed waveform features; If the time multiple relationship, the specific energy relationship are stably satisfied between the potential primary echo, the potential secondary echoes and the potential tertiary echoes, and the smoothed waveform features satisfy the adjusted similarity threshold and the continuous period number requirement, it is confirmed that the potential primary echo is a real water bottom primary echo.

[0009] Preferably, the checking the waveform stability of the potential secondary echoes and the potential tertiary echoes comprises: capturing waveform data of the potential secondary echoes and the potential tertiary echoes; adjusting the length of the processing time window of the waveform data according to the water noise level and the instantaneous signal-to-noise ratio of the sonar signal; Within the processing time window, identify and remove outliers from the waveform data; The waveform data after removing outliers is locally averaged to obtain a smooth waveform. The similarity between the smoothed waveform and the reference waveform is calculated using the sliding window cross-correlation method. If the similarity remains above the threshold for multiple consecutive periods, the waveform is determined to be stable.

[0010] Preferably, the step of confirming the potential primary echo as the actual underwater primary echo if the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the smoothed waveform features satisfy the adjusted similarity threshold and the consecutive period number requirement, includes: A track record is established for each potential echo chain that conforms to the time multiple relationship, the specific energy relationship, and the waveform morphology stability. The track record includes the arrival time of the chain, the ship's position, heading, and speed. The spatial continuity of each potential echo chain is continuously tracked within a continuous detection period, and the depth change rate of the potential echo chain is calculated. If the depth change rate is less than a preset change rate threshold, and the waveform characteristics of the potential echo chain are more similar to the historical waveform characteristics of the corresponding chain in the track record than the waveform threshold, then the continuity score of the potential echo chain is increased. If the potential echo chain fails to maintain spatial continuity in the current period, the continuity score of the potential echo chain is reduced. If the continuity score of the potential echo chain reaches a preset high confidence threshold, then the potential main echo is confirmed as the real main underwater echo. If multiple potential echo chains reach the high confidence threshold, the potential echo chain with the shortest arrival time is selected as the main actual underwater echo. If no potential echo chain reaches the high confidence threshold within the current detection period, then depth data output is suppressed; If a potential echo chain exists with a continuity score at a moderate level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, a warning is issued: "Local strong reflector detected, depth data uncertain." If the continuity score of all potential echo chains is low, a warning is issued that “bottom signal is unstable and depth data is unreliable”.

[0011] Preferably, the step of reducing the continuity score of the potential echo chain if it fails to maintain spatial continuity in the current period includes: Determine the duration for which the potential echo chain fails to maintain spatial continuity; If the duration is less than a preset instantaneous interruption threshold, the continuity score of the potential echo chain is slightly reduced. If the duration is not less than the instantaneous interruption threshold, the continuity score of the potential echo chain is significantly reduced.

[0012] Preferably, if a potential echo chain exists with a continuity score at a moderate level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, then issuing a warning of "Local strong reflector detected, depth data uncertain" includes: Determine whether the depth change rate of the potential echo chain is within the preset instantaneous shallowing threshold range; Determine whether the similarity between the waveform shape of the potential echo chain and the historical record is higher than a preset instantaneous fluctuation threshold; If the depth change rate is within the instantaneous shallowing threshold and the waveform morphology similarity is higher than the instantaneous fluctuation threshold, then the potential echo chain is marked as an instantaneous local shallow point. Start a short-term tracking window; Within the short-term tracking window, the frequency and duration of the occurrence of the instantaneous local shallow points are monitored; If the frequency of occurrence of the instantaneous local shallow spot exceeds a preset density threshold or the duration exceeds a preset short-term dwell threshold, a warning message "Instantaneous shallow spot ahead, please be careful" will be issued. The display interface will flash to indicate that there is a momentary local shallowing of the current depth data.

[0013] Preferably, monitoring the frequency and duration of the instantaneous local shallow spots within the short-time tracking window includes: Obtain the signal waveform characteristics of the instantaneous local shallow point; Analyze the energy distribution of the signal waveform characteristics to identify whether the energy distribution exhibits multi-peak or broadening phenomena. Based on historical sonar data of the ship's current navigation waters, determine whether the signal waveform characteristics are consistent with the underwater reflection waveform characteristics in the historical sonar data; If the energy distribution of the signal waveform features exhibits a single peak and narrow span, and the signal waveform features are consistent with the underwater reflection waveform features, then the instantaneous local shallow point is confirmed as a real underwater shallow point, and the frequency and duration of the instantaneous local shallow point are monitored.

[0014] Preferably, monitoring the frequency and duration of the instantaneous local shallow spots includes: Identify the arrival time, waveform start point, and waveform end point of the instantaneous local shallow point signal; Based on the arrival time, the waveform start point, and the waveform end point, a time and depth matrix is ​​constructed, and the instantaneous local shallow point is mapped to the time and depth matrix; Two-dimensional connected component analysis is performed on the time and depth matrix to identify shallow point clusters in the time and depth matrix; Calculate the center arrival time, average depth, and number of shallow points within each shallow point cluster.

[0015] Secondly, the present invention provides a ship water depth detection system, comprising: The detection end is used to acquire the echo signal sequence, which is captured by applying an energy threshold below the energy threshold. The processing end includes an identification module for identifying potential primary echoes in the echo signal sequence and obtaining the arrival time of the potential primary echoes; based on the arrival time, searching for potential secondary echoes in the echo signal sequence, and determining whether the potential primary echoes and the potential secondary echoes satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echoes is weaker than the energy of the potential secondary echoes; The output terminal is used to confirm that the potential main echo is the actual main echo at the bottom of the water if the conditions are met, and to calculate the actual water depth based on the arrival time of the actual main echo at the bottom of the water; if the conditions are not met, a specific warning message is issued.

[0016] This invention discloses a method for detecting the depth of a vessel in water. By acquiring echo signal sequences with energy thresholds below the conventional identification threshold, it can effectively capture the true main echo signal from the seabed, which becomes extremely weak due to sound energy attenuation in complex water environments. Building upon this, the method no longer simply relies on the traditional logic of "arriving first and having the strongest energy." Instead, it innovatively introduces judgments regarding the "time multiple relationship" and "specific energy relationship (i.e., the energy of the potential main echo is weaker than that of the potential secondary echo)" between the potential main echo and the potential secondary echo. This key improvement enables the system to identify and correct the shortcomings of traditional methods that may misjudge secondary echoes as true water depth in shallow water areas, avoiding the calculation of erroneous depth values ​​approximately twice the true depth. When these relationships are met, the system can confirm that the potential main echo is the true main echo from the seabed and calculate the accurate true water depth accordingly; if these relationships are not met, a warning message is issued promptly to prevent crew members from operating based on erroneous data. Attached Figure Description

[0017] Figure 1 This is a flowchart of a method for detecting the depth of a ship in water area provided by an embodiment of the present invention; Figure 2 This is a schematic diagram of a ship water depth detection system provided in an embodiment of the present invention. Detailed Implementation

[0018] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Reference Figure 1 , Figure 1 This invention provides a flowchart of a method for detecting the depth of a ship in water, comprising the following steps: S11, Acquire the echo signal sequence, which is captured by applying an energy threshold; S12, Identify potential main echoes in the echo signal sequence and obtain the arrival time of the potential main echoes; S13, based on the arrival time, search for potential secondary echoes in the echo signal sequence, and determine whether the potential primary echo and the potential secondary echo satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echo is weaker than the energy of the potential secondary echo; S14, if satisfied, then confirm that the potential main echo is the actual main echo at the bottom of the water, and calculate the actual water depth based on the arrival time of the actual main echo at the bottom of the water; if not satisfied, then issue a specific warning message.

[0020] Specifically, the energy threshold can be set to a fixed low value, much lower than the recognition threshold typically used in traditional sonar systems, to ensure that even extremely weak reflected signals can be captured by the system. For example, this threshold can be preset based on historical data or empirical values. In another implementation, the energy threshold can be dynamically adjusted, for example, adaptively adjusted based on the average noise level of the water area or the instantaneous signal-to-noise ratio of the sonar equipment, to suppress noise interference as much as possible while ensuring signal acquisition capability.

[0021] For example, the system can scan the entire echo signal sequence, identify the first significant peak with energy above the low energy threshold as a potential primary echo, and record its arrival time. Alternatively, a signal feature-based identification method can be used, such as analyzing the rising edge and peak width of the echo signal to initially screen signals that meet the characteristics of underwater echoes as potential primary echoes.

[0022] After obtaining the arrival time of the potential primary echo, the system searches for potential secondary echoes within a time window approximately twice that arrival time. For example, a fixed time window can be set, such as twice the arrival time of the potential primary echo ± a preset error range. After finding a potential secondary echo, the system calculates the ratio of the arrival times of the potential primary echo to those of the potential secondary echo and determines if this ratio is close to 2. Simultaneously, the system compares the energies of the two echoes. If the energy of the potential primary echo is significantly weaker than that of the potential secondary echo, the specific energy relationship is considered satisfied. For example, an energy ratio threshold can be set; if the ratio of the energy of the potential primary echo to that of the potential secondary echo is lower than this threshold, the condition is met.

[0023] The proposed solution captures echo signals by introducing an energy threshold lower than the conventional identification threshold. Furthermore, it effectively solves the problem of depth misjudgment caused by the weak actual underwater echo signals in complex water environments by judging the time multiple relationship and specific energy relationship between potential primary echoes and potential secondary echoes.

[0024] This application further proposes a more robust depth detection method. By introducing the search and judgment of potential third echoes and combining the stability verification of the waveform morphology of potential second and third echoes, the method improves the accuracy and reliability of identifying the main echoes on the real seabed through multiple verifications.

[0025] The above-mentioned method involves searching for potential secondary echoes in the echo signal sequence based on the arrival time, and determining whether the potential primary echo and the potential secondary echo satisfy a time multiple relationship and a specific energy relationship. The specific energy relationship is that the energy of the potential primary echo is weaker than the energy of the potential secondary echo, including: Search for the potential secondary and tertiary echoes in the echo signal sequence; Determine whether the potential primary echo, the potential secondary echo, and the potential tertiary echo satisfy a time multiple relationship and a specific energy relationship; The stability of the waveforms of the potential secondary echo and the potential tertiary echo is verified. If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship, the specific energy relationship, and the waveform morphology stability, then the potential primary echo is confirmed as the actual underwater primary echo.

[0026] Specifically, searching for potential secondary and tertiary echoes in the echo signal sequence means that after receiving the sonar signal and acquiring the echo signal sequence, in addition to identifying the potential primary echo, the system further searches for possible potential secondary and tertiary echoes in subsequent echo signals based on the arrival time of the potential primary echo. These echoes are usually formed by multiple reflections of sound waves between the bottom and the surface of the water, and their arrival times have a specific multiple relationship with the primary echo.

[0027] Determining whether the potential primary echo, potential secondary echo, and potential tertiary echo satisfy a time multiple relationship and a specific energy relationship can be understood as analyzing the arrival times of these three consecutive echoes to verify whether they approximately satisfy a 1:2:3 multiple relationship (or an integer multiple relationship), while simultaneously examining their energy characteristics. For example, in the case of underwater reflections, the energy of the potential primary echo is usually weaker than that of the potential secondary echo, while the energy of the potential tertiary echo may further attenuate or maintain a specific relationship. This energy characteristic helps distinguish between true underwater echoes and non-underwater reflections.

[0028] In practical applications, stability verification of the waveforms of potential secondary and tertiary echoes involves analyzing their waveform characteristics, such as shape, width, and peak value. By comparing the stability of these waveform characteristics over a continuous detection period, it is possible to effectively distinguish stable echoes generated by underwater reflections from unstable echoes generated by noise, clutter, or transient obstacles. Stable waveform morphology is one of the important indicators of a true underwater echo.

[0029] Therefore, if the potential primary echo, potential secondary echo, and potential tertiary echo stably satisfy the aforementioned time multiple relationship, the aforementioned specific energy relationship, and waveform morphology stability, then the potential primary echo is confirmed as the actual primary echo from the seabed. This means that only when these three echoes exhibit highly consistent and stable characteristics in terms of time, energy, and waveform morphology are they confirmed as the actual primary echo from the seabed, thereby greatly improving the accuracy of seabed identification.

[0030] This application's solution effectively addresses the potential misjudgment issues that may arise in complex aquatic environments using traditional methods by introducing the detection of potential third echoes and waveform morphology stability verification. First, by searching for and judging potential third echoes, the system can establish a more complete "echo chain," namely a sequence of primary, secondary, and tertiary echoes. This multi-echo verification mechanism ensures that the confirmation of underwater reflections no longer relies solely on two echoes, but rather on cross-verification through more stringent time multiples and energy relationships between the three echoes, significantly reducing the probability of misjudgment caused by single or sporadic reflections. Second, stability verification of the waveform morphology of potential secondary and tertiary echoes further enhances the reliability of identification. Real underwater echoes typically possess relatively stable waveform characteristics, while reflections from noise, suspended matter, or transient obstacles in the water often exhibit irregular or unstable waveforms. Through continuous monitoring and stability assessment of waveform morphology, the system can effectively filter out these interferences, ensuring that the identified echoes indeed originate from stable underwater structures. It is precisely because of this multi-layered and rigorous verification mechanism that the proposed solution can more accurately and reliably identify the true main underwater echoes in complex and ever-changing aquatic environments.

[0031] This application further proposes a step to confirm that the potential primary echo is the actual underwater primary echo if the potential secondary echo, the potential tertiary echo, and the potential primary echo stably satisfy the time multiple relationship, the specific energy relationship, and the waveform morphology stability. Adjust the similarity threshold and the number of consecutive periods required for the waveform morphology stability verification based on the ship's speed and the rate of change of water depth. The waveform features of the continuously captured potential secondary echo and potential tertiary echo are smoothed to obtain smoothed waveform features. If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the smoothed waveform features satisfy the adjusted similarity threshold and the continuous period number requirement, then the potential primary echo is confirmed as the actual underwater primary echo.

[0032] Specifically, the similarity threshold and the number of consecutive periods are adjusted based on the ship's speed and the rate of change of water depth to make the waveform stability verification process more adaptable. For example, when the ship's speed is high or the rate of change of water depth is large, the similarity threshold can be appropriately relaxed or the number of consecutive periods can be reduced to allow for a certain degree of waveform deformation or temporary instability, thereby avoiding misjudgment. Conversely, when the ship's speed is slow or the water depth is relatively stable, the similarity threshold can be increased or the number of consecutive periods can be increased to ensure higher recognition accuracy and anti-interference capability. This adjustment can be achieved through preset lookup tables, empirical formulas, or adaptive algorithms.

[0033] The smoothing process for the waveform features of continuously captured potential secondary and tertiary echoes aims to eliminate or reduce random noise and transient fluctuations in the signal, thereby obtaining more stable and representative waveform features. Various techniques can be employed for smoothing, such as moving average filtering, Gaussian filtering, or Kalman filtering. By weighted averaging or state estimation of waveform data within a continuous time window, noise is effectively suppressed, making the waveform features clearer and more stable, thus providing more reliable input for subsequent similarity calculations.

[0034] Therefore, when the potential primary echo, potential secondary echo, and potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the waveform characteristics after smoothing meet the similarity threshold and continuous period number requirements adjusted according to the current environmental conditions, the potential primary echo can be confirmed with high confidence as the real underwater primary echo.

[0035] Through the above technical solutions, this application significantly improves the accuracy and robustness of ship depth detection. By dynamically adjusting calibration parameters according to the ship's navigation status and the water environment, the system can better adapt to different operating conditions, avoiding the limitations of fixed parameters and effectively reducing the probability of false alarms and missed alarms. Furthermore, the smoothing of waveform features further enhances the system's resistance to noise, ensuring reliable waveform information can be extracted even in complex acoustic environments, thereby improving the confidence level of identifying the main echoes from the actual seabed. Therefore, this application can provide more stable and reliable depth data, providing more accurate assurance for ship navigation safety.

[0036] In response, this application further proposes a method for stability verification of the waveform morphology of the aforementioned potential secondary echo and the aforementioned potential tertiary echo, which includes: Capture the waveform data of the potential secondary echo and the potential tertiary echo; The length of the processing time window for the waveform data is adjusted based on the water noise level and the instantaneous signal-to-noise ratio of the sonar signal. Within the processing time window, identify and remove outliers from the waveform data; The waveform data after removing outliers is locally averaged to obtain a smooth waveform. The similarity between the smoothed waveform and the reference waveform is calculated using the sliding window cross-correlation method. If the similarity remains above the threshold for multiple consecutive periods, the waveform is determined to be stable.

[0037] Specifically, capturing waveform data of potential secondary and tertiary echoes refers to extracting complete time-domain waveform information of signal segments identified as potential secondary and tertiary echoes after the sonar system receives the echo signal. This includes, but is not limited to, characteristics such as signal amplitude, phase, and duration. This waveform data forms the basis for subsequent morphological analysis.

[0038] The length of the waveform data processing time window is adjusted based on the water noise level and the instantaneous signal-to-noise ratio (SNR) of the sonar signal. This aims to enable the waveform analysis process to adaptively respond to different underwater acoustic environments. For example, when the water noise level is high or the instantaneous SNR of the sonar signal is low, the processing time window can be appropriately shortened to reduce noise interference with waveform feature extraction and improve the response speed to instantaneous signal changes. Conversely, when the noise level is low and the SNR is good, the processing time window can be appropriately extended to obtain more complete waveform information and improve the robustness of the analysis.

[0039] In practical applications, identifying and removing outliers in waveform data within the aforementioned processing time window refers to using statistical methods (e.g., outlier detection based on standard deviation, median filtering, etc.) or preset thresholds to detect and remove spikes, glitches, or discontinuities in the waveform data caused by transient interference, noise, or sensor malfunctions. This step aims to purify the waveform data and ensure the accuracy of subsequent processing.

[0040] Furthermore, local averaging is performed on the waveform data after outlier removal to obtain a smooth waveform. The purpose is to eliminate high-frequency noise and random fluctuations in the data, making the waveform clearer and more stable, which facilitates subsequent similarity calculations. Local averaging can employ various smoothing algorithms such as moving average and Gaussian filtering.

[0041] Furthermore, a sliding window cross-correlation method is employed to calculate the similarity between the smoothed waveform and the reference waveform. This involves comparing the smoothed potential second and third echo waveforms with a pre-stored reference waveform representing typical underwater echo characteristics. The sliding window cross-correlation method can assess the similarity between two waveforms at different time offsets, thereby identifying the best match and quantifying their similarity. The reference waveform can be obtained from historical experience data or through pre-calibration.

[0042] Therefore, if the similarity remains above a preset threshold for multiple consecutive periods, the waveform is considered stable. This means that the system not only focuses on the waveform similarity within a single detection period, but also emphasizes its continuity and consistency over time, thereby effectively avoiding misjudgments caused by transient interference.

[0043] Through the above technical solutions, this application significantly improves the accuracy and reliability of ship depth detection in water conditions. By adaptively adjusting the waveform data processing time window, the system can better adapt to changes in noise and signal-to-noise ratio under different water environments, improving the ability to capture effective echo signals. Outlier removal and local averaging effectively purify the waveform data, reducing the impact of transient interference and random noise on waveform morphology judgment, resulting in more accurate waveform feature extraction.

[0044] If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the smoothed waveform features satisfy the adjusted similarity threshold and the consecutive period number requirement, then the potential primary echo is confirmed as the actual underwater primary echo, as follows: Establishing a track record for each potential echo chain that meets the time multiple relationship, specific energy relationship, and waveform stability criteria means that when a sonar system identifies a potential primary echo and its corresponding potential secondary and tertiary echoes within a certain detection period, and these echoes satisfy preset time multiple relationships, specific energy relationships, and waveform stability checks, this set of echo signals is considered a "potential echo chain." For long-term tracking and evaluation, an independent track record is created for it. This track record is used to store key information related to the potential echo chain, such as its arrival time when it was first identified, the ship's precise position at that moment (e.g., latitude and longitude), the ship's heading, and its speed. This information constitutes the initial state of the potential echo chain and provides the basic data for its subsequent spatial continuity tracking.

[0045] The system continuously tracks the spatial continuity of each potential echo chain within consecutive detection cycles and calculates the depth change rate for each potential echo chain. This can be understood as the system attempting to match newly identified potential echo chains with existing potential echo chains in established track records during subsequent detection cycles. Matching criteria include, but are not limited to, proximity of arrival times, reasonable changes in vessel position, and similarity of waveform characteristics. Once a match is successful, the potential echo chain is considered to have maintained spatial continuity. Based on this, the depth change is calculated using the arrival time of the chain in the current detection cycle and the arrival time in the previous cycle, combined with the speed of sound, and further, the depth change rate of the potential echo chain is calculated. The calculation of the depth change rate helps assess the stability or changing trend of the underwater topography and is an important indicator for judging the reliability of the echo chain.

[0046] In practical applications, if the depth change rate is less than a preset change rate threshold, and the waveform characteristics of the potential echo chain are more similar to the historical waveform characteristics of the corresponding chain in the track record than the waveform threshold, the continuity score of the potential echo chain is increased. This means that when a potential echo chain remains spatially continuous, its depth changes are within an acceptable range, and its waveform characteristics are highly consistent with historical records, the echo chain is considered highly reliable, and therefore its continuity score is improved. The continuity score is a cumulative indicator used to quantify the reliability and stability of a potential echo chain.

[0047] Furthermore, if a potential echo chain fails to maintain spatial continuity in the current period, its continuity score is reduced. This indicates that when a potential echo chain fails to be successfully tracked or matched in a probing period, its reliability is questioned, and therefore its continuity score is correspondingly lowered. This mechanism helps to promptly identify and eliminate unstable or spurious echo signals.

[0048] Furthermore, if the continuity score of a potential echo chain reaches a preset high confidence threshold, the potential primary echo is confirmed as the actual primary echo from the seabed. When a potential echo chain is continuously tracked and evaluated, and its continuity score accumulates to a sufficiently high level, it indicates that the echo chain has extremely high reliability. At this point, its corresponding potential primary echo is finally confirmed as the actual primary echo from the seabed and used to calculate the actual ship depth.

[0049] If multiple potential echo chains meet the high confidence threshold, the one with the shortest arrival time is selected as the primary true bottom echo. In some complex waters, multiple potential echo chains that meet the high confidence threshold may exist simultaneously. In this case, to ensure that the depth data closest to the bottom is obtained, the system will prioritize selecting the potential echo chain with the earliest arrival time (i.e., the shallowest depth) as the final primary true bottom echo.

[0050] Simultaneously, if no potential echo chain reaches the high confidence threshold within the current detection period, depth data output is suppressed. This is a safety mechanism; when the system cannot identify sufficiently reliable primary echoes from the actual seabed, it temporarily stops outputting depth data to prevent misjudgment and ensure accurate data output.

[0051] Furthermore, if a potential echo chain exists with a continuity score at a moderate level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, a warning will be issued: "Local strong reflector detected, depth data uncertain." In this case, there may be an underwater local obstacle or strong reflector whose echo signal, while having some continuity, has not yet reached the highest confidence level, and the indicated depth suddenly becomes shallower. The system will issue a warning to alert the operator to the potential hazard.

[0052] Finally, if the continuity score of all potential echo chains is low, a warning of "unstable bottom signal, unreliable depth data" is issued. When the reliability score of all potential echo chains is low, it indicates that the current water environment is complex, the bottom signal is unstable, and the system cannot provide reliable depth data. In this case, a general warning will be issued, indicating that the data is unreliable.

[0053] Through the above technical solution, this application can significantly improve the accuracy and reliability of ship depth detection. By introducing track recording and continuity scoring mechanisms for potential echo chains, the system is no longer limited to instantaneous judgment based on a single detection, but can perform long-term, dynamic tracking and evaluation of underwater echo signals. This enables the system to more effectively identify and eliminate false echoes when facing complex underwater topography, underwater obstacles, or signal fluctuations, thereby avoiding misjudgments.

[0054] This application further proposes a more refined adjustment to the continuity score of potential echo chains to distinguish between interruptions of different durations, thereby improving the system's adaptability and robustness to changes in underwater signals.

[0055] Specifically, if the potential echo chain fails to maintain spatial continuity in the current period, the continuity score of the potential echo chain is reduced, including: Determine the duration for which the potential echo chain fails to maintain spatial continuity; If the duration is less than a preset instantaneous interruption threshold, the continuity score of the potential echo chain is slightly reduced. If the duration is not less than the instantaneous interruption threshold, the continuity score of the potential echo chain is significantly reduced.

[0056] The "duration of the potential echo chain failing to maintain spatial continuity" refers to the time interval from the last time the potential echo chain was successfully tracked to the current period when it failed to be tracked. This duration can be calculated based on the detection period and the number of consecutive periods that failed to be tracked. For example, if each detection period is 0.1 seconds and the potential echo chain fails to maintain spatial continuity for 3 consecutive periods, then the duration is 0.3 seconds.

[0057] The "instantaneous interruption threshold" is a preset time value used to distinguish between brief, acceptable signal interruptions and continuous signal interruptions that may indicate changes in the real environment. This threshold can be set according to the actual application scenario, the performance of the sonar equipment, and the complexity of the aquatic environment. For example, in calm waters, the instantaneous interruption threshold can be set smaller, while in complex waters or during high-speed navigation, the threshold can be appropriately increased to tolerate more instantaneous fluctuations. "Slight reduction" refers to a small reduction in the continuity score, such as lowering the score by a preset fixed value or attenuating it by a small percentage. Its purpose is to slightly penalize the reliability of the potential echo chain without completely negating its validity. "Significant reduction" refers to a larger reduction in the continuity score, such as lowering the score by a large fixed value, attenuating it by a large percentage, or even resetting the score to a lower level. Its purpose is to impose a more severe penalty on longer-lasting signal interruptions to quickly eliminate potential echo chains that may no longer represent the true underwater environment.

[0058] Through the above technical solution, this application can effectively improve the accuracy and stability of ship depth detection. Compared with simply reducing the continuity score, this solution avoids misjudgments caused by brief signal fluctuations by distinguishing between transient and continuous interruptions, thereby reducing unnecessary depth data suppression or warning messages and improving system availability. Simultaneously, for longer-lasting signal interruptions, it can promptly and significantly reduce their continuity score, accelerating the elimination of unreliable echo chains and ensuring a higher confidence level for the final confirmed true bottom echo, thus making the calculated true water depth more reliable. This is particularly important in complex aquatic environments or in the presence of transient interference, significantly enhancing the system's anti-interference capability and adaptability.

[0059] As a specific implementation, suppose a ship is navigating while its sonar system continuously tracks a potential echo chain. During a certain detection cycle, the signal of this potential echo chain is temporarily lost due to the sudden appearance of a clump of bubbles or a school of fish in the water, failing to maintain spatial continuity. The system first determines the duration of this interruption. If the interruption lasts only one detection cycle (e.g., 0.1 seconds), and the preset instantaneous interruption threshold is 0.5 seconds, then the duration is less than the instantaneous interruption threshold. In this case, the system will slightly decrease the continuity score of the potential echo chain, for example, from 90 points to 85 points. This means that the system considers this likely a transient interference, and the echo chain still has a high probability of being a genuine underwater echo. In the next cycle, if the echo chain is successfully tracked again, its score can be increased again based on subsequent performance.

[0060] For example, if the signal of a potential echo chain is lost for five consecutive detection cycles (e.g., 0.5 seconds), and the preset instantaneous interruption threshold is 0.2 seconds, then the duration is not less than the instantaneous interruption threshold. In this case, the system will significantly reduce the continuity score of the potential echo chain, for example, from 90 points to 30 points, or even lower. This indicates that the system considers the reliability of the echo chain to have significantly decreased and may no longer represent the actual seabed. This prompts the system to more quickly find and confirm other more reliable potential echo chains as the main echoes from the actual seabed, or, if no other high-confidence echo chains are available, to issue a timely warning of "unstable seabed signal, unreliable depth data" to avoid providing incorrect depth data. This differentiated processing allows the system to make more reasonable and intelligent responses to different degrees of signal interruption.

[0061] In some embodiments described above, when the continuity score of a potential echo chain is at a moderate level but has not reached the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, the system will issue a warning: "Local strong reflector detected, depth data uncertain." However, this warning may not effectively distinguish between a momentary local shallow spot and a persistent but still uncertain shallow water area, resulting in inaccurate warning information and difficulty in guiding vessels to perform refined hazard avoidance operations. If the above problems are not addressed, misjudgments or delays may occur in complex waters, affecting navigation safety.

[0062] In response, this application further proposes a more refined warning mechanism to identify and alert to momentary local shallow spots, thereby providing more targeted navigation safety information.

[0063] If a potential echo chain exists with a continuity score at a moderate level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, a warning will be issued: "Local strong reflector detected, depth data uncertain," as detailed below. The determination of whether the depth change rate of a potential echo chain is within a preset instantaneous shallowing threshold aims to assess the degree of sudden shallowing. The instantaneous shallowing threshold can be understood as the maximum permissible instantaneous rate of depth decrease, and its setting should take into account factors such as the ship's speed, the complexity of the water environment, and the detection frequency of the sonar system. For example, when the ship is traveling at a higher speed, the instantaneous shallowing threshold can be appropriately relaxed to avoid excessively frequent false alarms; while in low-speed or complex waters, this threshold can be tightened to improve sensitivity to potential hazards.

[0064] Simultaneously, the similarity between the waveform morphology of the potential echo chain and historical records is determined to be higher than a preset instantaneous fluctuation threshold. This is used to assess whether the characteristics of the echo signal differ significantly from normal underwater echoes. The instantaneous fluctuation threshold defines the acceptable range of waveform morphology similarity, aiming to distinguish echoes caused by changes in underwater topography from anomalous echoes caused by underwater obstacles or strong reflectors. For example, when the waveform morphology similarity is lower than this threshold, it may mean that the echo does not originate from the normal underwater environment but from a localized strong reflector.

[0065] If both of the above conditions are met simultaneously—that is, the rate of change in depth is within the instantaneous shallowing threshold and the waveform similarity is higher than the instantaneous fluctuation threshold—then the potential echo chain is marked as an instantaneous local shallow spot. An instantaneous local shallow spot refers to a shallow water point that appears locally within a short period of time and may be caused by underwater obstacles or special terrain. Its characteristic is that the depth suddenly becomes shallower, but this may not be sustained.

[0066] To further confirm the nature of transient local shallow points, the system initiates a short-term tracking window. This short-term tracking window is a preset time period during which the system continuously monitors the frequency and duration of occurrence of points marked as transient local shallow points. The frequency of occurrence refers to the number of times a transient local shallow point appears within the short-term tracking window, while the duration refers to the length of time a single transient local shallow point retains its characteristics.

[0067] This application refines the previously vague warning, "Local strong reflector detected, depth data uncertain," into a more detailed warning, "Temporary shallow spot ahead, please be cautious," accompanied by an intuitive flashing indicator. This allows operators to better understand the underwater situation, distinguish between transient obstacles and persistent shallow water areas, thereby avoiding unnecessary panic or delays and significantly improving the safety and decision-making efficiency of vessels navigating in complex waters.

[0068] In some preferred embodiments, a specific example is given below. Suppose a ship is sailing and its sonar system continuously acquires echo signals. At a certain moment, the system detects a potential echo chain with a moderate continuity score and an arrival time significantly shallower than the previously confirmed depth. According to the above scheme, the system first determines the depth change rate of the potential echo chain. If the change rate is within a preset instantaneous shallowing threshold (e.g., a depth drop exceeding 0.5 meters per second), and its waveform morphology has a similarity to historical records higher than a preset instantaneous fluctuation threshold (e.g., similarity greater than 0.8), then the potential echo chain is marked as an instantaneous local shallow point.

[0069] The system then initiates a short-term tracking window, lasting for, for example, 5 seconds. Within this window, the system continuously monitors the frequency and duration of the instantaneous local shallow spot. If the instantaneous local shallow spot appears 3 times within 5 seconds (exceeding a preset density threshold, such as 2 times), or if a single instantaneous local shallow spot lasts for 2 seconds (exceeding a preset short-term dwell time threshold, such as 1 second), the system will immediately issue a voice warning, "Instantaneous shallow spot ahead, please be careful," and the current depth data area on the ship's navigation display will flash red to alert the operator. In this way, the ship operator can quickly identify and respond to such instantaneous, localized shallow water situations, such as underwater floating objects or small reefs, thereby adjusting the course or slowing down in time and effectively avoiding potential collision risks.

[0070] In some embodiments described above, this application proposes monitoring the frequency and duration of instantaneous local shallow points within a short-term tracking window. However, in practical applications, relying solely on arrival time or preliminary waveform analysis may not be sufficient to completely distinguish between actual shallow points on the seabed and instantaneous reflection signals generated by other highly reflective bodies in the water (such as schools of fish, floating objects, etc.). Without further verification, this could lead to false alarms or misjudgments of the underwater topography, thereby affecting the safety of ship navigation and the accuracy of decision-making.

[0071] This application further proposes monitoring the frequency and duration of the occurrence of the instantaneous local shallow points within the short-time tracking window, including: Obtain the signal waveform characteristics of the instantaneous local shallow point; Analyze the energy distribution of the signal waveform characteristics to identify whether the energy distribution exhibits multi-peak or broadening phenomena. Based on historical sonar data of the ship's current navigation waters, determine whether the signal waveform characteristics are consistent with the underwater reflection waveform characteristics in the historical sonar data; If the energy distribution of the signal waveform features exhibits a single peak and narrow span, and the signal waveform features are consistent with the underwater reflection waveform features, then the instantaneous local shallow point is confirmed as a real underwater shallow point, and the frequency and duration of the instantaneous local shallow point are monitored.

[0072] Specifically, acquiring the signal waveform characteristics of the instantaneous local shallow point refers to digitally sampling and extracting features from the echo signal received by the sonar system and initially identified as an instantaneous local shallow point. This may include recording time-domain and frequency-domain information such as the amplitude, phase, and frequency of the echo signal to form complete waveform data.

[0073] The analysis of the energy distribution of the signal waveform characteristics, identifying whether the energy distribution exhibits multi-peak or broadening phenomena, aims to distinguish different types of reflection sources through waveform morphology analysis. For example, genuine underwater reflections typically exhibit concentrated energy, a single-peak waveform, and relatively narrow broadening, due to specular or diffuse reflection of sound waves at flat or regular underwater interfaces. Conversely, if the energy distribution exhibits multi-peak or broadening phenomena, it may indicate that the reflection source is not a single, regular underwater interface, but rather may be caused by multiple irregular scatterers (such as schools of fish, aquatic plants, floating objects, etc.) or complex water structures (such as bubbles, turbulence). The echo signals from these reflectors typically have more complex energy distributions and longer durations.

[0074] In practical applications, based on historical sonar data of the ship's current navigation area, it is determined whether the signal waveform characteristics are consistent with the underwater reflection waveform characteristics in the historical sonar data. The purpose is to verify the currently detected signal using prior knowledge. Historical sonar data may include known underwater topographic features, typical underwater reflection waveforms, and common water clutter characteristics of the area. By comparing the signal waveform characteristics of the current instantaneous local shallow point with this historical data, it is possible to more accurately determine whether the signal originates from the actual underwater environment. For example, correlation analysis, pattern recognition algorithms, or machine learning models can be used to evaluate the similarity between the current waveform and historical underwater reflection waveforms.

[0075] Therefore, if the energy distribution of the signal waveform features exhibits a single peak and narrow width, and the signal waveform features are consistent with the underwater reflection waveform features, then the instantaneous local shallow point is confirmed to be a real underwater shallow point. This means that after the rigorous verification of the above two steps, the instantaneous local shallow point is considered a reliable shallow point caused by the real underwater structure.

[0076] This application significantly improves the accuracy of instantaneous local shallow point identification and effectively reduces the false alarm rate. Compared to schemes based solely on arrival time or preliminary energy judgment, this application, by introducing energy distribution analysis of signal waveform characteristics and comparison with historical sonar data, can more accurately distinguish real shallow points on the seabed from other strong reflectors in the water. This allows ships to obtain more reliable depth data, avoiding unnecessary evasive actions due to false warnings, thereby improving navigation safety and efficiency. Furthermore, the accurate identification of real shallow points on the seabed also provides more precise basic data for subsequent channel planning and underwater topographic mapping.

[0077] This application further proposes monitoring the occurrence frequency and duration of the instantaneous local shallow points, including: Identify the arrival time, waveform start point, and waveform end point of the instantaneous local shallow point signal; Based on the arrival time, the waveform start point, and the waveform end point, a time and depth matrix is ​​constructed, and the instantaneous local shallow point is mapped to the time and depth matrix; Two-dimensional connected component analysis is performed on the time and depth matrix to identify shallow point clusters in the time and depth matrix; Calculate the center arrival time, average depth, and number of shallow points within each shallow point cluster.

[0078] Specifically, identifying the arrival time, waveform start point, and waveform end point of the instantaneous local shallow point signal means accurately determining the position of each echo signal identified as an instantaneous local shallow point on the time axis and its specific waveform boundaries. The arrival time refers to the time required for the sound wave to travel from transmission to reception, which is directly related to depth information; the waveform start point and waveform end point define the effective duration of the echo signal, which is helpful for subsequent waveform feature analysis and noise removal.

[0079] Specifically, constructing a time-depth matrix based on the arrival time, the waveform start point, and the waveform end point organizes discrete instantaneous local shallow point data into a two-dimensional data structure with spatiotemporal continuity. The horizontal axis of this matrix can represent time or detection period, and the vertical axis represents depth. Each instantaneous local shallow point is mapped to a corresponding position in the matrix according to its arrival time (converted to depth) and detection period.

[0080] In practical applications, performing two-dimensional connected component analysis on the time and depth matrix to identify shallow point clusters refers to using connected component algorithms in image processing or data analysis to find instantaneous local shallow points that are adjacent or related in time and depth within the time and depth matrix. These related points are considered a "cluster," representing the persistent shallow point characteristics within a specific time period and depth range. For example, four-connected or eight-connected algorithms can be used to determine whether adjacent pixels (representing instantaneous local shallow points) belong to the same connected component. Through this analysis, scattered noise points can be distinguished from real shallow points with a certain degree of persistence and spatial clustering.

[0081] Furthermore, calculating the center arrival time, average depth, and number of shallow points within each shallow point cluster provides a quantitative description of the identified clusters. The center arrival time represents the average position of the cluster over time; the average depth provides the typical depth of the shallow point region represented by the cluster; and the number of shallow points within the cluster reflects the persistence or intensity of the shallow point characteristic. These statistics provide a more stable and representative basis for subsequent judgments and warnings.

[0082] The above technical solution transforms scattered, instantaneous, localized shallow point data into structured and statistically significant shallow point cluster information, significantly improving the robustness and accuracy of underwater shallow point identification. This method effectively filters out transient noise and isolated strong reflectors, ensuring that the monitored shallow point information is more representative and reliable, thereby providing more accurate depth data and more timely safety warnings for ship navigation.

[0083] Reference Figure 2 This invention provides a schematic diagram of a ship water depth detection system, comprising: The detection end is used to acquire the echo signal sequence, which is captured by applying an energy threshold below the energy threshold. The processing end includes an identification module for identifying potential primary echoes in the echo signal sequence and obtaining the arrival time of the potential primary echoes; based on the arrival time, searching for potential secondary echoes in the echo signal sequence, and determining whether the potential primary echoes and the potential secondary echoes satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echoes is weaker than the energy of the potential secondary echoes; The output terminal is used to confirm that the potential main echo is the actual main echo at the bottom of the water if the conditions are met, and to calculate the actual water depth based on the arrival time of the actual main echo at the bottom of the water; if the conditions are not met, a specific warning message is issued.

[0084] It should be noted that the ship water depth detection system provided in this embodiment of the invention is used to execute all the process steps of the ship water depth detection method in the above embodiment. The working principle and beneficial effect of the two are one-to-one, so they will not be described again.

[0085] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without creative effort.

[0086] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for detecting the depth of a ship in water, characterized in that, The method includes: Acquire an echo signal sequence, which is captured by applying an energy threshold; Identify potential main echoes in the echo signal sequence and obtain the arrival time of the potential main echoes; Based on the arrival time, search for potential secondary echoes in the echo signal sequence, and determine whether the potential primary echo and the potential secondary echo satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echo is weaker than the energy of the potential secondary echo. If the conditions are met, the potential primary echo is confirmed as the actual primary echo at the bottom of the water, and the actual water depth is calculated based on the arrival time of the actual primary echo at the bottom of the water. If the conditions are not met, a specific warning message will be issued.

2. The method for detecting the depth of a ship in water as described in claim 1, characterized in that, The step of searching for potential secondary echoes in the echo signal sequence based on the arrival time, and determining whether the potential primary echo and the potential secondary echo satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echo is weaker than the energy of the potential secondary echo, includes: Search for the potential secondary and tertiary echoes in the echo signal sequence; Determine whether the potential primary echo, the potential secondary echo, and the potential tertiary echo satisfy a time multiple relationship and a specific energy relationship; The stability of the waveforms of the potential secondary echo and the potential tertiary echo is verified. If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship, the specific energy relationship, and the waveform morphology stability, then the potential primary echo is confirmed as the actual underwater primary echo.

3. The method for detecting the depth of a ship in water as described in claim 2, characterized in that, If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship, the specific energy relationship, and the waveform morphology stability, then the potential primary echo is confirmed as the actual underwater primary echo, including: Adjust the similarity threshold and the number of consecutive periods required for the waveform morphology stability verification based on the ship's speed and the rate of change of water depth. The waveform features of the continuously captured potential secondary echo and potential tertiary echo are smoothed to obtain smoothed waveform features. If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the smoothed waveform features satisfy the adjusted similarity threshold and the continuous period number requirement, then the potential primary echo is confirmed as the actual underwater primary echo.

4. The method for detecting the depth of a ship in water as described in claim 2, characterized in that, The stability verification of the waveform morphology of the potential secondary echo and the potential tertiary echo includes: Capture the waveform data of the potential secondary echo and the potential tertiary echo; The length of the processing time window for the waveform data is adjusted based on the water noise level and the instantaneous signal-to-noise ratio of the sonar signal. Within the processing time window, identify and remove outliers from the waveform data; The waveform data after removing outliers is locally averaged to obtain a smooth waveform. The similarity between the smoothed waveform and the reference waveform is calculated using the sliding window cross-correlation method. If the similarity remains above the threshold for multiple consecutive periods, the waveform is determined to be stable.

5. The method for detecting the depth of a ship in water as described in claim 3, characterized in that, If the potential primary echo, the potential secondary echo, and the potential tertiary echo stably satisfy the time multiple relationship and the specific energy relationship, and the smoothed waveform features satisfy the adjusted similarity threshold and the consecutive period number requirement, then confirming the potential primary echo as the true underwater primary echo includes: A track record is established for each potential echo chain that conforms to the time multiple relationship, the specific energy relationship, and the waveform morphology stability. The track record includes the arrival time of the chain, the ship's position, heading, and speed. The spatial continuity of each potential echo chain is continuously tracked within a continuous detection period, and the depth change rate of the potential echo chain is calculated. If the depth change rate is less than a preset change rate threshold, and the waveform characteristics of the potential echo chain are more similar to the historical waveform characteristics of the corresponding chain in the track record than the waveform threshold, then the continuity score of the potential echo chain is increased. If the potential echo chain fails to maintain spatial continuity in the current period, the continuity score of the potential echo chain is reduced. If the continuity score of the potential echo chain reaches a preset high confidence threshold, then the potential main echo is confirmed as the real main underwater echo. If multiple potential echo chains reach the high confidence threshold, the potential echo chain with the shortest arrival time is selected as the main actual underwater echo. If no potential echo chain reaches the high confidence threshold within the current detection period, then depth data output is suppressed; If there is a potential echo chain with a continuity score at a medium level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, a warning is issued: "Local strong reflector detected, depth data uncertain." If the continuity score of all potential echo chains is low, a warning is issued: "Unstable bottom signal, unreliable depth data".

6. The method for detecting the depth of a ship in water as described in claim 5, characterized in that, If the potential echo chain fails to maintain spatial continuity in the current period, the continuity score of the potential echo chain is reduced, including: Determine the duration for which the potential echo chain fails to maintain spatial continuity; If the duration is less than a preset instantaneous interruption threshold, the continuity score of the potential echo chain is slightly reduced. If the duration is not less than the instantaneous interruption threshold, the continuity score of the potential echo chain is significantly reduced.

7. The method for detecting the depth of a ship in water as described in claim 5, characterized in that, If a potential echo chain exists with a continuity score at a moderate level but not reaching the high confidence threshold, and its arrival time is significantly shallower than the previously confirmed depth, a warning is issued: "Local strong reflector detected, depth data uncertain," including: Determine whether the depth change rate of the potential echo chain is within the preset instantaneous shallowing threshold range; Determine whether the similarity between the waveform shape of the potential echo chain and the historical record is higher than a preset instantaneous fluctuation threshold; If the depth change rate is within the instantaneous shallowing threshold and the waveform morphology similarity is higher than the instantaneous fluctuation threshold, then the potential echo chain is marked as an instantaneous local shallow point. Start a short-term tracking window; Within the short-term tracking window, the frequency and duration of the occurrence of the instantaneous local shallow points are monitored; If the frequency of occurrence of the instantaneous local shallow spot exceeds a preset density threshold or the duration exceeds a preset short-term dwell threshold, a warning message "Instantaneous shallow spot ahead, please be careful" will be issued. The display interface will flash to indicate that there is a momentary local shallowing of the current depth data.

8. The method for detecting the depth of a ship in water as described in claim 7, characterized in that, Within the short-time tracking window, monitoring the frequency and duration of the occurrence of the instantaneous local shallow points includes: Obtain the signal waveform characteristics of the instantaneous local shallow point; Analyze the energy distribution of the signal waveform characteristics to identify whether the energy distribution exhibits multi-peak or broadening phenomena. Based on historical sonar data of the ship's current navigation waters, determine whether the signal waveform characteristics are consistent with the underwater reflection waveform characteristics in the historical sonar data; If the energy distribution of the signal waveform features exhibits a single peak and narrow span, and the signal waveform features are consistent with the underwater reflection waveform features, then the instantaneous local shallow point is confirmed as a real underwater shallow point, and the frequency and duration of the instantaneous local shallow point are monitored.

9. A method for detecting the depth of a ship in water as described in claim 7, characterized in that, The monitoring of the frequency and duration of the occurrence of the instantaneous local shallow points includes: Identify the arrival time, waveform start point, and waveform end point of the instantaneous local shallow point signal; Based on the arrival time, the waveform start point, and the waveform end point, a time and depth matrix is ​​constructed, and the instantaneous local shallow point is mapped to the time and depth matrix; Two-dimensional connected component analysis is performed on the time and depth matrix to identify shallow point clusters in the time and depth matrix; Calculate the center arrival time, average depth, and number of shallow points within each shallow point cluster.

10. A ship water depth detection system, characterized in that, The system includes: The detection end is used to acquire the echo signal sequence, which is captured by applying an energy threshold below the energy threshold. The processing end includes an identification module for identifying potential primary echoes in the echo signal sequence and obtaining the arrival time of the potential primary echoes; based on the arrival time, searching for potential secondary echoes in the echo signal sequence, and determining whether the potential primary echoes and the potential secondary echoes satisfy a time multiple relationship and a specific energy relationship, wherein the specific energy relationship is that the energy of the potential primary echoes is weaker than the energy of the potential secondary echoes; The output terminal is used to confirm that the potential main echo is the actual main echo at the bottom of the water if the conditions are met, and to calculate the actual water depth based on the arrival time of the actual main echo at the bottom of the water; if the conditions are not met, a specific warning message is issued.

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