An underwater beacon positioning system and method

Abstract

The application provides an underwater beacon positioning system and method, comprising an underwater beacon unit, an underwater acoustic baseline array, an overwater positioning unit and a display and control ground station; the underwater beacon unit is used for receiving an underwater acoustic inquiry signal and transmitting an underwater acoustic response signal carrying water depth information; the underwater acoustic baseline array comprises at least three array elements and is used for transmitting the underwater acoustic inquiry signal and synchronously receiving the underwater acoustic response signal; the overwater positioning unit is used for processing the underwater acoustic response signal and solving to obtain target coordinates; and the display and control ground station receives solving data of the overwater positioning unit and displays underwater target information. The application solves the defects of poor portability of underwater positioning equipment, high beacon power consumption and short endurance, uneven distribution of computing power, low refresh rate, slow target loss recovery and insufficient positioning accuracy of related technologies through integration of a folding lightweight baseline array, a low-power adaptive response beacon, a multi-processor distributed solving architecture, automatic gain adaptive threshold tracking recovery and water depth fusion three-dimensional positioning.

Description

Technical Field

[0001] This application belongs to the field of underwater acoustic positioning technology, and in particular relates to an underwater beacon positioning system and method. Background Technology

[0002] Underwater acoustic positioning is a core supporting technology for marine search and rescue, underwater operations, and underwater personnel rescue. Ultra-short baseline / short baseline underwater acoustic positioning relies on surface arrays to receive acoustic signals from underwater beacons and completes joint positioning through signal propagation time difference. It is widely used in scenarios such as searching for people who have fallen into the water, tracking AUVs / ROVs, and recovering underwater equipment. However, related underwater positioning equipment is mostly fixed and large-sized, with low system integration and poor portability. Underwater beacons have high standby current, continuously emit high-frequency underwater acoustic signals after falling into the water, have poor power consumption control, and insufficient endurance. Furthermore, the allocation of positioning computational power is unreasonable, the ability to autonomously track and recover after signal loss is weak, it cannot synchronously transmit its own depth data, the operational interaction is limited, and positioning errors are large. Summary of the Invention

[0003] In view of this, this application aims to propose an underwater beacon positioning system and method to at least solve one problem in the related art.

[0004] To achieve the above objectives, this application provides an underwater beacon positioning system, including an underwater beacon unit, an underwater acoustic baseline array, a surface positioning unit, and a display and control ground station. The underwater beacon unit receives underwater acoustic interrogation signals in a low-power listening state, and enters a response state after detecting an underwater acoustic interrogation signal that meets the valid interrogation conditions, acquiring its own water depth information and transmitting an underwater acoustic response signal carrying the water depth information. The underwater acoustic baseline array includes at least three array elements, used to transmit underwater acoustic interrogation signals and synchronously receive underwater acoustic response signals. The surface positioning unit processes the underwater acoustic response signals and, based on the time delay data of the at least three array elements and the water depth information,... The target coordinates are calculated using the spatial position information of the array elements of the underwater acoustic baseline array. The surface positioning unit is also used to determine the signal quality status of the current positioning period by weighting the signal quality indicators obtained in the current positioning period, and to switch between normal tracking state, weak signal state and reacquisition state according to the signal quality status, and to adjust the positioning detection parameters in different states. In the reacquisition state, the surface positioning unit adjusts the positioning detection parameters to reacquire the underwater acoustic response signal, and resumes normal tracking state after the preset signal quality recovery conditions are met simultaneously in multiple consecutive positioning periods. The display and control ground station receives the data calculated by the surface positioning unit and displays the underwater target information.

[0005] Furthermore, the surface positioning unit includes a first processing unit and a second processing unit. The first processing unit performs digital filtering, ping-pong buffering, normalized sliding correlation, and candidate correlation peak extraction on the synchronous sampling data of the array elements, and outputs the initial time delay estimate corresponding to each array element. The second processing unit includes a main processor and at least two slave processors, wherein the at least two slave processors are configured to receive the initial time delay estimate corresponding to one or more array elements in parallel, and perform subsampling time delay fine estimation to obtain the target time delay estimate corresponding to each array element. The main processor receives the target time delay estimate output by the slave processors and calculates the target coordinates of the underwater beacon by combining the water depth information and the spatial position information of the array elements.

[0006] Furthermore, the first processing unit synchronously acquires the signal data of the array elements through a multi-channel AD processor, performs bandpass filtering on the synchronously sampled data to obtain the target operating frequency data, and uses a ping-pong buffer mechanism to perform parallel read and write processing on the target operating frequency data.

[0007] The first processing unit performs sliding correlation operation on the buffered data of each array element to obtain the corresponding correlation sequence, and performs correlation sequence normalization processing in combination with signal energy. The normalized correlation sequence is then searched to obtain candidate correlation peaks and their corresponding sampling point positions.

[0008] The first processing unit filters valid candidate correlation peaks by the peak threshold, peak width range, and difference between primary and secondary peak values ​​of the candidate correlation peaks, generates corresponding peak confidence scores, determines the initial time delay estimate based on the sampling point position corresponding to the valid candidate correlation peak, and outputs the initial time delay estimate and the neighborhood waveform data of the valid candidate correlation peak to the slave processor.

[0009] Furthermore, the processor receives effective candidate correlation peak neighborhood waveform data from the processor in parallel, and performs fitting optimization on the correlation peak waveform based on the subsampling interpolation algorithm to obtain the subsampling offset. Combined with the initial time delay estimate, sampling frequency and pre-calibrated system fixed time delay compensation amount, the target time delay estimate is calculated, and the reliability index of the time delay result is generated simultaneously.

[0010] The main processor receives the target delay estimates and corresponding reliability indices output by each slave processor, and calculates the target coordinates of the underwater beacon by combining the position information and attitude information of the surface positioning unit, the array element installation and calibration parameters of the underwater acoustic baseline array, and the water depth information.

[0011] Furthermore, the main processor performs consistency verification on the latency data of each array element based on the target latency estimate and reliability index corresponding to each array element, and determines the contribution of each array element's latency data to the target coordinate solution process based on the reliability index; for array element latency data that does not meet the preset latency consistency condition or whose reliability is lower than the preset reliability threshold, its contribution to the target coordinate solution process is reduced or it is removed from the target coordinate solution of the current positioning cycle.

[0012] The main processor establishes target position constraints based on the array element delay data, water depth information, and array element spatial position information after consistency verification. It obtains the candidate target coordinates of the underwater beacon through iterative solution and determines the validity of the current positioning result based on the positioning residual corresponding to the candidate target coordinates. When the positioning residual does not meet the preset residual conditions, it reselects candidate correlation peak combinations or adjusts the array element delay data participating in the target coordinate calculation until the target coordinates that meet the preset residual conditions are obtained or the positioning of the current positioning cycle is determined to have failed.

[0013] Furthermore, the signal quality status of the current positioning cycle is determined comprehensively based on multiple normalized signal quality indicators. These indicators include at least two of the following: signal-to-noise ratio, peak difference between the main peak and secondary peak, consistency between the waveform in the neighborhood of the relevant peak and the reference correlation waveform, continuity of time delay between adjacent positioning cycles, and consistency of positioning residual. The surface positioning unit determines the current operating state as normal tracking, weak signal, or reacquisition based on the weighted result of the signal quality indicators, and applies different quality thresholds for entering and exiting the weak signal state to form hysteresis control.

[0014] If the signal quality status threshold is lower than the preset first threshold for a first number of consecutive cycles, the system enters a weak signal state; if the signal quality status threshold is higher than the preset second threshold for a second number of consecutive cycles, and the positioning residual meets the accuracy requirements, the system enters a normal tracking state; if there is no valid response signal or no valid positioning result within multiple preset third cycles, the system enters a reacquisition state; the preset first threshold is less than the preset second threshold.

[0015] Furthermore, the underwater beacon unit includes a sleep state, a listening state, a response state, and an anomaly handling state. In the sleep state, the underwater beacon unit shuts down the underwater acoustic transmitter amplifier and unnecessary receiving circuits. In the listening state, the receiving front end is turned on with a low duty cycle according to a preset listening cycle. After a valid interrogation is detected, the underwater acoustic transmitter amplifier is turned on to enter the response state. The listening cycle is adjusted according to the remaining power of the underwater beacon, and a high-power response is only initiated after a valid interrogation is confirmed. This reduces the average power consumption by controlling the duration of the receiving front end on, the duration of the response transmission, and the sleep state.

[0016] Furthermore, the positioning and detection parameters include receiver gain, correlation detection threshold, time delay search window, and underwater acoustic interrogation period.

[0017] Under normal tracking conditions, the surface positioning unit determines the delay search window for the current positioning cycle based on the target delay estimate obtained in the previous positioning cycle, and performs underwater acoustic response signal detection according to the first receiving gain, the first correlation detection threshold, and the first underwater acoustic interrogation cycle. When the signal quality status switches from normal tracking to weak signal status, the surface positioning unit performs at least one of the following actions: increasing the receiving gain, decreasing the correlation detection threshold, expanding the delay search window, and shortening the underwater acoustic interrogation cycle.

[0018] When the underwater acoustic response signal that meets the effective detection conditions or the positioning result that meets the preset positioning effectiveness conditions is not obtained in multiple consecutive positioning cycles, the underwater positioning unit switches to the reacquisition state and adjusts at least two of the following in a preset order: receiving gain, correlation detection threshold, time delay search window and underwater acoustic interrogation cycle, in order to expand the acquisition range of the underwater acoustic response signal.

[0019] After regaining the underwater acoustic response signal, the surface positioning unit recovers and confirms the correlation peak quality, inter-element time delay consistency, and positioning residual for multiple consecutive positioning cycles. After meeting the preset signal quality recovery conditions, the positioning detection parameters are gradually restored to the parameter range corresponding to the normal tracking state.

[0020] Furthermore, the underwater acoustic baseline array includes a central mounting component, at least three foldable array rods, and underwater acoustic transducers respectively disposed at the distal ends of the array rods. The underwater acoustic transducers constitute the array elements of the underwater acoustic baseline array. Each array rod is connected to the central mounting component through a hinged node. After the array rods are unfolded, a predetermined spatial position relationship of the array elements is formed. The central mounting component is provided with a clamping structure for fixing to the ship's side or shore-based support. A watertight cable channel is provided inside the array rods and is connected to the waterborne positioning unit through a watertight connector.

[0021] Furthermore, this application also provides an underwater beacon positioning method, applied to an underwater beacon positioning system, comprising: controlling an underwater acoustic baseline array to transmit underwater acoustic interrogation signals, and controlling an underwater beacon unit to detect underwater acoustic interrogation signals in a low-power listening state; after the underwater beacon unit detects an underwater acoustic interrogation signal that meets the valid interrogation conditions, controlling the underwater beacon unit to switch to a response state; wherein, the underwater beacon unit acquires its own water depth information and transmits an underwater acoustic response signal carrying the water depth information; synchronously receiving the underwater acoustic response signal using the underwater acoustic baseline array, performing synchronous sampling, digital filtering, and sliding correlation processing on the received signals of each array element to obtain candidate correlation peaks corresponding to each array element, and filtering valid candidate correlation peaks based on the peak value characteristics and waveform characteristics of the candidate correlation peaks; obtaining the corresponding candidate correlation peaks for each array element based on the valid candidate correlation peaks. The corresponding initial time delay estimation is used to perform subsampling time delay fine estimation on the neighborhood waveforms of the effective candidate correlation peaks, obtaining the target time delay estimate for each array element and a credibility index characterizing the reliability of the target time delay estimate; based on the target time delay estimate and credibility index for each array element, the time delay consistency between array elements is checked, and the target coordinates are calculated by combining the water depth information and the spatial position information of the array elements of the underwater acoustic baseline array, obtaining the target coordinates of the underwater beacon and the corresponding positioning residual; after each positioning cycle, at least one of the candidate correlation peak quality, target time delay estimate, positioning residual, and current signal quality status of that positioning cycle is used as feedback information for the next positioning cycle, and the positioning detection parameters for the next positioning cycle are determined using the feedback information; the target coordinates are sent to the display and control ground station for display.

[0022] This application also provides an electronic device, including: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the above-described underwater beacon positioning method.

[0023] This application also provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the above-described underwater beacon positioning method.

[0024] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described underwater beacon positioning method.

[0025] This application provides an underwater beacon positioning system that integrates a foldable lightweight array, a low-power adaptive response beacon, a multi-processor distributed computing architecture, automatic gain adaptive threshold tracking recovery, and water depth fusion three-dimensional positioning, achieving miniaturized and portable deployment, long-endurance underwater beacon, high-precision and high-refresh-rate positioning, and rapid autonomous relocking of the target after signal loss.

[0026] By employing low-power listening and on-demand response via underwater beacons, continuous high-power emission is avoided when there is no effective interrogation, thereby reducing average power consumption. Based on signal quality status, the receiver gain, detection threshold, search window, and interrogation period are adjusted according to the actual underwater acoustic environment, increasing the acquisition probability when the signal weakens and gradually backing down parameters after signal recovery to reduce parameter oscillations. Through depth-constrained weighted 3D positioning, the depth measured by the pressure sensor is directly incorporated into the position equation, rather than merely used as display information, and the influence of different array elements on the solution results is adjusted in conjunction with the array element signal quality. Through multi-processor hierarchical data flow, front-end related computations are separated from fine-grained delay and coordinate calculations, thereby reducing the load on a single processor. The folding, stretching, and clamping structure allows the underwater acoustic baseline array to quickly switch between transport and operating states, and array element geometric calibration ensures that the spatial relationships of the unfolded array elements can be used for positioning calculations. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0028] Figure 1 This is a schematic diagram illustrating the overall principle of the underwater beacon positioning system according to an embodiment of this application.

[0029] Figure 2 This is a schematic diagram of the underwater acoustic baseline array structure according to an embodiment of this application;

[0030] Figure 3 This is a three-dimensional structural diagram of the underwater beacon unit according to an embodiment of this application;

[0031] Figure 4 This is a general block diagram of the hardware system of the waterborne positioning unit according to an embodiment of this application;

[0032] Figure 5 This is a flowchart illustrating the underwater beacon positioning system according to an embodiment of this application.

[0033] Figure 6 This is a schematic diagram of an electronic device according to an embodiment of this application. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0035] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] Underwater acoustic positioning is a core supporting technology for marine search and rescue, underwater operations, and underwater personnel rescue. Radio signals attenuate extremely strongly in water, making it impossible to directly use GPS or BeiDou for underwater target positioning; inertial navigation suffers from positioning errors that accumulate over time, making it difficult to maintain high-precision positioning for extended periods. Therefore, underwater acoustic transponder positioning has become the mainstream solution for calculating the absolute position of underwater targets.

[0039] Ultra-short baseline / short baseline underwater acoustic positioning relies on a surface array to receive acoustic signals from underwater beacons and completes joint positioning through the signal propagation time difference. It is widely used in scenarios such as search and rescue of people who have fallen into the water, AUV / ROV tracking, and recovery of underwater equipment. Small search and rescue underwater positioning equipment consists of three main parts: an underwater beacon unit, a surface receiving and processing unit, and an underwater acoustic array.

[0040] Traditional short-baseline positioning arrays in related technologies are mostly fixed, large-sized structures that cannot be folded and stored. Their overall size and weight are significant, making rapid deployment on ships and shore-based systems difficult. The surface-based calculation unit, array, and host computer are separated into multiple independent waterproof connectors, resulting in fragmented equipment that is inefficient for single-person carrying and emergency search and rescue deployment. Similar equipment generally exceeds 600mm in folded size and weighs over 3kg, hindering rapid transport in emergency rescue. Conventional underwater beacons have high standby current and continuously emit high-frequency underwater acoustic signals after falling into the water, resulting in short lithium battery life. They lack adaptive interrogation and response mechanisms, emitting sound waves at fixed intervals regardless of the presence of search and rescue equipment on the surface, leading to rapid battery depletion in long-term idle scenarios. Furthermore, the lack of automatic gain control and adaptive detection threshold algorithms makes them prone to losing interrogation signals at long distances and in turbid waters, preventing the establishment of a response link.

[0041] Traditional solutions rely solely on a single DSP to complete all computations, including signal acquisition, related time delay estimation, coordinate calculation, and network transmission. This results in excessive computational load and a low position refresh rate. FPGAs only handle simple logic control and do not participate in underwater acoustic signal sliding correlation calculations, thus limiting the accuracy of time delay estimation. After a single signal loss, it takes a long time to rescan and recapture the target, leading to slow recovery speed after tracking loss and a positioning refresh rate of less than 2 times per second.

[0042] Existing systems, when underwater beacons are obstructed or underwater acoustic propagation losses increase, rely on fixed gain and detection thresholds, failing to adaptively improve signal detection sensitivity. When there is no response after a signal timeout, they simply repeat interrogation pulses without dynamically adjusting the receiving gain and detection threshold, making target loss and prolonged inability to re-lock onto the beacon highly likely, leading to a high risk of search and rescue interruption. Underwater beacons only transmit acoustic signals in one direction and cannot synchronously transmit their own depth data. The surface unit relies solely on slant range calculations for two-dimensional plane coordinates, without combining pressure sensor depth information for three-dimensional joint positioning, resulting in large positioning errors. Conventional equipment can only achieve a positioning accuracy of 5% or more of the slant range.

[0043] like Figure 1 As shown, the underwater beacon positioning system of this application embodiment includes an underwater beacon unit 1, an underwater acoustic baseline array 2, a surface positioning unit 3, and a display and control ground station.

[0044] The underwater beacon unit 1 is deployed with the target to be located or carried by personnel and worn underwater by people awaiting search and rescue. It is automatically triggered when it falls into the water. It can receive underwater acoustic interrogation signals and respond with sound carrying water depth data.

[0045] The underwater acoustic baseline array 2 is a foldable structure that can be deployed on a surface platform, ship's side, shore-based support, or other carrier that can stably submerge the array elements. It can be used to transmit underwater acoustic interrogation signals and receive underwater acoustic response signals. The underwater acoustic baseline array 2 is connected to the surface positioning unit 3 via a watertight cable. The surface positioning unit 3 is connected to the display and control ground station via Ethernet, serial bus, or other data interfaces.

[0046] The waterborne positioning unit 3 adopts an IPX7 waterproof sealing structure and has a built-in multi-processing hardware platform (such as FPGA + multi-DSP hardware platform) to complete signal conditioning, acquisition, time delay estimation, and three-dimensional coordinate calculation. The waterborne positioning unit can also receive GPS / BeiDou positioning information as well as heading, roll, and pitch information output by the compass and inertial measurement unit, which are used to uniformly convert the array element positions and target positions to the navigation coordinate system.

[0047] The search and rescue control ground station receives data calculated by the surface positioning unit via Ethernet and displays the geodetic coordinates, motion trajectory, and depth information of the underwater target.

[0048] In some embodiments, reference Figure 2 The baseline array adopts a three-pronged foldable split structure, with a folded storage size of 400×100×100mm and a fully unfolded size of 800×400mm. The entire unit weighs ≤2kg. The array pole is telescopic and detachable, with three omnidirectional underwater acoustic transducers evenly arranged at the underwater end. The baseline length is 400mm. A 10-pin waterproof and watertight connector is set on the top of the array, which connects to the waterborne positioning unit through a waterproof cable. The array supports 90-degree bending and fixing, and can be quickly clamped to the ship's side or shore railing for rapid deployment.

[0049] Therefore, the baseline array adopts a foldable three-pronged lightweight structure, which can be carried by a single person and quickly clamped to the ship's side or shore railing. It does not require large hoisting equipment and can be quickly deployed in emergency water rescue scenarios, solving the shortcomings of traditional equipment that are large in size and cumbersome to transport and deploy.

[0050] In some embodiments, reference Figure 3 The underwater beacon unit has a shell size of 100×60×35mm, a weight of ≤500g, a waterproof and pressure-resistant depth of 100m, and an ultimate pressure resistance of 200m. Internally, it features a low-power ARM main control board, a 35-45kHz omnidirectional underwater acoustic transducer, a miniature pressure sensor, and a 3.2-4.2V lithium battery power supply module. The circuit power supply characteristics include: standby current ≤10mA during water immersion detection; peak current during acoustic operation ≤500mA; average power consumption ≤60mW for a 5s transmission cycle and ≤40mW for a 10s transmission cycle. When the underwater beacon unit is not submerged, it is powered off and enters sleep mode; upon triggering a water immersion detection, it enters a low-power intermittent acoustic mode; upon receiving an underwater acoustic interrogation signal, it activates a full-power response mode, with the response pulse containing water depth data collected by the pressure sensor.

[0051] Therefore, the underwater beacon unit distinguishes between two operating modes: intermittent transmission during standby after falling into the water and full-power interrogation and response. Standby current and average power consumption are strictly controlled. When there is no surface search and rescue equipment, it only emits low-frequency intermittent sound, which greatly reduces power consumption.

[0052] In some embodiments, reference Figure 4The water positioning unit has a shell size of 150×100×25mm, IPX7 waterproof rating, and weighs ≤1kg. The panel integrates a power indicator, an Ethernet indicator, and a status indicator. It has three external interfaces: a 2-pin DC9-30V power socket, a 10-pin array interface, and a 100Mbps / 1Gbps compatible Ethernet interface. The silent power consumption is 400mW, and the average positioning power consumption is 10W. The internal hardware platform adopts a distributed architecture of FPGA + three DSPs. The FPGA integrates SRAM0 / SRAM1 cache and is responsible for 8-channel AD acquisition, digital bandpass filtering, coarse estimation of sliding correlation delay, serial port / GPS / compass logic control, and transmit power drive. DSP1 is the main processing chip, which receives GPS and compass attitude correction data, integrates beacon depth and propagation time difference of three array elements, calculates the target geodetic coordinates, and handles Ethernet network communication threads. DSP2 and DSP3 are slave processing chips, which receive coarse delay data from the FPGA, refine the delay estimation accuracy through interpolation algorithms, and upload the optimized delay data to DSP1 via the McBSP bus. Hardware expansion SDRAM and FLASH are used for DSP and FPGA data caching, respectively, and 100 Mbps Ethernet meets the upload rate of raw underwater acoustic data of more than 9.6 Mbps.

[0053] Therefore, underwater acoustic signal filtering and coarse correlation calculation are offloaded to the FPGA, and the two DSPs perform time delay interpolation optimization in parallel. The main DSP focuses on coordinate fusion calculation, avoiding the computing power bottleneck of a single DSP. Combined with the water depth feedback from the pressure sensor, three-dimensional joint positioning is achieved, which effectively improves the positioning accuracy and refresh rate.

[0054] refer to Figure 5The underwater beacon positioning system of this application includes the following workflow: (1) Search and rescue personnel board a ship carrying a baseline array and a surface positioning unit, unfold the folding array and fix it to the ship's side, and immerse it underwater; the surface unit is powered on and connected to the display and control ground station via network cable; (2) The underwater beacon worn by the person who fell into the water enters the water and automatically wakes up to enter a low-power intermittent listening state; (3) The search and rescue personnel issue a positioning start command through the display and control ground station, and the surface unit continuously transmits 35-45kHz interrogation LFM pulses and records the transmission time synchronously; (4) The underwater beacon detects the matching interrogation signal, collects its own water depth data, generates a response sound wave and transmits it outward; (5) The three underwater acoustic transducers of the baseline array receive the response signal and transmit it to the surface positioning unit F. The PGA completes AD acquisition, filtering, and sliding correlation coarse time delay estimation; (6) The FPGA distributes the preprocessed data to DSP2 and DSP3, and the two DSPs interpolate and optimize the time delay accuracy, and upload it to DSP1; (7) The main DSP1 reads GPS and compass shipborne attitude data, integrates the three-channel array element time difference and beacon water depth, and calculates the geodetic coordinates of the underwater target in three-dimensional joint positioning; (8) The calculated coordinates, depth, slant range, and track data are transmitted to the display and control ground station via Ethernet, and the interface draws the target trajectory in real time; If no response signal is returned within the preset response waiting time (such as 0.4s), the surface unit automatically lowers the detection threshold, increases the receiving gain, and repeatedly transmits the interrogation pulse until the beacon signal is recaptured, and continues to cycle the positioning.

[0055] The underwater beacon positioning system of this application features an integrated waterproof design, making it highly adaptable to various environments. The surface positioning unit is IPX7 waterproof, and all external interfaces use standard watertight connectors. The pressure-resistant housing of the underwater beacon is suitable for deep-water search and rescue scenarios. The system has a unified interface, simple wiring, and stable operation in high-humidity and splash-prone marine environments, with low maintenance difficulty. Furthermore, the positioning system is highly versatile and adaptable to various search and rescue scenarios. It can be used for emergency search and rescue of people who have fallen into the water, and can also be used for tracking and positioning small underwater robots, underwater sensors, and seabed equipment. It is compatible with both shore-based fixed deployment and mobile search and rescue operations from ships. The standardized Ethernet interface can connect to various ruggedized display and control terminals, offering strong expandability.

[0056] In this embodiment, the surface positioning unit controls the underwater acoustic baseline array to transmit underwater acoustic interrogation signals and records the reference time of the interrogation transmission. The underwater beacon unit detects the interrogation signals only during low-power listening periods. After confirming the validity of the interrogation, it reads the water depth information and sends an underwater acoustic response signal carrying the water depth information. At least three elements of the underwater acoustic baseline array synchronously receive the underwater acoustic response signals. The surface positioning unit obtains the candidate correlation peaks, target delay estimates, and confidence indices for each element, and combines the water depth information, element spatial location information, and element installation calibration parameters to complete the target coordinate calculation. After the positioning cycle ends, the system uses the correlation peak quality, signal-to-noise ratio, inter-element delay consistency, and positioning residual of that cycle to update the positioning detection parameters for the next positioning cycle, thereby forming a closed loop across positioning cycles.

[0057] The following explanation uses three receiving array elements as an example. When the number of array elements is four or more, synchronous sampling channels and delay constraints can be added in the same way, and redundant array elements can be used to perform abnormal array element removal, weighted positioning, or fault tolerance. The specific chip models, frequencies, sizes, and thresholds mentioned in the embodiments of this application are only used to illustrate one possible implementation and do not constitute a limitation on the scope of protection.

[0058] In some embodiments, the underwater acoustic baseline array includes a central mounting member, at least three foldable array rods, and underwater acoustic transducers respectively disposed at the distal ends of each array rod, with each transducer constituting an element of the underwater acoustic baseline array. Each array rod is connected to the central mounting member via a hinged joint, which is equipped with an unfolding limiting structure and a locking structure, allowing the array rod to repeatedly reach a predetermined mechanical position after unfolding from its folded position. The central mounting member is equipped with a clamping structure that can be fixed to a ship's side, shore railing, or temporary support frame. A watertight cable channel is formed inside the array rod, with the element cables led along the inside of the array rod to a top watertight connector, and then connected to a surface positioning unit via the watertight connector. The unfolding limiting structure ensures the repeatability of the array element coordinates after each unfolding, thereby reducing the workload of on-site recalibration.

[0059] During factory calibration or field calibration, an array coordinate system B is established using the mechanical reference point of the underwater acoustic baseline array, and the nominal position vectors of the array elements in the array coordinate system are recorded. To eliminate the inherent hardware delay error of the underwater acoustic acquisition channels, calibration signals are sent using sound sources at known locations, and the arrival times measured for each channel are compared with the theoretical arrival times to obtain the fixed receiving delay compensation for each channel.

[0060] The element installation calibration parameters of the underwater acoustic baseline array include the core static correction parameters required for array operation, including at least the element position correction, the fixed reception delay compensation for each channel, and the installation offset angle of the array relative to the reference coordinate system of the waterborne carrier. Among them, the element position correction is used to compensate for the element position deviation caused by mechanical installation tolerances; the installation offset angle is used to correct the fixed installation angle error between the array and the carrier body coordinate system, ensuring the accuracy of coordinate transformation.

[0061] In actual system operation, the system combines the position information output by the surface positioning unit and the attitude information output by the attitude sensing unit to complete the real-time three-dimensional position calculation of each array element in the navigation coordinate system. This scheme uses the navigation coordinate system N as a unified reference coordinate system, where the real-time position vector of the surface platform reference point in the navigation coordinate system N is: The direction cosine matrix for transformation from array coordinate system B to navigation coordinate system N is: Then the real-time three-dimensional position vector of the i-th (i≥1) array element in the navigation coordinate system N Solve using the following formula:

[0062]

[0063] Among them, R can be obtained by GPS / BeiDou positioning module; It can be calculated by combining the bow angle, roll angle, pitch angle of the water platform with the array installation skew angle, and is used to achieve attitude alignment from the local coordinate system of the array to the geographic navigation coordinate system; The coordinates of the i-th array element are after factory calibration and error correction during on-site installation.

[0064] In some embodiments, the GPS / BeiDou positioning data, platform attitude data, and underwater acoustic sampling data collected during system operation are independently acquired multi-source heterogeneous data. The different acquisition and update frequencies of these data types, and directly using positioning and attitude parameters from different times to calculate array element positions, introduce timing errors, affecting the accuracy of sound source positioning. Therefore, this application embodiment employs a timestamp interpolation synchronization method to achieve data timing alignment. All positioning data, attitude data, and acoustic sampling data are equipped with high-precision timestamps. Using the sampling time of the underwater acoustic signal as a reference, platform position data and attitude data from adjacent times before and after that sampling time are extracted. A linear interpolation algorithm is used to solve for the precise platform position and attitude parameters corresponding to the instant of acoustic sampling. These parameters are then substituted into the array element position calculation formula to complete the calculation, effectively eliminating system errors caused by the asynchronous timing of multi-source data and ensuring the overall accuracy of array position calculation and underwater acoustic signal processing.

[0065] In some embodiments, the underwater beacon unit includes a pressure sensor. The pressure sensor is connected to the external water pressure and is used to detect the ambient pressure at the location of the underwater beacon. The underwater beacon unit is configured with at least a sleep state, a listening state, a response state, and an anomaly handling state. In the sleep state, the underwater acoustic transmitter power amplifier and unnecessary receiving circuitry are turned off, and only the water ingress detection, low-power clock, and wake-up logic remain operational. The water ingress detection can employ liquid continuity detection, pressure surge detection, or a combination of both, and can require that the water ingress criterion be met for multiple consecutive sampling windows before switching to the listening state, in order to reduce false wake-ups caused by water droplets, salt spray, or transient continuity.

[0066] When the underwater beacon unit is in listening mode, the underwater beacon periodically activates the underwater acoustic receiving front-end according to a preset listening cycle. If no valid interrogation is detected within the receiving window, the receiving front-end is turned off and returns to low-power wait mode; when a valid interrogation is detected, the controller keeps the receiving link active and activates the pressure sensor and transmit power amplifier, entering the response state. After the response is completed, if the hardware and data self-tests are normal, it returns to the listening state; if a buffer overflow, invalid pressure sensor, power supply abnormality, or software timeout is detected, it enters the exception handling state, performs module reset, parameter reloading, or system reinitialization before returning to the listening state.

[0067] In some embodiments, the monitoring period can be adjusted in stages based on the remaining battery charge (SOC). For example, a shorter monitoring period is used when the SOC is above a first charge threshold, a medium monitoring period is used when the SOC is between the first and second charge thresholds, and a longer monitoring period is used when the SOC is below the second charge threshold. To ensure that queries can still be captured under low duty cycle monitoring conditions, the surface positioning unit can continuously send a query sequence covering at least one monitoring period during the initial acquisition or reacquisition phase; after tracking is established, the next monitoring and response period can be predicted based on the response time of the previous positioning period.

[0068] In some embodiments, upon detecting a valid interrogation, the underwater beacon unit uses a pressure sensor to measure the absolute pressure at its current location and determines water depth information based on the pressure difference between the surface reference pressure and the absolute pressure at the current location. The surface reference pressure can be atmospheric pressure collected before the underwater beacon enters the water, or real-time surface pressure collected by a surface pressure sensor and transmitted to the underwater beacon unit during system deployment. The water density can be a pre-set freshwater density or seawater density, or it can be corrected based on temperature and salinity measurements.

[0069] It should be noted that water depth information can also be obtained using methods based on hydrostatic pressure conversion, such as pre-calibrated pressure-water depth relationships, piecewise linear lookup tables, interpolation, or sensor internal compensation algorithms. For pressure data, conventional methods such as moving average, median filtering, amplitude limiting filtering, or low-pass filtering can be used for smoothing, as long as water depth information representing the depth of the underwater beacon's location can be obtained.

[0070] As an example, a pressure sensor can acquire pressure data at a sampling frequency of 10-100 Hz, calculate the average value after removing the maximum and minimum values ​​from the most recent 5-20 pressure samples, and convert the average value into water depth. The water depth information can be quantized and encoded at a resolution of 0.1 m, 0.05 m, or other preset resolutions and then incorporated into the signal frame of the underwater acoustic response signal.

[0071] In some embodiments, the underwater acoustic interrogation signal uses a linear frequency modulated (LFM) signal to balance correlation processing gain and narrowband interference immunity. As one implementation, the acoustic operating frequency band of the interrogation and response signals can be located in the 35-45 kHz range, or other frequency bands can be used depending on the bandwidth and operating distance of the underwater acoustic transducer.

[0072] In some embodiments, the underwater beacon unit pre-stores a reference template corresponding to the interrogation waveform. After receiving the discrete signal, the receiving front end first performs working band filtering, and then performs sliding correlation. Valid interrogation conditions include at least two or more of the following: the correlation peak exceeds the current detection threshold, the correlation peak width is within a preset peak width range, the main peak and the secondary peak have a preset difference, and the consistency between the waveform in the vicinity of the correlation peak and the reference correlation waveform meets preset conditions. High-power response is only initiated when the valid interrogation conditions are met, thereby avoiding unnecessary transmissions triggered by noise and occasional interference.

[0073] In some embodiments, the underwater acoustic response signal can adopt a composite frame structure of "range synchronization segment + data segment". The range synchronization segment uses a known LFM or other recognizable waveform to accurately extract the arrival time of the surface positioning unit; the data segment carries the underwater beacon identifier, quantized and encoded water depth information, frame number, and check field, and can be modulated using FSK, PSK, differential phase shift keying, or segmented LFM. The water depth field can be encoded at a fixed quantization resolution, for example, forming an integer depth code with 0.1m as the quantization unit; the water depth information is recovered after the receiver verifies the signal.

[0074] In some embodiments, the surface positioning unit includes a first processing unit and a second processing unit. The first processing unit performs digital filtering, ping-pong buffering, normalized sliding correlation, and candidate correlation peak extraction on the synchronously sampled data of array elements, and outputs the initial time delay estimate corresponding to each array element. The second processing unit includes a master processor and at least two slave processors, wherein the at least two slave processors are configured to receive the initial time delay estimate corresponding to one or more array elements in parallel, and perform subsampling time delay fine estimation to obtain the target time delay estimate corresponding to each array element. The master processor receives the target time delay estimate output by the slave processors and calculates the target coordinates of the underwater beacon by combining the water depth information and the spatial position information of the array elements.

[0075] It should be noted that the initial time delay estimation can be obtained using sampling point position conversion methods in related technologies. For example, the initial arrival time of the candidate correlation peak relative to the unified reception time reference can be determined based on the integer sampling point position corresponding to the candidate correlation peak, the synchronous sampling frequency, and the start time of the current sampling data block. The unified reception time reference can be the start time of the sampling frame, the start time of the data block, the interrogation signal transmission reference time, or the system clock provided by the waterborne positioning unit, as long as all array elements use the same time reference and the arrival time difference between array elements can be calculated.

[0076] In some embodiments, the first processing unit may be implemented using an FPGA, and the main processor and slave processor of the second processing unit may be DSPs, CPUs, or other digital processors. As a hardware implementation, the first processing unit uses an FPGA connected to a multi-channel 16-bit analog-to-digital converter. Three or more array element channels share the same sampling clock and the same frame trigger signal, thereby ensuring consistent sampling time bases among array elements. The sampling frequency is significantly higher than the highest frequency of the operating signal; for example, when the operating frequency band is 35-45kHz, a sampling frequency of 510kHz can be used.

[0077] The first processing unit performs digital bandpass filtering on each synchronously sampled data stream to remove low-frequency flow noise, ship mechanical vibration, and high-frequency electrical noise outside the operating frequency band. The digital filter can adopt an FIR structure, and its coefficients are stored in on-chip ROM. The filtered data enters two buffers, A and B: when buffer A is written to the current data block by the AD channel, the data in buffer B is read by the relevant arithmetic module; the read and write roles of the two buffers are swapped in the next data block, thereby realizing parallel sampling and arithmetic and avoiding sampling interruptions caused by processing time.

[0078] In some embodiments, let the discrete sampled data of the i-th (i≥1) array element after filtering be... The locally stored reference response synchronization template is If the template length is L, then the sliding correlation value at the candidate sampling position m is... Calculate according to the following formula:

[0079]

[0080] To reduce the impact of changes in received amplitude, received gain, and underwater acoustic propagation attenuation on the detection threshold, energy normalization is performed on the sliding correlation calculation results. The normalized correlation value... The expression is as follows:

[0081]

[0082]

[0083]

[0084] In the above formula, This represents the sliding correlation value of the i-th array element at sampling position m; The correlation value after energy normalization; The received signal energy within the current sliding data window; The energy of the reference template itself; It is a regularization constant greater than zero, used to prevent the denominator from approaching zero and causing numerical anomalies under low signal energy conditions. Its dimensions are similar to... Maintain consistency.

[0085] It should be noted that the above sliding correlation expression applies to cases where both the filtered sampled data and the reference response synchronization template are real-valued sequences. If the first processing unit converts the received signal into a complex baseband signal or an analytic signal, complex conjugate correlation processing in correlation techniques can be used, i.e., using the complex conjugate sequence of the reference template in the correlation operation. The reference template can maintain its original amplitude or can be pre-processed with mean removal, energy normalization, or amplitude normalization; the received data can also undergo DC removal processing before the correlation operation. The goal is to ensure that the position of the correlation peak reflects the arrival position of the underwater acoustic response synchronization segment.

[0086] It should be noted that the regularization constant It is a small number greater than zero, and its dimensions are consistent with the square root of the energy product in the denominator of the normalized related formula. Fixed empirical values ​​can be used, or the values ​​can be determined according to a preset ratio based on the quantization noise of the analog-to-digital converter, the noise energy during periods without signal, or the energy of the reference template. When the energy of the current sliding data window is lower than the preset minimum energy threshold, the normalized correlation calculation at that position can be skipped directly, or the corresponding normalized correlation value can be set to a preset low value, as long as numerical anomalies and invalid candidate peaks under low energy conditions can be avoided.

[0087] The first processing unit processes the normalized correlation sequence. The search process identifies local maxima and retains only candidate correlation peaks that are within a preset time delay search window and whose correlation peak value is higher than the correlation detection threshold. For each candidate correlation peak, at least the peak value, peak width, sampling point location, local noise estimate, and neighborhood waveform data are recorded. The peak width is defined as the number of consecutive sampling points whose correlation value is greater than a preset proportion of the peak value; the difference between primary and secondary peak values ​​is defined as the difference or ratio between the highest and second highest peak values ​​within the same time delay search window.

[0088] It should be noted that the estimated local noise value can be determined based on the correlation sequence outside the neighborhood of the candidate correlation peak, the correlation value after excluding the main peak within the search window, or data collected during periods without response. The local signal-to-noise ratio can be determined using conventional methods such as the ratio of peak power to average noise power, the ratio of peak neighborhood energy to noise window energy, or the ratio of correlation peak value to noise root mean square value. The consistency between the waveform in the neighborhood of the correlation peak and the reference correlation waveform can be evaluated using conventional methods such as correlation coefficient, cosine similarity, normalized cross-correlation, mean square error, or mean absolute error, as long as it can distinguish between the true response correlation peak and noise peak or multipath peak.

[0089] Candidate correlation peaks are jointly screened using multiple conditions, including: peak value greater than or equal to a detection threshold; peak width between minimum and maximum peak width; difference between the main peak and secondary peaks not less than a preset difference value; and similarity between the neighboring waveform and the reference correlation waveform not less than a waveform similarity threshold. Candidate peaks that meet all conditions are marked as valid candidate correlation peaks. The first processing unit obtains an initial time delay estimate based on the sampling point position m corresponding to the valid candidate correlation peak, and outputs the initial time delay estimate, neighboring waveform data, and peak confidence to at least two slave processors of the second processing unit.

[0090] In some embodiments, the peak confidence score is used to characterize the credibility of the actual underwater acoustic response signal corresponding to the candidate correlation peak. It can be calculated by multiple components, including the normalized correlation peak value, the difference between primary and secondary peaks, the degree of peak width deviation from the theoretical value, and the local signal-to-noise ratio. After normalizing each component, a weighted fusion is performed to obtain the peak confidence score. It should be noted that this peak confidence score is mainly used for candidate peak ranking, weight allocation in back-end positioning operations, and removal of abnormal pseudo-peaks. The specific weight combination is not limited and can be adjusted and configured according to actual working conditions.

[0091] It should be noted that peak confidence can be obtained using methods such as weighted summation, weighted averaging, hierarchical assignment, threshold counting, table lookup mapping, or fuzzy comprehensive evaluation. Specifically, a higher evaluation value can be assigned when the normalized correlation peak is larger, the difference between the main peak and secondary peaks is greater, the local signal-to-noise ratio is higher, and the waveform consistency is higher; conversely, a lower evaluation value can be assigned when the peak width deviates more from the reference peak width. Each evaluation component can be mapped to a unified value range before fusion, as long as it can characterize the credibility of the candidate correlation peak corresponding to the real underwater acoustic response signal.

[0092] In some embodiments, the second processing unit receives initial delay estimates and effective candidate correlation peak neighborhood waveforms from one or more array elements in parallel from the processor. Since the initial delay estimate output by the first processing unit uses integer sampling points as the smallest unit, there is a time quantization error of at most one sampling period, which cannot meet the requirements of high-precision delay measurement. Therefore, this embodiment performs subsampling interpolation calculation based on candidate peak neighborhood waveform data to achieve fine-grained correction of delay accuracy.

[0093] In some embodiments, a three-point parabolic interpolation algorithm is used to solve for the subsampling offset. This is done for the integer sampling point position of the candidate peak corresponding to the i-th array element. Extract the normalized correlation values ​​corresponding to the previous, current, and next positions of the sampling point, respectively, and denot them as follows: , , The subsampling offset is calculated using the following formula. :

[0094]

[0095] In the formula, For the i-th element candidate peak relative to integer sampling points The subsampling offset, under normal effective signal conditions. The absolute value of the denominator is no greater than 0.5. To ensure the stability of the interpolation results, a preset stability threshold for the denominator is established. When the absolute value of the denominator in the above formula is less than this threshold, it is determined that the waveform of the relevant peak is too flat or severely affected by noise, and the parabolic interpolation result is invalid. In this case, a forced reset can be performed. This reduces the reliability of the corresponding delay results, or it switches to a high-precision interpolation algorithm such as local sinc interpolation or cubic interpolation to complete the subsampling correction.

[0096] After obtaining the subsampling offset, the accurate signal arrival time is calculated by combining the system's synchronous sampling frequency and channel calibration parameters. The subsampling offset is converted into a time deviation, and the fixed delay compensation amount pre-calibrated for the i-th receiving channel is subtracted to eliminate the inherent delay error of the hardware link. Finally, the estimated arrival time of the target signal of the i-th array element is obtained with reference to a unified receiving time base.

[0097] In some embodiments, to further improve the anti-interference capability and accuracy stability of the positioning solution, a time delay reliability index is generated synchronously for the time delay estimation results of each array element. . Using a normalized quantization method, the closer the value is to 1, the higher the reliability of the time delay estimation result. The time delay reliability index is calculated by comprehensively considering multiple dimensions of features, mainly including the correlation peak confidence, subsampling fitting residual, local signal-to-noise ratio, and the time delay continuity characteristics of adjacent positioning cycles.

[0098] It should be noted that the time delay reliability index can be obtained using methods such as weighted summation, weighted averaging, hierarchical assignment, table lookup mapping, threshold judgment, or fuzzy comprehensive evaluation. Higher peak confidence, higher local signal-to-noise ratio, smaller subsampling fitting residuals, and smaller deviations between the current time delay and historical predicted time delays can be set as higher time delay reliability. If a certain evaluation component cannot be obtained, it can be removed from the current fusion process and the weights of the remaining components can be reallocated, or a preset neutral value can be assigned, as long as it can characterize the reliability of the target arrival time estimation result.

[0099] The system's main processor relies on latency reliability metrics to perform data filtering and weight allocation. Low-quality latency data below the preset confidence threshold can be reduced in terms of its computational weight in the positioning calculation, or it can be directly removed from the coordinate calculation dataset of the current positioning cycle. This can effectively suppress latency calculation errors caused by noise and abnormal waveforms, and ensure the accuracy and stability of the overall sound source positioning results.

[0100] It should be noted that the positioning weights can be determined using conventional methods such as hierarchical assignment, linear mapping, nonlinear mapping, normalized weighting, inverse variance weighting, or lookup table mapping, based on the latency confidence level. For example, the latency confidence level can be divided into high confidence, medium confidence, and low confidence intervals, and positioning weights can be configured for each interval from high to low. Alternatively, the normalized latency confidence level can be directly used as the initial positioning weights, and then the positioning weights participating in the current positioning calculation can be normalized.

[0101] In some embodiments, the main processor establishes target position constraints based on the array element delay data after consistency verification, water depth information, and array element spatial position information. It obtains candidate target coordinates of the underwater beacon through iterative solution and determines the validity of the current positioning result based on the positioning residual corresponding to the candidate target coordinates. When the positioning residual does not meet the preset residual conditions, it reselects candidate correlation peak combinations or adjusts the array element delay data participating in the target coordinate calculation until the target coordinates that meet the preset residual conditions are obtained or the positioning of the current positioning cycle is determined to have failed.

[0102] This embodiment employs a joint positioning mode combining inter-element arrival time difference with water depth constraints. This avoids interference from common time delay components such as the surface transmission propagation delay of interrogation signals and the fixed internal response delay of underwater beacons on positioning accuracy, and eliminates system bias caused by global fixed time delay. The first element is selected as the reference element. Let the total number of effective elements participating in this positioning calculation be M, satisfying M≥3. For the i-th element (i=2,3,…,M), calculate the relative time delay difference between elements after channel delay correction:

[0103]

[0104] In the formula, Let be the arrival time of the underwater acoustic response signal of the i-th array element. Let be the time difference between the arrival of the underwater acoustic response signal between the i-th array element and the reference array element. Under the condition that each receiving channel shares a synchronous sampling clock and completes fixed channel delay correction, common time terms such as the beacon response transmission time can be eliminated by subtracting between array elements.

[0105] A local North-East-Earth rectangular coordinate system is used as the reference coordinate system for positioning and calculation. The water surface reference plane is defined as the z=0 plane, with the vertical downward direction as the positive z-axis. Let the three-dimensional position vector of the underwater beacon to be solved be... The precise position of the i-th element in the navigation coordinate system is: The effective underwater acoustic propagation speed of the system is The difference in sound propagation distance between array elements and the difference in time delay satisfy the following theoretical constraint relationship:

[0106]

[0107] Simultaneously, the system collects underwater beacon depth data h in real time through a pressure sensor, forming a high-precision depth constraint. Considering multiple sources of error, including time delay measurement noise, residual errors from array element installation and calibration, and pressure sensor measurement errors, this embodiment constructs a weighted least-squares positioning objective function. The optimal target coordinates are then solved through iterative optimization. The objective function expression is:

[0108]

[0109] In the formula, To locate and solve the objective function; The positioning weight of the i-th array element is determined jointly by the latency confidence of the current array element and the latency confidence of the reference array element. Higher latency data corresponds to higher solution weight. The z-axis coordinates of the underwater beacon to be solved; The depth constraint weights can be determined based on the pressure depth measurement variance and the distance difference measurement variance converted from the time delay measurement variance. The time delay measurement variance is converted into the distance difference measurement variance through the effective propagation speed of underwater acoustics, thus balancing the fitting accuracy of the time delay difference constraint and the depth constraint. For effective underwater sound propagation speed, preset fixed values ​​can be used when water temperature and salinity environmental parameters are stable. When the system is equipped with a temperature and salinity sensor or a sound velocity profile module, environmental parameters can be updated in real time and dynamically corrected. This enhances adaptability to complex water conditions.

[0110] It should be noted that the positioning weight and depth constraint weight can be determined through known location sound source calibration, historical positioning data statistics, measurement variance estimation, or simulation experiments, or fixed empirical values ​​can be used. The effective underwater acoustic propagation speed can be a preset fixed sound speed, or it can be corrected based on water temperature, salinity, pressure, or sound speed profile data using conventional methods such as empirical sound speed relationships, table lookup interpolation, layered averaging, or on-site acoustic calibration.

[0111] The main processor uses the position directly below the underwater acoustic baseline array, the predicted position from the previous positioning cycle, or the coarse geometric solution as initial values ​​for iteration. It then employs the Gauss-Newton algorithm, the damped Gauss-Newton algorithm, or the Levenberg-Marquardt algorithm to iteratively find the minimum value of the objective function. For example, using the damped Gauss-Newton algorithm, a weighted residual vector composed of the distance difference residual and the depth residual is constructed. Solve for the Jacobian matrix H of the residual vector with respect to the target position. The formula for updating in a single iteration is as follows:

[0112]

[0113] in, This is the estimated beacon position value for the k-th iteration; This is the position correction amount for a single iteration; is a damping coefficient greater than 0, used to suppress iterative divergence and improve iterative stability; I is the identity matrix.

[0114] It should be noted that the residual vector can be composed of the weighted distance difference residuals corresponding to each effective matrix element and the water depth constraint residuals. The distance difference residuals can be scaled according to the corresponding positioning weights, and the water depth constraint residuals can be scaled according to the depth constraint weights. The Jacobian matrix can be obtained analytically or numerically using finite difference methods, as long as it remains consistent with the residual vector and the positioning objective function used.

[0115] In some embodiments, a dual-iteration convergence criterion is set: when the iteration position correction amount If the objective function change is less than the preset convergence threshold, or the change in objective function between two adjacent iterations is less than the preset convergence threshold, the iteration is considered converged and the optimal position solution is output. If the convergence condition is not met even after the number of iterations reaches the preset maximum number of iterations, the current candidate peak combination solution is considered invalid, marked as a low-confidence result, and other candidate peak combinations are switched to solve again.

[0116] In some embodiments, after iterative convergence, the positioning accuracy residual index of the current positioning cycle is calculated based on the optimal position solution, and the root mean square of the distance difference residual of each array element is used as the positioning residual.

[0117] It should be noted that the positioning residual can also be determined using methods such as weighted sum of squares, weighted absolute value, mean square error, weighted root mean square error, maximum absolute error, or median absolute deviation, and can also be further evaluated by combining the deviation between the candidate target depth and water depth information. Preset residual conditions can be set using a single threshold, tiered thresholds, or relative thresholds. The threshold can be determined through known location sound source calibration, historical positioning data statistics, simulation experiments, or based on sampling frequency, array element baseline length, and target positioning accuracy requirements.

[0118] In some embodiments, due to multipath interference caused by reflections from the sea surface, seabed, ship hull, and shoreline, the correlation detection sequence of a single array element can generate multiple local peaks, easily leading to false delays and false positioning solutions. To suppress multipath interference, the first processing unit of the underwater beacon positioning system of this application retains multiple valid candidate correlation peaks for each array element within the delay search window. The main processor performs cross-array element candidate peak combination screening and physical consistency verification. The candidate peak combinations that pass the initial screening of physical consistency are substituted into the least squares objective function to complete the iterative solution and calculate the corresponding positioning residuals. For multiple sets of valid candidate combinations that can converge, a comprehensive cost function is constructed to complete the optimal solution screening, comprehensively integrating positioning accuracy, delay reliability, peak quality, and other multi-dimensional indicators. The system selects the combination with the minimum comprehensive cost that meets the requirements of water depth range, maximum effective distance, and number of effective array elements as the final positioning output result for the current period.

[0119] If an instruction manual is required, the comprehensive cost function can be constructed based on one or more of the following: positioning residual, array element delay reliability, candidate correlation peak quality, candidate target depth rationality, candidate target effective range, and effective array element quantity. The comprehensive cost function can be calculated using methods such as weighted summation, weighted average, weighted sum of squares, weighted absolute value, weighted least squares, root mean square error, hierarchical scoring, or fuzzy comprehensive evaluation.

[0120] If the positioning residual of the current optimal solution still exceeds the preset threshold, the system activates an adaptive fault-tolerance mechanism: it prioritizes switching to other candidate peak combinations and resolving; if no candidate combinations are available, it reduces the solution weight of low-confidence array elements according to the reliability weight of each array element's delay, or directly removes low-confidence array elements when the number of effective array elements meets the minimum solution requirement, and iterates again to solve the problem. If the number of remaining effective array elements after removing abnormal data is insufficient to meet the minimum number of array elements in the positioning model, the positioning for the current positioning cycle is determined to have failed.

[0121] In some embodiments, the signal quality status of the current positioning period is based on multiple normalized... Signal The quality indicators are determined comprehensively. Signal Quality indicators include at least two of the following: signal-to-noise ratio, peak value difference between the main peak and secondary peaks, consistency between the waveform in the neighborhood of the correlated peak and the reference correlated waveform, continuity of time delay between adjacent positioning cycles, and consistency of positioning residuals. The waterborne positioning unit is based on... Signal The weighted result of the quality indicators determines the current operating state as normal tracking, weak signal, or reacquisition. Different quality thresholds are used for entering and exiting the weak signal state to form hysteresis control. Specifically, normal tracking is characterized by obtaining valid response signals and high-precision positioning results for multiple consecutive cycles; weak signal is characterized by normal response detection and positioning calculation, but with a significant decrease in overall signal quality and accuracy; and reacquisition is characterized by no valid response signals or no valid positioning results for multiple consecutive cycles.

[0122] In some embodiments, to avoid frequent jittering and oscillation switching of the state near the threshold, this application employs a hysteresis threshold control mechanism, setting differentiated thresholds for entering / exiting the weak signal state. Let the entry into the weak signal state... Signal quality state Threshold is Restored to normal tracking status Signal quality state Threshold is And satisfy > The state switching rules are as follows: when the overall quality is continuous... The period is lower than When the system switches from normal tracking state to weak signal state, it continuously... The cycle is higher than Furthermore, the system can only recover from a weak signal state to a normal tracking state when the positioning residual meets the accuracy requirements; if continuous If no valid response or location result is obtained within a certain number of cycles, the system enters the reacquisition state. , , All values ​​are integers not less than 1, and can be adaptively configured according to the system refresh rate and false detection tolerance. For example, in one embodiment, it can be set to... It is 0.45. It is 0.65; For 2, 3. The value is 3.

[0123] It should be noted that the number of consecutive cycles, the state entry threshold, and the state exit threshold can be determined through historical data statistics, experiments with sound sources at known locations, or on-site debugging. The number of consecutive cycles used to enter the weak signal state, enter the reacquisition state, and resume normal tracking state can be the same or set separately; different values ​​for the state entry threshold and the state exit threshold can form hysteresis intervals.

[0124] In some embodiments, the positioning detection parameters include receiver gain, correlation detection threshold, time delay search window, and underwater acoustic interrogation period. The system can adaptively and hierarchically adjust the positioning detection parameters according to the operating state, achieving adaptive control for weak signal enhancement detection, strong signal stable tracking, and rapid reacquisition after lock-on loss.

[0125] Under normal tracking conditions, the system estimates the target delay of the previous cycle and predicts the arrival time of the signal in the current cycle by linear extrapolation. A narrow range of normal search half-windows is set on both sides of the prediction time to significantly reduce the amount of related computation, while suppressing noise spurious peak interference outside the window, thus ensuring tracking accuracy and real-time performance.

[0126] When the system switches from normal tracking to weak signal state, a detection capability enhancement strategy is activated, performing at least one or more of the following graded adjustments: increasing receiver gain, lowering the relevant detection threshold, expanding the delay search window, and shortening the underwater acoustic interrogation cycle. After the system enters reacquisition state, the detection parameters are iteratively adjusted according to a preset priority, preferably by first expanding the delay search window, then increasing receiver gain, lowering the detection threshold, and shortening the interrogation cycle, thereby progressively improving the weak signal acquisition capability.

[0127] It should be noted that the receiving gain can be adjusted using conventional methods such as fixed step adjustment, hierarchical lookup table adjustment, or automatic gain control; the relevant detection threshold can be determined using methods such as a fixed threshold, a noise mean multiple threshold, a noise standard deviation threshold, or a constant false alarm rate threshold; the center of the time delay search window can be determined based on the results of the previous positioning cycle, historical averages, linear extrapolation values, or motion state prediction values; the underwater acoustic interrogation cycle can be a fixed cycle or a hierarchical cycle that matches the underwater beacon monitoring cycle. Each parameter can be set with its own allowable upper and lower limits and levels.

[0128] Once the system recaptures a valid underwater acoustic response signal, it does not immediately restore normal parameters. Instead, it enters a hysteresis recovery confirmation phase, continuing the weak signal state determination logic. For several consecutive positioning cycles, the following conditions must be met simultaneously: the correlation peak quality is higher than the recovery threshold, the array element delay difference meets the physical consistency constraint, and the positioning residual is lower than the accuracy threshold, before the signal can be considered to have stably recovered. Subsequently, with an adjustment step size smaller than that of the recapture phase, the gain is gradually reduced, the detection threshold is raised, the search window is narrowed, and the query cycle is extended, slowly restoring the system to the normal tracking parameter range. Thus, through this adaptive parameter adjustment strategy, frequent state oscillations and switching can be avoided, improving the system's operational stability.

[0129] In some embodiments, after completing the calculation for each positioning cycle, the system stores key information such as the candidate peak quality parameters, target delay estimation, positioning residual, and signal operating status of the current cycle into the cycle status register. Before the start of the next cycle, the main processor reads historical status data and adaptively updates the search window center, window width, receiver gain, detection threshold, and query cycle of the current cycle, realizing closed-loop adaptive control between successive cycles and forming an intelligent tracking and acquisition mechanism based on historical status.

[0130] In one specific application, the search and rescue vessel is equipped with an underwater acoustic baseline array, a surface positioning unit, and a display and control ground station. Before use, the three foldable array rods are unfolded to their limit positions and fixed to the ship's side by the clamping structure of the central mounting component, ensuring that all three underwater acoustic transducers are submerged in water. The surface positioning unit loads the array element spatial coordinates, channel fixed delay compensation, initial receiving gain, relevant detection thresholds, search window, and interrogation cycle. The display and control ground station establishes a data connection with the surface positioning unit and reads the ship's positioning and attitude data.

[0131] The person who falls into the water wears an underwater beacon. After entering the water, the beacon enters a low-power listening state from a dormant state. The surface positioning unit controls the underwater acoustic baseline array to transmit interrogation signals. The underwater beacon performs working frequency band filtering and interrogation template correlation within the listening window. When the interrogation signal simultaneously meets the valid interrogation conditions such as relevant peak threshold, peak width, and template consistency, the water depth is calculated from the pressure sensor, and an underwater acoustic response frame carrying the beacon identifier and water depth information is constructed.

[0132] The synchronization segment of the underwater acoustic response frame is received synchronously by at least three array elements. The first processing unit performs normalized sliding correlation to obtain candidate correlation peaks for each array element; valid candidate correlation peaks are selected based on peak threshold, peak width, difference between primary and secondary peaks, and waveform consistency. At least two slave processors complete fine estimation of subsampling delay and generate delay reliability indices. The main processor calculates the delay difference between array elements, performs a physical consistency check first, then obtains the coordinates of candidate targets and calculates the positioning residual.

[0133] When the target coordinates for the current positioning cycle meet the preset validity conditions, the surface positioning unit sends the target coordinates, water depth, current positioning quality, and selectable slant range and track information to the display and control ground station. The display and control ground station can display the target position on a map or local coordinate interface and generate a motion track using continuous positioning results.

[0134] Embodiments of this application also provide an electronic device, including: a memory for storing a computer program; and a processor for executing the computer program to perform the following steps:

[0135] The underwater acoustic baseline array is controlled to transmit an underwater acoustic interrogation signal, and the underwater beacon unit is controlled to detect the underwater acoustic interrogation signal in a low-power listening state; after the underwater beacon unit detects an underwater acoustic interrogation signal that meets the valid interrogation conditions, the underwater beacon unit is controlled to switch to the response state; wherein, the underwater beacon unit acquires its own water depth information and transmits an underwater acoustic response signal carrying the water depth information.

[0136] The underwater acoustic response signal is received synchronously using an underwater acoustic baseline array. The received signals of each array element are synchronously sampled, digitally filtered, and subjected to sliding correlation processing to obtain candidate correlation peaks corresponding to each array element. Valid candidate correlation peaks are then selected based on the peak value characteristics and waveform characteristics of the candidate correlation peaks.

[0137] Based on the effective candidate correlation peaks, the initial time delay estimates corresponding to each array element are obtained. Subsampling time delay fine estimation is performed on the neighborhood waveforms of the effective candidate correlation peaks to obtain the target time delay estimates corresponding to each array element and the reliability index characterizing the reliability of the target time delay estimates.

[0138] Based on the target delay estimation and reliability index corresponding to each array element, the delay consistency between array elements is verified, and the target coordinates are calculated by combining the water depth information and the spatial position information of the array elements of the underwater acoustic baseline array, so as to obtain the target coordinates of the underwater beacon and the corresponding positioning residual.

[0139] At the end of each positioning cycle, at least one of the following—candidate correlation peak quality, target delay estimate, positioning residual, and current signal quality status—is used as feedback information for the next positioning cycle. This feedback information is then used to determine the positioning detection parameters for the next positioning cycle. The target coordinates are then sent to the display and control ground station for display.

[0140] like Figure 6 As shown, the electronic device may include one or more processors 102 (processor 102 may include, but is not limited to, a processing system such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data. In one exemplary embodiment, the electronic device may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 6 The structure shown is for illustrative purposes only and does not limit the structure of the electronic device described above. For example, the electronic device may also include components that are more... Figure 6 The more or fewer components shown, or having the same Figure 6 Equivalent functions or ratios shown Figure 6 The functions shown have more different configurations.

[0141] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the underwater beacon positioning method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thus implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage systems, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102. Examples of the above-described networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0142] The transmission device 106 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by a communication provider for the computer terminal. In one example, the transmission system device includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet.

[0143] Embodiments of this application also provide a computer-readable storage medium storing a computer program configured to execute the steps described in the above-described embodiment of an underwater beacon positioning method when running.

[0144] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0145] Specific examples in this embodiment can be found in the examples described in the above embodiments and exemplary implementations, and will not be repeated here.

[0146] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing systems. They can be centralized on a single computing system or distributed across a network of multiple computing systems. Optionally, they can be implemented using program code executable by a computing system, thereby storing them in a storage system for execution by the computing system. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0147] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An underwater beacon positioning system, characterized in that: Includes underwater beacon units, underwater acoustic baseline arrays, surface positioning units, and display and control ground stations; The underwater beacon unit is used to receive underwater acoustic interrogation signals in a low-power listening state, and enters a response state after detecting an underwater acoustic interrogation signal that meets the valid interrogation conditions, obtains its own water depth information and transmits an underwater acoustic response signal carrying the water depth information. The underwater acoustic baseline array includes at least three array elements for transmitting the underwater acoustic interrogation signal and synchronously receiving the underwater acoustic response signal; The underwater positioning unit is used to process the underwater acoustic response signal and calculate the target coordinates based on the time delay data of the at least three array elements, the water depth information, and the spatial position information of the array elements of the underwater acoustic baseline array. The waterborne positioning unit is also used to determine the signal quality state of the current positioning period by weighting the signal quality indicators obtained in the current positioning period, and to switch between normal tracking state, weak signal state and reacquisition state according to the signal quality state, and to adjust the positioning detection parameters in different states; the positioning detection parameters include receiver gain, correlation detection threshold, time delay search window and underwater acoustic interrogation period; the signal quality indicators include at least two of the following: signal-to-noise ratio, peak value difference between the main peak and the secondary peak, consistency between the waveform in the neighborhood of the correlation peak and the reference correlation waveform, time delay continuity between adjacent positioning periods, and consistency of positioning residual; The waterborne positioning unit adjusts the positioning detection parameters in the re-acquisition state to re-acquire the underwater acoustic response signal, and resumes normal tracking state after the preset signal quality recovery condition is met simultaneously for multiple consecutive positioning cycles. The ground station receives the data calculated by the surface positioning unit and displays the underwater target information.

2. The underwater beacon positioning system according to claim 1, characterized in that: The waterborne positioning unit includes a first processing unit and a second processing unit. The first processing unit performs digital filtering, ping-pong buffering, normalized sliding correlation, and candidate correlation peak extraction on the synchronous sampling data of the array elements, and outputs the initial time delay estimate corresponding to each array element. The second processing unit includes a main processor and at least two slave processors, wherein the at least two slave processors are configured to receive the initial time delay estimate corresponding to one or more array elements in parallel, and perform subsampling time delay fine estimation to obtain the target time delay estimate corresponding to each array element. The main processor receives the target time delay estimate output by the slave processors and calculates the target coordinates of the underwater beacon by combining the water depth information and the spatial position information of the array elements.

3. The underwater beacon positioning system according to claim 2, characterized in that: The first processing unit synchronously acquires the signal data of the array element through a multi-channel AD processor, performs bandpass filtering on the synchronously sampled data to obtain the target operating frequency data, and uses a ping-pong buffer mechanism to perform parallel read and write processing on the target operating frequency data. The first processing unit performs sliding correlation operation on the buffered data of each array element to obtain the corresponding correlation sequence, and completes the correlation sequence normalization processing in combination with signal energy. The normalized correlation sequence is then searched to obtain candidate correlation peaks and their corresponding sampling point positions. The first processing unit filters valid candidate correlation peaks by the peak threshold, peak width range, and difference between primary and secondary peak values ​​of the candidate correlation peaks, generates corresponding peak confidence, determines the initial time delay estimate based on the sampling point position corresponding to the valid candidate correlation peak, and outputs the initial time delay estimate and the neighborhood waveform data of the valid candidate correlation peak to the slave processor.

4. The underwater beacon positioning system according to claim 3, characterized in that: The processor receives the effective candidate correlation peak neighborhood waveform data of the array element in parallel, performs fitting optimization on the correlation peak waveform based on the subsampling interpolation algorithm, solves for the subsampling offset, and calculates the target delay estimate by combining the initial delay estimate, sampling frequency and pre-calibrated system fixed delay compensation amount, and simultaneously generates a reliability index of the delay result. The main processor receives the target delay estimates and corresponding reliability indices output by each slave processor, and calculates the target coordinates of the underwater beacon by combining the position information and attitude information of the surface positioning unit, the array element installation and calibration parameters of the underwater acoustic baseline array, and the water depth information.

5. An underwater beacon positioning system according to claim 4, characterized in that: The main processor performs consistency verification on the delay data of each array element based on the target delay estimate and reliability index corresponding to each array element, and determines the contribution of the delay data of each array element in the target coordinate solution process based on the reliability index; for array element delay data that does not meet the preset delay consistency condition or whose reliability is lower than the preset reliability threshold, its contribution in the target coordinate solution process is reduced or it is removed from the target coordinate solution of the current positioning cycle. The main processor establishes target position constraints based on the array element delay data, water depth information, and array element spatial position information after consistency verification. It obtains the candidate target coordinates of the underwater beacon through iterative solution and determines the validity of the current positioning result based on the positioning residual corresponding to the candidate target coordinates. When the positioning residual does not meet the preset residual condition, the candidate correlation peak combination is reselected or the array element delay data participating in the target coordinate calculation is adjusted until the target coordinates that meet the preset residual condition are obtained or the current positioning cycle is determined to have failed.

6. The underwater beacon positioning system according to claim 1, characterized in that: The waterborne positioning unit determines its current operating state as normal tracking, weak signal, or reacquisition based on the weighted result of the signal quality indicators. It uses different signal quality thresholds for entering and exiting the weak signal state to form hysteresis control. Specifically, if the signal quality threshold is lower than a preset first threshold for a first set number of consecutive cycles, it enters the weak signal state; if the signal quality threshold is higher than a preset second threshold for a second set number of consecutive cycles, and the positioning residual meets the accuracy requirements, it enters the normal tracking state; if there is no valid response signal or no valid positioning result for multiple preset third cycles, it enters the reacquisition state. The preset first threshold is less than the preset second threshold.

7. The underwater beacon positioning system according to claim 1, characterized in that: The underwater beacon unit includes a dormant state, a listening state, a response state, and an anomaly handling state; The underwater beacon unit shuts down the underwater acoustic transmitter amplifier and unnecessary receiving circuits in the sleep state. In the listening state, it turns on the receiving front end with a low duty cycle according to a preset listening period. After detecting a valid query, it turns on the underwater acoustic transmitter amplifier to enter the response state. The listening period is adjusted according to the remaining power of the underwater beacon, and a high-power response is only initiated after a valid query is confirmed. This reduces the average power consumption by controlling the duration of the receiving front end on, the duration of the response transmission, and the sleep period.

8. An underwater beacon positioning system according to claim 1, characterized in that: Under normal tracking conditions, the surface positioning unit determines the delay search window for the current positioning cycle based on the target delay estimate obtained in the previous positioning cycle, and performs underwater acoustic response signal detection according to the first receiving gain, the first correlation detection threshold, and the first underwater acoustic interrogation cycle. When the signal quality state switches from normal tracking state to weak signal state, the surface positioning unit performs at least one of the following actions: increasing the receiving gain, decreasing the correlation detection threshold, expanding the delay search window, and shortening the underwater acoustic interrogation cycle. When the underwater acoustic response signal that meets the effective detection conditions or the positioning result that meets the preset positioning effectiveness conditions is not obtained in multiple consecutive positioning cycles, the underwater positioning unit switches to the reacquisition state and performs graded adjustments on at least two of the receiving gain, the relevant detection threshold, the time delay search window and the underwater acoustic interrogation cycle according to the preset adjustment order, so as to expand the acquisition range of the underwater acoustic response signal. After regaining the underwater acoustic response signal, the underwater positioning unit recovers and confirms the correlation peak quality, inter-element delay consistency, and positioning residual for multiple consecutive positioning cycles. After meeting the preset signal quality recovery conditions, the positioning detection parameters are gradually restored to the parameter range corresponding to the normal tracking state.

9. An underwater beacon positioning system according to claim 1, characterized in that: The underwater acoustic baseline array includes a central mounting component, at least three foldable array rods, and underwater acoustic transducers respectively disposed at the distal ends of the array rods. The underwater acoustic transducers constitute the array elements of the underwater acoustic baseline array. Each array rod is connected to the central mounting component through a hinged node. After the array rods are unfolded, they form a predetermined spatial position relationship of the array elements. The central mounting component is provided with a clamping structure for fixing to the ship's side or shore-based support. The array rods are provided with watertight cable channels and are connected to the surface positioning unit through watertight connectors.

10. An underwater beacon positioning method, applied to the underwater beacon positioning system of claim 1, characterized in that, include: Control the underwater acoustic baseline array to transmit underwater acoustic interrogation signals, and control the underwater beacon unit to detect the underwater acoustic interrogation signals in a listening state; After the underwater beacon unit detects an underwater acoustic interrogation signal that meets the valid interrogation conditions, it controls the underwater beacon unit to switch to the response state; wherein, the underwater beacon unit acquires its own water depth information and transmits an underwater acoustic response signal carrying the water depth information; The underwater acoustic response signal is received synchronously using an underwater acoustic baseline array. The received signals of each array element are synchronously sampled, digitally filtered, and subjected to sliding correlation processing to obtain the candidate correlation peaks corresponding to each array element. Valid candidate correlation peaks are then selected based on the peak value characteristics and waveform characteristics of the candidate correlation peaks. Based on the effective candidate correlation peaks, the initial time delay estimate corresponding to each array element is obtained. Subsampling time delay fine estimation is performed on the neighborhood waveform of the effective candidate correlation peaks to obtain the target time delay estimate corresponding to each array element and the credibility index characterizing the reliability of the target time delay estimate. Based on the target delay estimation and reliability index corresponding to each array element, the delay consistency between array elements is verified, and the target coordinates are calculated by combining the water depth information and the array element spatial position information of the underwater acoustic baseline array to obtain the target coordinates of the underwater beacon and the corresponding positioning residual. After each positioning cycle ends, at least one of the following is used as feedback information for the next positioning cycle: candidate correlation peak quality, target delay estimate, positioning residual, and current signal quality status. The positioning detection parameters for the next positioning cycle are then determined using the feedback information. The target coordinates are sent to the display and control ground station for display.

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