An underwater acoustic positioning system and an underwater acoustic positioning method

Abstract

The underwater acoustic positioning system comprises a center node, a transmitting node group, and a receiving node group. The transmitting node group comprises at least three transmitting nodes which are separately arranged and are connected with each other and the center node. The receiving node group comprises at least one receiving node which is connected with one transmitting node and the center node. The underwater acoustic positioning system and method can complete self-positioning by transmitting a first acoustic signal through the transmitting node group, and the center node can calculate accurate coordinates of each transmitting node based on a time difference data set. The receiving node can calculate a target position in combination with the coordinate information and a time difference data set related to an underwater target, so as to effectively offset the interference caused by a complex marine environment and guarantee the positioning accuracy. When some nodes fail, the non-failed nodes can still maintain the basic signal transmitting, receiving and data transmission functions.

Description

Technical Field

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

[0002] In deep-sea scientific exploration, the precise positioning of detector units is crucial for reconstructing the path of the target. Due to environmental factors such as deep-sea current disturbances, electromagnetic waves are severely attenuated in water, making long-distance information transmission impossible. Sound waves then become the only effective carrier for long-distance information transmission in the deep sea.

[0003] Currently, although positioning technologies such as ultra-short baseline and long baseline based on acoustic signal time delay measurement can achieve centimeter-level accuracy, they still have two major drawbacks: First, the multipath effect and sound velocity error caused by the complex marine environment seriously affect the accuracy of time delay measurement; second, the existing system hardware architecture is not adaptable to the high-pressure environment of the deep sea, and the system reliability and fault tolerance are insufficient. Once some nodes fail, the entire positioning mission often fails. Summary of the Invention

[0004] This disclosure provides an underwater acoustic positioning system and an underwater acoustic positioning method to at least solve the above-mentioned technical problems existing in the prior art.

[0005] A first aspect of this disclosure provides an underwater acoustic positioning system, comprising:

[0006] Central node;

[0007] A group of transmitting nodes includes at least three separately deployed, interconnected transmitting nodes, each of which is connected to the central node; and

[0008] A receiving node group includes at least one receiving node, each of the at least one receiving node being connected to a corresponding transmitting node and communicating with the central node;

[0009] The transmitting node group is used to transmit a first acoustic signal to obtain a time difference dataset;

[0010] The central node is used to calculate the coordinate information of each of the transmitting nodes in the transmitting node group based on the time difference dataset, and send the coordinate information to the corresponding receiving node;

[0011] The receiving node group is used to receive the second acoustic signal from the transmitting node group to obtain a time difference of arrival dataset related to the underwater target, and to calculate the spatial position of the underwater target based on the time difference of arrival dataset and the coordinate information;

[0012] The central node and each of the transmitting nodes are connected by a watertight connector to form a support structure;

[0013] The receiving node is movably connected to one of the transmitting nodes via a watertight connector, allowing the receiving node to swing freely relative to the transmitting node.

[0014] In one possible implementation, the central node includes a control module, a timing module, a power management module, and a communication module;

[0015] The control module is electrically connected to the timing module, the power management module and the communication module respectively, and is used to coordinate and control the timing module, the power management module and the communication module;

[0016] The communication module is used to interact with the transmitting node group and the receiving node group.

[0017] In one embodiment, the central node further includes a housing, and the control module, the timing module, and the power management module are integrated inside the housing;

[0018] The bottom of the housing is provided with a power supply port, a communication port and a hub port, and the communication module is located on the top of the housing.

[0019] In one embodiment, the hub port is connected to a sound velocity measuring device and / or a flow velocity measuring device and / or a temperature, salinity, and pressure measuring device, and the control module is configured to acquire sound velocity data and / or flow velocity data and / or temperature, salinity, and pressure data in real time through the hub port.

[0020] In one possible implementation, the timing module includes a high-precision atomic clock or a cable synchronization timing unit, used to provide a unified time reference to the underwater acoustic positioning system.

[0021] In one embodiment, the transmitting node includes a transmitting module, which includes a power amplifier circuit, a matched filter circuit, and a transceiver conversion circuit.

[0022] In one embodiment, the receiving node includes a receiving module, which includes a preamplifier circuit, a bandpass filter circuit, a time-varying gain control amplifier circuit, and an analog-to-digital converter circuit connected in sequence.

[0023] A second aspect of this disclosure provides an underwater acoustic positioning method applied to the underwater acoustic positioning system described in any of the above-described embodiments, the method comprising:

[0024] The transmitting node group transmits the first acoustic signal to acquire the time difference dataset;

[0025] The central node calculates the coordinate information of each transmitting node in the transmitting node group based on the time difference dataset, and sends the coordinate information to the corresponding receiving node;

[0026] The transmitting node group transmits a second acoustic signal;

[0027] The receiving node group receives the second acoustic signal and obtains a time difference of arrival dataset related to the underwater target;

[0028] The receiving node group calculates the spatial location of the underwater target based on the time difference of arrival dataset and the coordinate information.

[0029] In one possible implementation, the transmitting node group transmits a first acoustic signal to acquire a time difference dataset, including:

[0030] Each of the aforementioned transmitting nodes transmits a first acoustic signal according to a preset timing sequence;

[0031] The first sound signal transmitted each time is received by the central node and the other transmitting nodes in the transmitting node group except the current transmitting node, and their respective arrival times are recorded.

[0032] Based on the arrival time, calculate the first time difference data between each of the transmitting nodes and the central node, and the second time difference data between each of the transmitting nodes;

[0033] The first time difference data and the second time difference data constitute the time difference dataset.

[0034] This disclosed underwater acoustic positioning system achieves self-localization by transmitting a first acoustic signal through a group of transmitting nodes. The central node calculates the precise coordinates of each transmitting node based on a time difference dataset. The receiving node then combines this coordinate information with a time difference dataset related to the underwater target to calculate the target's position. This effectively counteracts the interference of multipath effects and sound velocity errors caused by the complex marine environment, ensuring positioning accuracy. The transmitting nodes in the group are interconnected, and each receiving node establishes a connection with the transmitting nodes and communicates with the central node, providing node redundancy and independent operation capabilities. When some nodes fail, the remaining nodes can still maintain basic signal transmission, reception, and data transmission functions, preventing the entire positioning task from failing due to the failure of a single point or some nodes, thus improving the system's adaptability to the complex, high-pressure environment of the deep sea.

[0035] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0036] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0037] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0038] Figure 1 This illustration shows the overall structure of an underwater acoustic positioning system according to an embodiment of the present disclosure. Figure 1 ;

[0039] Figure 2 This illustration shows the overall structure of an underwater acoustic positioning system according to an embodiment of the present disclosure. Figure 2 ;

[0040] Figure 3 A schematic diagram of the structure of the central node of an underwater acoustic positioning system according to an embodiment of the present disclosure is shown;

[0041] Figure 4 This diagram illustrates the internal structure of the central node of an underwater acoustic positioning system according to an embodiment of the present disclosure.

[0042] Figure 5 This diagram illustrates the architecture of a transmitting module of an underwater acoustic positioning system according to an embodiment of the present disclosure.

[0043] Figure 6 This diagram illustrates the receiver module architecture of a receiver node in an underwater acoustic positioning system according to an embodiment of the present disclosure.

[0044] Figure 7 The flowchart of an underwater acoustic positioning method according to an embodiment of this disclosure is shown. Figure 1 ;

[0045] Figure 8 The flowchart of an underwater acoustic positioning method according to an embodiment of this disclosure is shown. Figure 2 .

[0046] The following are the labeling instructions in the diagram: 1. Central Node; 2. Transmitter Node Group; 3. Receiver Node Group; 4. Watertight Connector; 11. Housing; 12. Control Module; 13. Timing Module; 14. Power Management Module; 15. Communication Module; 16. Power Supply Port; 17. Communication Port; 18. Hub Port; 19. Built-in Battery; 200. Transmitter Module; 300. Receiver Module. Detailed Implementation

[0047] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0048] Reference Figure 1 and Figure 2 As shown, this disclosure provides an exemplary embodiment of an underwater acoustic positioning system, including a central node 1, a transmitting node group 2, and a receiving node group 3. The transmitting node group 2 includes at least three separately deployed and interconnected transmitting nodes, each connected to the central node 1. The receiving node group 3 includes at least one receiving node, each connected to a corresponding transmitting node and communicatively connected to the central node 1. The transmitting node group 2 transmits a first acoustic signal to obtain a time difference dataset. The central node 1 calculates the coordinate information of each transmitting node in the transmitting node group 2 based on the time difference dataset and sends the coordinate information to the corresponding receiving node. The receiving node group 3 receives a second acoustic signal from the transmitting node group 2 to obtain a time difference of arrival dataset related to the underwater target, and calculates the spatial position of the underwater target based on the time difference of arrival dataset and the coordinate information.

[0049] In this embodiment, the central node 1 serves as the system's control core, data processing core, and communication hub, enabling bidirectional communication and data processing with the transmitting node group 2 and the receiving node group 3. The transmitting node group 2 is deployed in a separate configuration, comprising at least three transmitting nodes (e.g., T1, T2, T3…Tn, n≥3). These transmitting nodes are interconnected via acoustic or wired communication, and each transmitting node establishes a wired or wireless communication connection with the central node 1. For example, in deep-sea environments, a watertight wired connection or underwater acoustic communication connection is preferred. The separate deployment of the transmitting nodes maintains a preset distance between them, specifically set according to the positioning range requirements, to form an underwater positioning reference network. Each transmitting node has the ability to transmit acoustic signals, receive acoustic signals from other transmitting nodes, and communicate with the central node 1. The receiving node group 3 includes multiple receiving nodes (such as R1…Rm, m≥1). Each receiving node establishes a corresponding connection with a transmitting node. Specifically, a wired connection can be achieved through a watertight connector 4 for power transmission and data interaction. All receiving nodes establish a communication connection with the central node 1 to support underwater acoustic communication or wired communication.

[0050] The following detailed explanation uses an example with four transmitting and four receiving nodes. Transmitting node group 2 consists of four interconnected transmitting nodes, which can be arranged in a rectangular pattern at predetermined locations within the underwater detection area. Each transmitting node establishes a bidirectional connection with the central node 1 via a communication cable or timing cable to enable data and command exchange. Receiving node group 3 consists of four receiving nodes, each connected to one transmitting node. Each receiving node also establishes a communication connection with the central node 1 via an acoustic communication link. In actual operation, the central node 1 sends a self-positioning start command to transmitting node group 2. Upon receiving the command, each transmitting node in transmitting node group 2 transmits a first acoustic signal (i.e., a positioning reference acoustic signal, such as a pulse acoustic signal of a specific frequency) in a predetermined order or synchronously. Because the transmitting nodes are deployed separately but interconnected, each transmitting node, after transmitting its own first sound signal, receives the first sound signals transmitted by all other transmitting nodes. It records the time of its own first sound signal transmission and the arrival times of the first sound signals from other transmitting nodes using its built-in timing unit, and then calculates the propagation delay difference of the first sound signals between the transmitting nodes. Simultaneously, the central node 1 receives the first sound signals transmitted by all transmitting nodes, records the arrival times of each first sound signal, and calculates the propagation delay difference between the transmitting nodes and the central node 1 by combining the transmission times of each transmitting node. Each transmitting node uploads its collected delay difference data to the central node 1, forming a complete time difference dataset. After obtaining the complete time difference dataset, the central node 1, combined with real-time collected sound velocity data or using a preset standard sound velocity, uses itself as the coordinate origin and employs algorithms including but not limited to triangulation or long baseline positioning to calculate the precise coordinate information of each transmitting node in transmitting node group 2. After the calculation is completed, central node 1 sends the coordinate information of each transmitting node to the corresponding receiving node (i.e., the receiving node that has established a corresponding connection with the transmitting node) through the communication link, realizing the accurate transmission of coordinate reference. After completing the transmission of the first acoustic signal and coordinate calibration, transmitting node group 2 transmits the second acoustic signal (i.e., the target positioning acoustic signal, which can use the same or different frequency as the first acoustic signal for easy differentiation and processing) according to a preset cycle or command. Each receiving node in receiving node group 3 synchronously receives the second acoustic signal transmitted by transmitting node group 2, records the time of arrival of each second acoustic signal at the receiving node through the built-in timing unit, and calculates the time delay difference of the second acoustic signals from different transmitting nodes to the same receiving node by combining the known coordinate information of each transmitting node. The time delay difference data collected by all receiving nodes together constitute the arrival time difference dataset. Based on the arrival time difference dataset it has acquired, and combined with the coordinate information of the corresponding transmitting node sent by central node 1, each receiving node calculates the spatial position of the underwater target it is located in. The positioning results can be uploaded by the receiving node to central node 1, and then central node 1 summarizes and transmits them to the surface platform or user terminal.

[0051] As another implementation, the number of receiving nodes can be flexibly configured according to actual detection needs. In this embodiment, the transmitting node group 2 still includes four interconnected transmitting nodes, deployed in the same way as in the previous embodiment, to complete the system's self-localization and coordinate calibration. The receiving node group 3 includes one receiving node, which can be connected to any transmitting node via a watertight connector 4 to obtain power or serve as a physical installation base, while establishing a communication connection with the central node 1. In the workflow, after the transmitting node group 2 completes self-localization, the central node 1 sends the calculated coordinate information of all transmitting nodes to this single receiving node. Subsequently, when the transmitting node group 2 transmits a second acoustic signal, the receiving node independently receives the acoustic signals of all transmitting nodes, records the arrival time of each signal, and uses the obtained coordinate information of all transmitting nodes to calculate the spatial position of the platform to which it is attached or the associated underwater target.

[0052] In summary, the underwater acoustic positioning system disclosed herein achieves self-localization by transmitting a first acoustic signal through the transmitting node group 2. The central node 1 calculates the precise coordinates of each transmitting node based on the time difference dataset. The receiving node then combines this coordinate information with the time difference dataset related to the underwater target to calculate the target position. This effectively offsets the interference of multipath effects and sound speed errors caused by the complex marine environment on the positioning results, ensuring positioning accuracy. The transmitting nodes in the transmitting node group 2 are interconnected, and each receiving node establishes a connection with the transmitting nodes and communicates with the central node 1. The system possesses node redundancy and independent operating capabilities. When some nodes fail, the remaining nodes can still maintain basic signal transmission, reception, and data transmission functions, avoiding the failure of the entire positioning task due to the failure of a single point or some nodes, thus improving the system's adaptability to the complex, high-pressure environment of the deep sea.

[0053] Reference Figure 2 As shown, in one possible embodiment, the central node 1 is connected to each transmitting node via a watertight connector 4 to form a support structure, and the receiving node is movably connected to one of the transmitting nodes via the watertight connector 4 so that the receiving node can swing freely relative to the transmitting node.

[0054] In this embodiment, the central node 1 and each transmitting node are mechanically connected and integrated with signal and power transmission via watertight connectors 4. The watertight connectors 4 are encapsulated in a metal shell 11, housing multi-core conductive terminals and sealing gaskets. During connection, bolts are used to secure the connector interface of the transmitting node to the corresponding interface of the central node 1, forming a unified support structure with all transmitting nodes. The layout of this support structure can be designed according to positioning requirements, such as triangular or rectangular shapes. The receiving node is connected to the connected transmitting node via the watertight connectors 4, allowing the receiving node to swing freely relative to the transmitting node without compromising the watertightness of the connector or the continuity of signal and power transmission. The support structure between the central node 1 and the transmitting nodes ensures that after the transmitting node group 2 is deployed on the seabed, the relative position of each transmitting node to the central node 1 remains fixed, unaffected by deep-sea currents or seabed topographic changes. This structure provides a stable reference framework for the self-calibration of the transmitting node coordinates, avoiding coordinate calibration errors caused by transmitting node displacement and ensuring the accuracy of the time difference data acquisition. The movable connection structure between the receiving node and the transmitting node allows the receiving node to swing freely with the movement of the underwater target or the disturbance of the ocean current, so that the acoustic signal receiving module 300 of the receiving node can always be adjusted to the optimal attitude, effectively reducing the risk that the receiving node cannot effectively receive acoustic signals due to the fixed attitude caused by the movement of the target or the impact of the ocean current.

[0055] Reference Figure 3 and Figure 4 As shown, in one possible embodiment, the central node 1 includes a control module 12, a timing module 13, a power management module 14, and a communication module 15. The control module 12 is electrically connected to the timing module 13, the power management module 14, and the communication module 15, respectively, and is used to coordinate and control the timing module 13, the power management module 14, and the communication module 15. The communication module 15 is used to exchange data with the transmitting node group 2 and the receiving node group 3.

[0056] In this embodiment, each module is electrically connected via integrated wiring on a PCB board or dedicated connectors. The control module 12, as the core coordination unit of the central node 1, establishes bidirectional electrical connections with the timing module 13, power management module 14, and communication module 15, respectively, enabling command issuance, status monitoring, and data interaction for each module, and uniformly scheduling the entire workflow of the central node 1. The timing module 13, as a high-precision timing unit, is electrically connected to the control module 12, receiving synchronization calibration commands from the control module 12 and feeding back high-precision timing signals to provide a unified time reference for the central node 1 and the entire system. The power management module 14, as a power supply control unit, is electrically connected to the control module 12, receiving power allocation commands from the control module 12, and simultaneously transmitting load status data of each module to the control module 12 through a feedback interface to achieve dynamic power supply adjustment. The communication module 15, as a bidirectional data interaction unit, is electrically connected to the control module 12, receiving communication control commands from the control module 12, transmitting data from the transmitting node group 2 and the receiving node group 3, and simultaneously feeding back the communication link status to the control module 12. Communication module 15 includes a transceiver module, a signal acquisition and processing module, and a photoelectric conversion module. The signal acquisition and processing module is electrically connected to the transceiver module and is responsible for acquiring and preprocessing the signals from the transceiver module. Power management module 14 is electrically connected to the photoelectric conversion module and provides stable power to the photoelectric conversion module. The photoelectric conversion module is communicatively connected to transmitting node group 2 and receiving node group 3 to realize data interaction between central node 1 and external nodes. In actual operation, after the system starts, control module 12 first initializes each module and sends a power supply command to power management module 14. Power management module 14 starts external power supply or backup battery power supply to provide stable voltage to each module. Control module 12 sends a synchronization start command to timing module 13. Timing module 13 starts high-precision timing and outputs a time reference signal to control module 12. Control module 12 sends the synchronization signal to transmitting node group 2 and receiving node group 3 through communication module 15 to complete the timing synchronization of the entire system. Control module 12 sends the first sound signal transmission command to transmitting node group 2, and communication module 15 sends the first sound signal transmission command to transmitting node group 2. Block 15 receives the time difference dataset uploaded by transmitting node group 2 and transmits it to control module 12. Control module 12 calls the positioning algorithm and, combined with the time reference of timing module 13, calculates the coordinates of the transmitting node. Control module 12 sends the coordinate information of the transmitting node to receiving node group 3 through communication module 15, and simultaneously sends a second acoustic signal transmission command to transmitting node group 2. Communication module 15 receives the time difference dataset uploaded by receiving node group 3 and transmits it to control module 12. Control module 12 coordinates receiving node group 3 to complete the underwater target position calculation, and finally uploads the positioning result to the surface platform through communication module 15. During operation, power management module 14 provides real-time feedback on the load status of each module to control module 12, and control module 12 dynamically adjusts the power supply. Communication module 15 provides feedback on the link status, and control module 12 switches communication links as needed to ensure stable system operation.

[0057] In one embodiment, the central node 1 further includes a housing 11, and the control module 12, timing module 13, and power management module 14 are integrated inside the housing 11. The bottom of the housing 11 is provided with a power supply port 16, a communication port 17, and a hub port 18, and the communication module 15 is provided at the top of the housing 11.

[0058] In this embodiment, the outer shell 11 can be integrally molded from titanium alloy, possessing high strength, high pressure resistance, and corrosion resistance, making it suitable for deep-sea environments. The outer shell 11 can be designed as a cylindrical structure, with a buffer pad on the inner wall to cushion the impact of ocean currents and protect the module from shock, ensuring the stability of the internal module. The control module 12, timing module 13, power management module 14, and built-in battery 19 are all integrated inside the outer shell 11. The built-in battery 19 is connected to the charging and discharging interface of the power management module 14 via positive and negative terminals. The power management module 14 monitors the external power supply status in real time. When the external power supply is normal, the power management module 14 controls the external power supply to power the internal module and simultaneously charges the built-in battery 19. When the external power supply is interrupted, the power management module 14 switches to power supply from the built-in battery 19 to ensure continuous system operation. The communication module 15 is fixed to the top of the outer shell 11, with its acoustic signal transceiver surface exposed outside the outer shell 11 to avoid obstruction by the outer shell 11 structure or external sediments. The communication module 15 is connected to the internal control module 12 via a sealed cable that passes through the housing 11. Sealing gaskets are provided at the cable perforations to ensure the watertightness of the housing 11. The bottom of the housing 11 has three standardized ports: a power supply port 16, a communication port 17, and a hub port 18. The interfaces face outwards from the bottom of the housing 11 to facilitate quick docking with the watertight connector 4 during underwater deployment.

[0059] It should be noted that each transmitting node and receiving node adopts the same shell 11 structure as the central node 1. The internal circuit modules of each node are configured according to functional differences, while the external mechanical structure maintains a unified standard. Whether it is the central node 1, the transmitting node, or the receiving node, they are all equipped with communication ports 17, and can be connected to the communication gateway and control terminal of the surface platform through communication cables or timing cables to form a complete underwater acoustic positioning system. Further details will not be provided here.

[0060] In one embodiment, the hub port 18 is connected to a sound velocity measuring device and / or a flow velocity measuring device and / or a temperature, salinity, and pressure measuring device, and the control module 12 is configured to acquire sound velocity data and / or flow velocity data and / or temperature, salinity, and pressure data in real time through the hub port 18.

[0061] In this embodiment, the sound velocity measurement device is used to collect seawater sound velocity data in real time. This can be, but is not limited to, a temperature, salinity, and depth gauge or a high-precision sound velocity profiler, supporting the output of sound velocity values ​​or raw data on temperature, salinity, and pressure. The current velocity measurement device is used to collect seawater current velocity and direction data in real time. This can be, but is not limited to, an acoustic Doppler current profiler or a current meter, outputting current velocity values ​​and current direction angles. The hub port 18 has a built-in interface conversion chip, supporting mixed access of devices with different communication protocols without the need for an additional protocol converter. In practical applications, only the sound velocity measurement device, only the current velocity measurement device, or both can be connected. The control module 12 can automatically identify the type of connected device and adapt to the corresponding data processing logic. Thus, by dynamically correcting sound propagation speed errors using real-time sound velocity data and compensating for flow-induced path offsets using real-time current velocity data, the two work together to reduce positioning errors. This approach can adapt to different detection needs, simplifying device configuration when only sound velocity correction is required, and allowing simultaneous access of two devices in complex environments, ensuring stable operation under scenarios such as changes in sound velocity profiles and strong current disturbances.

[0062] In one embodiment, the timing module 13 includes a high-precision atomic clock or cable synchronization timing unit for providing a unified time reference to the underwater acoustic positioning system.

[0063] In this embodiment, the high-precision atomic clock uses a rubidium or cesium atomic clock for deep-sea long-distance, high-precision positioning scenarios. It has an autonomous timekeeping function and can maintain high-precision timing even without external signals. The cable synchronization time synchronization unit is used for shallow-sea short-distance, low-cost positioning scenarios. It can establish a synchronization link with the transmitting node group 2 and the receiving node group 3 through a watertight cable. Both units are electrically connected to the control module 12. Both the high-precision atomic clock and the cable synchronization time synchronization unit can provide a high-standard time reference, ensuring the accuracy of time difference measurement and providing core support for high-precision positioning.

[0064] Reference Figure 5 As shown, in one possible embodiment, the transmitting node includes a transmitting module 200, which includes a power amplifier circuit, a matched filter circuit, and a transceiver conversion circuit.

[0065] In this embodiment, the power amplifier circuit, matching filter circuit, and transceiver conversion circuit are integrated on the same PCB substrate. The input terminal of the transmitting module 200 is electrically connected to the signal processing circuit (i.e., the signal generation unit built into the transmitting node) to receive the raw electrical signal to be transmitted. The output terminal of the transmitting module 200 is electrically connected to the transducer (underwater acoustic signal transceiver device) through the transceiver conversion circuit to realize the conversion between electrical signals and acoustic signals. The transceiver conversion circuit is also electrically connected to the receiving circuit (the signal receiving unit built into the transmitting node) to realize the switching between transmitting and receiving states. The power amplifier circuit is used to receive the weak electrical signal output by the signal processing circuit, and to increase the signal amplitude and power amplification through the power amplifier chip to meet the power requirements of long-distance underwater acoustic signal transmission. One end of the matching filter circuit is connected to the output terminal of the power amplifier circuit, and the other end is connected to the input terminal of the transceiver conversion circuit. The matching filter circuit is used to match the output impedance of the power amplifier circuit to the input impedance of the transducer, reducing reflection loss during signal transmission. In addition, the matching filter circuit adopts a bandpass filter network with a filtering frequency band consistent with the operating frequency band of the acoustic signal, filtering out power supply noise and high-frequency interference signals introduced by the power amplifier circuit. The transceiver switching circuit can switch between transmit and receive modes. When switching to transmit mode, the path between the matching filter circuit and the transducer is connected, and the path between the transducer and the receiving circuit is disconnected, ensuring that the amplified signal is transmitted to the transducer without any signal leakage to the receiving circuit. When switching to receive mode, the path between the transducer and the receiving circuit is connected, and the path between the matching filter circuit and the transducer is disconnected, to prevent the received signal from being interfered with by the power amplifier circuit. Specifically, the transmitting module 200 operates in two phases: a transmitting phase and a receiving phase. During the transmitting phase, the signal processing circuit generates an electrical signal to be transmitted and transmits it to the power amplifier circuit of the transmitting module 200. The power amplifier circuit amplifies the weak signal to its rated power and outputs it to the matching filter circuit. After impedance matching and noise filtering, the matching filter circuit transmits the clean, high-power signal to the transceiver conversion circuit. The transceiver conversion circuit switches to the transmitting state, and the signal is converted into an acoustic signal by the transducer and transmitted underwater. During the receiving phase, the transducer receives acoustic signals from other transmitting nodes and converts them into electrical signals. The transceiver conversion circuit synchronously switches to the receiving state and transmits the electrical signal to the receiving circuit. At this time, the power amplifier circuit is in standby mode, and the matching filter circuit is disconnected from the receiving path to avoid interference with the received signal.

[0066] Reference Figure 6 As shown, in one possible embodiment, the receiving node includes a receiving module 300, which includes a preamplifier circuit, a bandpass filter circuit, a time-varying gain control amplifier circuit, and an analog-to-digital converter circuit connected in sequence.

[0067] In this embodiment, the receiving module 300 of the receiving node includes a preamplifier circuit, a bandpass filter circuit, a time-varying gain control amplifier circuit, and an analog-to-digital converter circuit, all connected in series according to the signal flow direction. The input terminal of the receiving module 300 is electrically connected to the transducer to receive the weak analog electrical signal converted by the transducer; the output terminal of the receiving module 300 is electrically connected to the signal processing circuit (the digital signal processing unit built into the receiving node) to output a digitized received signal for subsequent time delay measurement. The preamplifier circuit receives the weak electrical signal output by the transducer and amplifies the signal amplitude through a low-noise operational amplifier to improve the detectability of the weak signal; the bandpass filter circuit is connected to the output terminal of the preamplifier circuit, allowing only acoustic signals within the system's operating frequency band to pass through, filtering out marine environmental noise, such as low-frequency ocean current noise and high-frequency electromagnetic interference; the time-varying gain control amplifier circuit is connected to the output terminal of the bandpass filter circuit, dynamically adjusting the amplification gain according to the signal arrival time; the analog-to-digital converter circuit is connected to the output terminal of the time-varying gain control amplifier circuit, converting the conditioned analog signal into a digital signal and transmitting it to the signal processing circuit for time delay measurement. In simple terms, the signal conditioning process of the receiving module 300 at the receiving node is as follows: The transducer receives the underwater acoustic signal from the transmitting node and converts it into a weak analog electrical signal; the weak electrical signal is input to the preamplifier circuit to improve signal detectability; the amplified signal enters the bandpass filter circuit to filter out noise outside the operating frequency band and output a clean target frequency band signal; the clean signal enters the time-varying gain control amplifier circuit, and the signal processing circuit outputs a control voltage according to the signal arrival time to dynamically adjust the gain, so that the near-field signal is not saturated and the far-field signal is strong enough; the conditioned analog signal enters the analog-to-digital converter circuit to be converted into a bit-digital signal and transmitted to the signal processing circuit for subsequent accurate measurement of the time difference of arrival.

[0068] Reference Figure 7 As shown, this disclosure also provides an underwater acoustic positioning method, applicable to the underwater acoustic positioning system in any of the above-described embodiments. The underwater acoustic positioning method includes:

[0069] S11. The transmitting node group transmits the first acoustic signal to obtain the time difference dataset.

[0070] Each transmitting node in the transmitting node group transmits in rounds, sending its first acoustic signal one by one. After completing its own transmission, each transmitting node receives the first acoustic signals transmitted in rounds by other transmitting nodes. Through this process, the time difference data of the acoustic signals transmitted by the transmitting nodes arriving at the central node and other transmitting nodes is obtained. This data together constitutes the time difference dataset.

[0071] S12. The central node calculates the coordinate information of each transmitting node in the transmitting node group based on the time difference dataset, and sends the coordinate information to the corresponding receiving node.

[0072] The central node receives the time difference dataset uploaded by the transmitting node group, combines it with the real-time sound velocity data obtained by the sound velocity measurement device connected through the hub port, and calculates the precise coordinate information of each transmitting node in the transmitting node group with itself as the coordinate origin; then, the central node sends the coordinate information of each transmitting node to the corresponding receiving node.

[0073] S13, The transmitting node group transmits the second acoustic signal.

[0074] The transmitting node group synchronously transmits a second acoustic signal according to a preset cycle or the command of the central node. The second acoustic signal is also the target positioning acoustic signal, and its frequency is the same as that of the first acoustic signal or is distinguished by encoding.

[0075] S14. The receiving node group receives the second acoustic signal and obtains the time difference of arrival dataset related to the underwater target.

[0076] Each receiving node in the receiving node group synchronously receives the second acoustic signal transmitted by the transmitting node group and records the arrival time of the second acoustic signal from each transmitting node. Each receiving node summarizes the time difference between the arrival times of the second acoustic signals from different transmitting nodes at the same receiving node to form an arrival time difference dataset.

[0077] S15. The receiving node group calculates the spatial location of the underwater target based on the time difference of arrival dataset and coordinate information.

[0078] Each receiving node calculates the spatial location of its underwater target based on the coordinate information of the corresponding transmitting node obtained in S12, combined with the time difference of arrival dataset in S14, using a positioning algorithm.

[0079] Therefore, the underwater acoustic positioning method disclosed herein completes self-positioning by transmitting a first acoustic signal through a group of transmitting nodes. The central node calculates the precise coordinates of each transmitting node based on the time difference dataset. The receiving node then combines this coordinate information with the time difference dataset related to the underwater target to calculate the target position. This effectively offsets the interference of multipath effects and sound speed errors caused by the complex marine environment on the positioning results, ensuring positioning accuracy. Each transmitting node in the transmitting node group is interconnected, and each receiving node is connected to a transmitting node in a one-to-one correspondence and communicates with the central node. When some nodes fail, the undisturbed nodes can still maintain basic signal transmission, reception, and data transmission functions, avoiding the failure of the entire positioning task due to the failure of a single point or some nodes, and improving the system's adaptability to the complex environment of deep-sea high pressure.

[0080] Furthermore, referring to Figure 8 As shown, in one possible implementation, S11, the transmitting node group transmits a first acoustic signal to acquire a time difference dataset, including:

[0081] S111. Each transmitting node transmits the first sound signal according to the preset timing sequence.

[0082] Specifically, the n transmitting nodes T1 to Tn in the transmitting node group transmit the first sound signal in a fixed order of T1→T2→…→Tn, and the transmission interval between adjacent transmitting nodes is a preset value to avoid signal conflict.

[0083] S112. The first transmitted signal is received by the central node and the other transmitting nodes in the transmitting node group, excluding the current transmitting node, and their respective arrival times are recorded.

[0084] Each transmitting node sends its first acoustic signal to the central node and all other transmitting nodes in the system except itself. After completing its own transmission, each node receives the first acoustic signals from the other transmitting nodes in their respective rounds. Taking transmitting node T1 as an example, after T1 completes its transmission, it is T2's turn to transmit. Then T1, T3, ..., Tn receive the signals transmitted by T2; and so on, with each of the n transmitting nodes transmitting in turn and receiving signals from the n-1 other transmitting nodes (excluding itself) in their respective rounds. For each first acoustic signal transmitted, such as the acoustic signal transmitted by T1 or T2, the central node and the other transmitting nodes in the transmitting node group (excluding the current transmitting node) record the precise time when the signal arrives at themselves.

[0085] S113. Based on the arrival time, calculate the first time difference data between each transmitting node and the central node, and the second time difference data between each transmitting node and each other.

[0086] The first time difference data and the second time difference data constitute the time difference dataset.

[0087] Specifically, the time difference between the transmitting node and the central node is obtained by subtracting the arrival time of the signal received by the central node from the first transmission time of the first sound signal transmitted by each transmitting node. This is the first time difference data. The time difference between the transmitting node and any other transmitting node is obtained by subtracting the arrival time of the signal received by other transmitting nodes from the first transmission time of the first sound signal transmitted by each transmitting node. This is the second time difference data.

[0088] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0090] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. An underwater acoustic positioning system, characterized in that, include: Central node (1); The transmitting node group (2) includes at least three transmitting nodes that are separately deployed and interconnected with each other, and each of the transmitting nodes is connected to the central node (1); The receiving node group (3) includes at least one receiving node, each of which is connected to a corresponding transmitting node and is communicatively connected to the central node (1). The transmitting node group (2) is used to transmit a first acoustic signal to obtain a time difference dataset; The central node (1) is used to calculate the coordinate information of each of the transmitting nodes in the transmitting node group (2) according to the time difference dataset, and send the coordinate information to the corresponding receiving node; The receiving node group (3) is used to receive the second acoustic signal of the transmitting node group (2) to obtain the arrival time difference dataset related to the underwater target, and calculate the spatial position of the underwater target based on the arrival time difference dataset and the coordinate information; The central node (1) is connected to each of the transmitting nodes via a watertight connector (4) to form a support structure; the receiving node is movably connected to one of the transmitting nodes via a watertight connector (4) so ​​that the receiving node can swing freely relative to the transmitting node; Each transmitting node in the transmitting node group (2) transmits the first sound signal according to the preset timing sequence. For each first sound signal transmitted, the central node (1) and the other transmitting nodes in the transmitting node group (2) except the current transmitting node receive and record their respective arrival times. Based on the arrival times, the first time difference data between each transmitting node and the central node (1) and the second time difference data between each transmitting node are calculated. The first time difference data and the second time difference data constitute the time difference dataset.

2. The underwater acoustic positioning system according to claim 1, characterized in that, The central node (1) includes a control module (12), a timing module (13), a power management module (14), and a communication module (15). The control module (12) is electrically connected to the timing module (13), the power management module (14) and the communication module (15) respectively, and is used to coordinate and control the timing module (13), the power management module (14) and the communication module (15); The communication module (15) is used to interact with the transmitting node group (2) and the receiving node group (3) for data exchange.

3. The underwater acoustic positioning system according to claim 2, characterized in that, The central node (1) also includes a housing (11), and the control module (12), the timing module (13) and the power management module (14) are integrated inside the housing (11); The bottom of the housing (11) is provided with a power supply port (16), a communication port (17) and a hub port (18), and the communication module (15) is provided on the top of the housing (11).

4. The underwater acoustic positioning system according to claim 3, characterized in that, The hub port (18) is connected to a sound velocity measuring device and / or a flow velocity measuring device and / or a temperature, salinity, and pressure measuring device. The control module (12) is configured to acquire sound velocity data and / or flow velocity data and / or temperature, salinity, and pressure data in real time through the hub port (18).

5. The underwater acoustic positioning system according to claim 2, characterized in that, The timing module (13) includes a high-precision atomic clock or cable synchronization timing unit, which is used to provide a unified time reference to the underwater acoustic positioning system.

6. The underwater acoustic positioning system according to claim 1, characterized in that, The transmitting node includes a transmitting module (200), which includes a power amplifier circuit, a matched filter circuit, and a transceiver conversion circuit.

7. The underwater acoustic positioning system according to claim 1, characterized in that, The receiving node includes a receiving module (300), which includes a preamplifier circuit, a bandpass filter circuit, a time-varying gain control amplifier circuit, and an analog-to-digital converter circuit connected in sequence.

8. An underwater acoustic positioning method, applied to the underwater acoustic positioning system according to any one of claims 1-7, characterized in that, The method includes: The transmitting node group (2) transmits the first acoustic signal and acquires the time difference dataset; The central node (1) calculates the coordinate information of each transmitting node in the transmitting node group (2) based on the time difference dataset, and sends the coordinate information to the corresponding receiving node; The transmitting node group (2) transmits a second acoustic signal; The receiving node group (3) receives the second acoustic signal and obtains the time difference of arrival data related to the underwater target; The receiving node group (3) calculates the spatial location of the underwater target based on the arrival time difference dataset and the coordinate information.

9. The underwater acoustic positioning method according to claim 8, characterized in that, The transmitting node group (2) transmits a first acoustic signal and acquires a time difference dataset, including: Each of the aforementioned transmitting nodes transmits a first acoustic signal according to a preset timing sequence; For each first sound signal transmitted, the arrival time of each signal is received by the central node (1) and the other transmitting nodes in the transmitting node group (2) except for the current transmitting node. Based on the arrival time, calculate the first time difference data between each of the transmitting nodes and the central node (1), and the second time difference data between each of the transmitting nodes; The first time difference data and the second time difference data constitute the time difference dataset.

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