Underwater acoustic communication system and communication method for underwater trawl monitoring

Abstract

The invention provides an underwater acoustic communication system for underwater trawl monitoring and a communication method thereof. The system comprises a master control node and a sensor node. And the master control node dynamically adjusts the broadcast power of the master control node by querying a power-depth mapping table according to the depth sensor data. After a sensor node receives a broadcast signal, a signal quality detection circuit is used for obtaining the received signal strength and the signal-to-noise ratio, inclination angle data of an attitude sensor are synchronously read, a link quality-power mapping table is comprehensively inquired, and the optimal response power is calculated. According to the invention, hardware perception and intelligent decision are combined through a master-slave node cooperative bidirectional adaptive power control mechanism, so that the problems of poor reliability and over-high energy consumption of underwater acoustic communication caused by net deformation, depth change and violent swinging of node postures in trawl operation are effectively solved; and the optimal balance between the communication link reliability and the node energy consumption in a complex dynamic environment is realized.

Description

Technical Field

[0001] This invention relates to the fields of underwater acoustic communication and automated control technology, and more specifically, to an underwater acoustic communication system and method with adaptive power consumption regulation suitable for monitoring underwater trawling operations in the ocean. Background Technology

[0002] In marine trawl fishing, real-time monitoring of the underwater conditions of the trawl net (such as net opening height, opening angle, temperature, salinity, etc.) is crucial for improving catch efficiency and reducing damage to the seabed ecosystem.

[0003] Underwater acoustic communication is the primary technology for achieving wireless data transmission underwater. In the specific scenario of trawling monitoring, underwater acoustic communication nodes face the following significant challenges: (1) Dynamic time-varying channel: During the towing process, the shape of the trawler changes continuously, causing the distance between nodes and the underwater acoustic channel conditions (such as multipath effect and propagation loss) to fluctuate drastically.

[0004] (2) Influence of node attitude: The sensor nodes attached to the flexible netting swing violently with the water flow, and the directivity of their underwater acoustic transducers will change instantaneously, significantly degrading the quality of the communication link.

[0005] (3) Energy constraints: Sensor nodes are powered by batteries, which are difficult to replace after deployment. Therefore, minimizing power consumption while ensuring communication reliability is the key to extending the system's lifespan. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes an underwater acoustic communication system and method for monitoring underwater trawl nets, resolving the coupling challenges between underwater acoustic communication reliability, energy consumption, and node attitude changes in dynamically changing trawl net environments. Through collaborative hardware and software design, communication power consumption adapts to environmental changes.

[0007] The present invention is implemented using the following technical solutions: An underwater acoustic communication system for monitoring underwater trawl nets is proposed, comprising: The main control node is deployed on the trawl net or the hull; the main control node consists of a main controller, an underwater acoustic communication device and a first power supply module. Several sensor nodes are deployed on the trawl netting; each sensor node consists of a controller, an underwater acoustic modem, a hydrological sensor, and a second power module. The master control node also includes: a depth sensor for detecting the depth information of the master control node and a first storage unit for storing a depth-power mapping table; The sensor node further includes: a signal quality detection circuit for detecting the received signal strength and signal-to-noise ratio, and a second storage unit for storing a link quality-power mapping table; The master control node determines the transmission power level based on depth information and controls its underwater acoustic communication device to broadcast signal frames at the determined transmission power level; the sensor node receives the signal frames, detects the received signal strength and signal-to-noise ratio, determines the minimum response power level based on the received signal strength and signal-to-noise ratio, and controls its underwater acoustic modem to send the packaged hydrological data to the master control node at the minimum response power level.

[0008] In some embodiments of the present invention, the sensor node further includes an attitude sensor for detecting the attitude data of the sensor node; after receiving a signal frame, the sensor node accesses a second storage unit based on the received signal strength, signal-to-noise ratio and attitude data, queries the link quality-power mapping table, and obtains the transmit power level of the underwater acoustic modem.

[0009] In some embodiments of the present invention, if the attitude data exceeds a preset threshold, the sensor node adds a power compensation value to the queried transmit power level and uses it as the transmit power of the underwater acoustic modem.

[0010] In some embodiments of the present invention, after the master control node receives the hydrological data packets sent by the sensor node, it calculates the communication success rate; if communication fails for a set number of consecutive times, it increases the current transmission power level; and it updates the depth-power mapping table in real time according to the historical communication success rate.

[0011] In some embodiments of the present invention, the master control node further includes a first environmental sensor group for detecting at least one environmental parameter among temperature, attitude, and flow rate; The sensor node also includes a second environmental sensor group for detecting at least one environmental parameter among temperature, attitude, and flow rate. The master control node and sensor nodes update the depth-power mapping table and the link quality-power mapping table in real time based on the environmental parameters detected by the first environmental sensor group and the second environmental sensor group, respectively.

[0012] In some embodiments of the present invention, a relay communication link is established between sensor nodes. When a sensor node cannot communicate directly with the master control node, data is relayed to the master control node through other sensor nodes.

[0013] A hydroacoustic communication method for underwater trawl net monitoring is proposed and applied to the hydroacoustic communication system for underwater trawl net monitoring described above. The communication method includes: S1: The master node determines the transmit power level of its underwater acoustic communication device based on its depth information; S2: The master control node periodically broadcasts beacon frames at a defined transmit power level; S3: The sensor node receives beacon frames and detects the received signal strength and signal-to-noise ratio; S4: Sensor nodes determine their minimum response power level based on received signal strength and signal-to-noise ratio; S5: The sensor node controls the underwater acoustic modem to package the hydrological data and control its transmission to the master node at the lowest response power level.

[0014] In some embodiments of the present invention, step S3 further includes: Synchronously acquire attitude data detected by the attitude sensor; Then S4 is: The sensor node determines its minimum response power level based on the received signal strength, signal-to-noise ratio and attitude data.

[0015] In some embodiments of the present invention, the method further includes: If the attitude data exceeds the preset threshold, compensation will be made for the lowest response power level. In S5, the compensated power is used as the transmit power of the underwater acoustic modem.

[0016] In some embodiments of the present invention, the method further includes: After receiving the hydrological data packets sent by the sensor nodes, the master control node calculates the communication success rate. If communication fails for a set number of consecutive times, the current transmission power level will be increased. The depth-power mapping table is updated in real time based on historical communication success rates.

[0017] In some embodiments of the present invention, the method further includes: Acquire a first environmental parameter detected by a first environmental sensor group; the first environmental sensor group is configured in the master control node, and the first environmental parameter is at least one of temperature, attitude and flow rate; Acquire a second environmental parameter detected by a second environmental sensor group; the second environmental sensor group is configured in a sensor node, and the second environmental parameter is at least one of temperature, attitude, and flow rate; The master node updates the depth-power mapping table based on the first environmental parameter; the sensor node updates the link quality-power mapping table based on the second environmental parameter.

[0018] In some embodiments of the present invention, when the communication failure between the sensor node and the master control node exceeds a set number, data is relayed to the master control node through other sensor nodes based on the relay communication link established between the sensor nodes.

[0019] Compared with the prior art, the advantages and positive effects of the present invention include: (1) It realizes bidirectional adaptive power adjustment and energy saving. Compared with the limitations of existing one-way (master or slave) power adjustment, the present invention enables the master and slave (sensor node) nodes to coordinately adjust the transmission power to realize bidirectional closed-loop power control; the power adjustment is based on multi-dimensional information such as depth, real-time link quality and node attitude, which is more accurate and scientific, and minimizes energy consumption while ensuring communication reliability.

[0020] (2) Attitude compensation is introduced, which significantly improves communication reliability. This invention uses the sensor node attitude as a key parameter for power regulation. Through hardware circuits and lookup table mechanisms, it effectively compensates for the directional loss caused by node swaying, and effectively improves the communication success rate in harsh sea conditions and dynamic trawling scenarios.

[0021] (3) The adaptive power adjustment algorithm is materialized into specific hardware modules such as sensors, detection circuits and storage units, and the working logic is coordinated to make the underwater acoustic communication system architecture clearer, faster in response and easier to integrate into the existing trawling monitoring system.

[0022] (4) Introduce a multimodal environment perception and online learning mechanism. Through environmental parameters such as temperature, attitude, and flow velocity, as well as historical communication data, dynamically update the power mapping table so that the system can adapt to the complex and ever-changing underwater environment and further optimize the power regulation strategy.

[0023] (5) Enhance the robustness and coverage of the system by means of inter-node relay communication. When the direct communication link fails, communication can still be maintained through multi-hop relay.

[0024] Other features and advantages of the present invention will become clearer after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions are used to explain the invention but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0026] Figure 1 The layout structure of an underwater trawl underwater acoustic communication system; Figure 2 The system architecture of existing underwater trawl communication systems; Figure 3 This invention presents an underwater acoustic communication system architecture for monitoring underwater trawl nets. Figure 4 This is a schematic diagram of the steps of the underwater acoustic communication method for underwater trawl monitoring proposed in this invention; Figure 5 This is a schematic diagram of the execution steps of the underwater acoustic communication method for monitoring underwater trawls, as given in an embodiment of the present invention. Reference numerals: 100, Master control node; 101, Master controller; 102, Underwater acoustic communication device; 103, First power supply module; 104, Depth sensor; 105, First storage unit; 106, First environmental sensor group; 200, Sensor node; 201, Slave controller; 202, Underwater acoustic modem; 203, Hydrological sensor; 204, Second power supply module; 205, Signal quality detection circuit; 206, Second storage unit; 207, Attitude sensor; 208, Second environmental sensor group. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] This invention addresses the underwater acoustic communication system for trawl nets. By employing a bidirectional adaptive power control mechanism with master-slave node collaboration, it combines hardware perception with intelligent decision-making. The aim is to solve the problems of poor reliability and excessive energy consumption in underwater acoustic communication caused by net deformation, depth changes, and severe node attitude swings during trawl net operations. This invention achieves an optimal balance between communication link reliability and node energy consumption in complex dynamic environments.

[0029] like Figure 1 As shown, the underwater trawl acoustic communication system includes a main control node 100 deployed on the trawl net or hull and at least one sensor node 200 deployed on the trawl net.

[0030] like Figure 2 As shown, the main control node 100 consists of a main controller 101, an underwater acoustic communication unit 102, and a first power supply module 103. The main controller 101 is a low-power microcontroller from the STM32L4 series; the underwater acoustic communication unit 102 is a programmable power level module, whose power level can be set via serial port commands. The main controller 101 controls the underwater acoustic communication unit 102 to transmit and receive underwater acoustic signals; the first power supply module 103 supplies power to each module.

[0031] Sensor node 200 consists of a slave controller 201, an underwater acoustic modem 202, a hydrological sensor 203, and a second power supply module 204. The slave controller 201 also uses a low-power STM32L4 series microcontroller; the underwater acoustic modem 202 is a module compatible with the master control node; the underwater acoustic modem 202 and the hydrological sensor 23 are connected to the slave controller 201. The hydrological sensor 203 collects hydrological data around the trawl net, and the slave controller 201 controls the underwater acoustic modem 202 to communicate with the underwater acoustic communication unit 102 of the master control node 100, receiving data from the underwater acoustic communication unit 102 and reporting hydrological data to the underwater acoustic communication unit 102. The second power supply module 204 supplies power to each module.

[0032] In the existing underwater trawl acoustic communication system, the master control node 100 initiates queries or receives reported data from the sensor node 200, while the sensor node 200 responds to the queries from the master control node 100, reports measured hydrological data, or issues an active alarm.

[0033] To address the trade-off between reliability and energy consumption in underwater acoustic communication caused by the dynamic environment of trawl operations, existing underwater acoustic modems are designed with multiple adjustable power levels, estimating the power to be switched based on the distance between sensor node 200 and master control node 100. However, in the highly dynamic and complex environment of trawl operations, the position and shape of the trawl net and trawl net fabric continuously change under the influence of ocean currents, and the actual communication distance is constantly changing. Switching power solely based on distance requires an additional positioning system, which increases the system's complexity and cost, and also introduces significant errors.

[0034] This invention addresses the characteristics of the dynamically changing environment of trawling nets by proposing an underwater acoustic communication system that adapts to environmental changes in communication power consumption. The aforementioned underwater acoustic communication system for trawling nets undergoes the following modifications: (1) such as Figure 3 As shown, the master control node 100 is also equipped with a depth sensor 104 and a first storage unit 105. The depth sensor 104 is connected to the master controller 101 and uses a high-precision pressure sensor MS5837 to acquire the depth information of the master control node 100. The first storage unit 105 is the FLASH inside the MCU and is used to store the power-depth mapping table calibrated by the sea trial data. The depth-power mapping table stores several data on the correspondence between depth and transmission power, so that the master control node 100 can realize preliminary adaptive power adjustment based on depth information.

[0035] (2) The sensor node 200 is also equipped with a signal quality detection circuit 205 and a second storage unit 206. The signal quality detection circuit 205 is connected to the controller 201 and is used to detect the strength RSSI and signal-to-noise ratio SNR of the received signal in real time. The second storage unit 206 stores the link quality-power mapping table calibrated by the previous experiment. The link quality-power mapping table stores several data on the correspondence between link quality and transmission power, so that the sensor node 200 can realize response power adjustment based on the quality of the received signal.

[0036] In this embodiment of the invention, the control node 200 is further configured with an attitude sensor 207; the attitude sensor 207 is connected to the slave controller 201 and is used to monitor the spatial attitude of the sensor node 200 in real time. After receiving the signal transmitted by the master control node 100, the slave controller 201, on the one hand, uses the signal quality detection circuit 205 to detect the signal strength RSSI and signal-to-noise ratio SNR, and on the other hand, the attitude sensor 207 detects the attitude data of the sensor node 200. The slave controller 201 synchronously reads the RSSI, SNR and attitude data, accesses the second storage unit 206 to query the link quality-power mapping table, obtains the dynamic transmit power level of the underwater acoustic modem 202, and the underwater acoustic modem 202 packages the hydrological data and sends it to the master control node 100 at the queried transmit power level.

[0037] In this embodiment of the invention, if the attitude data (e.g., the tilt angle of the sensor) exceeds a preset threshold, the transmit power level queried from the link quality-power mapping table will be automatically increased by a preset power compensation value and used as the transmit power of the underwater acoustic modem 202.

[0038] In this embodiment of the invention, the master control node 100 receives hydrological data packets sent by the sensor node 200 and records the communication success rate. If multiple consecutive communication failures occur, the master controller 101 increases the current transmission power level to achieve adaptive optimization of the system. Furthermore, the depth-power mapping table is updated in real time based on the historical communication success rate and the increased transmission power level to achieve adaptive learning optimization.

[0039] In this embodiment of the invention, the master node 100 is further configured with a first environmental sensor group 106 for detecting at least one environmental parameter among temperature, attitude, and flow rate; the sensor node 200 is further configured with a second environmental sensor group 208 for detecting at least one environmental parameter among temperature, salinity, and flow rate. The first environmental sensor group 106 is connected to the master controller 101, which can update the depth-power mapping table online based on environmental parameters and historical communication success rates to achieve adaptive learning. The second environmental sensor group 208 is connected to the slave controller 201, which can update the link quality-power mapping table online based on environmental parameters and historical communication success rates to achieve adaptive learning.

[0040] In this embodiment of the invention, sensor nodes 200 can establish relay communication links through an underwater acoustic modem 202. When a sensor node cannot communicate directly with the master control node 100, data can be relayed through other sensor nodes, improving the robustness of the system.

[0041] Through the above modifications, the main control node 100 can adjust the broadcast power based on depth, historical communication success rate, and environmental parameters, while the sensor node 200 determines the optimal response power based on the received signal quality (strength and signal-to-noise ratio), attitude data, historical communication success rate, and environmental parameters. The two nodes work together to complete data transmission and form a closed-loop feedback, constituting a fine power adaptive adjustment mechanism based on multi-source information fusion, which minimizes energy consumption while ensuring communication reliability.

[0042] Based on the aforementioned underwater acoustic communication system for underwater trawl monitoring, this invention also proposes an underwater acoustic communication method applied to this system, such as... Figure 4 As shown, it includes: S1: The master node determines the transmit power level of its underwater acoustic communication device based on its depth information.

[0043] The master control node 100 obtains real-time depth information through its depth sensor 104 and queries the pre-stored power-depth mapping table accordingly to adaptively adjust the transmission power level of its underwater acoustic communication device 102.

[0044] S2: The master node periodically broadcasts beacon frames at a determined transmit power level.

[0045] Master node 100 periodically broadcasts beacon frames containing current power level information based on the queried power level.

[0046] S3: The sensor node receives beacon frames and detects the received signal strength and signal-to-noise ratio.

[0047] Sensor node 200 receives the beacon frame and measures the received signal strength RSSI and signal-to-noise ratio SNR in real time through its signal quality detection circuit 205.

[0048] S4: Sensor nodes determine their minimum response power level based on received signal strength and signal-to-noise ratio.

[0049] Sensor node 200 combines the RSSI and SNR data, queries the pre-stored link quality-power mapping table, and obtains the minimum response power level required to ensure communication reliability.

[0050] S5: The sensor node controls the underwater acoustic modem to package the hydrological data and send it to the master node at the lowest response power level.

[0051] Sensor node 200 controller underwater acoustic modem 202 packages the hydrological data detected by hydrological sensor 203 and sends the hydrological data to master node 100 with the lowest response power level obtained by querying.

[0052] In embodiments of the present invention, such as Figure 5 As shown, when the sensor node 200 detects the received signal strength and signal-to-noise ratio, it simultaneously acquires the attitude data detected by the attitude sensor 207, such as real-time tilt data. The sensor node 200 integrates the RSSI, SNR and tilt data, queries the pre-stored link quality-power mapping table, and obtains the minimum response power level required to ensure communication reliability.

[0053] If the attitude data detected by the attitude sensor 207 exceeds a preset threshold, a preset power compensation value is automatically added to the lowest response power level obtained from the query as the final adapted transmit power of the underwater acoustic modem 202.

[0054] S6: The master node counts the communication success rate.

[0055] The master control node 100 receives hydrological data packets sent by the sensor node 200 and calculates the communication success rate.

[0056] S7: If communication fails for a set number of consecutive times, the master control node increases the transmit power level and returns to step S2.

[0057] If communication fails multiple times in a row, the main controller 101 will increase the current transmit power level to achieve adaptive optimization of the system.

[0058] S8: Update the depth-power mapping table in real time based on historical communication success rates.

[0059] The underwater acoustic communication process of the underwater acoustic communication system proposed in this invention will be described in detail below with a specific embodiment. Master node 100 broadcasts: After the trawl net is launched, the depth sensor 104 of master node 100 continuously measures its own depth information. The master controller 101 reads the depth information periodically (e.g., every second) and queries the power-depth mapping table in the first storage unit 105 to obtain the transmission power level of the underwater acoustic communicator 102. For example, low power P1 is used at depths <50m, medium power P2 is used at 50m-100m, and high power P3 is used at depths >100m. Then, the transmission power of the underwater acoustic communicator 102 is set through serial port commands. Subsequently, the underwater acoustic communicator 102 broadcasts a beacon frame containing the node ID, timestamp, and current power level.

[0060] Sensor node 200 response: After receiving the beacon frame, the underwater acoustic modem 202 of sensor node 200 triggers an interrupt to wake up the slave controller 201. The slave controller 201 then performs the following operations: a. Parse beacon frames.

[0061] b. By querying the register of the underwater acoustic modem 202, the received signal strength RSSI and signal-to-noise ratio SNR of the frame are obtained from the signal quality detection circuit 205.

[0062] c. Read the current tilt angle data θ of the attitude sensor 207 via the I2C bus.

[0063] d. Combining the three parameters (RSSI, SNR, θ), query the link quality-power mapping table in the second storage unit 206 to obtain a minimum response power level. If θ is greater than a preset safety threshold (e.g., 30 degrees), a fixed power compensation amount ΔP is added to that level to obtain the final response power level P_resp.

[0064] e. Set the transmit power of the underwater acoustic modem 202 to P_resp via serial port commands, and use this power to package and send out the data from the hydrological sensor 203.

[0065] Environmental Awareness: The master node 100 detects environmental parameters such as temperature, attitude, and flow rate through the first environmental sensor group 106, while the sensor node 200 detects environmental parameters through the second environmental sensor group 208. The master node 100 and sensor node 200 update the depth-power mapping table and link quality-power mapping table in real time based on the environmental parameters.

[0066] Relay communication: If a sensor node 200 cannot communicate directly with the master control node 100, it will relay the data through a nearby sensor node 200 until the data reaches the master control node 100.

[0067] Closed-loop feedback: Master node 100 receives data packets and records the communication success rate. If multiple communication failures occur consecutively, master controller 101 can appropriately increase the power level corresponding to the current depth to achieve long-term adaptive optimization of the system. Master node 100 and sensor node 200 update the depth-power mapping table and link quality-power mapping table based on the historical communication success rate.

[0068] It should be noted that the signal quality detection circuit 205 in this invention adopts an existing circuit architecture design, which can be implemented by those skilled in the art using conventional techniques, and is not a part limited by this invention.

[0069] It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An underwater acoustic communication system for monitoring underwater trawl nets, comprising: The main control node is deployed on the trawl net or hull; The main control node consists of a main controller, an underwater acoustic communication device, and a first power supply module; Several sensor nodes are deployed on the trawl netting; each sensor node consists of a controller, an underwater acoustic modem, a hydrological sensor, and a second power module. Its features are, The master control node also includes: a depth sensor for detecting the depth information of the master control node and a first storage unit for storing a depth-power mapping table; The sensor node further includes: a signal quality detection circuit for detecting the received signal strength and signal-to-noise ratio, and a second storage unit for storing a link quality-power mapping table; The master control node determines the transmission power level based on depth information and controls its underwater acoustic communication device to broadcast signal frames at the determined transmission power level; the sensor node receives the signal frames, detects the received signal strength and signal-to-noise ratio, determines the minimum response power level based on the received signal strength and signal-to-noise ratio, and controls its underwater acoustic modem to send the packaged hydrological data to the master control node at the minimum response power level.

2. The underwater acoustic communication system for monitoring underwater trawls according to claim 1, characterized in that, The sensor node also includes an attitude sensor for detecting the attitude data of the sensor node. After receiving a signal frame, the sensor node accesses the second storage unit based on the received signal strength, signal-to-noise ratio, and attitude data, queries the link quality-power mapping table, and obtains the transmit power level of the underwater acoustic modem.

3. The underwater acoustic communication system for monitoring underwater trawls according to claim 2, characterized in that, If the attitude data exceeds a preset threshold, the sensor node adds a power compensation value to the queried transmit power level and uses it as the transmit power of the underwater acoustic modem.

4. The underwater acoustic communication system for monitoring underwater trawls according to claim 1, characterized in that, After receiving hydrological data packets sent by the sensor nodes, the master control node calculates the communication success rate; if communication fails for a set number of consecutive times, the current transmission power level is increased. The depth-power mapping table is updated in real time based on historical communication success rates.

5. The underwater acoustic communication system for monitoring underwater trawls according to claim 1 or 4, characterized in that, The master control node also includes a first environmental sensor group for detecting at least one environmental parameter among temperature, attitude and flow rate; The sensor node also includes a second environmental sensor group for detecting at least one environmental parameter among temperature, attitude, and flow rate. The master control node and sensor nodes update the depth-power mapping table and the link quality-power mapping table in real time based on the environmental parameters detected by the first environmental sensor group and the second environmental sensor group, respectively.

6. A method for underwater acoustic communication for monitoring underwater trawls, applied to the underwater acoustic communication system for monitoring underwater trawls as described in any one of claims 1-5, characterized in that, The communication method includes: S1: The master node determines the transmit power level of its underwater acoustic communication device based on its depth information; S2: The master control node periodically broadcasts beacon frames at a defined transmit power level; S3: The sensor node receives beacon frames and detects the received signal strength and signal-to-noise ratio; S4: Sensor nodes determine their minimum response power level based on received signal strength and signal-to-noise ratio; S5: The sensor node controls the underwater acoustic modem to package the hydrological data and send it to the master node at the lowest response power level.

7. The underwater acoustic communication method for monitoring underwater trawls according to claim 6, characterized in that, Step S3 also includes: Synchronously acquire attitude data detected by the attitude sensor; Then S4 is: The sensor node determines its minimum response power level based on the received signal strength, signal-to-noise ratio and attitude data.

8. The underwater acoustic communication method for monitoring underwater trawls according to claim 7, characterized in that, The method further includes: If the attitude data exceeds the preset threshold, compensation will be made for the lowest response power level. In S5, the compensated power is used as the transmit power of the underwater acoustic modem.

9. The underwater acoustic communication method for monitoring underwater trawls according to claim 6, characterized in that, The method further includes: After receiving the hydrological data packets sent by the sensor nodes, the master control node calculates the communication success rate. If communication fails for a set number of consecutive times, the current transmission power level will be increased. The depth-power mapping table is updated in real time based on historical communication success rates.

10. The underwater acoustic communication system for monitoring underwater trawls according to claim 6 or 9, characterized in that, The method further includes: Acquire a first environmental parameter detected by a first environmental sensor group; the first environmental sensor group is configured in the master control node, and the first environmental parameter is at least one of temperature, attitude and flow rate; Acquire a second environmental parameter detected by a second environmental sensor group; the second environmental sensor group is configured in a sensor node, and the second environmental parameter is at least one of temperature, attitude, and flow rate; The master node updates the depth-power mapping table based on the first environmental parameter; the sensor node updates the link quality-power mapping table based on the second environmental parameter.

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