A seawater aquaculture net cage synchronous monitoring system and method based on a broadband frequency modulation sonar array

Abstract

This invention discloses a synchronous monitoring system and method for marine aquaculture cages based on a broadband frequency-modulated sonar array. Addressing the problems of poor performance of existing monitoring methods in turbid water and severe mutual interference when multiple sonars work together, the system of this invention includes multiple broadband rotating scanning sonars deployed along the vertical line of the center of the aquaculture water body, and a central control and processing unit. Each sonar has a built-in positive / negative frequency-modulated waveform program and a matched filter processor. The central control and processing unit assigns orthogonal transmission waveforms to adjacent sonars and achieves precise synchronous rotating scanning of all sonars through multi-threaded control; the sonar ends use matched filters to perform local processing of echoes, effectively suppressing adjacent channel interference; the central control and processing unit fuses the preprocessed data from each sonar to generate a three-dimensional acoustic image of the interior of the aquaculture water body. This invention solves the problem of multi-sonar co-frequency interference and achieves high data update rate and interference-free synchronous monitoring of the internal space of marine aquaculture cages and other facilities.

Description

Technical Field

[0001] This invention relates to the field of marine aquaculture monitoring technology, specifically to an acoustic system and method for monitoring the behavior, density distribution, and integrity of aquatic organisms inside large-scale marine aquaculture facilities (such as deep-sea cages, aquaculture vessels, and aquaculture platforms). Background Technology

[0002] With the development of marine ranching and deep-sea aquaculture, the scale of aquaculture cages, workboats, and platforms is increasing daily, with aquaculture water volumes reaching tens or even hundreds of thousands of cubic meters. Traditional video monitoring methods are severely limited by poor water light transmittance and short observation distances, failing to meet the need for all-time, all-area monitoring of large water volumes (especially at night or in turbid waters). Active sonar technology, due to its advantages of being unaffected by light and having a long detection range, has become an ideal alternative. However, applying sonar technology to the interior of enclosed or semi-enclosed aquaculture water bodies faces unique challenges:

[0003] 1) Spatial limitations and multipath interference: In limited, enclosed, and highly reflective aquaculture water bodies (net cages, boat holds), sound wave reflections caused by the inner walls of the net cages or holds, netting, and other structures create complex reverberation. The multipath interference and sonar interference problems are more severe and complex than in open water, greatly interfering with the target signal.

[0004] 2) Challenges of multi-sonar coordination: In order to achieve comprehensive and blind-spot-free coverage of large water bodies, it is usually necessary to deploy multiple sonars for monitoring. When multiple sonars work at the same time, the sound wave signals they emit will propagate and reflect in the complex water environment, causing one sonar to receive direct path interference or multipath reflection interference from the signals emitted by other sonars, which seriously confuses the target echo, resulting in disordered monitoring images, misjudgment or missed detection of targets.

[0005] 3) Coverage and cost balance: While simply increasing the number of sonars can expand coverage, it will significantly increase system cost, power consumption and data processing complexity, and the aforementioned interference problems will be exacerbated.

[0006] In existing technologies, single sonars are mainly deployed in facilities such as the walls of aquaculture tanks, resulting in large blind spots and limited monitoring range, making it impossible to assess the fish situation in the entire aquaculture water body; or a time-division multiplexing (TDMA) method is used to allow sonars to work in turn, but this sacrifices the real-time monitoring and data refresh rate, and cannot meet the need for synchronous monitoring of rapid fish behavior, real-time net status, etc.

[0007] Therefore, there is an urgent need for a new monitoring system and method that can achieve high resolution, high data update rate, and interference-free collaborative operation across the entire water body of large-scale aquaculture. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies and provide a system and method that can effectively suppress mutual interference between sonar arrays and achieve real-time synchronous monitoring of the entire aquaculture water body. Through innovative sonar array layout design, signal waveform design, and combined signal processing, this invention achieves clear and reliable real-time acoustic monitoring of the entire water body within confined spaces such as marine aquaculture cages.

[0009] This invention provides a synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array, characterized by comprising: a sonar array unit including at least two broadband rotating scanning sonars, the sonars being arranged along the center vertical line of the aquaculture water body to be monitored; and a central control and processing unit, communicatively connected to all sonars; wherein the central control and processing unit is configured to: allocate linear frequency-modulated signals with mutually orthogonal transmitted waveforms to adjacent sonars, and control all sonars to perform synchronous rotating scanning; each sonar is configured to: transmit the linear frequency-modulated signal allocated by the central control and processing unit, and process the received echo signal using a matched filter that matches its own transmitted signal to suppress interference from other sonars.

[0010] Preferably, the number of sonars N satisfies: N ≥ H / (2R·tan(θ / 2)), where H is the depth of the aquaculture water, θ is the vertical beam opening angle of the sonar, R is the expected detection radius of the sonar in the vertical beam opening direction, and the sonars are deployed at equal or non-equal intervals from top to bottom along the center vertical line of the aquaculture water to be monitored.

[0011] Preferably, the mutually orthogonal linear frequency modulation (LFM) signals include positive LFM signals and negative LFM signals with opposite signs of frequency modulation slopes, and the central control and processing unit is specifically configured to: assign positive LFM signals to odd-numbered sonars and negative LFM signals to even-numbered sonars, or vice versa.

[0012] Preferably, each sonar has built-in two transmission waveform programs, positive frequency modulation and negative frequency modulation, as well as a matched filter processor. The matched filter processor is used to perform local matched filtering processing on the received echo signal according to the transmission waveform configured for this sonar. The central control and processing unit is also configured to: receive the data uploaded by each sonar after local matched filtering processing, and fuse it based on the spatial position and real-time pointing information of each sonar to generate a three-dimensional acoustic image or a two-dimensional tomographic image of the interior of the aquaculture water body to be monitored.

[0013] Preferably, the central control and processing unit includes: a waveform control module, used to send waveform configuration commands to each sonar and assign orthogonal waveforms to adjacent sonars; a synchronization control module, used to control all sonars to rotate and scan synchronously by assigning an independent control thread to each sonar and sending synchronization commands based on a unified clock; a synchronization calibration module, used to perform orientation calibration after each rotation based on the position sensor data of each sonar; and a data fusion and imaging module, used to fuse the preprocessed data uploaded by each sonar and generate a three-dimensional acoustic image or a two-dimensional tomographic image of the interior of the aquaculture water body to be tested based on the spatial position and real-time pointing information of each sonar.

[0014] This invention also provides a method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array, characterized by the following steps: Step 1, determining the number of sonars N based on the depth H of the aquaculture water, the expected detection radius R, and the vertical beam opening angle θ of the sonar, and deploying the sonar array along the vertical line of the center of the water body, where N ≥ H / (2R·tan(θ / 2)); Step 2, configuring transmission waveforms with opposite frequency modulation directions for adjacent sonars in the array; Step 3, controlling all sonars to synchronously perform rotation scanning and signal transmission and reception, and performing position verification and fine-tuning in each rotation cycle based on the position sensor information of each sonar during the scanning process to ensure rotation synchronization in the next cycle; Step 4, performing matched filtering processing on the echo signals received by each sonar using filters that match its own transmission waveform to suppress adjacent channel interference; Step 5, uploading the processed data from each sonar to the central control and processing unit for fusion to generate monitoring information for the aquaculture water body.

[0015] Preferably, step 2 specifically includes: configuring a positive linear frequency modulation waveform for odd-numbered sonars and a negative linear frequency modulation waveform for even-numbered sonars, or vice versa.

[0016] Preferably, step 3 includes: the central control and processing unit controls the sonar to rotate synchronously by assigning an independent control thread to each sonar and issuing synchronization time commands to each thread based on a unified clock; and during the rotation process, periodic orientation calibration and fine-tuning are performed using the position sensors of each sonar.

[0017] Preferably, in step 5, the monitoring information includes three-dimensional acoustic images or two-dimensional tomographic images of the interior of the aquaculture water body.

[0018] Preferably, the method further includes analyzing three-dimensional acoustic images or two-dimensional tomographic images to extract three-dimensional density distribution, behavioral trajectories, individual size estimates, and / or information on the integrity status of aquaculture facilities of the cultured organisms.

[0019] Beneficial effects

[0020] Compared with existing technologies, this invention addresses the problems of poor performance of existing monitoring methods in turbid water, severe mutual interference when multiple sonars work together, and low data update rates. It completely solves the problem of multi-sonar co-frequency interference, achieving high data update rates and interference-free synchronous monitoring of the internal spaces of marine aquaculture cages and other facilities. It can acquire real-time data on fish distribution, behavioral trajectories, and facility status, providing a reliable technical means for the assessment of aquaculture biological resources, behavioral analysis, and facility safety monitoring. Specifically, this invention has the following significant advantages:

[0021] (1) Significantly suppress co-channel interference: Through orthogonal waveform design and local matched filtering, not only is adjacent channel interference suppressed on the direct path, but also multipath interference signals formed by reflections through netting, bulkheads, etc. are also suppressed. Thus, at the signal processing level, multiple sonars can work in parallel at the same frequency in dense space, realizing true synchronous real-time monitoring.

[0022] (2) Optimize system architecture and real-time performance: The matched filtering process is completed locally at the sonar end, which greatly reduces the data processing burden of the central processing unit, reduces the data transmission bandwidth requirements, and improves the overall system response speed and real-time performance.

[0023] (3) Optimized coverage and cost: Based on the quantitative layout method of water depth and sonar performance, the system achieves complete vertical coverage of the entire water body with the minimum number of sonars, avoiding resource waste and achieving high system cost-effectiveness.

[0024] (4) Improve imaging quality and synchronization accuracy: The broadband frequency modulation signal itself has high distance resolution. Combined with local matched filtering, it improves the overall signal-to-noise ratio and detection accuracy of the system while suppressing interference. Through threaded precise rotation control and closed-loop calibration of position sensors, the spatial synchronization of multi-sonar scanning is ensured, so that clear and stable acoustic images can still be obtained in complex multipath environments.

[0025] (5) Achieve panoramic three-dimensional perception: The system can output three-dimensional dynamic information inside the water body through high-precision synchronous acquisition and spatial data fusion, providing aquaculture managers with panoramic insights far exceeding two-dimensional plane or local point monitoring, thereby providing panoramic data support for refined aquaculture management decisions such as precise feeding, disease early warning and escape prevention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0027] Figure 1This is a flowchart of the synchronous monitoring method for marine aquaculture cages based on a broadband frequency-modulated sonar array in Embodiment 1 of the present invention.

[0028] Figure 2 This is a schematic diagram illustrating the application and deployment of the synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array in deep-sea cages, as described in Embodiment 2 of the present invention.

[0029] Figure 3 This is a waveform diagram of adjacent sonars using positive chirp-up and negative chirp-down signals in Embodiment 2 of the present invention;

[0030] Figure 4 This is a schematic diagram comparing the signals before and after matched filtering in Embodiment 2 of the present invention, demonstrating the suppression effect on adjacent channel interference. Detailed Implementation

[0031] The following describes specific embodiments of the present invention in conjunction with typical application scenarios. It should be noted that the following embodiments are merely for facilitating understanding of the technical solutions of the present invention and do not constitute a limitation on the scope of protection of the present invention. Those skilled in the art can make adaptive adjustments to the following embodiments without departing from the concept of the present invention, and these modifications all fall within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment aims to illustrate the basic structure and working principle of the system of the present invention, and provides a synchronous monitoring system for marine aquaculture cages based on a broadband frequency modulated sonar array, including a sonar array unit and a central control and processing unit.

[0034] The sonar array unit comprises at least two broadband rotating scanning sonars. These sonars are arranged at equal or non-equal intervals from top to bottom along the center vertical line of the aquaculture water body. The number of sonars N is determined by the depth H of the aquaculture water body and the vertical beam opening angle θ of each sonar using formula (1):

[0035] N≥H / (2R·tan(θ / 2)) (1)

[0036] Where R is the expected detection radius of the sonar in the vertical opening direction. Each sonar has a 360-degree horizontal rotation scanning capability and built-in programs for both positive and negative frequency modulation (FM) transmission waveforms, as well as a matching filter processor. Using this matched filter processor, the received mixed echo signal is processed by a filter that matches the sonar's own transmission waveform. Because the positive and negative frequency modulation signals have low cross-correlation, this processing can greatly enhance the echo of its own transmitted signal while significantly suppressing interference from adjacent sonar transmission signals.

[0037] The central control and processing unit communicates with all sonars, assigns orthogonal linear frequency modulated signals to adjacent sonars, and controls all sonars to perform synchronous rotation scanning, thereby unifying the array's operating timing, signal transmission, and data acquisition. This unit includes:

[0038] 1) Waveform Control Module: Through a unified control thread, waveform configuration commands are broadcast to each sonar based on its address, assigning either positive or negative frequency modulation (FM) waveforms to ensure orthogonality between adjacent sonar waveforms. Specifically, odd-numbered sonars are assigned positive FM (Up-Chirp) signals, and even-numbered sonars are assigned negative FM (Down-Chirp) signals, or vice versa. The bandwidth of the FM signal is sufficient to distinguish echoes from different sonars.

[0039] 2) Rotation control module: Each sonar is assigned an independent control thread, which sends rotation commands sequentially according to the sonar address. A command is sent once for each minimum rotation angle to ensure that all sonars rotate synchronously.

[0040] 3) Synchronization calibration module: Each sonar is equipped with a 0° position detection sensor. After each 360° rotation, the system calibrates the position of each sonar based on the position sensor data to ensure array synchronization.

[0041] 4) Data fusion and imaging module: Receives echo data uploaded by each sonar and processed by local matching filtering. Combines the spatial position and real-time pointing information of each sonar to perform data fusion and coordinate unification, and generates a three-dimensional acoustic image or two-dimensional tomographic image of the aquaculture water body.

[0042] This embodiment also provides a method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array, used to implement the above system.

[0043] Figure 1 This is a flowchart of the synchronous monitoring method for marine aquaculture cages based on a broadband frequency-modulated sonar array in Embodiment 1 of the present invention.

[0044] like Figure 1 As shown, the synchronous monitoring method for marine aquaculture cages based on a broadband frequency-modulated sonar array in this embodiment includes the following steps:

[0045] Step S1, Array Deployment Planning: Based on the depth H of the aquaculture water, the expected detection radius R, and the vertical beam opening angle θ of the sonar, determine the number of sonars N and their installation positions on the vertical line of the center of the water body, where N ≥ H / (2R·tan(θ / 2)).

[0046] Step S2, System Initialization and Waveform Configuration: Start the system. The central control and processing unit sends waveform configuration instructions to each sonar in broadcast mode and assigns different frequency modulation directions (one positive and one negative) to adjacent sonars according to the sonar address.

[0047] Step S3, Synchronous Scanning and Data Acquisition: The central control and processing unit controls the rotation of each sonar through independent threads. Using a high-precision system clock as the time reference, the central control and processing unit sends synchronized timestamps or pulse signals to the independent control threads of each sonar. The rotation drive units of each sonar execute angular steps according to this time reference, thereby achieving microsecond-level time synchronization, ensuring that all sonars rotate synchronously and transmit configured waveform signals while simultaneously receiving echo signals.

[0048] Step S4, Local signal preprocessing: Each sonar uses its built-in matched filter processor to perform matched filtering on the received raw mixed echo signal to obtain range-azimuth data after preliminary interference suppression, and uploads the preprocessed data to the central control and processing unit.

[0049] Step S5, Central Data Fusion and Imaging: The central control and processing unit receives the preprocessed data uploaded by all sonars, combines the real-time horizontal rotation angle, vertical position and azimuth calibration information of each sonar, performs data fusion and coordinate unification in space, and constructs a three-dimensional acoustic image or two-dimensional tomographic image of the aquaculture water body.

[0050] Step S6, Synchronous Calibration: During the scanning process, the current transducer orientation is obtained using the position sensors built into each sonar. Position verification and fine-tuning are performed in each rotation cycle according to the preset 0° calibration point to ensure synchronous rotation in the next cycle.

[0051] Step S7, Information Extraction and Application: Analyze the generated three-dimensional acoustic images to extract information on the density distribution, individual size, behavioral trajectories (such as aggregation and dispersion) of farmed organisms (such as fish schools), as well as the integrity of aquaculture facilities (such as netting).

[0052] Example 2

[0053] This embodiment uses a circular deep-sea aquaculture cage as an example to specifically demonstrate the application of the present invention.

[0054] Figure 2 This is a schematic diagram illustrating the application and deployment of the synchronous monitoring system for marine aquaculture cages based on a broadband frequency modulated sonar array in deep-sea cages, as described in Embodiment 2 of the present invention.

[0055] like Figure 2As shown, a cylindrical deep-sea cage with a diameter of 50 meters and a depth of 40 meters is used. A broadband rotating scanning sonar with a vertical beam opening angle θ of 30° is selected, with an expected detection radius R of 25 meters (covering the edge of the cage). Calculated according to formula (1) in Example 1:

[0056] N≥40 / (2×25×tan(15°)) ≈2.99

[0057] Therefore, at least three sonars are required. To improve coverage uniformity, ensure some overlap between vertical beams, and avoid monitoring blind spots, one more sonar is added to the minimum number during actual deployment, resulting in a total of four sonars (T1-T4). On the vertical line in the center of the cage, starting from the water surface, one sonar is placed approximately every 8 meters, for a total of four sonars (numbered T1-T4).

[0058] Figure 3 This is a waveform diagram of adjacent sonars using positive chirp-up and negative chirp-down signals in Embodiment 2 of the present invention.

[0059] Figure 4 This is a schematic diagram comparing the signals before and after matched filtering in Embodiment 2 of the present invention, demonstrating the suppression effect on adjacent channel interference.

[0060] The central control and processing unit configures positive frequency modulation (FM) signals for T1 and T3, and negative FM signals for T2 and T4 via broadcast commands. A waveform comparison of the positive and negative FM signals used by adjacent sonars can be found here. Figure 3 All sonars are synchronously started under independent thread control of the central control and processing unit, rotating and scanning at a speed of 30 revolutions per minute. The raw echo received by T1 contains its own signal echo (strong), interference from T2 (weak, due to waveform orthogonality), and interference from T3 / T4 (even weaker). T1's local matched filter processor processes this mixed signal using a positive frequency modulated matched filter. The suppression effect of matched filtering on adjacent channel interference can be found in [reference needed]. Figure 4 This significantly suppressed interference from adjacent channels such as T2, resulting in clear preprocessed data (including distance-azimuth information) for the T1 detection area. After the four preprocessed data streams were uploaded to the central control and processing unit, they were fused to generate a real-time dynamic map of the three-dimensional distribution of the fish population within the entire cage. Each rotation involved the sonar's position sensors reporting their azimuth angles, which the central control and processing unit compared and fine-tuned to ensure synchronization for the next cycle.

[0061] Example 3

[0062] This embodiment uses the cabin of an aquaculture vessel as an example to specifically demonstrate the application of the present invention.

[0063] For rectangular aquaculture pods on aquaculture vessels, the sonar array is placed at the intersection of the two diagonals of the pod, arranged perpendicularly to the centerline of the pod. Matched filtering preprocessing is performed locally on the sonar. The data fusion algorithm of the central processing unit needs to transform the preprocessed sonar data from the spherical coordinate system to a Cartesian coordinate system with the pod as the reference, generating easily observable longitudinal and transverse sectional views of the pod. The system focuses on monitoring whether the fish distribution is uniform and whether there are any abnormal clusters. By comparing three-dimensional data from consecutive time frames, the system can further analyze the movement speed and direction of the fish school, achieving behavioral trajectory tracking.

[0064] The core signal processing principle upon which this invention relies is as follows: Let the expression of the transmitted positive frequency modulated signal be:

[0065] (2)

[0066] The negative frequency modulation signal is:

[0067] (3)

[0068] In the formula, Let be the center frequency, k be the frequency modulation slope, and t be time. The peak value of its cross-correlation function is much lower than the peak value of its autocorrelation function, which is the theoretical basis for interference suppression. Matched filtering utilizes this characteristic to effectively suppress orthogonal interference at the sonar end.

[0069] The above description is only an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array, characterized in that, include: A sonar array unit includes at least two broadband rotating scanning sonars, which are arranged along the center vertical line of the aquaculture water body to be monitored. as well as, The central control and processing unit is communicatively connected to all of the sonar arrays. The central control and processing unit is configured to: allocate linear frequency modulated signals with mutually orthogonal transmitted waveforms to adjacent sonars, and control all sonars to perform synchronous rotation scanning; Each sonar is configured to transmit a linear frequency modulated signal allocated by the central control and processing unit, and to process the received echo signal using a matched filter processor that matches its own transmitted signal to suppress interference from other sonars. The number of sonars, N, satisfies: N ≥ H / (2R·tan(θ / 2)), where H is the depth of the aquaculture water to be monitored, θ is the vertical beam opening angle of the sonar, and R is the expected detection radius of the sonar in the vertical beam opening direction. The sonar arrays are deployed at equal or non-equal intervals from top to bottom along the vertical line of the center of the aquaculture body to be monitored.

2. The synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 1, characterized in that: in, The mutually orthogonal linear frequency modulation (LFM) signals include positive LFM signals and negative LFM signals with opposite signs of their frequency modulation slopes. Furthermore, the central control and processing unit is specifically configured to: assign positive linear frequency modulation (LFM) signals to odd-numbered sonars and negative LFM signals to even-numbered sonars, or vice versa.

3. The synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 1, characterized in that: in, Each sonar has built-in programs for both positive and negative frequency modulation transmission waveforms, as well as a matched filter processor. The matched filter processor is used to perform local matched filtering on the received echo signal according to the transmitted waveform configured for this sonar. The central control and processing unit is also configured to: receive data uploaded by each sonar after local matching and filtering, fuse the data based on the spatial position and real-time pointing information of each sonar, and generate a three-dimensional acoustic image or a two-dimensional tomographic image of the interior of the aquaculture water body to be monitored.

4. The synchronous monitoring system for marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 1, characterized in that: The central control and processing unit includes: The waveform control module is used to send waveform configuration commands to each sonar and assign orthogonal waveforms to adjacent sonars. The synchronization control module controls all sonars to rotate and scan synchronously by assigning an independent control thread to each sonar and issuing synchronization commands based on a unified clock. The synchronous calibration module is used to perform orientation calibration based on the position sensor data of each sonar unit after each rotation. The data fusion and imaging module is used to fuse the preprocessed data uploaded by each sonar and generate a three-dimensional acoustic image or a two-dimensional tomographic image of the interior of the aquaculture water body to be monitored based on the spatial position and real-time pointing information of each sonar.

5. A method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array, characterized in that, Includes the following steps: Step 1: Determine the number of sonars N based on the depth H of the aquaculture water body to be monitored, the expected detection radius R, and the vertical beam opening angle θ of the sonar, and deploy the sonar array along the vertical line of the center of the water body, where N ≥ H / (2R·tan(θ / 2)). Step 2: Configure transmission waveforms with opposite frequency modulation directions for adjacent sonars in the array; Step 3: Control all sonars to perform synchronous rotation scanning and signal transmission and reception. During the scanning process, perform position verification and fine-tuning in each rotation cycle based on the position sensor information of each sonar to ensure synchronous rotation in the next cycle. Step 4: For the echo signals received by each sonar, matched filtering is performed using a filter that matches its own transmitted waveform to suppress adjacent channel interference. Step 5: Upload the data processed by each sonar to the central control and processing unit for fusion to generate monitoring information for the aquaculture water body.

6. The method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 5, characterized in that: in, Step 2 specifically includes: Configure a positive linear frequency modulation waveform for odd-numbered sonars and a negative linear frequency modulation waveform for even-numbered sonars, or vice versa.

7. The method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 5. Its features are: in, Step 3 includes: The central control and processing unit controls the synchronous rotation of the sonar by assigning an independent control thread to each sonar and issuing synchronization time commands to each thread based on a unified clock. During the rotation process, the sonar position sensors are used to perform periodic orientation calibration and fine-tuning.

8. The method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 5, characterized in that: in, In step 5, the monitoring information includes three-dimensional acoustic images or two-dimensional tomographic images of the interior of the aquaculture water body.

9. The method for synchronous monitoring of marine aquaculture cages based on a broadband frequency-modulated sonar array according to claim 8, characterized in that: in, Further, it includes analyzing the three-dimensional acoustic images or two-dimensional tomographic images to extract the three-dimensional density distribution, behavioral trajectory, individual size estimation, and / or the integrity status information of the cultured organisms.

Images