Research And Experimental Verification On Key Technologies Of Wideband Split-beam Fish Finder

The wideband split-beam fish finder is an important tool for the rational assessment of the current status of fishery resources,the monitoring of marine pastures,the monitoring of large-scale cage fish farming,and fish behavior.It is also an indispensable instrument for Marine observation carried out by surface fishery ships in the three-dimensional observation system constructed by "transparent ocean" project.In this paper,the research content is Qingdao Marine science and technology fund,director of the national laboratory project as the foundation,to develop wideband split beam sounder key technology research and test,in combination with scientific sounder research status and development trend at home and abroad,in accordance with the need of efficient and accurate detection of Marine fishery resources,wideband split beam sounder detection performance prediction model is put forward,and the MATLAB software simulation analysis under different background;To carry out research on the principle of cross-correlation time delay and split beam space positioning;Combined with the characteristics of Marine fishery detection target,the application of wideband signal and pulse compression technology in range resolution and single fish target recognition was studied.The acoustic test platform was built,the pool test was carried out,and the performance of the algorithm was verified,which laid a foundation for the later development of the wide-band split-beam detector.The main contents of this paper are as follows:(1)In order to anticipate the influence of different parameters on the detection performance of the wideband split-beam fish finder,the basic principle is described in detail and the system architecture diagram is given.On this basic,according to the detection method and active sonar equation,the key parameter expressions such as sound source level,propagation loss,environmental noise,volume reverberation,detection domain,and directivity are clarified,and the volume reverberation under noise background is given Effective range prediction model under background,noise background and volume reverberation background.Then has carried on the simulation and analysis of the detection performance under different background,compared the narrowband and broadband system ability to resist reverberation,the frequency of different sea condition is obtained for different target strength fish detection performance,the influence of broadband system has the ability to resist reverberation,actual use environment,the influence of different parameters on the detection performance,wideband division of long-distance,high resolution sounder development provides the improvement direction of the wideband split-beam fish finder.(2)The application of split beam technology and wideband signal in fishery was studied.According to the working mode of the fish detector and the ultra-short baseline positioning technique,the solution formula of the target fish's spatial position is given.The fuzzy function characteristics of LFM and the application of pulse compression technology in single fish target recognition are analyzed.The target recognition criterion of single fish in wideband system is proposed.(3)According to the requirements of the subject,the detailed parameters of the instruments needed for the acoustic test platform were given,and the acoustic test platform was built in the silencer tank of the fishery machinery and instrument research institute.The algorithm proposed in this paper is applied to this platform to realize the cross-correlation delay estimation.In the pulse compression range resolution test,two 36 mm alloy balls were used to hang and drop along the direction of the acoustic axis and get closer and closer,and the target discrimination effect after uncompressed and pulse compression was observed.The actual test results were consistent with the theoretical analysis results of MATLAB simulation.The criteria of single fish target amplitude screening and single target overlapping echo recognition in broadband system are proposed.