Study On An Underwater Acoustic Remote Monitor System For Bred Fish In Net Cages Of Deep Water

With the development of coastal water fish culture, the shortcoming that traditional fish culture in net cage there exists in itself also reveals more and more obvious ,like the little output, kind of bad quality, environmental pollution, etc. To keep developing in sea aquaculture, it is necessary to develop fish culturing in net cages of deep water. Nowadays, this technology is being popularized in coastland of the whole country. But it is difficult for fisher folks to check that weather the fish is still in the cage or not by their eyes, because of the feculent water and its depth. So it is urgency for us to research and develop fish monitoring device in deep-sea cage, which could ring the alarm in time once fish escape. As the deep-sea cages move to the zone far away from the seashore and cover more and more areas on sea, a higher requirement for fish monitor is proposed at the same time. It is that fish monitors must be more intellectualized and integrated. The paper focuses on studying remote monitoring fish in deep-sea cage far from the shore base on summarizing the methods of fish monitoring and analyzing its difficulties. The paper introduced current status of deep-sea fish monitoring home and abroad,analyzed methods of fish monitoring, discussed the way to extract fish echo from noise and reverberation, and proposed a system to monitor fish in deep water far way base on wireless module. Finally, an industrialized system is designed preliminarily. The system can be divided into two parts. One is local device on sea, the other is central computer in the monitoring station. The local device is made up of signal emission circuit, echo-receiving circuit, and data acquisition ,storage circuit. Communication between local device and central computer is realized in wireless module. The local device executes orders that were sent from central computer. And the data sent from local device was processed and displayed in the form of picture on central computer.The experiments in a water pool and net cages in sea area of Xiamen and Quanzhou-Weitou are performed. The experimental results show that the blind area is about 0.8 to 1 meters, the instrument is reliable, simply operated, and parameters can be changed freely. Data processing and display in real time goes well on the central computer which is in the station within 500 meters from net-cagesThe innovation of the paper is that communication between local devices on sea and central computer is realized in wireless module and a convenient operation platform based on VB is developed on central computer. So it avoids the bothering of arranging cable in the sea, and makes entire system divide the work clearly. Further more the system which is easy to be configured and maintained, adapts to the working circumstance on sea.