Research And Development On The Data Acquisition And Transmission System Of Water Quality Of Deep Water Cage Culture

With the gradual shortage of marine wildlife, seafood supply is increasinglydependent on marine aquaculture, while the traditional mariculture model with a historyof many years has been on the verge of the developing limit. Since the60s and70s in thelast century, Japan, Norway and other countries have explored a new aquaculture model-deep water cage culture with some success, the other coastal countries also follow todevelop this technology.Deep water cage culture is characterized with high-investment, high-risk,high-yield and so on, which mainly involves such frontier technologies as new material,digital design and manufacture, automatic equipment control and digital management.Among them the automatic monitoring technology, which consists of two maintechnologies as data acquisition and transmission, is the core technology of the digitalmanagement. So, the countries all over the world pay increasing attention to the researchinto the data acquisition and monitoring in cages. However，most of these data collectedare related to culture object or facilities, only a small portion of them to the water qualitywith problems as a single object, high cost, lower practicality, and difficulty in applyingto the deep cage aquaculture. In view of this situation, this paper studied and developedthe automatic acquisition and transmission system of the sea water temperature, PH valueand dissolved oxygen with their important roles in aquaculture.In order to acquire water temperature, PH value and dissolved oxygen timely,accurately and reliably, by analyzing the environmental characteristics of deep watercage culture, a systematic design scheme able to automatically collect those water qualitydata and send them wirelessly to the receiver located on the land was put forward. Butthe data transmission from cages to the land server belongs to remote communication andthere are too many cages, so, it will increase costs if the cages communicate directly withthe server. Therefore, the system combined short with long distance transmission, namely,the data first collected from multiple cages are sent wirelessly to the mariculture platform,and then sent together to the land server from the PC fixed at the mariculture platform. Consequently, the data acquisition terminals at cages, the host computer and the methodof communication are needed for respective study and development.The main work and the results of the research in this paper are as follows:（1）The research into data transmission.According to the analysis for the functional requirements of the system,environmental characteristics, transmission distance and staff labor intensity, etc,traditional wireless transmission is difficult to meet the communication requirements inall respects from acquisition terminals to the host computer, so, the new-emerging Zigbeewith strong anti-interference ability and flexible network organization was used as thefront short distance data transmission network while the GPRS network with strongability of automatic restore and the function of retransmission in the event of delay wasused to transmit the data from the host computer at the mariculture platform to the landserver. On the basis of the research into the two communication networks, this paper putsforward a solution for its own data transmission system. The result of its running andtesting shows that the network works very well in real-time performance, reliability andautomatic restore ability.（2）the development of hardware and software at the acquisition terminal.The acquisition terminal involves power-supply system, temperature, PH value,dissolved oxygen acquisition modules and an acquisition card. In hardware, becauseenergy supply on the sea is not easy，the paper designed a set of power solutionapplicable to the data acquisition and transmission system. For data acquisition, becausethe original signal is weakly acquired by temperature, pH value, dissolved oxygensensors, the existing cheaper temperature magnifier was selected while the specialcircuits for the conditioning of PH and dissolved oxygen were designed. In order toeasily update, maintain and reduce developing costs, a PIC16F877A microcontroller waschosen as the core component of the acquisition card, and the peripheral circuits andcommunication circuit of the acquisition card were designed. In software, under theMAPLAB IDE v8.40development environment, the C-language was employed todevelop the AD acquisition program, data transmission program and their auxiliaryprograms. Finally，the testing result shows high real time and accuracy.(3)The design of the host’s software.At the mariculture platform, a PC was chosen as the host computer, so only itssoftware needs to be designed. The LabVIEW was chosen to design the PC’s software forconverting the data acquired into the physical quantities of corresponding parameters andadding temperature compensation to PH, then displaying, storing andsending them to the land server, also sending acquisition orders to the acquisition terminals. The testdemonstrats the software meets the functional requirements.The innovations of this paper are the following two main points:（1）The terminal acquisition equipment with high integration, low cost, goodextensibility and practicability has been developed.（2）Atransmission scheme for multi-sites acquisition is devised.Through the work in this paper, the developed system of seawater quality dataacquisition and transmission can be used to collect temperatures, PH values anddissolved oxygen of seawater timely, automatically and accurately, and can be extendedto acquire other data when needed. With the later information processing in the landserver, it will realize the remote automatic monitoring of deep water cage aquacultureand the further development for the digital expert management system of the deep watercage culture.