A Expanding Design of Environmental Monitoring System for Net Cage Culture

• Main Authors: chao-ming chou, 周昭明
• Other Authors: Chung-Cheng Chang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/56946465519277100045

碩士 === 國立臺灣海洋大學 === 電機工程學系 === 99 === For developing environmental monitoring system of large cage aquaculture which is EVER SPRING MARINE AQUACULTURE CO.,LTD , we expand to 200 sampling sites system. There are 25 sampling sites in existing automatic cage .In this study, we use 89S52 controller and high resolution ADC to read the output voltage which is between 0 and 5 volts. We also design 200 channels scanning circuit which includes 13 CD4067 multiplexers and two 74LS244 buffers. Three models of cages are designed for this study. The first model contains one main cage installed four temperature sensors、one pressure sensor and one flow meter. The second model includes four vice cages; each vice cage is installed four temperature sensors and one pressure sensor. The third model, which is called extended cage model, includes seven extended cages. There are five sensors in each extended cage .every sensor in the extended cage can simulate one cage . The system includes the capacity of 200 sampling sites. Therefore, total of 40 cages are used for the model The temperature sensor circuit was used to measure the output voltage at room temperature .The average calculated output voltage is about 2.53V, the change rate for each centigrade C is 100mV/℃ , the output voltage will be divided into 1023 equal parts and converted to ASCII code by using AD7810 10bits ADC. Therefore, temperature division is 0.0488℃,voltage division is.00488 V. 2.7 V would be the reference voltage of differential amplifier .When the temperature of sensors is at 50℃, the average output voltage is 4.86Volt, therefore it can be a temperature sensing range of -3.15℃±1℃~50℃±2℃. 100Ω resistor load was added to the pressure sensor output, the current output of pressure sensor is 4mA ~ 20mA.The voltage on the resistor was obtained by differential amplifier , the voltage drop of pressure sensor is available from 0.4V to 2V when water depth is 0 to 10m,slope rate of water depth is 0.16V/m. Finally, the test and water tank experiments were done to verify the system function. LabView was used to display temperature and water depth, then the 200 multi-channels cage environment detection system was finished.