Aquaculture Feed buoy Control - Part 2: Telemetry, Data Handling and Shore-Based Control

A critical part of an aquaculture operation is feeding the fish the right amount of food at the right rate at the right time, and monitoring this operation and the environmental conditions at the site. The UNH Open Ocean Aquaculture demonstration project is working on its third automated, remote feeding buoy for offshore aquaculture. A central part of the buoys is the control system, consisting of (1) a computer and software in the feed buoy controlling operations, (2) the two-way telemetry link between the offshore buoy and shore station with its supporting computers and Internet links back to UNH and the (3) the user friendly interface at a control center. All the activities monitored by the controller in the feed buoy are stored in files each hour in the buoy to document what has happened. These files are relayed hourly to shore by a 900 MHz spread spectrum telemetry link. When this data is received on shore it is stored on a computer, and at regular intervals sent to the UNH campus for archiving and study. Also, the real-time data is relayed via an internet link to the control center, so that the current drawn, amount of feed supplied, etc. can be monitored. New files that control the timing of activities and control an activity can be created at the control center to alter a programmed activity based on observations of the offshore system status. These files are automatically sent to the coastal shore station and relayed to the feed buoy at the start of the next hour's cycle. Thus, feed buoy activities can be regularly altered in response to monitoring of the fish. The system also monitors such environmental quantities as the depth of the cage with a pressure sensor and the temperature of the water at three depths in the fish cage to warn if it is too warm for the fish, and thus provide a record of the environment around the fish. A system of video cameras in the fish cage observes the fish before, during and after feeding to evaluate the feeding program and fish activity. The video images are captured, compressed, and telemetered to shore to the control center. While the 900 MHz link can handle the routine transfer of data and files, this link is not able to provide the continuous real-time images desired by operations managers. A 2.4 GHz radio utilizing 802.11b protocol with a 24 db gain antenna on shore could not reliably telemeter data the 7.5 nm from the buoy to shore. The third feed buoy is evolving using all of the previously learned knowledge and incorporating several new technologies that will aid in the difficult task of offshore aquaculture. Most importantly, new telemetry equipment that utilizes the current 900 MHz spread spectrum band at higher bandwidth will yield a robust communications package that will allow for better control and monitoring of the offshore feed systems