Power and data transmission in an underwater vehicle for the monitoring of Malta Channel and marine protected areas

In this paper an underwater towfish vehicle, designed for environmental monitoring of Malta channel, is described. On board the vehicle, three different sensors are installed in order to monitor the values of nitrates, hydrocarbons, conductivity, temperature and pH of seawater. Each of these sensors is provided with RS232 serial interface to cope with a data acquisition board designed to collect and send the data recorded on board the vessel. The collection of data is accompanied by further specification: the exact time and location of sampling. For this reason, we make use of an underwater acoustic positioning system named 'USBL' (Ultra-Short Baseline), which, by exploiting the communication system through radio waves, detects the absolute position of the towfish from a vessel and calculates geographic coordinates. All instruments inside the vehicle are powered by a special towing cable provided with electric cables inside allowing both the passage of current for power supplying and data transmission. Finally, on board computer allows to monitor and display, in real time, the stream of data coming from the towfish acquisition system including all data detected by sensors, kinematic parameters, data concerning absolute and relative positioning, dynamic behavior, and manual/semi-automatic control strategy.