Technology for wireless sensor networks under water

Unauthorised underwater activities can be made increasingly silent and can vary from traditional submarines to UUV:s and divers. The needs are also changing from stationary equipment, for reconnaissance, to rapidly deployable. The aim with the project "distributed detection" is to respond to those needs and to enable surveillance of areas at sea, as well in harbour and costal areas. The proposed method is based upon a number of sensor nodes placed at the bottom, in the area under surveillance, by means of for example a ship or an AUV. The nodes are without any wired connection but communicate by underwater communication to achieve secure detection, tracking and classification. To realize such a system there are mainly five areas that need to be studied: localization of nodes, target features, distributed detection, communication and implementation. The nodes must localize themselves after deployment. One section in the report is about technology for that. The lion's share of the work has been put down on detection since this is a key issue. The project has developed a new detection algorithm for mutually communicating sensor nodes. Its performance has been evaluated by simulation in a few cases. As is clear, with a large probability it is possible to detect relatively quiet submarines with a distance between nodes of a few hundred meters. The report is concluded with recommendations about future activities in the area.