Sea Border Surveillance

Project SeaBILLA aims to the improvement of the European Sea Borders Surveillance, toward the employment and integration of heterogeneous sensors belonging to land, sea, air and space segments. Besides the development and management of the SeaBILLA website and repository, the role of RaSS within the project concerns definition and the study of a distributed maritime radar network given by a fleet of AIS-equipped co-operating vessels. Such proposed system, referred to as “Radar Network of Co-operating Vessels” (RNCV), exploits the presence of a navigation radar and of an AIS transceiver on board of service and commercial vessels, gathering radar plots from moving sensors and processing this information to periodically update an electronic chart with both the AIS traffic and the not-AIS, but detected traffic.


The proposed system is an experimental one and the primary scope of our research is to evaluate the contribution in terms of space/time radar coverage provided by the RNCV on a given scenario, in a given time interval. In order to accomplish this task we employ real AIS data gathered by MSSIS and pre-processed by NATO’s CMRE and we define several virtual fleets of co-operating vessel in order to observe the consequent behaviour of the relative time radar coverage maps.


Fig. 1 shows a simplified sketch of the RNCV system, while Fig. 2 shows on the right the cloud of AIS plots collected by MMSI during 1 month of spring 2012. These data are pre-processed by the CMRE to define routes and suppress anomalies.
After this initial analysis, three different categories of marine traffic are defined: “commercial” (ships following the route Suez-Gibraltar and vice-versa); “service 1” (ships running from an harbour to a different harbour, or offshore platform, within the considered area) and “service 2” (ships making a round trip from and to the same harbour).


Fig. 3 shows the recurrence of AIS plots for the considered vessels and the tracks of three potential RNCV fleets composed by 10 ships belonging respectively to the three categories.


Fig. 4 and 5 show the space/time radar coverage map of the system in several configuration, varying the number and the nature of the ships employed in the co-operating network. The palette indicates the percentage of time during which a given point is covered by at least one co-op. ship-borne radar, with respect to the total duration of the dataset.