This project brings forward a passive bistatic radar (PBR) based on Galileo transmissions for maritime surveillance. The exploitation of existing transmissions for PBR applications is becoming increasingly attractive due to their low costs, covert operation, and reduced environmental pollution. Galileo is particularly suited for the proposed task since it comprises a satellite constellation, ensuring that any point on Earth is permanently illuminated by a number of satellites. This feature potentially enables surveillance both in coastal areas and the open sea. In this project a ground based receiver is considered for coastal monitoring while the receiver is placed on mobile platforms to assure open sea surveillance.
The feasibility of such a system will be evaluated and the required techniques will be studied and developed in order to propose an original and innovative solution to solve a major European problem using European technology.
The improvement of maritime traffic safety is a subject of growing interest; this problem has been tackled by many projects at European level. However, the existing systems are based on the use of AIS trasponders. This does not guarantee the identification of non-cooperative vessels, which can be responsible for many illegal actions, such as smuggling, illegal fishing, oil pollution, or illegal immigration by water. On the other hand, radar systems do not rely on any identification feedback from the vessel (e.g. AIS messages). Thus, radar systems are able to detect and identify non-cooperative targets.
Among radar systems, passive radars can perform this task without resorting to dedicated transmitters. Passive Bistatic Radars, in fact, exploit illuminators of opportunity as potential transmitters. Nevertheless, they guarantee low cost, null environmental impact and they are intrinsically covert. As there is no need for a dedicated transmitter, this makes PBR inherently low cost and hence attractive for a broad range of applications. The use of advanced and low impact technologies, such as space-based and terrestrial-based passive radar systems, makes it possible to improve the performance of current maritime surveillance systems. Moreover, by using many different existing sources, which complement one another, the global and continuous monitoring of a large area can be achieved.
A global maritime traffic surveillance can be obtained by combining the terrestrial asset, that is represented by the DVB-T and DAB based passive radars, with the space asset, which includes passive radars based on spaceborne illuminators. So doing, the former guarantees a standard radar coverage (i.e. VTS radar systems’ coverage), the latter allows for offshore coverage.
Broadcast transmitters in Geostationary Earth Orbits (GEOs) guarantee a constantly covered area. A drawback is that very long integration times (order of tens of seconds) are required to yield an acceptable Signal to Noise Ratio (SNR). However, in a maritime environment, such integration times are acceptable because of the slow motion of targets of interest.