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The Norwegian Defence Research Establishment and industry partners develop a new sensor concept for maritime surveillance by passive detection of X-band navigation radars from a micro-satellite in polar LEO. The Phase-A study was finished June 2001. According to the International Convention for the Safety Of Life At Sea (SOLAS), all vessels longer than 45 m are required to be equipped with X- band navigation radar. The proposed localization of vessels is based on in-orbit detection and processing of navigation radar signals, using precise direction-finding techniques for geolocation. The optimum sensor configuration is side viewing towards the horizon, giving an approximately 1200 km wide swath for detection of the radar's main lobe signal. From polar LEO, the sensor can cover Norwegian waters more than four times per day. This exceeds the coverage of existing SAR systems by more than a factor of four, and at a much lower price. An orthogonal microwave antenna array and a multi-channel receiver are used for acquisition of the radar signals. Utilizing advanced signal processing, the angle of arrival of individual pulses is determined with a precision that corresponds to an error smaller than 1 km in the geographic position. The orbit and attitude determination systems of the platform are high performance and closely connected to the payload, to give satellite position and orientation with knowledge or 15 m and 0.001 degree(s), respectively. A high degree of on-board autonomy is required to process the radar signals to user-data packets. The satellite provides a dedicated downlink channel to broadcast the vessel traffic data to compact user terminals in near real time.
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