Sea surface target detection in 3D coherent radar

One of the challenging tasks of 3D coherent radar is to detect sea surface target in the case, when radar is deployed at the shore. The Radar Cross-Section (RCS) of small objects, such as lifeboat, is at the level of several square meters (0 - 6 dBsm). At the same time the radar has to detect big ships with effective RCS at the level of 30-50 dBsm. The sea clutter level strongly depends on sea state and varies from -30 dBsm for calm sea to 10 dBsm for high sea state. The Doppler processing in case of sea targets is only of little help, while in many cases targets can be motionless or move with very low radial velocity, comparable with wave velocity. The paper presents the idea of joining coherent and non-coherent processing to improve the detection of small sea targets at high sea state, ensuring the false alarm rate at the level acceptable by tracker.