Detection of surface targets in sea clutter by shipborne radar

Doppler techniques do not aid detection by shipborne radar of small (drifting) surface targets in sea clutter, and such targets have no velocity spectrum distinguishable from that of the clutter. However, clutter decorrelation by rapid antenna scan, followed by camera or direct-view storage-tube integration, can give impressive gains in target/clutter visibility. With relative-motion displays, own ship´s motion severely limits possible integration time by shifting the effective spot area of integration as the target is approached; this is neatly avoided by using a `true-motion¿ display. Further gains may be possible (at least for hovercraft radar) by using an antenna with a vertical difference pattern in which the null is laid on the sea surface as a fence.