High-resolution radar scattering characteristics of a disturbed sea surface and floating debris

A study was made of high-resolution radar returns from a disturbed sea surface and from rigid debris floating on such a surface. The goal was to determine if there are differences between the scatter from the sea and that from debris that would permit sea return to be suppressed and debris return to be detected. The study involved both theoretical and experimental efforts. Measurement revealed that sea return was relatively improbable in any given resolution cell and that when it did occur it lasted only a second or two. Also, such return was always heavily amplitude modulated with modulation frequencies much higher than those on debris echoes. These findings were explained theoretically and used in developing a debris-avoidance radar concept for high-speed ships.