Alternative term: F.M. radar
A form of radar in which the radiated wave is frequency modulated, and the frequency of an echo is compared with the frequency of the transmitted wave at the instant of reception, thus enabling range to be measured.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Centre of buoyancy
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM