In about 1946 work was begun both in the United States and in the United Kingdom on the development of radar beacons which could be used to make certain required points more conspicuous and to increase their detection range.

Two basic types of beacon were considered: ramarks, which are intended to give bearing information only and which appear on the PPI as a bright radial line passing through the position of the ramark, and racons, which give range as well as bearing information. The range information is given by die beacon transmitting one or more short pulses, the first of which appears on the PPI at the correct range and bearing of the beacon.