ABSTRACT
As a historical backdrop to the problem of position fixing at sea it should be understood that prior to the introduction of differential mode global positioning, there were four categories of radio and electronic positioning systems.1 The first of these was the hyperbolic method developed originally in World War II for aircraft navigation and ship positioning. The aircraft system was known as GEE2 and the precursor system to the Decca Navigator was first used during the Normandy landings in June 1944. Various hyperbolic survey navigation systems were developed in the 1950s-70s. These included Raydist, Rana, Toran, Lambda and Decca systems such as Hi-Fix, Hi-Fix 6 and Hyperfix. Systems such as Pulse-8 and Loran were time comparison as opposed to phase comparison hyperbolic systems.
