The development of gun-laying radar receivers type G.L. Mk.I, G.L. Mk.I* and G.L./E.F.

The paper describes the principal problems and features of the earlier G.L. receiver types. G.L. Mk.I and its sequel G.L. Mk.I* were conceived as an adjunct to optical methods of fire control, the radar information contributing only the range co-ordinate. This, however, was of sufficient importance to justify the programme on account of the directness and accuracy of the radar ranging process. The methods of exploiting these features by potentiometric scaling from the time base are described. Details of the radio receiver are given, including band-width figures, signal/noise ratio and cross-talk requirements. Some details of the elaborate potentiometer and the production problem which it constituted are described. The modifications constituting the G.L. Mk.I* are listed. The G.L./E.F. conversion equipment, by which the essential features and principles of G.L. Mk.II were grafted on to G.L. Mk.I is described in considerable detail. The paper concludes with a short account of the high-angle aerial system (or ¿Double Slowcock¿) for the G.L./E.F. equipment.