GB739797A - Improvements in or relating to radar simulation apparatus - Google Patents

Abstract

739,797. Radar trainers. COMMUNICATIONS PATENTS, Ltd. July 20, 1954, No. 21137/54. Class 40 (7). A radar trainer giving a display simulating the appearance of echoes from target objects and also of interference, for example sea clutter, comprises a display screen on which is combined an image of the interference derived from a cinematograph film and an image of object echo indications derived from a cathode-ray tube display. In one embodiment the images on a continuous loop of film 3 showing the appearance of sea clutter on a P.P.I. are piojected by a projector 4 on to a half-silvered mirror 5 at 45 degrees to the axis and focused on a ground glass display screen 6. The length of film is such as to show an integral number of complete P.P.I. scans so that the radial brightening line appears to rotate uniformly. A projection type cathode-ray tube 7 is provided with a rotating deflection coil 8 fed from saw-tooth generator 9. Suitably tuned brightening pulses are fed to the control grid 10 to simulate radar echoes and the resulting display is projected by lens system 11 through mirror 5 on to screen 6 where it is combined with the projected display. To synchronize the scanning of tube 7 with the movement of the radial brightening line of the projected image a mechanical connection 12 is provided. The signals applied at 10 may be obtained from a radar system or they may be produced synthetically. If the tube 7 has target indications produced by steady deflection potentials, or a switched series of such potentials, the linkage 12 may be omitted. The ground glass screen may be replaced by a phosphor screen excited by the light or infra-red rays projected on to it from the projector 4 and tube 7.