Patent GB-1061568-A (GB)
Title: Improvements in and relating to position plotting apparatus for use in conjunction with radar
Inventor: PARRISH JOSEPH REGINALD
IPC: G01S1/02
Filed: 1962-12-21
Abstract: 1,061,568. True motion radar display. AUTOPLOT Ltd. Dec. 18, 1963 [Dec. 21, 1962], No. 48355/62. Addition to 878,901. Heading H4D. [Also in Division G1] Permanent relative motion and true motion plots are simultaneously produced from a C.R.T. radar display by means comprising two superposed plotting sheets 3 and 4, Fig. 4, one sheet 3, moving with respect to the other in a manner corresponding to the motion of the radar carrying craft, and a marking device 9, movable to a position with respect to the other sheet 4 corresponding to the position on the C.R.T. display, of the response to be plotted, to simultaneously produce aligned marks on both plotting sheets. The upper sheet 3, on which a true motion plot is produced, is moved in one direction, corresponding to a component of the motion of the radar-carrying craft, by rollers 5, whilst the relative motion between the two sheets in the orthogonal direction, to represent the other orthogonal component, is produced by the movement of the marking device and lower sheet 4, both mounted in a carriage 20, by means of a rack-and-pinion drive 6. The marking device 9 comprises an electrical heating element travelling along a gantry 7 which in turn is rotated about a point representing the radar-carrying craft. The position of the marking device along the gantry represents the range of the plot, and is controlled by gears 33 and 34, whilst the angular position of the gantry representing the bearing of the plot is controlled by gears 18 and 19. Both movements are made in correspondence with a bearing curser or strobe and a range marker,: provided on the C.R.T. screen and operated by a control personnel until a desired response is intercepted on the C.R.T. screen, whence a button is pressed and the heating element in the marking device energized. The lower sheet 4 comprises a sheet of red plastic, through which the heating element burns a hole. The upper sheet 3 is a roll of paper, which is marked by a burn hole, or by the deposit of the products of the burning of the lower sheet. A central hole is provided in the lower sheet through which a second heating element marker 8 protrudes, to produce marks on the upper sheet representing the path of the radar carrying craft. Symbols representing the time of these latter plots may also be produced by the central marker 8. The sheets are illuminated by a panel 10 of electroluminescent material having a radial slot for the movement of the marker 9. The relative motion plots therefore show as a bright series of dots against a red background whilst the true motion plots appear as dark dots superimposed thereon. Facilities are provided for using various maximum displayed ranges and a simple electromechanical computer may control the movement between the two plotting sheets, from information from compass instruments &c. At night-time during non-critical situations, the brightness of the panel 10 may be reduced so that only the relative motion display is visible. The brightness may be increased to show both plots when collision avoidance manoeuvres are necessary.