Patent GB-1015673-A (GB)
Title: Improvements in radar simulation displays
IPC: G09B9/40
Filed: 1961-11-24
Abstract: 1,015,673. Radar simulators. GENERAL PRECISION Inc. Nov. 24, 1961 [Nov. 25, 1960], No. 42121/61. Headings H4D and H4F. The invention relates to a radar training apparatus, including a terrain model and a closed circuit television system, for simulating a forward-looking aircraft radar display, the object of the invention being to simulate a controllable clearance plane display (that is only those terrain features which lie above an arbitrarily chosen level will be displayed) and to simulate slant range distortion (that is both the peak and base of a mountain have the same slant range and thus give rise to a single intense radar blip) as in an actual aircraft. General features.-A silicon rubber belt 11 fabricated in layers corresponding to the contours of the terrain is driven by the servocontrolled motor 19 past a cathode-ray tube flying spot scanner 20. The pencil light beam 12 from the scanner 20 is focused by the lens 21 which represents the position of the simulated aircraft. The scanner 20, lens 21 and vidicon pick-up tube 13 are mounted on a single carriage 23 which is movable vertically, laterally and angularly with respect to the belt 11 to simulate the attitude of the aircraft. Mode of operation.-The flying spot scanner 20, the camera 13 and the display monitor 14 are each controlled by a waveform generator 28 to simultaneously scan equal azimuthal sectors, the rate of radial scan of each device being different. The radial frequency of the flying spot scanner 20 is 180 lines a second each line being separated from the next by 1 degree. As the beam of light 12 from the scanner 20 moves radially a signal α is generated by a ramp function generator 33 proportional to its angle of deflection from the vertical. This signal α together with a constant signal corresponding to the initial condition a = 0 is fed to a computer 39 which generates a signal proportional to sin α and then to a multiplier 40 which multiplies the sin α information by a constant V 0  representative of the scanning velocity of the display tube 14. The camera 13 and the display tube 14 are each controlled by the " sync " generator 36 to scan at a line frequency of 15 kc/s. but the radial timebase generator 41 of the camera 13 is also supplied with the signal proportional to V o  sin α so that its radial scan velocity is proportional to V 0  sin α. This has the effect of delaying the instantaneous radial position of the scanning beam of the camera 13 with respect to that of the display monitor 14 to produce a slant range distorted display, objects of equal slant range but different plan range being displayed at the same instant (Fig. 2, not shown). In order to simulate clearance plane operation, a switch 56 is closed to apply to blanking signal to the video amplifier 26 during each line scan period when the instantaneous amplitude of the radial timebase applied to the camera tube 13 exceeds a value h cl tan α(h cl  = perpendicular distance of the clearance plane below the aircraft, Fig. 3, not shown) as determined by a voltage comparator 55. The blanking may alternatively be applied to the camera 13 or the display monitor 14.