Patent GB-779473-A (GB)
Abstract: 779,473. Air traffic supervision; electric selective signalling systems. HUBER, J. July 5, 1955 [July 6, 1954], No. 19385/55. Classes 40 (1) and 118 (2). An arrangement for determining, transmitting and evaluating signals concerning aircraft location comprises an observation and distance indicating apparatus having a pointer slidable over a map and a device for initiating electrical impulses dependent upon the position of the pointer at the moment of initiation, and further means for the automatic conversion of the electrical impulses into a visual indication at a central receiving point. A telescope sighting means (Fig. 2, not shown) is pivotally mounted over a map 8 and controls a pointer 9 which is also coupled to a distance-estimating device (Fig. 3, not shown) built into the telescope such that its end indicates on the map 8 the estimated position of an observed aircraft. On operation of a trigger the pointer 9 is mechanically depressed and feeds positive electric supply to co-ordinate cross-wires on the map-in the example shown, to wires 2 and 6. At the same time it closes switch 45 to energize solenoid 22 which attracts pawl 25 and energizes solenoid 47 to break the original circuit at 46. Spring 23 returns pawl 25 which rotates ratchet wheel 24 one tooth and opens the circuit of solenoid 47 at 49. Thus a drum switch comprising discs 27, 28 to 29, 30 (shown developed) is rotated step-bystep about axis 21 until brush 34 (fed from pointer 9) makes contact on disc 28 to energize solenoid 44. This stops further rotation of the drum by opening contacts 48. The drum thus rotates a number of steps corresponding to the horizontal co-ordinate indicated by pointer 9, and in doing so transmits to line 70 a corresponding number of impulses by virtue of brush 38 and contacts 32 on the disc 30. The solenoid 44 also closes contacts 52 to energize a relay Z1 which after a suitable time delay energizes a solenoid 53 to step another drum switch which sends out impulses over line 70 from disc 64 in accordance with the vertical co-ordinate indicated by pointer 9. It is stopped when solenoid 68 opens contacts 69. Contacts 71 are simultaneously closed and energize relay Z2 which after a time delay applies negative supply to solenoid 53 such that the drum switch homes to the position shown, where brush 65 is disconnected from positive supply of disc 63. When pointer 9 is moved out of contact with map 8 solenoid 44 is de-energized and makes contacts 48 so that the first drum switch homes until brush 42 finds gap 51 in disc 40. The impulses transmitted over line 70 are fed to a control centre where a lamp is lit on a display map by means known in communication technique and basically similar to that described for producing the impulses. The signals may be further relayed to a larger map covering the area supervized by several observation posts. Means for automatically extinguishing the optical display after a preset time (in order to display later information) may comprise a capacitor circuit whose time-constant may be varied by a control lever (Fig. 6, not shown) to suit the degree of aircraft activity. Additional information may be conveyed by telephone or may be centrally displayed by a television system.