Patent GB-601255-A (GB)
Title: Position indication systems
IPC: G01S13/91
Filed: 1945-04-20
Abstract: 601,255. Indicating systems for showing positions of aircraft. STANDARD TELEPHONES & CABLES, Ltd. April 20, 1945, No. 10026. Convention date, April 28, 1944. [Class 40 (i)] In a system for displaying continuously the positions of aircraft in relation to a flying lane or airfield, each aircraft signals its identity, direction, distance and altitude to a cathode-ray indicator and an operator displays this information to a controller on a three-dimensional display field in which each aircraft is represented by a luminous dot. To facilitate this operation, the lamps of the display field are energized in parallel with lamps in a local twodimensional field which the operator sees more or less superimposed on the cathode-ray indicator. Since the aircraft are assumed to be flying in predetermined paths, e.g. in approach lanes or circling the airfleld, the operator after selecting an appropriate display lamp initially, arranges for the successive illumination of subsequent lamps automatically at a speed appropriate to that of the aircraft concerned. Three-dimensional lamp indicator. In the case of landing control, the approach and departure and a perimeter circle are marked by a series of vertical display elements 81 as shown in Fig. 5. These elements are, as shown in Fig. 6, formed from a bundle of rods of plastic material bent over at different heights and having their other ends associated with individual lamps. In the case of traffic control, the display corresponds to the lanes between several airfields. Control of cathode-ray tube indicators. In the case of traffic control, some of the channels of a multiplex transmission system of the type in which each channel is associated in turn with an ultra high-frequency radio transmitter and receiver are used for the transmission of pulses which initiate the transmission from the aircraft of pairs of pulses and for the reception of such pairs. The first pulse in each pair is sent back immediately and so gives an indication of the distance, via a repeater tower, of the craft. The second pulse is arbitrarily delayed in accordance with the altitude of the craft. The resulting display consists of a pair of luminous dots on a horizontal scale as at 128, Fig. 9. The dots are modulated in brightness in accordance with the identification code of the aircraft, the position dot being bright while the altitude dot is dark. The indicator for landing control is similarly controlled except that the reply pulse from the aircraft is initiated by the reception of a signal from a rotary beacon (not shown) synchronized with a rotary receiving system 61 and with rotary deflection windings 70 on the indicators. These windings are fed with saw-tooth current and the resulting display consists of a pair of groups of dots such as 103 indicating the direction and distance of the craft and separated by a distance representing its altitude. Control of three-dimensional and checking displays. By means of uniselectors, a set of which is provided for each aircraft &c, the circuits of which are not described, the operator selects a row of lamps 104, Figs. 8, 10 or 127, Fig. 9, in the checking display, corresponding to the position of the aircraft and a lamp in the row corresponding to its height. He then sets the row-selecting switch running at a speed corresponding to that of the aircraft and as each row is selected the lamp corresponding to the height is selected automatically by means not shown. To facilitate the initial selection and to check the correctness of the automatic operation, the checking display is more or less superposed on the cathode-ray tube display in a viewing screen, as shown in Figs. 8 and 9, both displays having graduations to facilitate comparison. The lamps of the three-dimensional display are connected in parallel with the checking lamps. Both sets of lamps are caused to flash with the code of the aircraft that they represent. Telephone communication. The operator controlling the display has a number of telephone jacks and calling lamps for communicating with the traffic controller for whose benefit the three-dimensional display is set up and who also has telephone jacks for communication with the operators. It is stated that contact between the telephone plug and each sleeve of the latter jacks may be made to extinguish a corresponding one of the lamps in the display, so that when the plug is inserted, communication is established with the particular operator controlling that lamp. A particular calling lamp will light before that operates and indicate which aircraft is under consideration. Specifications 10723/45 as open to inspection under Sect. 91 and 595,022, [Group XL], are referred to.