Patent GB-356906-A (GB)
Title: Improvements in or relating to navigational guide systems
IPC: G01S1/02
Filed: 1930-08-15
Abstract: 356,906. Determining positions acoustically. HAMMOND, J. H., Hesperus Avenue, Gloucester, Massachusetts, U.S.A. Aug. 15, 1930, No. 24483. Convention date, Aug. 17, 1929. [Class 118 (ii).] To assist an aviator to land in foggy weather or in other conditions of poor visibility, wireless direction finders, which may be replaced by equivalent sound-ranging equipment, are used to ascertain the altitude and position of the machine relative to the aerodrome, and this information is transferred to a central station where it is superposed on a map of the surrounding locality. The map is then televised by wireless to the aviator so that he is able to observe on the receiving screen the progress of his craft relatively to the topography of the landing ground and its immediate surroundings. The directive aerials at the stations 21, 22, 23, Fig. 1, are originally set in the vertical plane with the windings normal to the line connecting them to the centre of the landing ground. Any subsequent movement, either in elevation or azimuth, is thereafter transmitted automatically through electric repeaters to an independent station 25, containing the television transmitter. As he approaches the aerodrome, the aviator transmits a calling signal to allow the direction finders to locate both his position and elevation. The calling signal is rapidly interrupted by means of a commutator switch to allow the subsequent television transmission to be received during the quiescent periods. The movements of the frame aerials at the points 21, 22, 23 are communicated by electric repeaters to three lamps 127, 128, 129, Fig. 4, mounted on a disc 104 forming part of the complete co-ordinating apparatus shown in Fig. 5 and located at the independent station 25. The spacing of the lamps corresponds to that of the direction finders so that the point of intersection of the three light rays follows the position of the aircraft in space. This movement is superposed on a map of the surrounding district mounted on a disc 207 located above the disc 104 and shown separately in Fig. 6. Superposition is effected by adjusting a lens 140 so as to focus on the convergence of the light rays, the lens 140 being so connected through gearing 149, 243 to a lamp 234 mounted over the map that one follows the other's movement. The altitude of the aeroplane is obtained from the vertical angles A, B, C, Fig. 1, which are automatically transferred to a known type of height finder and the corresponding figures are shown in an aperture 277, Fig. 6. The wind velocity ascertained separately is indicated in the opposite aperture 252, whilst its direction is shown by a central pointer 209. The aviator's actual course of flight is also indicated by an arrow 210, Fig. 6, controlled by a trailing arm attached to the lamp 234. An image of all the information thus assembled on the map, Fig. 6, is then radiated by a television transmitter to the aircraft where it is projected through a lens 313 on the dashboard of the aeroplane by a television receiver 318, Fig. 12, comprising a lamp 316, scanning disc 311, and a synchronizing control 323 for the motor 308. Intermittent transmission of the calling signal and reception of the televised picture is effected by a commutator aerial switch 301 driven by the motor 308 through a slip-stream generator 283. Alternatively a single strip on the televized image may be omitted by fitting an insulated break on the switch, the aviator transmitting his calling signal during this interval.