Patent GB-230462-A (GB)
Title: Electro-magnetic, acoustic, or like means for indicating navigable channels for ships
IPC: G01S1/02
Filed: 1925-03-04
Abstract: 230,462. Soc. Industrielle des ProcÚdes W. A. Loth. March 7, 1924, [Convention date]. Bearings, determining; leader gear for assisting navigation; thermionic amplifiers and detectors.-The navigator of a ship is enabled to ascertain his position in relation to a navigable channel N by comparing the times at which signals are received or are interrupted from stations A, A<1>, A<2>, which transmit beams of luminous, wireless or acoustic waves rotating at angular speeds so varied that when signals from two given stations are received simultaneously the ship is known to be on the required channel. The channels thus marked out may lead up to the forked ends E of leader-gear, and the receiving apparatus may be combined with means for detecting leader-gear signals. The correctness of the relative timing of the signals is checked by control stations B, fitted up as receiving stations. The transmitting stations are distinguished by the wave-length or by the modulation frequency of the signals they emit. By observing which of two such signals is heard first it is possible to determine on which side of the course the ship has erred; and to facilitate this determination the station A may change its wavelength or other characteristic to that of the station A<2>, and vice versa, when the beams cross the line A<1>, A<2>. The distance by which a ship has erred may be determined by observing the time-interval between the receipt of the signals from two stations and the absolute speeds of rotation may be such that at all points along the course a given time interval denotes the same degree of error. The wave-length or modulation frequency of the signals may vary from point to point of the course so as to indicate distances from the starting point. Several courses may be marked out by signals having different characteristics, and the points where courses cross may be indicated by special signals. The timecontrol mechanisms may be synchronised from time to time by the interchange of special signals. Wireless directional transmitters. The rotating beam may be furnished by a frame comprising an endless insulated winding 1, Fig. 3. on a fixed cylinder and pairs of insulated brushes 2 arranged on radial arms at angles less than 180‹ and adapted to be rotated simultaneously at variable speeds. The brushes make contact with bared portions of the winding 1 or with contacts connected thereto. The two pairs of brushes are respectively coupled to different oscillating circuits 3, 3, and the maximum intensity of radiations occurs along the bisector of the angle between the brushes. Wireless receivers combined with leader gear circuits. Fig. 6 is a diagram of multiplex receiving apparatus carried by the ship. Signals having different wave-lengths are selected by differently tuned circuits which by means of the switches 12 - - 18 can be connected in any combination to the amplifier-detector system 10, 11, 7, 8, the resulting notes being picked up by telephones 26 bridged across audio-frequency tuned circuits 27. The two high-frequency transformers 21, 22, and low-frequency transformers 23, 24, 25, can be connected in any required combination by means of the switches shown. The leader-gear audio-frequency detector frames 20 can also be put in circuit by means of of the switch 19. Alternatively two differently tuned aerials may be connected through detectoramplifier apparatus to the two telephones of a head-set, means for putting in circuit the leadergear detectors being also provided.