GB1360345A - Method of and apparatus for locating and following sound emitting objects in water - Google Patents

Abstract

1360345 Position finding systems FRIED KRUPP GmbH 28 March 1972 [24 July 1971] 14575/72 Heading H4D In the location and tracking of a sound emitter in water, acoustic location of the emitter is effected by floating buoys whose locations relative to an aircraft are determined from the aircraft. An emitter 13, such as a transponder or ship is located at one apex of a location triangle DW derived by two buoys 11, 12. The emitter location, using a reference direction N, is radioed to an aircraft 14. The latter is located at the apex of a location triangle DF including the buoys whose locations are determined from the aircraft. In one embodiment (not shown) each buoy is located by radar, enabling determination of the triangle DF. By manoeuvering the aircraft to bring the displayed triangles DF, DW into coincidence, or coded details thereof into agreement, the aircraft is brought to a position above the emitter 13. Preferably, however, and as shown the aircraft does not determine the location triangle DF by means of an active radar method, but rather effects directional reception of the location data radioed from the buoys. To this end the aircraft 14 includes a receiver having a directional aerial 34 of frame construction. Alternatively, a ferrite or dipole directional aerial can be used. In more detail, Fig. 2, signals 5 from the emitter 13 are received directionally at each buoy 11 or 12 by an acoustic-electric transducer system 21 and fed to a location evaluator 27 which transforms the signals into directional information, for example into North-related bearings # 1 , # 3 . This information can, in addition, be coded to indicate from which buoy it arises. A data transformer 28 transforms the signals which are then transmitted as radio waves from an omni-directional aerial 23. At the aircraft 14, the received signals pass to a decoder 35 and thence to a radar position display 36 which may give a display of the two triangles DF, DW to be brought into coincidence or may give a digital indication of the angles #F, #W to be made identical. In a modification, the bearing angles # 2 , # 4 of the received radio waves are determined with respect to North. Thus, upon failure of one buoy, the bearing angle of the signals from the other buoy remains as reference information to permit replacement of the failed buoy. The derivation of the North-related location data is achieved by means of a data evaluation additionally provided in the aircraft. The number of buoys used is not limited to two.