GB526658A - Improvements in or relating to apparatus for indicating the position of objects emitting or reflecting radio beams - Google Patents

Abstract

526,658. Locating objects by reflected waves. SPERRY GYROSCOPE CO. March 24, 1939, No. 9294. Convention date, April 13, 1938. Addition to 501,996. [Class 37] [Also in Group XL] Relates to means for locating the position of a distant transmitter (or of an invisible object capable of reflecting wireless waves) by scanning the field of exploration both horizontally and vertically, and correlating the received signals on the fluorescent screen of a cathode ray tube. The invention consists in replacing the two sets of rotating aerials described in the parent Specification by two sets of fixed aerials, which are arranged to produce a rotating lobe of maximum signal strength. In Fig. 1 the stationary aerials 3, 4, 5,. 6, mounted about a centre reflector 7, are used to make a horizontal scan at "framing" frequency, whilst the second aerial system 8 ...12 gives a vertical scan at " line " frequency. One pair of dipoles 6. 4 is connected to amplifiers 15, 16, the other pair of dipoles 3, 5 being coupled to amplifiers 17, 18. The grid bias on each amplifier is varied cyclically by voltages derived from the field-windings 33, 34 of a local generator with a rotor 30 which is driven from a motor 31. The result is that a rotating lobe of maximum signal strength is applied to a gas discharge tube 24. A third field-winding 35 supplies control voltages to one pair of the deflecting-plates of the cathode ray tube 37. A second aerial system 8 ...12 is similarly coupled to amplifiers 15<1> ... 18<1>, and a generator 28<1>, and applies a lobe of maximum signal strength at " line " frequency to the discharge tube 24. Cams 47, 48 ensure that only the forward half of each scanning cycle is effective. The arrangement is such that no electron stream flows through the cathode ray tube until the maximum lobe from both sets of aerials coincides with the direction of the object being scanned. At that moment, a spot of light is produced on the fluorescent screen 52 at a point which indicates the position of the distant object. When used by two aeroplanes in the air, danger of collision is avoided by keeping the position-indicating spot 54, Fig. 2, out of the centre circle 55. An auxiliary transmitter 60, Fig. 1, may be used to radiate waves which are reflected from the invisible object, when the invention is used for " spotting " or gun-fire control from the ground.