GB574676A - Improvements in arrangements for locating objects by electromagnetic waves - Google Patents

Abstract

574,676. Radiolocation systems. STANDARD TELEPHONES & CABLES, Ltd. April 28, 1942, No. 5720. Convention date, March 13, 1941. [Class 40 (v)] A system for locating objects comprises means for determining the distance of the object from a reference point by reflected electromagnetic waves, means for determining the direction of the object from the reference point, and a cathode-ray oscillograph, the beam of which is intermittently deflected to a position at which it indicates the distance, and from this position is further deflected in a radial direction corresponding to the direction of the object. Fig. 2 shows a system which may be carried on an aircraft and comprising four directional antennµ having reception patterns directed respectively upwardly, downwardly, to the right, and to the left, of the line of flight of the aircraft, which receive pulses generated by a transmitter 11, radiated by an antenna 12 and reflected from the object to be located. The energy difference of the signals received by the " Up " and " Down " antennµ is applied by a network 13 to a receiver 15 which applies a corresponding deflection potential between the vertical deflection plates 7, 8 of a cathode-ray indicator. Similarly, by way of a network 16 and receiver 18, a deflection potential corresponding to the difference of energy of the signals reaching the " Left " and " Right " antennµ is applied between the horizontal deflection plates. The beam as a result is deflected in a radial direction indicating the general direction of the object in relation to the line of flight. Thus, the trace 22 in Fig. 3 indicates an object below and to the right of the line of flight. The distance indications are obtained by scanning the beam by a time-base generator 30 synchronized with the pulse generator 11 and by applying to a brightness control grid, by way of the networks 13, 16 and a receiver 19, signals representing the sum of the energies received by the four antennµ from the reflected pulses. This produces a spot indicating the distance on a linear distancescale, shown as vertical in Fig. 3. The application to the deflecting plates of the potentials is delayed, so that it occurs only during a latter portion of the time during which the beam exists. In consequence, a spot is first formed on the vertical scale representing the distance of the object, and the linear trace such as 22 extending from it and representing the direction is formed subsequently. The four indications shown in Fig. 3 are such as would be obtained in succession when flying towards a reflecting object and correcting the line of flight by reference to them.