GB556567A - Improvements in radio direction finders - Google Patents

Abstract

556,567. Direction - finders. STANDARD TELEPHONES & CABLES, Ltd. (International Standard Electric Corporation). July 24, 1942, No. 10369. Drawings to Specification. [Class 40 (v)] A direction-finder using a continuously rotating aerial or search coil is provided with means for obtaining simultaneously two different diagrams on the screen of the cathode ray tube by alternating two circuits in rapid succession and with means for making one of the diagrams appear in the dotted lines by interrupting the circuit giving rise to such diagram at a frequency high compared with the frequency of alternation. The two circuits may be two receivers tuned to different transmitting stations, so that the two directions may be indicated simultaneously, Figs. 1, 2, 3 (not shown) or the two circuits may comprise circuits for receiving alternately from a directional aerial system alone or in combination with a non-directional aerial, so as to enable sense as well as direction to be determined, Figs. 4, 5 (not shown). The two circuits may be alternated by blocking valves therein alternately by two sets of square-wave pulses, and the dotted line obtained by modulating one set of pulses at a high frequency, Figs. 1 and 2 (not shown). Instead of blocking two valves alternately, two deflecting magnet systems displaced by 90 degrees and rotating round the cathoderay tube to deflect the beam may be used, the magnet systems being energized alternately by cam-controlled contacts synchronously with the switching in and out of the non-directional aerial. or by other means. Four arrangements of this kind are described, Figs. 4, 6, 7, 8 (not shown). Specification 519,351 is referred to.