GB579507A - Diversity radio-receiving system - Google Patents

Abstract

579,507. Wireless receiving systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 8, 1944, No. 8704. Convention date, May 6, 1943. [Class 40 (v)] In a diversity receiving system, antennas 1, 2, are adapted to be alternatively connected through valves 5, 6 to a receiver 9 having a detector 11 supplying an audio-frequency output over lead 12. Grid bias potentials for valves 5, 6 are supplied from a trigger circuit 13 such that when one of valves 5, 6 is conductive, the other is blocked. The trigger circuit is energized by the output of a modulator 15 supplied by a low frequency source 16. In the absence of a received signal, trigger circuit 13 is changed over at the frequency of source 16 to render valves 5, 6 alternately conducting. When a signal of sufficient strength is received on one of antennas 1, 2 an A.G.C. potential fed over line 17 blocks modulator 15 and prevents energization of trigger circuit 13 by source 16. Thus, whichever of valves 5, 6 is carrying the signal remains conducting and the other remains blocked. When this signal fades, the A.G.C. potential is reduced, so allowing source 16 to change over the trigger circuit, in which position it is locked by the increased A.G:C. potential due to the stronger signal on the other antenna. The best signal from any number of antennas may be selected by coupling them in pairs in this manner and treating the selected R.F. or I.F. outputs at 34 in the same way. Specification 537,937 and U.S.A. Specification 1,844,950 are referred to.