GB438568A - Improvements in or relating to radio receiving systems - Google Patents

Abstract

438,568. Wireless signalling. LORENZ AKT.-GES., C., 1, Lorenzweg, Tempelhof, Berlin. April 12, 1935, Nos. 11443, 11444, and 11445. Convention dates, April 18, 1934 and June 7, 1934. [Class 40 (v)] Relates to sys tems particularly for direction finding in which the reflected space - wave component of a signal is eliminated at the receiver so that the indication is given wholly by the ground wave. According to the invention the anode voltage on the output valve R, Figs. 1 and 3, is discharged by the groundwave impulse J, through a condenser C which then recharges slowly through a resistance W in accordance with the dotted-line curve S, so that the valve is nonconductive to the subsequent reflected impulses D. In order further to lessen the chance of interference from "reflected" signals, each signal element is split up into individual impulses with intervening spaces. For telegraphic signalling the valve is similarly made responsive only to the square-topped voltage impulse B, Fig. 3, corresponding to the time AT, the subsequent " irregularities " R due to the space-wave component being ineffective. The signals are recorded on an impulse voltmeter. In a directive A-N system in which the frame aerial is periodically reversed in polarity, a reversing switch is used to short-circuit the condenser C during the change-over, so as to ensure that it is fully discharged prior to receiving the next signal. Specification 381,856 is referred to.