GB146122A - Improvements in and relating to telegraphic reception - Google Patents

Abstract

146,122. Siemens & Halske Akt.-Ges. Sept. 27, 1918, [Convention date]. Receiving systems and apparatus.-The receiving or repeating system of a code telegraph system comprises a relay which amplifies sufficiently the dot impulses of small amplitude due to line inertia and limits the dash impulses of larger amplitude. A valve amplifier, an amplifier with a current limiting device, or a magnetomicrophonic relay with abutments may be employed. Transmitted impulses of the form shown at I, Fig. 1, and received in the form shown at II<a> would normally be amplified to a form shown in broken lines at III. By employing a valve amplifying arrangement shown in Fig. 2, the amplified impulses take the form shown in full lines at III, Fig. 1. The grid circuit of the valve contains a resistance r and a polarizing-battery b, and the receiver R is placed directly in the anode circuit. In a modification, the anode circuit contains a resistance shunted by a capacity and the receiver R, in order that the receiver may be influenced by changes of potential in the anode circuit, and is not normally energized. In further modifications, the amplifier is connected to line through a transformer, or capacities are placed between the lines and the resistance r, and these arrangements are employed when the received impulses take the form shown at II<b>, Fig. 1. In the modification shown in Fig. 6, the anode circuit of the valve V is coupled to the grid-filament circuit of a second valve V<2> through a condenser K<1>. The valve V<1> is arranged to amplify fully all the received impulses, but the time constants of the resistances R', R<2> are such that the amplification of the larger impulses, by the valve V<2>, is limited.