GB363403A - Distributors for telegraphy or the like - Google Patents

Abstract

363,403. Multiplex telegraphy. STANDARD TELEPHONES & CABLES, Ltd. and SANDEMAN, E. K., Columbia House, Aldwych, London. Sept. 18, 1930, No. 27891. [Classes 40 (iii) and 40 (v).] In a valve distributer for telegraphy and the like, each signal contact or time interval allotted to a signal element, is associated with a single valve, and the valves are sequentially rendered effective, to transmit the signal code elements set up, by a plurality of biasing waves fed simultaneously to each of the valves of the distributer. As shown in Fig. 1, biasing waves alpha1, alpha2, #1, #2 .. of frequencies dependent upon the number of letters set up per second on the contacts K of the transmitters P1, P2 .. are applied simultaneously to the grids of the valves Al, A2, A3 ... The waves alpha1, #1, gamma1, #1 and alpha2, #2, gamma2, #2 correspond in frequency, but differ in phase by 180‹ and are applied to the inputs of the valves so that a resultant wave of the form indicated in Fig. 2 is applied to the first valve during a cycle of sixteen time intervals as shown. The valve Al is biased so that it is made operative only during the first time interval to transmit to the line L a signal impulse from an a-c source C, if the associated contact K1 is closed. The biasing waves are fed to the valves so that in effect a resultant wave of the general form shown in Fig. 2, but displaced in phase by one time interval for each successive valve, is applied to the sequence of valves. Fig. 4 shows the circuit arrangements for the valve A1 in which the waves alpha1, #1, gamma1, #1 are applied through condensers 11 .. 14 and resistances 41 .. 44 respectively to the grid of the valve. Band pass filters F11.. , F21 .. F31 .., F41 .. passing the frequencies alpha1, #1, gamma1, #1 respectively are included to prevent the paralysing waves supplied to any valve from passing along the paths by which the waves are applied to other valves, and so appearing at the input of valves for which they are not intended. At the receiving end, a similar valve arrangement is provided, the valves being made operative in successive time intervals. The receiving printer relays included in the output circuits of the valves are operated only when a signal impulse is received during the time element corresponding to the valve in operation. Synchronism is maintained between the two ends by transmitting a wave alpha, from which the #, gamma and # waves at the two stations are derived. Specifications 344,444 and 348,543 are referred to.