GB363605A - Improvements in or relating to sending and receiving synchronised systems for television, telecinematography, telemechanical devices and other applications - Google Patents

Abstract

363,605. Synchronous movements. COMPAGNIE POUR LA FABRICATION DES COMPTEURS ET MATERIEL D'USINES A GAZ, 12, Place des Etats-Unis, Montrouge, Seine, France. May 14, 1931, No. 14291. Convention date, May 21, 1930. [Classes 40 (iii) and 40 (v).] Synchronizing signals are impressed on a carrier wave so as to alter its amplitude in a direction opposite to that produced by tele. graph, television or similar signals, Fig. 5, (not shown). Television signals are applied across a resistance R, Fig. 1, in the grid circuit of an oscillating valve 0 so as to reduce the amplitude of the current supplied to an aerial K. A commutator I on the transmitter shaft breaks the circuit of the primary P of a transformer in the plate circuit of the valve to produce a synchronizing signal of increased current in the aerial. At the receiver the voltage drop in a resistance p, Fig. 2, in the plate circuit of a detecting valve, produced by the signals, is opposed to a battery P, and in the case of the synchronizing signal is sufficiently low to permit a discharge through a neon tube L, which is in circuit with a resistance D and condenser V with values such that the natural period of the relaxation oscillation is equal to that of the synchronizing signal, as described in Specification 350,443. The synchronizing signals may be separated by a valve so biased that it does not respond to the television signals, Fig. 6 (not shown). The grid bias battery may connect the grid to a coupling resistance, Fig. 3 (not shown), or be in series with a resistance across which the signals are applied to the grid, Fig. 4 (not shown). To counteract fading, the grid bias of the valve 4, Fig. 7, responsive only to the synchronizing signals, is obtained from a resistance R, shunted by a large condenser C, in the circuit of a rectifying valve V fed from the amplified television signals through a transformer T. Alternatively the anode current of the selecting valve itself provides the grid bias by means of a resistance and condenser acting as a filter, or by several such filters in series, between the cathode and a point common to the grid and plate circuits, Fig. 8 (not shown). The valve may be indirectly heated so that the cathode can be given any desired potential. Specifications 356,506 and 356,637 also are referred to.