GB515360A - Improvements in or relating to television or other signal transmission systems - Google Patents

Abstract

515,360. Television. BLUMLEIN, A. D. May 30, 1938, No. 16080. [Class 40 (iii)] Auxiliary signals 2, which annul the difference between a recurrent reference amplitude (e.g. interruptions) and a related datum level (e.g. black), are added to television or like signals 1 prior to a point where the datum level is established so that the stabilization of the datum level is independent of changes in the gain of the signal channel prior to the point of stabilization. The television signals are generated by a cathode-ray scanner, the beam of which is periodically cut off by black-out pulses to introduce the interruptions, and the auxiliary signals are derived from the source of black-out pulses or from the beam current of the scanner by a resistance in the cathode lead, Fig. 2 (not shown). The auxiliary signal is added by a valve 4 in parallel with an amplifier 3 prior to a gain-controlling stage 5. The amplitude of a further auxiliary signal, which is added to the television signals to correct spurious signals such as "tilt" after the stabilization of the datum level, is controlled in a valve 8 simultaneously with the control of the television signals so that the correction of tilt is independent of the gain of the signalling channel. Specifications 442,666, 449,242, 462,110 and 490,845 are referred to.