GB332284A - Improvements in electrical transmission systems - Google Patents

Abstract

332,284. Western Electric Co., Md., (Bell Telephone Laboratories, Inc.). April 18, 1929. Television; duplex and multiplex signalling. - In television or highspeed copying-telegraphy the frequency ranges between the groups of frequencies constituting the picture signals are used for transmitting synchronizing, telegraphic, or other signals. The picture signals contain frequency bands around the linescanning frequency and its harmonics and with a width of about' 20 per cent of the line-scanning frequency, and the auxiliary signals are transmitted on frequencies approximately mid-way between the frequency bands of the picture signals. At the transmitter, Fig. 8, picture signals amplified from a. photo-electric cell 30, synchronizing current from an alternating current generator 23, and carrier-current telegraphic currents, from a key 120 are transmitted to a line 100 through a filter 90 (Figs. 10 and 11, not shown) which passes incoming telegraphic signals to a receiver 130. At the receiver, Fig. 9, the picture signals are transmitted to a lamp 270, the synchronizing signals to a motor 243 synchronized as described in Specification 292,597, and the telegraphic signals to a receiver 230, through a filter 210 (Figs. 12 and 13, not shown). Outgoing carriercurrent telegraphic signals are produced by a key 220.