GB350454A - Improvements in or relating to electrical image translating images - Google Patents

Abstract

350,454. Television. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Gray, F. ; 243, West 101st Street, and Hefele, J. R. ; 2476, Elm Place, both in New York, U.S.A.) March 10, 1930, No. 7788. Convention date, April 30, 1929. Addition to 332,284, [Class 40 (v), Wireless signalling &c.]. [Classes 40 (iii) and 40 (v).] In a system comprising a plurality of television transmitters, Fig. 6, the frequency components of one set of signals are interleaved with, or lie between, the frequency components of another set of signals throughout a range of frequencies, which is transmitted on a single channel 100. The speeds of scanning discs 21 are so arranged that, above say 5600 cycles, the respective frequency groups, which lie close to harmonics of the corresponding linescanning frequency, are more than 200 cycles apart. All the signals from one transmitter 20 are passed through a transformer 80 to a high-quality line 100, and the signals above 5600 cycles from the second transmitter are passed to the line through a filter 140 and a transformer 141. The signals below 5600 cycles from the second transmitter are passed through a filter 130 to a low-quality line 120. Oscillators 94 produce synchronizing frequencies between the frequency groups on the two lines. At the receiver, Fig. 7, the synchronizing frequency on the line 100 is abstracted by a filter 220, and the frequencies of one set of signals are passed to a receiver 280 through filters 231 .. 235, and the frequencies of the other set of signals are passed to a second receiver through filters 236, 237, 238. Alternatively a low-pass and a high-pass filter are n parallel and the latter is followed by harmonic band-pass filters for selecting the frequencies appropriate to each receiver, Fig. 8 (not shown). According to a modification the scanning speeds are so chosen that as few as possible of the frequency components overlap, Figs. 1 and 5 (not shown), and all the signals are transmitted over a single circuit. The signals may be applied direct to each receiver, when the interfering signals appear as a moving mottled background, or the signals are separated by filters except for the interfering frequencies, or the interfering frequency bands are eliminated at the transmitter. The frequencies of one set of signals in the range in which interference occurs may be changed, for example by modulation by a carrier frequency, to a value different from, for example higher than, the frequencies of the other set of signals. The signals may correspond to two objects at the same or different stations or to the same object for stereoscopic or colour reproduction or for simultaneous transmission of separate areas. Specification 350,455 is referred to.