Patent GB-1011258-A (GB)
Title: Improvements in and relating to wired broadcasting systems
Inventor: BASS PATRICK
IPC: H04N7/10
Filed: 1962-08-01
Abstract: 1,011,258. Colour television distribution systems. R & R RESEARCH Ltd. July 25, 1963 [Aug. 1, 1962], No. 29582/62. Heading H4R. In a colour television distribution transmitter adapted to receive television signals according to the S.E.C.A.M. system, i.e. signals in which the two components of the colour information signal are transmitted alternately during successive line scan periods together with a brightness information signal, an additional colour information signal is generated by delaying the original colour information signal by one line scan period and the additional colour information signal is added to the S.E.C.A.M. signal for transmission over the distribution network to the receivers which are equipped with switching means which alternately connects the colour information signal and the delayed colour information signal to one or other of two terminals whereby the two components of the colour information signal are available continuously at the two terminals so that they may be fed, together with the brightness information, to a matrix from which the red, green, and blue components of the picture are available to feed to the C.R.T. Transmitter, Fig. 2.-The S.E.C.A.M. signal is received at terminal 20 from an aerial or line and applied to a demodulator 21 to provide video signals on line 22. The brightness and colour information signals are passed through a modulator 23, provided with a carrier in the range 2-11 Mc/s., for transmission, via the combining device 28, over the distribution network at 29. The colour information signal on line 22 is also selected by filter 25 and passed to delay device 26 where it is delayed by one line scan period after which it may either be passed direct to the combining device 28, for transmission, or it may be demodulated in 30 and remodulated to an appropriate frequency band in modulator 31 before combination with the original colour component and brightness signal in device 28. Receiver, Fig. 3.-Brightness and colour component signals from the line at 32 are selected by selective amplifier 33 and demodulated by detector 35, the brightness signals being fed to the tube 36 while the colour component signals are selected by amplifier 37 and fed to demodulator 39. Similarly the delayed colour component signals are selected by the amplifier 34 and fed to the demodulator 40. The outputs from the demodulators 40 and 41 are fed, via a switch 42 which is synchronised by the line scan pulses detected in 43, to the matrix 48, the switching being such that line 45 is switched alternately to lines 47 and 46 in successive line scan periods while line 44 is switched alternately to lines 46 and 47. The matrix combines the two colour component signals on lines 46 and 47 and produces the three signals to feed to the red, blue, and green guns of the tube 36. If at the transmitter the delayed colour component was transmitted without demodulation and remodulation, i.e. as frequency modulation of a carrier situated at the high frequency end of the brightness information video frequency band, as in the original S.E.C.A.M. signal, the modulators 40 and 41 may be omitted and F.M. demodulators inserted in lines 46 and 47, Fig. 4 (not shown).