GB638568A - Colour television system - Google Patents

Abstract

638,568. Television. RADIO CORPORATION OF AMERICA. July 21, 1947, No. 19485. Convention date, Jan. 28, 1942. [Class 40 (iii)] In a colour television system in which separate groups of equal band-width signals representative of a plurality of primary colour images are simultaneously generated means are provided for shifting the frequency range of the group of generated signals and for transmitting simultaneously all the groups of signals so that the groups occupy contiguous but separate frequency ranges. The invention is described in connection with a three-colour television system in which green, blue and red colour selection image signal groups generated by picture signal generating tubes 19, 21, 23 are applied to a transmitter 154 over three separate paths in two of which (e.g. red and blue) frequency changing means 39, 41 and 48, 50 are included for shifting the position of the red and blue signal groups so that in the signal applied to the transmitter all three colour signal groups occupy contiguous ranges. To reduce the total band widths of the transmitted signal the band width of the red and blue signal groups may be reduced by up to 40 per cent by including appropriate means such as filters 38, 47 in the red and blue signal channels. It is stated that a reduction of this order in the band widths of the red and blue channels does not produce any noticeable change in definition.