GB1199801A - Improvements in or relating to Colour Television Transmission - Google Patents

Abstract

1,199,801. Colour television. MARCONI CO. Ltd. 5 Jan., 1968 [13 March, 1967], No. 11607/67. Heading H4F. In colour television transmitting apparatus comprising three colour signal camera tubes producing signals E R , EG and E B and a high definition luminance camera tube producing signal E Y , the invention relates to correction for the vertical component of aperture distortion in the luminance signal which does not require a delay line in the direct channel between the input and output terminals (L1 and L0, Fig. 3) of the luminance signal. In a first embodiment, Fig. 3, scanning rasters in the colour tubes are advanced relative to the scanning raster in the luminance tube by one scanning line and the resulting colour signals are delayed by one scanning line interval (delay lines RD, GD and BD) between their input and output terminals. The undelayed colour signals are combined in matrix M to produce a component correction or synthetic luminance signal Ey s comprising 0À3 E R +0À59 E G +0À11 E B , which is added A1 to the luminance signal E y at input terminal L1 after it has been delayed LD for one scanning line interval. The output of adder A1 is reversed in polarity by inverter P and added A2 to the luminance signal E y . The amplitude of the output from adder A2 is adjusted by an adjusting control represented by resistance AR and added A3 to the luminance signal E Y , the resulting luminance signal at output L0 being corrected for the vertical component of aperture distortion. In a second embodiment, Fig. 4 (not shown), both inputs to adder A1 are taken from matrix M, one input being taken thereto directly as in Fig. 3, and the second input being taken via a delay line (2LD) providing a delay of twice the scanning line period. This. second input replaces the input from L1 in Fig. 3. The adder A2 may be dispensed with so long as the control (represented by AR) for adjusting the amplitude of the correcting signal is ganged with a control for adjusting the amplitude of the undelayed luminance signal applied to adder A3. In a third embodiment, Fig. 5 (not shown), the low definition green signal is used instead of the low definition luminance signal (E YS ) and the green signal alone is delayed before transmission since only the scanning raster in the green colour tube is advanced by one line. In a fourth embodiment, Fig. 6 (not shown), the colour signals may be processed in accordance with a television system, e.g. NTSC, PAL or SECAM (Trade Mark) to produce a modulated colour sub-carrier which is delayed by a single delay device before transmission, the arrangement being otherwise as shown in Fig. 3.