Colour television studio equipment and problems

The paper outlines the nature of a studio complex and the problems which arise from the introduction of colour television beginning with those associated with the colour separation signals. Special reference is made to the problems arising from the use of four-tube colour cameras particularly from the point of view of monitoring their outputs as well as the methods of coding to ensure accurate colour reproduction on commercial receivers. In a studio using the PAL system of colour television certain extra pulses are required for use with the coders and the generation and distribution of these pulses is discussed. The problems arising in the coding process are dealt with and in particular special consideration is given to the problems due to the colour axis switching feature of the PAL system. The effect of the axis switching on the increased precision needed in the quadrature between the two axes is also considered as well as its effect on the crosstalk problems. The design of a practical operational coder is outlined with particular reference to the problems of carrier balance and the effect of the axis switching on this parameter. The effect of colour on the mixing equipment is considered and particular reference is made to the problem of burst-stabilization during the operation of the fader controls. The subject of special effects is also discussed including the production of synthetic colour captions from black and white originals. The synchronization of the various sources at the mixer is considered in outline in so far as it affects the mixer. The design of a suitable decoder for use with colour picture monitors in a colour studio is outlined and also the general arrangements for colour picture monitoring. The requirements of a signal distribution system within a studio complex are discussed with reference to such parameters as differential gain and chrominance luminance delay. Finally, the paper considers the method of line-up necessary to ensure that coding, - decoding and monitoring equipment is working correctly. In particular, a method is outlined whereby coding equipment can be completely set up using an oscilloscope to monitor the output of a coder.