Compatible enhancement of terrestrial PAL TV transmission

The BBC has been investigating the possibilities for the compatible enhancement of terrestrial PAL transmission towards high definition television. The investigation is essentially divided into three tasks: (1) minimising the artifacts introduced by composite coding to give the appearance of a component picture; (2) devising means of conveying additional information which will enable suitably equipped receivers to reproduce a picture subjectively as close as possible to an HDTV studio source e.g. 1250 lines interlaced, 50 Hz field frequency, 1920 pixels per line, and 16:9 aspect ratio; (3) carrying out (1) and (2) within the constraints of the current UHF frequency plan and in a way compatible with existing PAL receivers. The authors discuss the techniques involved in the investigation and the results obtained