The present status of Clean PAL systems

The various approaches to realizing a Clean PAL color television system, which luminance and chrominance interact minimally, are reviewed. Attention is focused on the Weston Clean PAL system which offers the possibility of simultaneous luminance and chrominance transmission while retaining the optimum spectral distribution for each. Starting with the original proposal, based on single line delay filters, it is shown how the system can be refined using more complex filters or enhanced, using an auxiliary signal to carry the lost information. The relationship with MAC was also discussed. It is shown that, using the most complex filters, a vertical chrominance performance superior to MAC is obtainable.