Abstract: A composite video signal is formed in which high luminance frequencies are modulated so that they occupy frequencies above the chrominance band. A sub-band coder is used to split the luminance frequency band into high and low frequencies at the coder, and an inverse sub-band coder combines the high-frequency luminance and the chrominance components. The two resultant signals are applied to a phase-segregated Weston Clean PAL coder to provide a composite video signal, which is compatible with a conventional PAL signal.

Abstract: An enhanced definition PAL signal (HD-PAL) may be received by a MAC receiver by decoding the signal received with a simple PAL decoder (10), time compressing the luminance and chrominance components of the decoded signal and encoding them in a MAC format (12). The MAC signal is then decoded using an HD-MAC decoder (14) and the signals are expanded by a post processor (16) prior to display.

Abstract: Encoded digital television signals having a defined bandwidth are transmitted at reduced bandwidth by regularly omitting (18) one in every n of the signal samples, where n is greater than two and is preferably three or four. At a receiver the omitted samples are regenerated by estimating (26) their values from the samples of the reduced-rate transmitted signal by making use of frequency components outside the normal defined bandwidth of the original signal. The estimation can be achieved by a symmetrical digital transversal filter of which one in every n coefficients is zero, the amplitude/frequency characteristics of the filter being unity throughout the defined bandwidth of the TV signal and antisymmetric about half the mean lower sample rate.