Abstract: An assembler and splitter of a Weston PAL (W-PAL) video signal has filter functions F.sub.1, F.sub.2 at the assembler for the luminance and chrominance components and corresponding functions F.sub.3, F.sub.4 at the splitter. The transfer functions are defined as F.sub.1 =(L.sub.2 +L.sub.1)/2+(L.sub.2 -L.sub.1)z-.sup.1 /2, F.sub.2 =-(H.sub.1 -H.sub.2)/2+(H.sub.1 +H.sub.2)z.sup.-1 /2, F.sub.3 =(L2-L.sub.1)/2+(L.sub.2 +L.sub.1)z.sup.-1 /2, F.sub.4 =(H.sub.1 +H2)/2-(H.sub.1 -H.sub.2)z.sup.-1 /2 and wherein H.sub.1 (f)=L.sub.2 (2fsc-f) and H.sub.2 (f)=L.sub.1 (2fsc-f). Thus the filters are non-sharp cut and are compatible with normal PAL.

Abstract: A video signal is coded for transmission in a restricted bandwidth by sub-dividing a frame of picture information into a set of constituent blocks, measuring the amount of picture activity in each block, sampling the information in each block at a rate related to the amount of picture activity in that block, and adding to the coded block a supplementary signal indicating the sampling rate used for the block. Thus a decision is made on a block-by-block basis as to whether the block is transmitted with full accuracy or whether it can be adequately reconstructed from the previous frames.