Abstract: A Viterbi decoder comprises a COFDM modulator, depuncture unit, a branch metrics unit an add-compare-select unit, memory, a best path unit, an error unit and a sequential controller for controlling the operation of the other units. The add-compare-select unit processes path metrics for pairs of states in parallel using a pipeline architecture. The add-compare-select unit also processes path data for pairs of states in parallel using a pipeline architecture. The best path select unit identifies the lowest cost surviving path which is in one frame and outputs a path data bit, produced a predetermined number of frames earlier, as decoded data.

Abstract: A method of controlling the colour balance of a video signal which comprises green, red and blue channel singals. Pixels are identified which have a green intensity within a peak intensity band. For these pixels, the red and blue intensities are examined to identify pixel subsets which are within respective red and blue peak bands. If the red and or blue peak bands are greater than the green peak band the gain of the red and/or blue channel(s) is increased. If the red and/or blue peak bands are lower than the green peak band, red and/or blue peak bands are determined for the entire video frame and are compared with the green peak band. If the red and/or blue peak bands for the entire frame are lower than that for the green channel, the gain of the red and/or blue channel(s) is increased.