Abstract: A composite digital video signal encoder comprises crosstalk measuring filters for measuring crosstalk between luminance and chrominance components of a composite digital video signal, a vertical comb filter and a vertical/temporal filter each operative to separate one of the luminance and chrominance components from the composite signal, a mixer for mixing output signals produced by the vertical and vertical/temporal filters, and a mixer control means responsive to the measured crosstalk to control the mixing ratio of the mixer in a sense to reduce cross effects in the mixed output signal resulting from the crosstalk.

Abstract: A digital PAL color television signal demodulator for demodulating the U and V color component signals from an input chrominance signal derived from a PAL color television signal which has been digitized by being sampled a predetermined number of times per horizontal line comprises a first memory storing values representing the phases of the sub-carrier signal, on which the U and V color component signals have been modulated, at the first sample position of each of the successive lines of four fields of the television signal, a second memory storing values representing the relative phases of successive sample positions along a horizontal line, means for deriving from the memories values representing the phases of successive sample positions of each of the successive samples in eight fields of the television signal, means to derive from the values derived from the memories quadrature amplitude values of the sub-carrier in synchronism with a sample frequency of the input chrominance signal, and multipliers and

Abstract: A method of detecting and correcting errors in digital audio signals comprises assembling digital data words each of which corresponds to a digital audio signal representing an analog audio sample into units of six data words, assembling with each unit six redundant words derived by exclusive-OR operations on the data word in each row and each column of the unit, assembling the data words and redundant words into sub-blocks and adding cyclic redundancy check code words to the sub-block, recording and reproducing each sub-block, after reproduction using the code words of each sub-block to set the logic state of error flags that have been added to each word in the sub-block, re-forming the units and assembling with each reproduced unit horizontal and vertical syndromes derived by exclusive-OR operations on the data words and redundant words in each row in each column of the unit, comparing the horizontal and vertical syndromes and resetting the logic state of the error flags in dependence on this comparison, de