HIGH EFFICIENCY CODING SYSTEM

PURPOSE:To prevent picture quality from being deteriorated and to improve the quality by transmitting the amplitude and phase of a chrominance subcarrier. CONSTITUTION:A timing signal generator 2 generates a clock pulse corresponding to four times the frequency of a chrominance subcarrier from an input analog signal. The clock pulse is converted into a digital signal by an A/D converter 1. The chrominance subcarrier is separated from the digital signal through a BPF 3 and a sampling point corresponding to each sampling point is obtained. A maximum value Ec(q) and a phase phi(q) are calculated by an arithmetic circuit 5 based upon the sampling value. On the other hand, the output of the BPF 3 is subtracted from a composite television(TV) signal by a subtractor 4 to obtain a brightness signal component from which the chrominance subcarrier component is removed and the brightness signal components and the found values Ec(q), phi(q) are collected and blocked in each fixed sampling number in horizontal and vertical directions. The numerical expression and positioning of these signals are adjusted so as to be easily converted in the succeeding conversion processing and then converted into coefficients by a discrete cosine conversion circuit 7. The converted coefficients are properly coded by a coding circuit 8 and then transmitted. On the receiving side, the original composite TV signal is decoded in the reversed order of the processing.