| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a system adaptation possible to a reliable decoder with high security and concealment at low cost by coupling the residual part of a chromaticity signal adding required longitudinal details and a luminance signal. SOLUTION: An analog chromaticity signal and an analog luminance signal are respectively and digitally read from buffers 84 and 82. A read clock signal is given to a double-balanced modulating circuit of a heterodyne circuit 100 through the use of a read clock signal from PLL 92 having the same wobble as that of the chromaticity signal. When difference occurs in the two signals, the wobble in the read clocks signal is subtracted from the wobble of the chromaticity signal and, in result, the phase of the chromaticity signal is stabilized without being affected by an envelope. The whole signals are coupled in a video signal adder 102 and a composite video signal having a longitudinal fly- back period, which is inserted between normal time is re-generated.</p> |
