| 摘要 |
PURPOSE:To prevent wire tapping caused by an illegal descrambler and to obtain satisfactorily reproduced images at a legal descrambler by executing a processing to shift horizontal synchronizing signals with the passage of time. CONSTITUTION:A scrambler 200 converts a TV signal (a) from a video source equipment 100 into a digital signal Da at a prescribed sampling frequency and outputs the signal to a RAM 7. The RAM 7 stores digital data for two scan lines according to a write signal WCLK of a synchronizing generation circuit 10 and outputs stored information MDa according to a read clock RCLK. In that case, a scramble processing is executed. A TV signal (c) is transmitted through a D/A converter 8. A synchronizing separator circuit 9 separates horizontal and vertical synchronizing signals, transmits them to the synchronizing generation circuit 10, generates a write/reset signal and a read/reset signal and controls synchronizing for writing the signal Da and reading the information MDa. The 1H time of the horizontal synchronizing signal is extended for every alphatime and when accumulated shift time exceeds the time of 1H line, video signals for the 1H line are erased and scrambled. |
