| 摘要 |
PURPOSE:To avoid easy detection of picture signals and to keep satisfactorily the privacy with a system where the variation amount of a certain time difference from the picture signal, by controlling optionally said time difference. CONSTITUTION:A horizontal/vertical synchronizing signal detecting part 1 detects both horizontal and vertical synchronizing signals for some of the picture signals applied to an input terminal 5. A delay time control circuit 2 detects the order of the input horizontal synchronizing signal based on the vertical synchronizing signal. While the delay amount of a variable delay circuit 3 is previously decided in response to each horizontal synchronizing signal, and the circuit 3 is controlled to obtain the prescribed delay time. The rest picture signals supplied to the terminal 5 receive the delay from the circuit 3 and are supplied to another terminal of a differential amplification part 4 to be scrambled and delivered through a terminal 6 after the difference calculated from the picture signals supplied directly. At the reception side some of the reception signals supplied to a terminal 13 undergoes detection for both horizontal and vertical synchronizing signals through a horizontal/vertical synchronizing signal detecting part 7. Then the control exactly equal to the transmission side is given to a variable delay circuit 10 by means of said detected horizontal and vertical synchronizing signals. |
