| 摘要 |
PURPOSE:To obtain a ciphered television signal, by inverting the synchronizing signal on a basis of the pedestal to expand it higher than video components and by leaving only one horizontal synchronizing signal for plural lines as it is. CONSTITUTION:The composite synchronizing signal is separated from the video signal from terminal 1 by synchronizing separating circuit 2. Meanwhile, vertical synchronizing signal separating circuit 3 is driven by the compositie synchronizing signal to obtain the vertical synchronizing signal, and synchronizing signal generator 4 is driven by this signal. Simultaneously, the continuous wave of a period euqal to that of the horizontal synchronizing signal is generated by period equalizing circuit 5. For these signals, synchronization is held by PLL 7. The horizontal driving signal and the verrical driving signal are given to switching signal generator 8, and the switching signal from generator 8 is suplied to synchronizing signal generator 9 for scramble to generate the synchronizing signal of one-integer of the horizontal driving signal, thereby ciphering the video signal in video switch 10. |
