| 摘要 |
PURPOSE:To enhance the effect of privacy picture by adding a scramble signal with a random waveform to a picture signal at the sender side thereby disabling the receiver side to eliminate the scramble signal for interception. CONSTITUTION:A scramble signal generator 1 at the sender side generates a scramble signal S. A picture signal V is added to the scramble signal S by an adder circuit 2 and the resulting signal is a scrambled picture signal (V+S). The signal (V+S) is sent to a V (for picture) modulation circuit 3 and sent through a scramble picture channel. On the other hand, the scramble signal S is fed to an S (for scramble) modulation circuit 4, where the signal is modulated and sent through a scramble channel. A V demodulation circuit 5 at the receiver side outputs the scrambled picture signal (V+S), which is given to a subtraction circuit 6. Moreover, the scramble signal S obtained from the S demodulation circuit 7 is fed to the subtraction circuit 5 via a subscriber control circuit 8. The picture signal V is decoded by the subtraction circuit 6. |
