| 摘要 |
PURPOSE:To enable priay communication by performing DCT encoding and variable length encoding to a digital video signal and further using digital compressed video signal adding scramble. CONSTITUTION:On a transmitter side 1, a digital video signal V2 outputted from an A/D converter 10 is converted to a DCT encoded video signal V3 by a DCT encoder 11. The signal V3 is inputted to a variable length encoder 12 and a variable length encoded video signal V4 and a video frame timing signal S1 are outputted from the encoder 12. While using this signal S1, an initial value K1 is generated at an initial value generator 16, and a PN signal sequence K2 is generated from this initial value K1 and the signal S1 by a PN generator 17. At an adder 18, the signal V4 and the sequence K2 are added, and a scrambled video signal V5 is outputted. At the same time, it is converted to a ciphered PN initial value K3 by a ciphering equipment 19. Next, a video synchronizing signal is added to the signal V5 by a video synchronization adder 13 and defined as a synchronizing signal added video signal V6. The signal V6, K3 and voice signal A are synthesized and outputted by a transmission line encoder 15. |
